The patch titled
Subject: proc/stat: convert to single_open_size()
has been added to the -mm tree. Its filename is
proc-stat-convert-to-single_open_size.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-stat-convert-to-single_open_size.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-stat-convert-to-single_open_size.patch
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------------------------------------------------------
From: Heiko Carstens <[email protected]>
Subject: 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 <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Ian Kent <[email protected]>
Cc: Hendrik Brueckner <[email protected]>
Cc: Thorsten Diehl <[email protected]>
Cc: Andrea Righi <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Stefan Bader <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
fs/proc/stat.c | 22 ++--------------------
1 file changed, 2 insertions(+), 20 deletions(-)
diff -puN fs/proc/stat.c~proc-stat-convert-to-single_open_size fs/proc/stat.c
--- a/fs/proc/stat.c~proc-stat-convert-to-single_open_size
+++ a/fs/proc/stat.c
@@ -184,29 +184,11 @@ static int show_stat(struct seq_file *p,
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 = {
_
Patches currently in -mm which might be from [email protected] are
proc-stat-convert-to-single_open_size.patch
fs-seq_file-fallback-to-vmalloc-allocation.patch
lib-scatterlist-make-arch_has_sg_chain-an-actual-kconfig.patch
lib-scatterlist-clean-up-useless-architecture-versions-of-scatterlisth.patch
linux-next.patch
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