On Tue 03-09-19 18:59:59, Park Sangwoo wrote: > >On Mon 02-09-19 13:34:54, Sangwoo� wrote: > >>>On Fri 30-08-19 18:25:53, Sangwoo wrote: > >>>> The highatomic migrate block can be increased to 1% of Total memory. > >>>> And, this is for only highorder ( > 0 order). So, this block size is > >>>> excepted during check watermark if allocation type isn't alloc_harder. > >>>> > >>>> It has problem. The usage of highatomic is already calculated at > >> NR_FREE_PAGES. > >>>> So, if we except total block size of highatomic, it's twice minus size of > >>allocated > >>>> highatomic. > >>>> It's cause allocation fail although free pages enough. > >>>> > >>>> We checked this by random test on my target(8GB RAM). > >>>> > >>>> Binder:6218_2: page allocation failure: order:0, mode:0x14200ca > >> (GFP_HIGHUSER_MOVABLE), nodemask=(null) > >>>> Binder:6218_2 cpuset=background mems_allowed=0 > >>> > >>>How come this order-0 sleepable allocation fails? The upstream kernel > >>>doesn't fail those allocations unless the process context is killed by > >>>the oom killer. > >> > >> Most calltacks are zsmalloc, as shown below. > > > >What makes those allocations special so that they fail unlike any other > >normal order-0 requests? Also do you see the same problem with the > >current upstream kernel? Is it possible this is an Android specific > >issue? > > There is the other case of fail order-0 fail. > ---- > hvdcp_opti: page allocation failure: order:0, mode:0x1004000(GFP_NOWAIT|__GFP_COMP), nodemask=(null) This is an atomic allocation and failing that one is not a problem usually. High atomic reservations might prevent GFP_NOWAIT allocation from suceeding but I do not see that as a problem. This is the primary purpose of the reservation. [...] > In my test, most case are using camera. So, memory usage is increased momentarily, > it cause free page go to under low value of watermark. > If free page is under low and 0-order fail is occured, its normal operation. > But, although free page is higher than min, fail is occurred. > After fix routin for checking highatomic size, it's not reproduced. But you are stealing from the atomic reserves and thus defeating the purpose of it. -- Michal Hocko SUSE Labs
