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tmpfs: fix mempolicy object leaks

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Fix several mempolicy leaks in the tmpfs mount logic.  These leaks are
slow - on the order of one object leaked per mount attempt.

Leak 1 (umount doesn't free mpol allocated in mount):
    while true; do
        mount -t tmpfs -o mpol=interleave,size=100M nodev /mnt
        umount /mnt
    done

Leak 2 (errors parsing remount options will leak mpol):
    mount -t tmpfs -o size=100M nodev /mnt
    while true; do
        mount -o remount,mpol=interleave,size=x /mnt 2> /dev/null
    done
    umount /mnt

Leak 3 (multiple mpol per mount leak mpol):
    while true; do
        mount -t tmpfs -o mpol=interleave,mpol=interleave,size=100M nodev /mnt
        umount /mnt
    done

This patch fixes all of the above.  I could have broken the patch into
three pieces but is seemed easier to review as one.

[akpm@linux-foundation.org: fix handling of mpol_parse_str() errors, per Hugh]
Signed-off-by: Greg Thelen <gthelen@google.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>

Change-Id: I96c06e9b7322b3ef146a0d04a57dc61dc801c177
This commit is contained in:
Greg Thelen 2013-02-22 16:36:02 -08:00 committed by surblazer
parent ce81fe0b60
commit 30ddc0def4
1 changed files with 10 additions and 3 deletions
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13
mm/shmem.c
View file

@ -2422,6 +2422,7 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
bool remount)
{
char *this_char, *value, *rest;
struct mempolicy *mpol = NULL;
while (options != NULL) {
this_char = options;
@ -2448,7 +2449,7 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
printk(KERN_ERR
"tmpfs: No value for mount option '%s'\n",
this_char);
return 1;
goto error;
}
if (!strcmp(this_char,"size")) {
@ -2491,19 +2492,24 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"mpol")) {
if (mpol_parse_str(value, &sbinfo->mpol, 1))
mpol_put(mpol);
mpol = NULL;
if (mpol_parse_str(value, &mpol, 1))
goto bad_val;
} else {
printk(KERN_ERR "tmpfs: Bad mount option %s\n",
this_char);
return 1;
goto error;
}
}
sbinfo->mpol = mpol;
return 0;
bad_val:
printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
value, this_char);
error:
mpol_put(mpol);
return 1;
}
@ -2646,6 +2652,7 @@ static void shmem_put_super(struct super_block *sb)
struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
percpu_counter_destroy(&sbinfo->used_blocks);
mpol_put(sbinfo->mpol);
kfree(sbinfo);
sb->s_fs_info = NULL;
}