On Tue, Sep 13, 2011 at 02:16:03PM -0700, Andrew Morton wrote:
> On Tue, 13 Sep 2011 16:22:48 -0400
> Jason Baron <jbaron@xxxxxxxxxx> wrote:
>
> > On Wed, Sep 07, 2011 at 08:04:29PM -0400, Josh Boyer wrote:
> > > On Tue, Aug 09, 2011 at 02:11:55PM -0400, Nelson Elhage wrote:
> > > > epoll can acquire recursively acquire ep->mtx on multiple "struct
> > > > eventpoll"s at once in the case where one epoll fd is monitoring
> > > > another epoll fd. This is perfectly OK, since we're careful about the
> > > > lock ordering, but it causes spurious lockdep warnings. Annotate the
> > > > recursion using mutex_lock_nested, and add a comment explaining the
> > > > nesting rules for good measure.
> > > >
> > > > Recent versions of systemd are triggering this, and it can also be
> > > > demonstrated with the following trivial test program:
> > > >
> > > > --------------------8<--------------------
> > > >
> > > > int main(void) {
> > > > int e1, e2;
> > > > struct epoll_event evt = {
> > > > .events = EPOLLIN
> > > > };
> > > >
> > > > e1 = epoll_create1(0);
> > > > e2 = epoll_create1(0);
> > > > epoll_ctl(e1, EPOLL_CTL_ADD, e2, &evt);
> > > > return 0;
> > > > }
> > > > --------------------8<--------------------
> > > >
> > > > Cc: stable@xxxxxxxxxx
> > > > Reported-by: Paul Bolle <pebolle@xxxxxxxxxx>
> > > > Tested-by: Paul Bolle <pebolle@xxxxxxxxxx>
> > > > Signed-off-by: Nelson Elhage <nelhage@xxxxxxxxxxx>
> > >
> > > Any progress on this heading upstream?
> > >
> >
> > Patch looks good to me, feel free to add:
> >
> > Acked-by: Jason Baron <jbaron@xxxxxxxxxx>
> >
> > However, I am going to have to re-base the epoll path I recently posted:
> > https://lkml.org/lkml/2011/9/2/295, if this goes in first. Perhaps,
> > Andrew (added to the 'cc), can help us sort out the ordering...
>
> I have already fixed up epoll-limit-paths.patch. You're planning on
> sending a new version of that patch. Please do base that on
> epoll-fix-spurious-lockdep-warnings.patch.
Ok, where can I get at these patches? With:
http://userweb.kernel.org/~akpm/mmotm/, still down.
Thanks,
-Jason
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
