This patch fixes 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.
Signed-off-by: Greg Thelen <gthe...@google.com>
---
mm/shmem.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index efd0b3a..ed2cb26 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2386,6 +2386,7 @@ static int shmem_parse_options(char *options, struct
shmem_sb_info *sbinfo,
bool remount)
{
char *this_char, *value, *rest;
+ struct mempolicy *mpol = NULL;
uid_t uid;
gid_t gid;
@@ -2414,7 +2415,7 @@ 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")) {
@@ -2463,19 +2464,23 @@ static int shmem_parse_options(char *options, struct
shmem_sb_info *sbinfo,
if (!gid_valid(sbinfo->gid))
goto bad_val;
} else if (!strcmp(this_char,"mpol")) {
- if (mpol_parse_str(value, &sbinfo->mpol))
+ mpol_put(mpol);
+ if (mpol_parse_str(value, &mpol))
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;
}
@@ -2551,6 +2556,7 @@ 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;
}
--
1.8.1.3
--
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