Messages in this thread Patch in this message | | | Date | Mon, 23 Jan 2012 15:39:34 -0800 | From | Greg KH <> | Subject | [48/90] fsnotify: dont BUG in fsnotify_destroy_mark() |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: Miklos Szeredi <mszeredi@suse.cz>
commit fed474857efbed79cd390d0aee224231ca718f63 upstream.
Removing the parent of a watched file results in "kernel BUG at fs/notify/mark.c:139".
To reproduce
add "-w /tmp/audit/dir/watched_file" to audit.rules rm -rf /tmp/audit/dir
This is caused by fsnotify_destroy_mark() being called without an extra reference taken by the caller.
Reported by Francesco Cosoleto here:
https://bugzilla.novell.com/show_bug.cgi?id=689860
Fix by removing the BUG_ON and adding a comment about not accessing mark after the iput.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/notify/mark.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- a/fs/notify/mark.c +++ b/fs/notify/mark.c @@ -135,9 +135,6 @@ void fsnotify_destroy_mark(struct fsnoti mark->flags &= ~FSNOTIFY_MARK_FLAG_ALIVE; - /* 1 from caller and 1 for being on i_list/g_list */ - BUG_ON(atomic_read(&mark->refcnt) < 2); - spin_lock(&group->mark_lock); if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) { @@ -182,6 +179,11 @@ void fsnotify_destroy_mark(struct fsnoti iput(inode); /* + * We don't necessarily have a ref on mark from caller so the above iput + * may have already destroyed it. Don't touch from now on. + */ + + /* * it's possible that this group tried to destroy itself, but this * this mark was simultaneously being freed by inode. If that's the * case, we finish freeing the group here.
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