Re: Kernel oops+crash on repeated auditd restarts

On Tue, 2012-04-24 at 02:12 -0300, Marcelo Cerri wrote: > On Mon, 23 Apr 2012 12:26:16 -0400, Eric Paris <eparis(a)redhat.com&gt; wrote: > Considering that the issue is specific to audit and it seems to occur > only with watches on directories, I investigated the audit_tree.c file > and found a probable cause. The untag_chunk() holds a reference to a > mark at the begging of the function and releases it at the end of it (on > the label out). However when it jumps to the "out" label, it calls > fsnotify_put_mark once more. > > Peter and Valentin, can you test this new patch to check if it > solves the oops problem? > > Eric, do you agree with this solution? > > Regards, > Marcelo > > --- >  kernel/audit_tree.c |    2 -- >  1 file changed, 2 deletions(-) > > diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c > index 5bf0790..b5bd9f9 100644 > --- a/kernel/audit_tree.c > +++ b/kernel/audit_tree.c > @@ -250,7 +250,6 @@ static void untag_chunk(struct node *p) >         spin_unlock(&hash_lock); >         spin_unlock(&entry->lock); >         fsnotify_destroy_mark(entry); > -       fsnotify_put_mark(entry); >         goto out; >     } > > @@ -293,7 +292,6 @@ static void untag_chunk(struct node *p) >     spin_unlock(&hash_lock); >     spin_unlock(&entry->lock); >     fsnotify_destroy_mark(entry); > -   fsnotify_put_mark(entry); >     goto out; > >  Fallback: This looks right to me.  The old audit logic before the switch to fsnotify was: -       inotify_evict_watch(&chunk->watch); -       mutex_unlock(&chunk->watch.inode->inotify_mutex); -       put_inotify_watch(&chunk->watch); Which I changed to: +       spin_unlock(&entry->lock); +       fsnotify_destroy_mark_by_entry(entry); +       fsnotify_put_mark(entry); The difference being that inotify_evict_watch() took a reference on chunk->watch, however fsnotify_destroy_mark_by_entry() does not.  So the fsnotify_put_mark() was incorrect. I'd love to hear testing results, and I'm going to try to figure out if I screwed that up other places....

-Eric