On 2019/01/03 3:19, Qian Cai wrote: > On 1/2/19 1:06 PM, Mel Gorman wrote: > >> While I recognise there is no test case available, how often does this >> trigger in syzbot as it would be nice to have some confirmation any >> patch is really fixing the problem. > > I think I did manage to trigger this every time running a mmap() workload > causing swapping and a low-memory situation [1]. > > [1] > https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/mem/oom/oom01.c wakeup_kswapd() is called because tlb_next_batch() is doing GFP_NOWAIT allocation. But since tlb_next_batch() can tolerate allocation failure, does below change in tlb_next_batch() help? #define GFP_NOWAIT (__GFP_KSWAPD_RECLAIM) - batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); + batch = (void *)__get_free_pages(__GFP_NOWARN, 0);
