On 2022/07/22 20:04, Michal Hocko wrote: > On Fri 22-07-22 19:45:39, Tetsuo Handa wrote: >> syzbot is reporting GFP_KERNEL allocation with oom_lock held when reporting >> memcg OOM [1]. Such allocation request might deadlock the system, for >> __alloc_pages_may_oom() cannot invoke global OOM killer due to oom_lock >> being already held by the caller. > > OK, I have misunderstood your previous wording and now I have realized > that there are 2 issues here. One of them is a (less likely) dead lock on > the oom_lock not making a fwd progress (that would require global OOM > racing with memcg OOM) and the other is the GFP_NOFS->GFP_KERNEL dependency > which can deadlock even without global the above race. > Correct? Correct. > > Sorry I could have realized that sooner. > No problem. Thanks for suggestion.
