Messages in this thread | | | Date | Thu, 16 Jul 2020 18:29:31 +0200 | From | Christian Brauner <> | Subject | Re: [PATCH v2] binder: Don't use mmput() from shrinker function. |
| |
On Thu, Jul 16, 2020 at 05:17:56PM +0200, Michal Hocko wrote: > On Fri 17-07-20 00:12:15, Tetsuo Handa wrote: > > syzbot is reporting that mmput() from shrinker function has a risk of > > deadlock [1], for delayed_uprobe_add() from update_ref_ctr() calls > > kzalloc(GFP_KERNEL) with delayed_uprobe_lock held, and > > uprobe_clear_state() from __mmput() also holds delayed_uprobe_lock. > > > > Commit a1b2289cef92ef0e ("android: binder: drop lru lock in isolate > > callback") replaced mmput() with mmput_async() in order to avoid sleeping > > with spinlock held. But this patch replaces mmput() with mmput_async() in > > order not to start __mmput() from shrinker context. > > > > [1] https://syzkaller.appspot.com/bug?id=bc9e7303f537c41b2b0cc2dfcea3fc42964c2d45 > > > > Reported-by: syzbot <syzbot+1068f09c44d151250c33@syzkaller.appspotmail.com> > > Reported-by: syzbot <syzbot+e5344baa319c9a96edec@syzkaller.appspotmail.com> > > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > > Reviewed-by: Michal Hocko <mhocko@suse.com>
Thanks for the careful review Michal! Does this need a Cc: stable?
Otherwise
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Thanks! Christian
| |