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This patch introduces our implementation of KAISER (Kernel Address Isolation to
have Side-channels Efficiently Removed), a kernel isolation technique to close
hardware side channels on kernel address information.
More information about the patch can be found on:
https://github.com/IAIK/KAISER
From: Richard Fellner <richard.fellner@student.tugraz.at>
From: Daniel Gruss <daniel.gruss@iaik.tugraz.at>
Subject: [RFC, PATCH] x86_64: KAISER - do not map kernel in user mode
Date: Thu, 4 May 2017 14:26:50 +0200
Link: http://marc.info/?l=linux-kernel&m=149390087310405&w=2
Kaiser-4.10-SHA1: c4b1831d44c6144d3762ccc72f0c4e71a0c713e5
To: <linux-kernel@vger.kernel.org>
To: <kernel-hardening@lists.openwall.com>
Cc: <clementine.maurice@iaik.tugraz.at>
Cc: <moritz.lipp@iaik.tugraz.at>
Cc: Michael Schwarz <michael.schwarz@iaik.tugraz.at>
Cc: Richard Fellner <richard.fellner@student.tugraz.at>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: <kirill.shutemov@linux.intel.com>
Cc: <anders.fogh@gdata-adan.de>
After several recent works [1,2,3] KASLR on x86_64 was basically
considered dead by many researchers. We have been working on an
efficient but effective fix for this problem and found that not mapping
the kernel space when running in user mode is the solution to this
problem [4] (the corresponding paper [5] will be presented at ESSoS17).
With this RFC patch we allow anybody to configure their kernel with the
flag CONFIG_KAISER to add our defense mechanism.
If there are any questions we would love to answer them.
We also appreciate any comments!
Cheers,
Daniel (+ the KAISER team from Graz University of Technology)
[1] http://www.ieee-security.org/TC/SP2013/papers/4977a191.pdf
[2] https://www.blackhat.com/docs/us-16/materials/us-16-Fogh-Using-Undocumented-CPU-Behaviour-To-See-Into-Kernel-Mode-And-Break-KASLR-In-The-Process.pdf
[3] https://www.blackhat.com/docs/us-16/materials/us-16-Jang-Breaking-Kernel-Address-Space-Layout-Randomization-KASLR-With-Intel-TSX.pdf
[4] https://github.com/IAIK/KAISER
[5] https://gruss.cc/files/kaiser.pdf
(cherry picked from Change-Id: I0eb000c33290af01fc4454ca0c701d00f1d30b1d)
Conflicts:
arch/x86/entry/entry_64.S (not in this tree)
arch/x86/kernel/entry_64.S (patched instead of that)
arch/x86/entry/entry_64_compat.S (not in this tree)
arch/x86/ia32/ia32entry.S (patched instead of that)
arch/x86/include/asm/hw_irq.h
arch/x86/include/asm/pgtable_types.h
arch/x86/include/asm/processor.h
arch/x86/kernel/irqinit.c
arch/x86/kernel/process.c
arch/x86/mm/Makefile
arch/x86/mm/pgtable.c
init/main.c
Signed-off-by: Hugh Dickins <hughd@google.com>
[bwh: Folded in the follow-up patches from Hugh:
- kaiser: merged update
- kaiser: do not set _PAGE_NX on pgd_none
- kaiser: stack map PAGE_SIZE at THREAD_SIZE-PAGE_SIZE
- kaiser: fix build and FIXME in alloc_ldt_struct()
- kaiser: KAISER depends on SMP
- kaiser: fix regs to do_nmi() ifndef CONFIG_KAISER
- kaiser: fix perf crashes
- kaiser: ENOMEM if kaiser_pagetable_walk() NULL
- kaiser: tidied up asm/kaiser.h somewhat
- kaiser: tidied up kaiser_add/remove_mapping slightly
- kaiser: kaiser_remove_mapping() move along the pgd
- kaiser: align addition to x86/mm/Makefile
- kaiser: cleanups while trying for gold link
- kaiser: name that 0x1000 KAISER_SHADOW_PGD_OFFSET
- kaiser: delete KAISER_REAL_SWITCH option
- kaiser: vmstat show NR_KAISERTABLE as nr_overhead
- kaiser: enhanced by kernel and user PCIDs
- kaiser: load_new_mm_cr3() let SWITCH_USER_CR3 flush user
- kaiser: PCID 0 for kernel and 128 for user
- kaiser: x86_cr3_pcid_noflush and x86_cr3_pcid_user
- kaiser: paranoid_entry pass cr3 need to paranoid_exit
- kaiser: _pgd_alloc() without __GFP_REPEAT to avoid stalls
- kaiser: fix unlikely error in alloc_ldt_struct()
- kaiser: drop is_atomic arg to kaiser_pagetable_walk()
Backported to 3.16:
- Add missing #include in arch/x86/mm/kaiser.c
- Use variable PEBS buffer size since we have "perf/x86/intel: Use PAGE_SIZE
for PEBS buffer size on Core2"
- Renumber X86_FEATURE_INVPCID_SINGLE to avoid collision
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 8efd755ac2fe262d4c8d5c9bbe054bb67dae93da upstream.
Some architectures (such as Alpha) rely on include/linux/sched.h definitions
in their mmu_context.h files.
So include sched.h before mmu_context.h.
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 84d77d3f06e7e8dea057d10e8ec77ad71f721be3 upstream.
It is the reasonable expectation that if an executable file is not
readable there will be no way for a user without special privileges to
read the file. This is enforced in ptrace_attach but if ptrace
is already attached before exec there is no enforcement for read-only
executables.
As the only way to read such an mm is through access_process_vm
spin a variant called ptrace_access_vm that will fail if the
target process is not being ptraced by the current process, or
the current process did not have sufficient privileges when ptracing
began to read the target processes mm.
In the ptrace implementations replace access_process_vm by
ptrace_access_vm. There remain several ptrace sites that still use
access_process_vm as they are reading the target executables
instructions (for kernel consumption) or register stacks. As such it
does not appear necessary to add a permission check to those calls.
This bug has always existed in Linux.
Fixes: v1.0
Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
[bwh: Backported to 3.16:
- Pass around only a write flag, not gup_flags
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit bfedb589252c01fa505ac9f6f2a3d5d68d707ef4 upstream.
During exec dumpable is cleared if the file that is being executed is
not readable by the user executing the file. A bug in
ptrace_may_access allows reading the file if the executable happens to
enter into a subordinate user namespace (aka clone(CLONE_NEWUSER),
unshare(CLONE_NEWUSER), or setns(fd, CLONE_NEWUSER).
This problem is fixed with only necessary userspace breakage by adding
a user namespace owner to mm_struct, captured at the time of exec, so
it is clear in which user namespace CAP_SYS_PTRACE must be present in
to be able to safely give read permission to the executable.
The function ptrace_may_access is modified to verify that the ptracer
has CAP_SYS_ADMIN in task->mm->user_ns instead of task->cred->user_ns.
This ensures that if the task changes it's cred into a subordinate
user namespace it does not become ptraceable.
The function ptrace_attach is modified to only set PT_PTRACE_CAP when
CAP_SYS_PTRACE is held over task->mm->user_ns. The intent of
PT_PTRACE_CAP is to be a flag to note that whatever permission changes
the task might go through the tracer has sufficient permissions for
it not to be an issue. task->cred->user_ns is always the same
as or descendent of mm->user_ns. Which guarantees that having
CAP_SYS_PTRACE over mm->user_ns is the worst case for the tasks
credentials.
To prevent regressions mm->dumpable and mm->user_ns are not considered
when a task has no mm. As simply failing ptrace_may_attach causes
regressions in privileged applications attempting to read things
such as /proc/<pid>/stat
Acked-by: Kees Cook <keescook@chromium.org>
Tested-by: Cyrill Gorcunov <gorcunov@openvz.org>
Fixes: 8409cca70561 ("userns: allow ptrace from non-init user namespaces")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit a8f97366452ed491d13cf1e44241bc0b5740b1f0 upstream.
Currently, we unconditionally make page table dirty in touch_pmd().
It may result in false-positive can_follow_write_pmd().
We may avoid the situation, if we would only make the page table entry
dirty if caller asks for write access -- FOLL_WRITE.
The patch also changes touch_pud() in the same way.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[carnil: backport for 3.16:
- Adjust context
- Drop specific part for PUD-sized transparent hugepages. Support
for PUD-sized transparent hugepages was added in v4.11-rc1
]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit d09b0137d204bebeaafed672bc5a244e9ac92edb upstream.
find_{smallest|biggest}_section_pfn()s find the smallest/biggest section
and return the pfn of the section. But the functions are defined as int.
So the functions always return 0x00000000 - 0xffffffff. It means if
memory address is over 16TB, the functions does not work correctly.
To handle 64 bit value, the patch defines
find_{smallest|biggest}_section_pfn() as unsigned long.
Fixes: 815121d2b5cd ("memory_hotplug: clear zone when removing the memory")
Link: http://lkml.kernel.org/r/d9d5593a-d0a4-c4be-ab08-493df59a85c6@gmail.com
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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inline function
commit 1dd2bfc86818ddbc95f98e312e7704350223fd7d upstream.
pfn_to_section_nr() and section_nr_to_pfn() are defined as macro.
pfn_to_section_nr() has no issue even if it is defined as macro. But
section_nr_to_pfn() has overflow issue if sec is defined as int.
section_nr_to_pfn() just shifts sec by PFN_SECTION_SHIFT. If sec is
defined as unsigned long, section_nr_to_pfn() returns pfn as 64 bit value.
But if sec is defined as int, section_nr_to_pfn() returns pfn as 32 bit
value.
__remove_section() calculates start_pfn using section_nr_to_pfn() and
scn_nr defined as int. So if hot-removed memory address is over 16TB,
overflow issue occurs and section_nr_to_pfn() does not calculate correct
pfn.
To make callers use proper arg, the patch changes the macros to inline
functions.
Fixes: 815121d2b5cd ("memory_hotplug: clear zone when removing the memory")
Link: http://lkml.kernel.org/r/e643a387-e573-6bbf-d418-c60c8ee3d15e@gmail.com
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit eb03aa008561004257900983193d024e57abdd96 upstream.
For every pfn aligned to minimum_order, dissolve_free_huge_pages() will
call dissolve_free_huge_page() which takes the hugetlb spinlock, even if
the page is not huge at all or a hugepage that is in-use.
Improve this by doing the PageHuge() and page_count() checks already in
dissolve_free_huge_pages() before calling dissolve_free_huge_page(). In
dissolve_free_huge_page(), when holding the spinlock, those checks need
to be revalidated.
Link: http://lkml.kernel.org/r/20160926172811.94033-4-gerald.schaefer@de.ibm.com
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Rui Teng <rui.teng@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 90cae1fe1c3540f791d5b8e025985fa5e699b2bb upstream.
As a part of memory initialisation the architecture passes an array to
free_area_init_nodes() which specifies the max PFN of each memory zone.
This array is not necessarily monotonic (due to unused zones) so this
array is parsed to build monotonic lists of the min and max PFN for each
zone. ZONE_MOVABLE is special cased here as its limits are managed by
the mm subsystem rather than the architecture. Unfortunately, this
special casing is broken when ZONE_MOVABLE is the not the last zone in
the zone list. The core of the issue is:
if (i == ZONE_MOVABLE)
continue;
arch_zone_lowest_possible_pfn[i] =
arch_zone_highest_possible_pfn[i-1];
As ZONE_MOVABLE is skipped the lowest_possible_pfn of the next zone will
be set to zero. This patch fixes this bug by adding explicitly tracking
where the next zone should start rather than relying on the contents
arch_zone_highest_possible_pfn[].
Thie is low priority. To get bitten by this you need to enable a zone
that appears after ZONE_MOVABLE in the zone_type enum. As far as I can
tell this means running a kernel with ZONE_DEVICE or ZONE_CMA enabled,
so I can't see this affecting too many people.
I only noticed this because I've been fiddling with ZONE_DEVICE on
powerpc and 4.6 broke my test kernel. This bug, in conjunction with the
changes in Taku Izumi's kernelcore=mirror patch (d91749c1dda71) and
powerpc being the odd architecture which initialises max_zone_pfn[] to
~0ul instead of 0 caused all of system memory to be placed into
ZONE_DEVICE at boot, followed a panic since device memory cannot be used
for kernel allocations. I've already submitted a patch to fix the
powerpc specific bits, but I figured this should be fixed too.
Link: http://lkml.kernel.org/r/1462435033-15601-1-git-send-email-oohall@gmail.com
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 556b969a1cfe2686aae149137fa1dfcac0eefe54 upstream.
There is a problem that when counting the pages for creating the
hibernation snapshot will take significant amount of time, especially on
system with large memory. Since the counting job is performed with irq
disabled, this might lead to NMI lockup. The following warning were
found on a system with 1.5TB DRAM:
Freezing user space processes ... (elapsed 0.002 seconds) done.
OOM killer disabled.
PM: Preallocating image memory...
NMI watchdog: Watchdog detected hard LOCKUP on cpu 27
CPU: 27 PID: 3128 Comm: systemd-sleep Not tainted 4.13.0-0.rc2.git0.1.fc27.x86_64 #1
task: ffff9f01971ac000 task.stack: ffffb1a3f325c000
RIP: 0010:memory_bm_find_bit+0xf4/0x100
Call Trace:
swsusp_set_page_free+0x2b/0x30
mark_free_pages+0x147/0x1c0
count_data_pages+0x41/0xa0
hibernate_preallocate_memory+0x80/0x450
hibernation_snapshot+0x58/0x410
hibernate+0x17c/0x310
state_store+0xdf/0xf0
kobj_attr_store+0xf/0x20
sysfs_kf_write+0x37/0x40
kernfs_fop_write+0x11c/0x1a0
__vfs_write+0x37/0x170
vfs_write+0xb1/0x1a0
SyS_write+0x55/0xc0
entry_SYSCALL_64_fastpath+0x1a/0xa5
...
done (allocated 6590003 pages)
PM: Allocated 26360012 kbytes in 19.89 seconds (1325.28 MB/s)
It has taken nearly 20 seconds(2.10GHz CPU) thus the NMI lockup was
triggered. In case the timeout of the NMI watch dog has been set to 1
second, a safe interval should be 6590003/20 = 320k pages in theory.
However there might also be some platforms running at a lower frequency,
so feed the watchdog every 100k pages.
[yu.c.chen@intel.com: simplification]
Link: http://lkml.kernel.org/r/1503460079-29721-1-git-send-email-yu.c.chen@intel.com
[yu.c.chen@intel.com: use interval of 128k instead of 100k to avoid modulus]
Link: http://lkml.kernel.org/r/1503328098-5120-1-git-send-email-yu.c.chen@intel.com
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Reported-by: Jan Filipcewicz <jan.filipcewicz@intel.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Len Brown <lenb@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 73223e4e2e3867ebf033a5a8eb2e5df0158ccc99 upstream.
I hit a use after free issue when executing trinity and repoduced it
with KASAN enabled. The related call trace is as follows.
BUG: KASan: use after free in SyS_get_mempolicy+0x3c8/0x960 at addr ffff8801f582d766
Read of size 2 by task syz-executor1/798
INFO: Allocated in mpol_new.part.2+0x74/0x160 age=3 cpu=1 pid=799
__slab_alloc+0x768/0x970
kmem_cache_alloc+0x2e7/0x450
mpol_new.part.2+0x74/0x160
mpol_new+0x66/0x80
SyS_mbind+0x267/0x9f0
system_call_fastpath+0x16/0x1b
INFO: Freed in __mpol_put+0x2b/0x40 age=4 cpu=1 pid=799
__slab_free+0x495/0x8e0
kmem_cache_free+0x2f3/0x4c0
__mpol_put+0x2b/0x40
SyS_mbind+0x383/0x9f0
system_call_fastpath+0x16/0x1b
INFO: Slab 0xffffea0009cb8dc0 objects=23 used=8 fp=0xffff8801f582de40 flags=0x200000000004080
INFO: Object 0xffff8801f582d760 @offset=5984 fp=0xffff8801f582d600
Bytes b4 ffff8801f582d750: ae 01 ff ff 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ
Object ffff8801f582d760: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
Object ffff8801f582d770: 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkk.
Redzone ffff8801f582d778: bb bb bb bb bb bb bb bb ........
Padding ffff8801f582d8b8: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ
Memory state around the buggy address:
ffff8801f582d600: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8801f582d680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801f582d700: fc fc fc fc fc fc fc fc fc fc fc fc fb fb fb fc
!shared memory policy is not protected against parallel removal by other
thread which is normally protected by the mmap_sem. do_get_mempolicy,
however, drops the lock midway while we can still access it later.
Early premature up_read is a historical artifact from times when
put_user was called in this path see https://lwn.net/Articles/124754/
but that is gone since 8bccd85ffbaf ("[PATCH] Implement sys_* do_*
layering in the memory policy layer."). but when we have the the
current mempolicy ref count model. The issue was introduced
accordingly.
Fix the issue by removing the premature release.
Link: http://lkml.kernel.org/r/1502950924-27521-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 16af97dc5a8975371a83d9e30a64038b48f40a2d upstream.
Patch series "fixes of TLB batching races", v6.
It turns out that Linux TLB batching mechanism suffers from various
races. Races that are caused due to batching during reclamation were
recently handled by Mel and this patch-set deals with others. The more
fundamental issue is that concurrent updates of the page-tables allow
for TLB flushes to be batched on one core, while another core changes
the page-tables. This other core may assume a PTE change does not
require a flush based on the updated PTE value, while it is unaware that
TLB flushes are still pending.
This behavior affects KSM (which may result in memory corruption) and
MADV_FREE and MADV_DONTNEED (which may result in incorrect behavior). A
proof-of-concept can easily produce the wrong behavior of MADV_DONTNEED.
Memory corruption in KSM is harder to produce in practice, but was
observed by hacking the kernel and adding a delay before flushing and
replacing the KSM page.
Finally, there is also one memory barrier missing, which may affect
architectures with weak memory model.
This patch (of 7):
Setting and clearing mm->tlb_flush_pending can be performed by multiple
threads, since mmap_sem may only be acquired for read in
task_numa_work(). If this happens, tlb_flush_pending might be cleared
while one of the threads still changes PTEs and batches TLB flushes.
This can lead to the same race between migration and
change_protection_range() that led to the introduction of
tlb_flush_pending. The result of this race was data corruption, which
means that this patch also addresses a theoretically possible data
corruption.
An actual data corruption was not observed, yet the race was was
confirmed by adding assertion to check tlb_flush_pending is not set by
two threads, adding artificial latency in change_protection_range() and
using sysctl to reduce kernel.numa_balancing_scan_delay_ms.
Link: http://lkml.kernel.org/r/20170802000818.4760-2-namit@vmware.com
Fixes: 20841405940e ("mm: fix TLB flush race between migration, and
change_protection_range")
Signed-off-by: Nadav Amit <namit@vmware.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Drop change to dump_mm()
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
|
commit 2ad654bc5e2b211e92f66da1d819e47d79a866f0 upstream.
When we change cpuset.memory_spread_{page,slab}, cpuset will flip
PF_SPREAD_{PAGE,SLAB} bit of tsk->flags for each task in that cpuset.
This should be done using atomic bitops, but currently we don't,
which is broken.
Tetsuo reported a hard-to-reproduce kernel crash on RHEL6, which happened
when one thread tried to clear PF_USED_MATH while at the same time another
thread tried to flip PF_SPREAD_PAGE/PF_SPREAD_SLAB. They both operate on
the same task.
Here's the full report:
https://lkml.org/lkml/2014/9/19/230
To fix this, we make PF_SPREAD_PAGE and PF_SPREAD_SLAB atomic flags.
v4:
- updated mm/slab.c. (Fengguang Wu)
- updated Documentation.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: Kees Cook <keescook@chromium.org>
Fixes: 950592f7b991 ("cpusets: update tasks' page/slab spread flags in time")
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit ad33bb04b2a6cee6c1f99fabb15cddbf93ff0433 upstream.
pmd_trans_unstable()/pmd_none_or_trans_huge_or_clear_bad() were
introduced to locklessy (but atomically) detect when a pmd is a regular
(stable) pmd or when the pmd is unstable and can infinitely transition
from pmd_none() and pmd_trans_huge() from under us, while only holding
the mmap_sem for reading (for writing not).
While holding the mmap_sem only for reading, MADV_DONTNEED can run from
under us and so before we can assume the pmd to be a regular stable pmd
we need to compare it against pmd_none() and pmd_trans_huge() in an
atomic way, with pmd_trans_unstable(). The old pmd_trans_huge() left a
tiny window for a race.
Useful applications are unlikely to notice the difference as doing
MADV_DONTNEED concurrently with a page fault would lead to undefined
behavior.
[akpm@linux-foundation.org: tidy up comment grammar/layout]
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[js] 3.12 backport: no pmd_devmap in 3.12 yet.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 8f182270dfec432e93fae14f9208a6b9af01009f upstream.
Currently we can have compound pages held on per cpu pagevecs, which
leads to a lot of memory unavailable for reclaim when needed. In the
systems with hundreads of processors it can be GBs of memory.
On of the way of reproducing the problem is to not call munmap
explicitly on all mapped regions (i.e. after receiving SIGTERM). After
that some pages (with THP enabled also huge pages) may end up on
lru_add_pvec, example below.
void main() {
#pragma omp parallel
{
size_t size = 55 * 1000 * 1000; // smaller than MEM/CPUS
void *p = mmap(NULL, size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS , -1, 0);
if (p != MAP_FAILED)
memset(p, 0, size);
//munmap(p, size); // uncomment to make the problem go away
}
}
When we run it with THP enabled it will leave significant amount of
memory on lru_add_pvec. This memory will be not reclaimed if we hit
OOM, so when we run above program in a loop:
for i in `seq 100`; do ./a.out; done
many processes (95% in my case) will be killed by OOM.
The primary point of the LRU add cache is to save the zone lru_lock
contention with a hope that more pages will belong to the same zone and
so their addition can be batched. The huge page is already a form of
batched addition (it will add 512 worth of memory in one go) so skipping
the batching seems like a safer option when compared to a potential
excess in the caching which can be quite large and much harder to fix
because lru_add_drain_all is way to expensive and it is not really clear
what would be a good moment to call it.
Similarly we can reproduce the problem on lru_deactivate_pvec by adding:
madvise(p, size, MADV_FREE); after memset.
This patch flushes lru pvecs on compound page arrival making the problem
less severe - after applying it kill rate of above example drops to 0%,
due to reducing maximum amount of memory held on pvec from 28MB (with
THP) to 56kB per CPU.
Suggested-by: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/1466180198-18854-1-git-send-email-lukasz.odzioba@intel.com
Signed-off-by: Lukasz Odzioba <lukasz.odzioba@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Ming Li <mingli199x@qq.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Drop change in deactivate_file_page()
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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|
commit 37511fb5c91db93d8bd6e3f52f86e5a7ff7cfcdf upstream.
Jörn Engel noticed that the expand_upwards() function might not return
-ENOMEM in case the requested address is (unsigned long)-PAGE_SIZE and
if the architecture didn't defined TASK_SIZE as multiple of PAGE_SIZE.
Affected architectures are arm, frv, m68k, blackfin, h8300 and xtensa
which all define TASK_SIZE as 0xffffffff, but since none of those have
an upwards-growing stack we currently have no actual issue.
Nevertheless let's fix this just in case any of the architectures with
an upward-growing stack (currently parisc, metag and partly ia64) define
TASK_SIZE similar.
Link: http://lkml.kernel.org/r/20170702192452.GA11868@p100.box
Fixes: bd726c90b6b8 ("Allow stack to grow up to address space limit")
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: Jörn Engel <joern@purestorage.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 561b5e0709e4a248c67d024d4d94b6e31e3edf2f upstream.
Commit 1be7107fbe18 ("mm: larger stack guard gap, between vmas") has
introduced a regression in some rust and Java environments which are
trying to implement their own stack guard page. They are punching a new
MAP_FIXED mapping inside the existing stack Vma.
This will confuse expand_{downwards,upwards} into thinking that the
stack expansion would in fact get us too close to an existing non-stack
vma which is a correct behavior wrt safety. It is a real regression on
the other hand.
Let's work around the problem by considering PROT_NONE mapping as a part
of the stack. This is a gros hack but overflowing to such a mapping
would trap anyway an we only can hope that usespace knows what it is
doing and handle it propely.
Fixes: 1be7107fbe18 ("mm: larger stack guard gap, between vmas")
Link: http://lkml.kernel.org/r/20170705182849.GA18027@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Debugged-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 197e7e521384a23b9e585178f3f11c9fa08274b9 upstream.
The 'move_paghes()' system call was introduced long long ago with the
same permission checks as for sending a signal (except using
CAP_SYS_NICE instead of CAP_SYS_KILL for the overriding capability).
That turns out to not be a great choice - while the system call really
only moves physical page allocations around (and you need other
capabilities to do a lot of it), you can check the return value to map
out some the virtual address choices and defeat ASLR of a binary that
still shares your uid.
So change the access checks to the more common 'ptrace_may_access()'
model instead.
This tightens the access checks for the uid, and also effectively
changes the CAP_SYS_NICE check to CAP_SYS_PTRACE, but it's unlikely that
anybody really _uses_ this legacy system call any more (we hav ebetter
NUMA placement models these days), so I expect nobody to notice.
Famous last words.
Reported-by: Otto Ebeling <otto.ebeling@iki.fi>
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit caaee6234d05a58c5b4d05e7bf766131b810a657 upstream.
By checking the effective credentials instead of the real UID / permitted
capabilities, ensure that the calling process actually intended to use its
credentials.
To ensure that all ptrace checks use the correct caller credentials (e.g.
in case out-of-tree code or newly added code omits the PTRACE_MODE_*CREDS
flag), use two new flags and require one of them to be set.
The problem was that when a privileged task had temporarily dropped its
privileges, e.g. by calling setreuid(0, user_uid), with the intent to
perform following syscalls with the credentials of a user, it still passed
ptrace access checks that the user would not be able to pass.
While an attacker should not be able to convince the privileged task to
perform a ptrace() syscall, this is a problem because the ptrace access
check is reused for things in procfs.
In particular, the following somewhat interesting procfs entries only rely
on ptrace access checks:
/proc/$pid/stat - uses the check for determining whether pointers
should be visible, useful for bypassing ASLR
/proc/$pid/maps - also useful for bypassing ASLR
/proc/$pid/cwd - useful for gaining access to restricted
directories that contain files with lax permissions, e.g. in
this scenario:
lrwxrwxrwx root root /proc/13020/cwd -> /root/foobar
drwx------ root root /root
drwxr-xr-x root root /root/foobar
-rw-r--r-- root root /root/foobar/secret
Therefore, on a system where a root-owned mode 6755 binary changes its
effective credentials as described and then dumps a user-specified file,
this could be used by an attacker to reveal the memory layout of root's
processes or reveal the contents of files he is not allowed to access
(through /proc/$pid/cwd).
[akpm@linux-foundation.org: fix warning]
Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: "Serge E. Hallyn" <serge.hallyn@ubuntu.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Update mm_access() calls in fs/proc/task_{,no}mmu.c too
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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|
commit 3c226c637b69104f6b9f1c6ec5b08d7b741b3229 upstream.
In do_huge_pmd_numa_page(), we attempt to handle a migrating thp pmd by
waiting until the pmd is unlocked before we return and retry. However,
we can race with migrate_misplaced_transhuge_page():
// do_huge_pmd_numa_page // migrate_misplaced_transhuge_page()
// Holds 0 refs on page // Holds 2 refs on page
vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
/* ... */
if (pmd_trans_migrating(*vmf->pmd)) {
page = pmd_page(*vmf->pmd);
spin_unlock(vmf->ptl);
ptl = pmd_lock(mm, pmd);
if (page_count(page) != 2)) {
/* roll back */
}
/* ... */
mlock_migrate_page(new_page, page);
/* ... */
spin_unlock(ptl);
put_page(page);
put_page(page); // page freed here
wait_on_page_locked(page);
goto out;
}
This can result in the freed page having its waiters flag set
unexpectedly, which trips the PAGE_FLAGS_CHECK_AT_PREP checks in the
page alloc/free functions. This has been observed on arm64 KVM guests.
We can avoid this by having do_huge_pmd_numa_page() take a reference on
the page before dropping the pmd lock, mirroring what we do in
__migration_entry_wait().
When we hit the race, migrate_misplaced_transhuge_page() will see the
reference and abort the migration, as it may do today in other cases.
Fixes: b8916634b77bffb2 ("mm: Prevent parallel splits during THP migration")
Link: http://lkml.kernel.org/r/1497349722-6731-2-git-send-email-will.deacon@arm.com
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Steve Capper <steve.capper@arm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit ef70762948dde012146926720b70e79736336764 upstream.
I saw need_resched() warnings when swapping on large swapfile (TBs)
because continuously allocating many pages in swap_cgroup_prepare() took
too long.
We already cond_resched when freeing page in swap_cgroup_swapoff(). Do
the same for the page allocation.
Link: http://lkml.kernel.org/r/20170604200109.17606-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 7258ae5c5a2ce2f5969e8b18b881be40ab55433d upstream.
memory_failure() chooses a recovery action function based on the page
flags. For huge pages it uses the tail page flags which don't have
anything interesting set, resulting in:
> Memory failure: 0x9be3b4: Unknown page state
> Memory failure: 0x9be3b4: recovery action for unknown page: Failed
Instead, save a copy of the head page's flags if this is a huge page,
this means if there are no relevant flags for this tail page, we use the
head pages flags instead. This results in the me_huge_page() recovery
action being called:
> Memory failure: 0x9b7969: recovery action for huge page: Delayed
For hugepages that have not yet been allocated, this allows the hugepage
to be dequeued.
Fixes: 524fca1e7356 ("HWPOISON: fix misjudgement of page_action() for errors on mlocked pages")
Link: http://lkml.kernel.org/r/20170524130204.21845-1-james.morse@arm.com
Signed-off-by: James Morse <james.morse@arm.com>
Tested-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 70feee0e1ef331b22cc51f383d532a0d043fbdcc upstream.
Kefeng reported that when running the follow test, the mlock count in
meminfo will increase permanently:
[1] testcase
linux:~ # cat test_mlockal
grep Mlocked /proc/meminfo
for j in `seq 0 10`
do
for i in `seq 4 15`
do
./p_mlockall >> log &
done
sleep 0.2
done
# wait some time to let mlock counter decrease and 5s may not enough
sleep 5
grep Mlocked /proc/meminfo
linux:~ # cat p_mlockall.c
#include <sys/mman.h>
#include <stdlib.h>
#include <stdio.h>
#define SPACE_LEN 4096
int main(int argc, char ** argv)
{
int ret;
void *adr = malloc(SPACE_LEN);
if (!adr)
return -1;
ret = mlockall(MCL_CURRENT | MCL_FUTURE);
printf("mlcokall ret = %d\n", ret);
ret = munlockall();
printf("munlcokall ret = %d\n", ret);
free(adr);
return 0;
}
In __munlock_pagevec() we should decrement NR_MLOCK for each page where
we clear the PageMlocked flag. Commit 1ebb7cc6a583 ("mm: munlock: batch
NR_MLOCK zone state updates") has introduced a bug where we don't
decrement NR_MLOCK for pages where we clear the flag, but fail to
isolate them from the lru list (e.g. when the pages are on some other
cpu's percpu pagevec). Since PageMlocked stays cleared, the NR_MLOCK
accounting gets permanently disrupted by this.
Fix it by counting the number of page whose PageMlock flag is cleared.
Fixes: 1ebb7cc6a583 (" mm: munlock: batch NR_MLOCK zone state updates")
Link: http://lkml.kernel.org/r/1495678405-54569-1-git-send-email-xieyisheng1@huawei.com
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Joern Engel <joern@logfs.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michel Lespinasse <walken@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: zhongjiang <zhongjiang@huawei.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 30809f559a0d348c2dfd7ab05e9a451e2384962e upstream.
On failing to migrate a page, soft_offline_huge_page() performs the
necessary update to the hugepage ref-count.
But when !hugepage_migration_supported() , unmap_and_move_hugepage()
also decrements the page ref-count for the hugepage. The combined
behaviour leaves the ref-count in an inconsistent state.
This leads to soft lockups when running the overcommitted hugepage test
from mce-tests suite.
Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
soft offline: 0x83ed600: migration failed 1, type 1fffc00000008008 (uptodate|head)
INFO: rcu_preempt detected stalls on CPUs/tasks:
Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
(detected by 7, t=5254 jiffies, g=963, c=962, q=321)
thugetlb_overco R running task 0 2715 2685 0x00000008
Call trace:
dump_backtrace+0x0/0x268
show_stack+0x24/0x30
sched_show_task+0x134/0x180
rcu_print_detail_task_stall_rnp+0x54/0x7c
rcu_check_callbacks+0xa74/0xb08
update_process_times+0x34/0x60
tick_sched_handle.isra.7+0x38/0x70
tick_sched_timer+0x4c/0x98
__hrtimer_run_queues+0xc0/0x300
hrtimer_interrupt+0xac/0x228
arch_timer_handler_phys+0x3c/0x50
handle_percpu_devid_irq+0x8c/0x290
generic_handle_irq+0x34/0x50
__handle_domain_irq+0x68/0xc0
gic_handle_irq+0x5c/0xb0
Address this by changing the putback_active_hugepage() in
soft_offline_huge_page() to putback_movable_pages().
This only triggers on systems that enable memory failure handling
(ARCH_SUPPORTS_MEMORY_FAILURE) but not hugepage migration
(!ARCH_ENABLE_HUGEPAGE_MIGRATION).
I imagine this wasn't triggered as there aren't many systems running
this configuration.
[akpm@linux-foundation.org: remove dead comment, per Naoya]
Link: http://lkml.kernel.org/r/20170525135146.32011-1-punit.agrawal@arm.com
Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
Tested-by: Manoj Iyer <manoj.iyer@canonical.com>
Suggested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 478fe3037b2278d276d4cd9cd0ab06c4cb2e9b32 upstream.
memcg_propagate_slab_attrs() abuses the sysfs attribute file functions
to propagate settings from the root kmem_cache to a newly created
kmem_cache. It does that with:
attr->show(root, buf);
attr->store(new, buf, strlen(bug);
Aside of being a lazy and absurd hackery this is broken because it does
not check the return value of the show() function.
Some of the show() functions return 0 w/o touching the buffer. That
means in such a case the store function is called with the stale content
of the previous show(). That causes nonsense like invoking
kmem_cache_shrink() on a newly created kmem_cache. In the worst case it
would cause handing in an uninitialized buffer.
This should be rewritten proper by adding a propagate() callback to
those slub_attributes which must be propagated and avoid that insane
conversion to and from ASCII, but that's too large for a hot fix.
Check at least the return value of the show() function, so calling
store() with stale content is prevented.
Steven said:
"It can cause a deadlock with get_online_cpus() that has been uncovered
by recent cpu hotplug and lockdep changes that Thomas and Peter have
been doing.
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(cpu_hotplug.lock);
lock(slab_mutex);
lock(cpu_hotplug.lock);
lock(slab_mutex);
*** DEADLOCK ***"
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1705201244540.2255@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
|
commit bd726c90b6b8ce87602208701b208a208e6d5600 upstream.
Fix expand_upwards() on architectures with an upward-growing stack (parisc,
metag and partly IA-64) to allow the stack to reliably grow exactly up to
the address space limit given by TASK_SIZE.
Signed-off-by: Helge Deller <deller@gmx.de>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
|
commit f4cb767d76cf7ee72f97dd76f6cfa6c76a5edc89 upstream.
Trinity gets kernel BUG at mm/mmap.c:1963! in about 3 minutes of
mmap testing. That's the VM_BUG_ON(gap_end < gap_start) at the
end of unmapped_area_topdown(). Linus points out how MAP_FIXED
(which does not have to respect our stack guard gap intentions)
could result in gap_end below gap_start there. Fix that, and
the similar case in its alternative, unmapped_area().
Fixes: 1be7107fbe18 ("mm: larger stack guard gap, between vmas")
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Debugged-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
|
commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream.
Stack guard page is a useful feature to reduce a risk of stack smashing
into a different mapping. We have been using a single page gap which
is sufficient to prevent having stack adjacent to a different mapping.
But this seems to be insufficient in the light of the stack usage in
userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
which is 256kB or stack strings with MAX_ARG_STRLEN.
This will become especially dangerous for suid binaries and the default
no limit for the stack size limit because those applications can be
tricked to consume a large portion of the stack and a single glibc call
could jump over the guard page. These attacks are not theoretical,
unfortunatelly.
Make those attacks less probable by increasing the stack guard gap
to 1MB (on systems with 4k pages; but make it depend on the page size
because systems with larger base pages might cap stack allocations in
the PAGE_SIZE units) which should cover larger alloca() and VLA stack
allocations. It is obviously not a full fix because the problem is
somehow inherent, but it should reduce attack space a lot.
One could argue that the gap size should be configurable from userspace,
but that can be done later when somebody finds that the new 1MB is wrong
for some special case applications. For now, add a kernel command line
option (stack_guard_gap) to specify the stack gap size (in page units).
Implementation wise, first delete all the old code for stack guard page:
because although we could get away with accounting one extra page in a
stack vma, accounting a larger gap can break userspace - case in point,
a program run with "ulimit -S -v 20000" failed when the 1MB gap was
counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
and strict non-overcommit mode.
Instead of keeping gap inside the stack vma, maintain the stack guard
gap as a gap between vmas: using vm_start_gap() in place of vm_start
(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
places which need to respect the gap - mainly arch_get_unmapped_area(),
and and the vma tree's subtree_gap support for that.
Original-patch-by: Oleg Nesterov <oleg@redhat.com>
Original-patch-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[Hugh Dickins: Backported to 3.16]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit cf01fb9985e8deb25ccf0ea54d916b8871ae0e62 upstream.
In the case that compat_get_bitmap fails we do not want to copy the
bitmap to the user as it will contain uninitialized stack data and leak
sensitive data.
Signed-off-by: Chris Salls <salls@cs.ucsb.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit dd8416c47715cf324c9a16f13273f9fda87acfed upstream.
With rw_page, page_endio is used for completing IO on a page and it
propagates write error to the address space if the IO fails. The
problem is it accesses page->mapping directly which might be okay for
file-backed pages but it shouldn't for anonymous page. Otherwise, it
can corrupt one of field from anon_vma under us and system goes panic
randomly.
swap_writepage
bdev_writepage
ops->rw_page
I encountered the BUG during developing new zram feature and it was
really hard to figure it out because it made random crash, somtime
mmap_sem lockdep, sometime other places where places never related to
zram/zsmalloc, and not reproducible with some configuration.
When I consider how that bug is subtle and people do fast-swap test with
brd, it's worth to add stable mark, I think.
Fixes: dd6bd0d9c7db ("swap: use bdev_read_page() / bdev_write_page()")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit e1587a4945408faa58d0485002c110eb2454740c upstream.
At the end of a window period, if the reclaimed pages is greater than
scanned, an unsigned underflow can result in a huge pressure value and
thus a critical event. Reclaimed pages is found to go higher than
scanned because of the addition of reclaimed slab pages to reclaimed in
shrink_node without a corresponding increment to scanned pages.
Minchan Kim mentioned that this can also happen in the case of a THP
page where the scanned is 1 and reclaimed could be 512.
Link: http://lkml.kernel.org/r/1486641577-11685-1-git-send-email-vinmenon@codeaurora.org
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Shiraz Hashim <shashim@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
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commit e02dc017c3032dcdce1b993af0db135462e1b4b7 upstream.
When @node_reclaim_node isn't 0, the page allocator tries to reclaim
pages if the amount of free memory in the zones are below the low
watermark. On Power platform, none of NUMA nodes are scanned for page
reclaim because no nodes match the condition in zone_allows_reclaim().
On Power platform, RECLAIM_DISTANCE is set to 10 which is the distance
of Node-A to Node-A. So the preferred node even won't be scanned for
page reclaim.
__alloc_pages_nodemask()
get_page_from_freelist()
zone_allows_reclaim()
Anton proposed the test code as below:
# cat alloc.c
:
int main(int argc, char *argv[])
{
void *p;
unsigned long size;
unsigned long start, end;
start = time(NULL);
size = strtoul(argv[1], NULL, 0);
printf("To allocate %ldGB memory\n", size);
size <<= 30;
p = malloc(size);
assert(p);
memset(p, 0, size);
end = time(NULL);
printf("Used time: %ld seconds\n", end - start);
sleep(3600);
return 0;
}
The system I use for testing has two NUMA nodes. Both have 128GB
memory. In below scnario, the page caches on node#0 should be reclaimed
when it encounters pressure to accommodate request of allocation.
# echo 2 > /proc/sys/vm/zone_reclaim_mode; \
sync; \
echo 3 > /proc/sys/vm/drop_caches; \
# taskset -c 0 cat file.32G > /dev/null; \
grep FilePages /sys/devices/system/node/node0/meminfo
Node 0 FilePages: 33619712 kB
# taskset -c 0 ./alloc 128
# grep FilePages /sys/devices/system/node/node0/meminfo
Node 0 FilePages: 33619840 kB
# grep MemFree /sys/devices/system/node/node0/meminfo
Node 0 MemFree: 186816 kB
With the patch applied, the pagecache on node-0 is reclaimed when its
free memory is running out. It's the expected behaviour.
# echo 2 > /proc/sys/vm/zone_reclaim_mode; \
sync; \
echo 3 > /proc/sys/vm/drop_caches
# taskset -c 0 cat file.32G > /dev/null; \
grep FilePages /sys/devices/system/node/node0/meminfo
Node 0 FilePages: 33605568 kB
# taskset -c 0 ./alloc 128
# grep FilePages /sys/devices/system/node/node0/meminfo
Node 0 FilePages: 1379520 kB
# grep MemFree /sys/devices/system/node/node0/meminfo
Node 0 MemFree: 317120 kB
Fixes: 5f7a75acdb24 ("mm: page_alloc: do not cache reclaim distances")
Link: http://lkml.kernel.org/r/1486532455-29613-1-git-send-email-gwshan@linux.vnet.ibm.com
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
|
thp" backport
This is a stable follow up fix for an incorrect backport. The issue is
not present in the upstream kernel.
Miroslav has noticed the following splat when testing my 3.2 forward
port of 8310d48b125d ("mm/huge_memory.c: respect FOLL_FORCE/FOLL_COW for
thp") to 3.12:
BUG: Bad page state in process a.out pfn:26400
page:ffffea000085e000 count:0 mapcount:1 mapping: (null) index:0x7f049d600
page flags: 0x1fffff80108018(uptodate|dirty|head|swapbacked)
page dumped because: nonzero mapcount
[iii]
CPU: 2 PID: 5926 Comm: a.out Tainted: G E 3.12.61-0-default #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
0000000000000000 ffffffff81515830 ffffea000085e000 ffffffff81800ad7
ffffffff815118a5 ffffea000085e000 0000000000000000 000fffff80000000
ffffffff81140f18 fff000007c000000 ffffea000085e000 0000000000000009
Call Trace:
[<ffffffff8100475d>] dump_trace+0x7d/0x2d0
[<ffffffff81004a44>] show_stack_log_lvl+0x94/0x170
[<ffffffff81005ce1>] show_stack+0x21/0x50
[<ffffffff81515830>] dump_stack+0x5d/0x78
[<ffffffff815118a5>] bad_page.part.67+0xe8/0x102
[<ffffffff81140f18>] free_pages_prepare+0x198/0x1b0
[<ffffffff81141275>] __free_pages_ok+0x15/0xd0
[<ffffffff8116444c>] __access_remote_vm+0x7c/0x1e0
[<ffffffff81205afb>] mem_rw.isra.13+0x14b/0x1a0
[<ffffffff811a3b18>] vfs_write+0xb8/0x1e0
[<ffffffff811a469b>] SyS_pwrite64+0x6b/0xa0
[<ffffffff81523b49>] system_call_fastpath+0x16/0x1b
[<00007f049da18573>] 0x7f049da18572
The problem is that the original 3.2 backport didn't return NULL page on
the FOLL_COW page and so the page got reused.
Reported-and-tested-by: Miroslav Beneš <mbenes@suse.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 22f6b4d34fcf039c63a94e7670e0da24f8575a5a upstream.
Today proc and sysfs do not contain any executable files. Several
applications today mount proc or sysfs without noexec and nosuid and
then depend on there being no exectuables files on proc or sysfs.
Having any executable files show on proc or sysfs would cause
a user space visible regression, and most likely security problems.
Therefore commit to never allowing executables on proc and sysfs by
adding a new flag to mark them as filesystems without executables and
enforce that flag.
Test the flag where MNT_NOEXEC is tested today, so that the only user
visible effect will be that exectuables will be treated as if the
execute bit is cleared.
The filesystems proc and sysfs do not currently incoporate any
executable files so this does not result in any user visible effects.
This makes it unnecessary to vet changes to proc and sysfs tightly for
adding exectuable files or changes to chattr that would modify
existing files, as no matter what the individual file say they will
not be treated as exectuable files by the vfs.
Not having to vet changes to closely is important as without this we
are only one proc_create call (or another goof up in the
implementation of notify_change) from having problematic executables
on proc. Those mistakes are all too easy to make and would create
a situation where there are security issues or the assumptions of
some program having to be broken (and cause userspace regressions).
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
[bwh: Backported to 3.16: we don't have super_block::s_iflags; use
file_system_type::fs_flags instead]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
|
commit 5abf186a30a89d5b9c18a6bf93a2c192c9fd52f6 upstream.
do_generic_file_read() can be told to perform a large request from
userspace. If the system is under OOM and the reading task is the OOM
victim then it has an access to memory reserves and finishing the full
request can lead to the full memory depletion which is dangerous. Make
sure we rather go with a short read and allow the killed task to
terminate.
Link: http://lkml.kernel.org/r/20170201092706.9966-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
|
commit 8310d48b125d19fcd9521d83b8293e63eb1646aa upstream.
In commit 19be0eaffa3a ("mm: remove gup_flags FOLL_WRITE games from
__get_user_pages()"), the mm code was changed from unsetting FOLL_WRITE
after a COW was resolved to setting the (newly introduced) FOLL_COW
instead. Simultaneously, the check in gup.c was updated to still allow
writes with FOLL_FORCE set if FOLL_COW had also been set.
However, a similar check in huge_memory.c was forgotten. As a result,
remote memory writes to ro regions of memory backed by transparent huge
pages cause an infinite loop in the kernel (handle_mm_fault sets
FOLL_COW and returns 0 causing a retry, but follow_trans_huge_pmd bails
out immidiately because `(flags & FOLL_WRITE) && !pmd_write(*pmd)` is
true.
While in this state the process is stil SIGKILLable, but little else
works (e.g. no ptrace attach, no other signals). This is easily
reproduced with the following code (assuming thp are set to always):
#include <assert.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#define TEST_SIZE 5 * 1024 * 1024
int main(void) {
int status;
pid_t child;
int fd = open("/proc/self/mem", O_RDWR);
void *addr = mmap(NULL, TEST_SIZE, PROT_READ,
MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
assert(addr != MAP_FAILED);
pid_t parent_pid = getpid();
if ((child = fork()) == 0) {
void *addr2 = mmap(NULL, TEST_SIZE, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
assert(addr2 != MAP_FAILED);
memset(addr2, 'a', TEST_SIZE);
pwrite(fd, addr2, TEST_SIZE, (uintptr_t)addr);
return 0;
}
assert(child == waitpid(child, &status, 0));
assert(WIFEXITED(status) && WEXITSTATUS(status) == 0);
return 0;
}
Fix this by updating follow_trans_huge_pmd in huge_memory.c analogously
to the update in gup.c in the original commit. The same pattern exists
in follow_devmap_pmd. However, we should not be able to reach that
check with FOLL_COW set, so add WARN_ONCE to make sure we notice if we
ever do.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170106015025.GA38411@juliacomputing.com
Signed-off-by: Keno Fischer <keno@juliacomputing.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Drop change to follow_devmap_pmd()
- pmd_dirty() is not available; check the page flags as in older
backports of can_follow_write_pte()
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
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commit e5bbc8a6c992901058bc09e2ce01d16c111ff047 upstream.
return_unused_surplus_pages() decrements the global reservation count,
and frees any unused surplus pages that were backing the reservation.
Commit 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in
return_unused_surplus_pages()") added a call to cond_resched_lock in the
loop freeing the pages.
As a result, the hugetlb_lock could be dropped, and someone else could
use the pages that will be freed in subsequent iterations of the loop.
This could result in inconsistent global hugetlb page state, application
api failures (such as mmap) failures or application crashes.
When dropping the lock in return_unused_surplus_pages, make sure that
the global reservation count (resv_huge_pages) remains sufficiently
large to prevent someone else from claiming pages about to be freed.
Analyzed by Paul Cassella.
Fixes: 7848a4bf51b3 ("mm/hugetlb.c: add cond_resched_lock() in return_unused_surplus_pages()")
Link: http://lkml.kernel.org/r/1483991767-6879-1-git-send-email-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reported-by: Paul Cassella <cassella@cray.com>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
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commit d05c5f7ba164aed3db02fb188c26d0dd94f5455b upstream.
We truncated the possible read iterator to s_maxbytes in commit
c2a9737f45e2 ("vfs,mm: fix a dead loop in truncate_inode_pages_range()"),
but our end condition handling was wrong: it's not an error to try to
read at the end of the file.
Reading past the end should return EOF (0), not EINVAL.
See for example
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1649342
http://lists.gnu.org/archive/html/bug-coreutils/2016-12/msg00008.html
where a md5sum of a maximally sized file fails because the final read is
exactly at s_maxbytes.
Fixes: c2a9737f45e2 ("vfs,mm: fix a dead loop in truncate_inode_pages_range()")
Reported-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Cc: Wei Fang <fangwei1@huawei.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
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commit dd111be69114cc867f8e826284559bfbc1c40e37 upstream.
When root activates a swap partition whose header has the wrong
endianness, nr_badpages elements of badpages are swabbed before
nr_badpages has been checked, leading to a buffer overrun of up to 8GB.
This normally is not a security issue because it can only be exploited
by root (more specifically, a process with CAP_SYS_ADMIN or the ability
to modify a swap file/partition), and such a process can already e.g.
modify swapped-out memory of any other userspace process on the system.
Link: http://lkml.kernel.org/r/1477949533-2509-1-git-send-email-jann@thejh.net
Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
|
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commit c2a9737f45e27d8263ff9643f994bda9bac0b944 upstream.
We triggered a deadloop in truncate_inode_pages_range() on 32 bits
architecture with the test case bellow:
...
fd = open();
write(fd, buf, 4096);
preadv64(fd, &iovec, 1, 0xffffffff000);
ftruncate(fd, 0);
...
Then ftruncate() will not return forever.
The filesystem used in this case is ubifs, but it can be triggered on
many other filesystems.
When preadv64() is called with offset=0xffffffff000, a page with
index=0xffffffff will be added to the radix tree of ->mapping. Then
this page can be found in ->mapping with pagevec_lookup(). After that,
truncate_inode_pages_range(), which is called in ftruncate(), will fall
into an infinite loop:
- find a page with index=0xffffffff, since index>=end, this page won't
be truncated
- index++, and index become 0
- the page with index=0xffffffff will be found again
The data type of index is unsigned long, so index won't overflow to 0 on
64 bits architecture in this case, and the dead loop won't happen.
Since truncate_inode_pages_range() is executed with holding lock of
inode->i_rwsem, any operation related with this lock will be blocked,
and a hung task will happen, e.g.:
INFO: task truncate_test:3364 blocked for more than 120 seconds.
...
call_rwsem_down_write_failed+0x17/0x30
generic_file_write_iter+0x32/0x1c0
ubifs_write_iter+0xcc/0x170
__vfs_write+0xc4/0x120
vfs_write+0xb2/0x1b0
SyS_write+0x46/0xa0
The page with index=0xffffffff added to ->mapping is useless. Fix this
by checking the read position before allocating pages.
Link: http://lkml.kernel.org/r/1475151010-40166-1-git-send-email-fangwei1@huawei.com
Signed-off-by: Wei Fang <fangwei1@huawei.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 082d5b6b60e9f25e1511557fcfcb21eedd267446 upstream.
In dissolve_free_huge_pages(), free hugepages will be dissolved without
making sure that there are enough of them left to satisfy hugepage
reservations.
Fix this by adding a return value to dissolve_free_huge_pages() and
checking h->free_huge_pages vs. h->resv_huge_pages. Note that this may
lead to the situation where dissolve_free_huge_page() returns an error
and all free hugepages that were dissolved before that error are lost,
while the memory block still cannot be set offline.
Fixes: c8721bbb ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Link: http://lkml.kernel.org/r/20160926172811.94033-3-gerald.schaefer@de.ibm.com
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Rui Teng <rui.teng@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 2247bb335ab9c40058484cac36ea74ee652f3b7b upstream.
Patch series "mm/hugetlb: memory offline issues with hugepages", v4.
This addresses several issues with hugepages and memory offline. While
the first patch fixes a panic, and is therefore rather important, the
last patch is just a performance optimization.
The second patch fixes a theoretical issue with reserved hugepages,
while still leaving some ugly usability issue, see description.
This patch (of 3):
dissolve_free_huge_pages() will either run into the VM_BUG_ON() or a
list corruption and addressing exception when trying to set a memory
block offline that is part (but not the first part) of a "gigantic"
hugetlb page with a size > memory block size.
When no other smaller hugetlb page sizes are present, the VM_BUG_ON()
will trigger directly. In the other case we will run into an addressing
exception later, because dissolve_free_huge_page() will not work on the
head page of the compound hugetlb page which will result in a NULL
hstate from page_hstate().
To fix this, first remove the VM_BUG_ON() because it is wrong, and then
use the compound head page in dissolve_free_huge_page(). This means
that an unused pre-allocated gigantic page that has any part of itself
inside the memory block that is going offline will be dissolved
completely. Losing an unused gigantic hugepage is preferable to failing
the memory offline, for example in the situation where a (possibly
faulty) memory DIMM needs to go offline.
Fixes: c8721bbb ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Link: http://lkml.kernel.org/r/20160926172811.94033-2-gerald.schaefer@de.ibm.com
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Rui Teng <rui.teng@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 3ddf40e8c31964b744ff10abb48c8e36a83ec6e7 upstream.
Commit 22f2ac51b6d6 ("mm: workingset: fix crash in shadow node shrinker
caused by replace_page_cache_page()") switched replace_page_cache() from
raw radix tree operations to page_cache_tree_insert() but didn't take
into account that the latter function, unlike the raw radix tree op,
handles mapping->nrpages. As a result, that counter is bumped for each
page replacement rather than balanced out even.
The mapping->nrpages counter is used to skip needless radix tree walks
when invalidating, truncating, syncing inodes without pages, as well as
statistics for userspace. Since the error is positive, we'll do more
page cache tree walks than necessary; we won't miss a necessary one.
And we'll report more buffer pages to userspace than there are. The
error is limited to fuse inodes.
Fixes: 22f2ac51b6d6 ("mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 31051c85b5e2aaaf6315f74c72a732673632a905 upstream.
inode_change_ok() will be resposible for clearing capabilities and IMA
extended attributes and as such will need dentry. Give it as an argument
to inode_change_ok() instead of an inode. Also rename inode_change_ok()
to setattr_prepare() to better relect that it does also some
modifications in addition to checks.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
[bwh: Backported to 3.16:
- Drop changes to orangefs, overlayfs
- Adjust filenames, context
- In nfsd, pass dentry to nfsd_sanitize_attrs()
- Update ext3 as well]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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|
This reverts commit be9df699432235753c3824b0f5a27d46de7fdc9e, which was
commit 31051c85b5e2aaaf6315f74c72a732673632a905 upstream. The backport
breaks fuse and makes a mess of xfs, which can be improved by picking
further upstream commits as I should have done in the first place.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit d3798ae8c6f3767c726403c2ca6ecc317752c9dd upstream.
When the underflow checks were added to workingset_node_shadow_dec(),
they triggered immediately:
kernel BUG at ./include/linux/swap.h:276!
invalid opcode: 0000 [#1] SMP
Modules linked in: isofs usb_storage fuse xt_CHECKSUM ipt_MASQUERADE nf_nat_masquerade_ipv4 tun nf_conntrack_netbios_ns nf_conntrack_broadcast ip6t_REJECT nf_reject_ipv6
soundcore wmi acpi_als pinctrl_sunrisepoint kfifo_buf tpm_tis industrialio acpi_pad pinctrl_intel tpm_tis_core tpm nfsd auth_rpcgss nfs_acl lockd grace sunrpc dm_crypt
CPU: 0 PID: 20929 Comm: blkid Not tainted 4.8.0-rc8-00087-gbe67d60ba944 #1
Hardware name: System manufacturer System Product Name/Z170-K, BIOS 1803 05/06/2016
task: ffff8faa93ecd940 task.stack: ffff8faa7f478000
RIP: page_cache_tree_insert+0xf1/0x100
Call Trace:
__add_to_page_cache_locked+0x12e/0x270
add_to_page_cache_lru+0x4e/0xe0
mpage_readpages+0x112/0x1d0
blkdev_readpages+0x1d/0x20
__do_page_cache_readahead+0x1ad/0x290
force_page_cache_readahead+0xaa/0x100
page_cache_sync_readahead+0x3f/0x50
generic_file_read_iter+0x5af/0x740
blkdev_read_iter+0x35/0x40
__vfs_read+0xe1/0x130
vfs_read+0x96/0x130
SyS_read+0x55/0xc0
entry_SYSCALL_64_fastpath+0x13/0x8f
Code: 03 00 48 8b 5d d8 65 48 33 1c 25 28 00 00 00 44 89 e8 75 19 48 83 c4 18 5b 41 5c 41 5d 41 5e 5d c3 0f 0b 41 bd ef ff ff ff eb d7 <0f> 0b e8 88 68 ef ff 0f 1f 84 00
RIP page_cache_tree_insert+0xf1/0x100
This is a long-standing bug in the way shadow entries are accounted in
the radix tree nodes. The shrinker needs to know when radix tree nodes
contain only shadow entries, no pages, so node->count is split in half
to count shadows in the upper bits and pages in the lower bits.
Unfortunately, the radix tree implementation doesn't know of this and
assumes all entries are in node->count. When there is a shadow entry
directly in root->rnode and the tree is later extended, the radix tree
implementation will copy that entry into the new node and and bump its
node->count, i.e. increases the page count bits. Once the shadow gets
removed and we subtract from the upper counter, node->count underflows
and triggers the warning. Afterwards, without node->count reaching 0
again, the radix tree node is leaked.
Limit shadow entries to when we have actual radix tree nodes and can
count them properly. That means we lose the ability to detect refaults
from files that had only the first page faulted in at eviction time.
Fixes: 449dd6984d0e ("mm: keep page cache radix tree nodes in check")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-and-tested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[Johannes Weiner: it's drastically different than the upstream change,
but a lot simpler because it predates the DAX stuff.]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 31051c85b5e2aaaf6315f74c72a732673632a905 upstream.
inode_change_ok() will be resposible for clearing capabilities and IMA
extended attributes and as such will need dentry. Give it as an argument
to inode_change_ok() instead of an inode. Also rename inode_change_ok()
to setattr_prepare() to better relect that it does also some
modifications in addition to checks.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
[bwh: Backported to 3.16:
- Drop changes to orangefs, overlayfs
- Adjust filenames, context
- In fuse, pass dentry to fuse_do_setattr()
- In nfsd, pass dentry to nfsd_sanitize_attrs()
- In xfs, pass dentry to xfs_setattr_nonsize() and xfs_setattr_size()
- Update ext3 as well]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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replace_page_cache_page()
commit 22f2ac51b6d643666f4db093f13144f773ff3f3a upstream.
Antonio reports the following crash when using fuse under memory pressure:
kernel BUG at /build/linux-a2WvEb/linux-4.4.0/mm/workingset.c:346!
invalid opcode: 0000 [#1] SMP
Modules linked in: all of them
CPU: 2 PID: 63 Comm: kswapd0 Not tainted 4.4.0-36-generic #55-Ubuntu
Hardware name: System manufacturer System Product Name/P8H67-M PRO, BIOS 3904 04/27/2013
task: ffff88040cae6040 ti: ffff880407488000 task.ti: ffff880407488000
RIP: shadow_lru_isolate+0x181/0x190
Call Trace:
__list_lru_walk_one.isra.3+0x8f/0x130
list_lru_walk_one+0x23/0x30
scan_shadow_nodes+0x34/0x50
shrink_slab.part.40+0x1ed/0x3d0
shrink_zone+0x2ca/0x2e0
kswapd+0x51e/0x990
kthread+0xd8/0xf0
ret_from_fork+0x3f/0x70
which corresponds to the following sanity check in the shadow node
tracking:
BUG_ON(node->count & RADIX_TREE_COUNT_MASK);
The workingset code tracks radix tree nodes that exclusively contain
shadow entries of evicted pages in them, and this (somewhat obscure)
line checks whether there are real pages left that would interfere with
reclaim of the radix tree node under memory pressure.
While discussing ways how fuse might sneak pages into the radix tree
past the workingset code, Miklos pointed to replace_page_cache_page(),
and indeed there is a problem there: it properly accounts for the old
page being removed - __delete_from_page_cache() does that - but then
does a raw raw radix_tree_insert(), not accounting for the replacement
page. Eventually the page count bits in node->count underflow while
leaving the node incorrectly linked to the shadow node LRU.
To address this, make sure replace_page_cache_page() uses the tracked
page insertion code, page_cache_tree_insert(). This fixes the page
accounting and makes sure page-containing nodes are properly unlinked
from the shadow node LRU again.
Also, make the sanity checks a bit less obscure by using the helpers for
checking the number of pages and shadows in a radix tree node.
Fixes: 449dd6984d0e ("mm: keep page cache radix tree nodes in check")
Link: http://lkml.kernel.org/r/20160919155822.29498-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Antonio SJ Musumeci <trapexit@spawn.link>
Debugged-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Implementation of page_cache_tree_insert() is different
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 5b398e416e880159fe55eefd93c6588fa072cd66 upstream.
I hit the following hung task when runing a OOM LTP test case with 4.1
kernel.
Call trace:
[<ffffffc000086a88>] __switch_to+0x74/0x8c
[<ffffffc000a1bae0>] __schedule+0x23c/0x7bc
[<ffffffc000a1c09c>] schedule+0x3c/0x94
[<ffffffc000a1eb84>] rwsem_down_write_failed+0x214/0x350
[<ffffffc000a1e32c>] down_write+0x64/0x80
[<ffffffc00021f794>] __ksm_exit+0x90/0x19c
[<ffffffc0000be650>] mmput+0x118/0x11c
[<ffffffc0000c3ec4>] do_exit+0x2dc/0xa74
[<ffffffc0000c46f8>] do_group_exit+0x4c/0xe4
[<ffffffc0000d0f34>] get_signal+0x444/0x5e0
[<ffffffc000089fcc>] do_signal+0x1d8/0x450
[<ffffffc00008a35c>] do_notify_resume+0x70/0x78
The oom victim cannot terminate because it needs to take mmap_sem for
write while the lock is held by ksmd for read which loops in the page
allocator
ksm_do_scan
scan_get_next_rmap_item
down_read
get_next_rmap_item
alloc_rmap_item #ksmd will loop permanently.
There is no way forward because the oom victim cannot release any memory
in 4.1 based kernel. Since 4.6 we have the oom reaper which would solve
this problem because it would release the memory asynchronously.
Nevertheless we can relax alloc_rmap_item requirements and use
__GFP_NORETRY because the allocation failure is acceptable as ksm_do_scan
would just retry later after the lock got dropped.
Such a patch would be also easy to backport to older stable kernels which
do not have oom_reaper.
While we are at it add GFP_NOWARN so the admin doesn't have to be alarmed
by the allocation failure.
Link: http://lkml.kernel.org/r/1474165570-44398-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Suggested-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit df08c32ce3be5be138c1dbfcba203314a3a7cd6f upstream.
The name for a bdi of a gendisk is derived from the gendisk's devt.
However, since the gendisk is destroyed before the bdi it leaves a
window where a new gendisk could dynamically reuse the same devt while a
bdi with the same name is still live. Arrange for the bdi to hold a
reference against its "owner" disk device while it is registered.
Otherwise we can hit sysfs duplicate name collisions like the following:
WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80
sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1'
Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015
0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec
ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351
0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8
Call Trace:
[<ffffffff8134caec>] dump_stack+0x63/0x87
[<ffffffff8108c351>] __warn+0xd1/0xf0
[<ffffffff8108c3cf>] warn_slowpath_fmt+0x5f/0x80
[<ffffffff812a0d34>] sysfs_warn_dup+0x64/0x80
[<ffffffff812a0e1e>] sysfs_create_dir_ns+0x7e/0x90
[<ffffffff8134faaa>] kobject_add_internal+0xaa/0x320
[<ffffffff81358d4e>] ? vsnprintf+0x34e/0x4d0
[<ffffffff8134ff55>] kobject_add+0x75/0xd0
[<ffffffff816e66b2>] ? mutex_lock+0x12/0x2f
[<ffffffff8148b0a5>] device_add+0x125/0x610
[<ffffffff8148b788>] device_create_groups_vargs+0xd8/0x100
[<ffffffff8148b7cc>] device_create_vargs+0x1c/0x20
[<ffffffff811b775c>] bdi_register+0x8c/0x180
[<ffffffff811b7877>] bdi_register_dev+0x27/0x30
[<ffffffff813317f5>] add_disk+0x175/0x4a0
Reported-by: Yi Zhang <yizhan@redhat.com>
Tested-by: Yi Zhang <yizhan@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Fixed up missing 0 return in bdi_register_owner().
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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