Messages in this thread Patch in this message | | | Date | Mon, 13 Jan 2014 07:04:41 +0100 | From | Jan Kara <> | Subject | Re: [PATCH mmotm/next] fanotify: fix corruption preventing startup |
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On Sat 11-01-14 22:54:15, Hugh Dickins wrote: > Two of my machines couldn't boot mmotm with fanotify enabled: > 0x40000020 was being or'ed into a group's notification_waitq next > pointer, with sad results. It comes from an over-simplification in > fanotify_merge(): test_event isn't NULL when the loop finds no merge. That's a really dumb bug. Thanks for the fix! It looks good, you can add: Reviewed-by: Jan Kara <jack@suse.cz>
I was wondering why I didn't see this problem during my testing. I was always running my tests with various debug options enabled (in a hope to catch more problems ;), in particular with spinlock debugging enabled which shifted the waitqueue pointers further and the corruption landed in spinlock debugging fields and never got noticed... Ew :-|
Honza > > Signed-off-by: Hugh Dickins <hughd@google.com> > --- > Fixes fsnotify-do-not-share-events-between-notification-groups.patch > > fs/notify/fanotify/fanotify.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > --- mmotm/fs/notify/fanotify/fanotify.c 2014-01-10 18:25:01.700448941 -0800 > +++ linux/fs/notify/fanotify/fanotify.c 2014-01-11 22:15:31.580961010 -0800 > @@ -37,16 +37,19 @@ static bool should_merge(struct fsnotify > static struct fsnotify_event *fanotify_merge(struct list_head *list, > struct fsnotify_event *event) > { > - struct fsnotify_event *test_event = NULL; > + struct fsnotify_event *test_event; > + bool do_merge = false; > > pr_debug("%s: list=%p event=%p\n", __func__, list, event); > > list_for_each_entry_reverse(test_event, list, list) { > - if (should_merge(test_event, event)) > + if (should_merge(test_event, event)) { > + do_merge = true; > break; > + } > } > > - if (!test_event) > + if (!do_merge) > return NULL; > > test_event->mask |= event->mask; -- Jan Kara <jack@suse.cz> SUSE Labs, CR
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