On 06/20/2018 01:55 PM, Michal Hocko wrote: > On Wed 20-06-18 20:20:38, Tetsuo Handa wrote: >> Sleeping with oom_lock held can cause AB-BA lockup bug because >> __alloc_pages_may_oom() does not wait for oom_lock. Since >> blocking_notifier_call_chain() in out_of_memory() might sleep, sleeping >> with oom_lock held is currently an unavoidable problem. > Could you be more specific about the potential deadlock? Sleeping while > holding oom lock is certainly not nice but I do not see how that would > result in a deadlock assuming that the sleeping context doesn't sleep on > the memory allocation obviously.
It is a mutex you are supposed to be able to sleep. It's even exported. >> As a preparation for not to sleep with oom_lock held, this patch brings >> OOM notifier callbacks to outside of OOM killer, with two small behavior >> changes explained below. > Can we just eliminate this ugliness and remove it altogether? We do not > have that many notifiers. Is there anything fundamental that would > prevent us from moving them to shrinkers instead? @Hocko Do you remember the lowmemorykiller from android? Some things might not be the right thing for shrinkers.
