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Commit 49cd0a5c authored by Greg Thelen's avatar Greg Thelen Committed by Linus Torvalds
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tmpfs: fix mempolicy object leaks 



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: default avatarGreg Thelen <gthelen@google.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5f00110f

mm/shmem.c

+10 −3
Original line number Original line Diff line number Diff line
@@ -2385,6 +2385,7 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 
			       bool remount)

			       bool remount)

{

{

	char *this_char, *value, *rest;

	char *this_char, *value, *rest;

	struct mempolicy *mpol = NULL;

	uid_t uid;

	uid_t uid;

	gid_t gid;

	gid_t gid;
@@ -2413,7 +2414,7 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 
			printk(KERN_ERR

			printk(KERN_ERR

			    "tmpfs: No value for mount option '%s'\n",

			    "tmpfs: No value for mount option '%s'\n",

			    this_char);

			    this_char);

			return 1;

			goto error;

		}

		}





		if (!strcmp(this_char,"size")) {

		if (!strcmp(this_char,"size")) {
@@ -2462,19 +2463,24 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 
			if (!gid_valid(sbinfo->gid))

			if (!gid_valid(sbinfo->gid))

				goto bad_val;

				goto bad_val;

		} else if (!strcmp(this_char,"mpol")) {

		} else if (!strcmp(this_char,"mpol")) {

			if (mpol_parse_str(value, &sbinfo->mpol))

			mpol_put(mpol);

			mpol = NULL;

			if (mpol_parse_str(value, &mpol))

				goto bad_val;

				goto bad_val;

		} else {

		} else {

			printk(KERN_ERR "tmpfs: Bad mount option %s\n",

			printk(KERN_ERR "tmpfs: Bad mount option %s\n",

			       this_char);

			       this_char);

			return 1;

			goto error;

		}

		}

	}

	}

	sbinfo->mpol = mpol;

	return 0;

	return 0;





bad_val:

bad_val:

	printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",

	printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",

	       value, this_char);

	       value, this_char);

error:

	mpol_put(mpol);

	return 1;

	return 1;





}

}
@@ -2550,6 +2556,7 @@ static void shmem_put_super(struct super_block *sb) 
	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);

	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);





	percpu_counter_destroy(&sbinfo->used_blocks);

	percpu_counter_destroy(&sbinfo->used_blocks);

	mpol_put(sbinfo->mpol);

	kfree(sbinfo);

	kfree(sbinfo);

	sb->s_fs_info = NULL;

	sb->s_fs_info = NULL;

}

}