On Sun, Mar 11, 2018 at 11:11:52PM +0500, Mikhail Gavrilov wrote: > $ uname -a > Linux localhost.localdomain 4.15.7-300.fc27.x86_64+debug #1 SMP Wed > Feb 28 17:32:16 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux > > > How reproduce: > 1. start virtual machine > 2. open https://oom.sy24.ru/ in Firefox which will helps occurred OOM. > Sorry I can't attach here html page because my message will rejected > as message would contained HTML subpart. > > Actual result virtual machine hang and even couldn't be force off. > > Expected result virtual machine continue work. > > [ 2335.903277] INFO: task CPU 0/KVM:7450 blocked for more than 120 seconds. > [ 2335.903284] Not tainted 4.15.7-300.fc27.x86_64+debug #1 > [ 2335.903287] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" > disables this message. > [ 2335.903291] CPU 0/KVM D10648 7450 1 0x00000000 > [ 2335.903298] Call Trace: > [ 2335.903308] ? __schedule+0x2e9/0xbb0 > [ 2335.903318] ? __lock_page+0xad/0x180 > [ 2335.903322] schedule+0x2f/0x90 > [ 2335.903327] io_schedule+0x12/0x40 > [ 2335.903331] __lock_page+0xed/0x180 > [ 2335.903338] ? page_cache_tree_insert+0x130/0x130 > [ 2335.903347] deferred_split_scan+0x318/0x340 I guess it's bad idea to wait the page to be unlocked in the relaim path. Could you check if this makes a difference: diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 87ab9b8f56b5..529cf36b7edb 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2783,11 +2783,13 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, list_for_each_safe(pos, next, &list) { page = list_entry((void *)pos, struct page, mapping); - lock_page(page); + if (!trylock_page(page)) + goto next; /* split_huge_page() removes page from list on success */ if (!split_huge_page(page)) split++; unlock_page(page); +next: put_page(page); } -- Kirill A. Shutemov
