tmpfs: fix mempolicy object leaks (49cd0a5c) · Commits · 戴 / test

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>

mm/shmem.c

+10 −3

Original line number	Diff line number	Diff line
		@@ -2385,6 +2385,7 @@ 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;

		@@ -2413,7 +2414,7 @@ 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")) {
		@@ -2462,19 +2463,24 @@ 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);
		mpol = NULL;
		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;

		}
		@@ -2550,6 +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;
		}

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