The patch titled
vfs: fix infinite loop caused by clone_mnt race
has been added to the -mm tree. Its filename is
vfs-fix-infinite-loop-caused-by-clone_mnt-race.patch
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: vfs: fix infinite loop caused by clone_mnt race
From: Miklos Szeredi <mszeredi@xxxxxxx>
If clone_mnt() happens while mnt_make_readonly() is running, the cloned
mount might have MNT_WRITE_HOLD flag set, which results in
mnt_want_write() spinning forever on this mount.
Needs CAP_SYS_ADMIN to trigger deliberately and unlikely to happen
accidentally. But if it does happen it can hang the machine.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/namespace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN fs/namespace.c~vfs-fix-infinite-loop-caused-by-clone_mnt-race fs/namespace.c
--- a/fs/namespace.c~vfs-fix-infinite-loop-caused-by-clone_mnt-race
+++ a/fs/namespace.c
@@ -595,7 +595,7 @@ static struct vfsmount *clone_mnt(struct
goto out_free;
}
- mnt->mnt_flags = old->mnt_flags;
+ mnt->mnt_flags = old->mnt_flags & ~MNT_WRITE_HOLD;
atomic_inc(&sb->s_active);
mnt->mnt_sb = sb;
mnt->mnt_root = dget(root);
_
Patches currently in -mm which might be from mszeredi@xxxxxxx are
linux-next.patch
vfs-fix-infinite-loop-caused-by-clone_mnt-race.patch
vfs-ignore-error-on-forced-remount.patch
vfs-fix-per-mount-read-write.patch
vfs-add-sb_force_remount_readonly-helper.patch
vfs-allow-mnt_want_write-to-sleep.patch
vfs-allow-mnt_want_write-to-sleep-fix.patch
vfs-keep-list-of-mounts-for-each-superblock.patch
vfs-protect-remounting-superblock-read-only.patch
vfs-fs_may_remount_ro-turn-unnecessary-check-into-a-warn_on.patch
vfs-mark-mounts-read-only-on-forced-remount.patch
fuse-use-clear_highpage-and-km_user0-instead-of-km_user1.patch
fuse-use-release_pages.patch
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