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authorHeiko Carstens <heiko.carstens@de.ibm.com>2014-07-02 15:22:37 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-07-03 09:21:54 -0700
commitf74373a5cc7a0155d232c4e999648c7a95435bb2 (patch)
tree9fe161e959fa98bf4dc32d994ab9f781aecc0ef8
parent0bc1f8b0682caa39f45ce1e0228ebf43acb46111 (diff)
/proc/stat: convert to single_open_size()
These two patches are supposed to "fix" failed order-4 memory allocations which have been observed when reading /proc/stat. The problem has been observed on s390 as well as on x86. To address the problem change the seq_file memory allocations to fallback to use vmalloc, so that allocations also work if memory is fragmented. This approach seems to be simpler and less intrusive than changing /proc/stat to use an interator. Also it "fixes" other users as well, which use seq_file's single_open() interface. This patch (of 2): Use seq_file's single_open_size() to preallocate a buffer that is large enough to hold the whole output, instead of open coding it. Also calculate the requested size using the number of online cpus instead of possible cpus, since the size of the output only depends on the number of online cpus. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Ian Kent <raven@themaw.net> Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Cc: Thorsten Diehl <thorsten.diehl@de.ibm.com> Cc: Andrea Righi <andrea@betterlinux.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Stefan Bader <stefan.bader@canonical.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/proc/stat.c22
1 files changed, 2 insertions, 20 deletions
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 9d231e9e5f0e..bf2d03f8fd3e 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -184,29 +184,11 @@ static int show_stat(struct seq_file *p, void *v)
static int stat_open(struct inode *inode, struct file *file)
{
- size_t size = 1024 + 128 * num_possible_cpus();
- char *buf;
- struct seq_file *m;
- int res;
+ size_t size = 1024 + 128 * num_online_cpus();
/* minimum size to display an interrupt count : 2 bytes */
size += 2 * nr_irqs;
-
- /* don't ask for more than the kmalloc() max size */
- if (size > KMALLOC_MAX_SIZE)
- size = KMALLOC_MAX_SIZE;
- buf = kmalloc(size, GFP_KERNEL);
- if (!buf)
- return -ENOMEM;
-
- res = single_open(file, show_stat, NULL);
- if (!res) {
- m = file->private_data;
- m->buf = buf;
- m->size = ksize(buf);
- } else
- kfree(buf);
- return res;
+ return single_open_size(file, show_stat, NULL, size);
}
static const struct file_operations proc_stat_operations = {