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Tetsuo Handa authored
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 a1b2289c ("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=bc9e7303f537c41b2b0cc2dfcea3fc42964c2d45Reported-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> Acked-by:
Todd Kjos <tkjos@google.com> Acked-by:
Christian Brauner <christian.brauner@ubuntu.com> Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/4ba9adb2-43f5-2de0-22de-f6075c1fab50@i-love.sakura.ne.jpSigned-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
f867c771