On Fri, 15 Jul 2016, Michal Hocko wrote: > On Fri 15-07-16 08:11:22, Mikulas Patocka wrote: > > > > The stacktraces showed that the kcryptd process was throttled when it > > tried to do mempool allocation. Mempool adds the __GFP_NORETRY flag to the > > allocation, but unfortunatelly, this flag doesn't prevent the allocator > > from throttling. > > Yes and in fact it shouldn't prevent any throttling. The flag merely > says that the allocation should give up rather than retry > reclaim/compaction again and again. > > > I say that the process doing mempool allocation shouldn't ever be > > throttled. Maybe add __GFP_NOTHROTTLE? > > A specific gfp flag would be an option but we are slowly running out of > bit space there and I am not yet convinced PF_LESS_THROTTLE is > unsuitable. PF_LESS_THROTTLE will make it throttle less, but it doesn't eliminate throttling entirely. So, maybe add PF_NO_THROTTLE? But PF_* flags are also almost exhausted. > I might be missing something but exactly this is what happens in > wait_iff_congested no? If the bdi doesn't see the congestion it wakes up > the reclaim context even before the timeout. Or are we talking past each > other? OK, I see that there is wait queue in congestion_wait. I didn't notice it before. Mikulas > -- > Michal Hocko > SUSE Labs > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>