Hi Aaron, Thank you for the patch! Yet something to improve: [auto build test ERROR on hnaz-linux-mm/master] url: https://github.com/0day-ci/linux/commits/Aaron-Tomlin/mm-page_alloc-try-oom-if-reclaim-is-unable-to-make-forward-progress/20210316-010203 base: https://github.com/hnaz/linux-mm master config: arc-randconfig-r024-20210315 (attached as .config) compiler: arceb-elf-gcc (GCC) 9.3.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://github.com/0day-ci/linux/commit/77338aaff2606a7715c832545e79370e849e3b4e git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Aaron-Tomlin/mm-page_alloc-try-oom-if-reclaim-is-unable-to-make-forward-progress/20210316-010203 git checkout 77338aaff2606a7715c832545e79370e849e3b4e # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arc If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All error/warnings (new ones prefixed by >>): mm/page_alloc.c: In function 'should_reclaim_retry': >> mm/page_alloc.c:4444:3: error: 'result' undeclared (first use in this function) 4444 | result false; | ^~~~~~ mm/page_alloc.c:4444:3: note: each undeclared identifier is reported only once for each function it appears in >> mm/page_alloc.c:4444:9: error: expected ';' before 'false' 4444 | result false; | ^~~~~~ | ; >> mm/page_alloc.c:4447:50: error: expected ';' before 'for' 4447 | return unreserve_highatomic_pageblock(ac, true) | ^ | ; mm/page_alloc.c:4426:18: warning: unused variable 'z' [-Wunused-variable] 4426 | struct zoneref *z; | ^ mm/page_alloc.c:4425:15: warning: unused variable 'zone' [-Wunused-variable] 4425 | struct zone *zone; | ^~~~ mm/page_alloc.c: In function '__alloc_pages_slowpath': >> mm/page_alloc.c:4720:11: error: expected ';' before ':' token 4720 | goto oom: | ^ | ; >> mm/page_alloc.c:4556:6: warning: variable 'compaction_retries' set but not used [-Wunused-but-set-variable] 4556 | int compaction_retries; | ^~~~~~~~~~~~~~~~~~ mm/page_alloc.c: At top level: mm/page_alloc.c:6136:23: warning: no previous prototype for 'memmap_init' [-Wmissing-prototypes] 6136 | void __meminit __weak memmap_init(unsigned long size, int nid, | ^~~~~~~~~~~ vim +/result +4444 mm/page_alloc.c 4409 4410 /* 4411 * Checks whether it makes sense to retry the reclaim to make a forward progress 4412 * for the given allocation request. 4413 * 4414 * We give up when we either have tried MAX_RECLAIM_RETRIES in a row 4415 * without success, or when we couldn't even meet the watermark if we 4416 * reclaimed all remaining pages on the LRU lists. 4417 * 4418 * Returns true if a retry is viable or false to enter the oom path. 4419 */ 4420 static inline bool 4421 should_reclaim_retry(gfp_t gfp_mask, unsigned order, 4422 struct alloc_context *ac, int alloc_flags, 4423 bool did_some_progress, int *no_progress_loops) 4424 { 4425 struct zone *zone; 4426 struct zoneref *z; 4427 bool ret = false; 4428 4429 /* 4430 * Costly allocations might have made a progress but this doesn't mean 4431 * their order will become available due to high fragmentation so 4432 * always increment the no progress counter for them 4433 */ 4434 if (did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER) 4435 *no_progress_loops = 0; 4436 else 4437 (*no_progress_loops)++; 4438 4439 /* 4440 * Make sure we converge to OOM if we cannot make any progress 4441 * several times in the row. 4442 */ 4443 if (*no_progress_loops > MAX_RECLAIM_RETRIES) > 4444 result false; 4445 /* Last chance before OOM, try draining highatomic_reserve once */ 4446 else if (*no_progress_loops == MAX_RECLAIM_RETRIES) > 4447 return unreserve_highatomic_pageblock(ac, true) 4448 4449 /* 4450 * Keep reclaiming pages while there is a chance this will lead 4451 * somewhere. If none of the target zones can satisfy our allocation 4452 * request even if all reclaimable pages are considered then we are 4453 * screwed and have to go OOM. 4454 */ 4455 for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, 4456 ac->highest_zoneidx, ac->nodemask) { 4457 unsigned long available; 4458 unsigned long reclaimable; 4459 unsigned long min_wmark = min_wmark_pages(zone); 4460 bool wmark; 4461 4462 available = reclaimable = zone_reclaimable_pages(zone); 4463 available += zone_page_state_snapshot(zone, NR_FREE_PAGES); 4464 4465 /* 4466 * Would the allocation succeed if we reclaimed all 4467 * reclaimable pages? 4468 */ 4469 wmark = __zone_watermark_ok(zone, order, min_wmark, 4470 ac->highest_zoneidx, alloc_flags, available); 4471 trace_reclaim_retry_zone(z, order, reclaimable, 4472 available, min_wmark, *no_progress_loops, wmark); 4473 if (wmark) { 4474 /* 4475 * If we didn't make any progress and have a lot of 4476 * dirty + writeback pages then we should wait for 4477 * an IO to complete to slow down the reclaim and 4478 * prevent from pre mature OOM 4479 */ 4480 if (!did_some_progress) { 4481 unsigned long write_pending; 4482 4483 write_pending = zone_page_state_snapshot(zone, 4484 NR_ZONE_WRITE_PENDING); 4485 4486 if (2 * write_pending > reclaimable) { 4487 congestion_wait(BLK_RW_ASYNC, HZ/10); 4488 return true; 4489 } 4490 } 4491 4492 ret = true; 4493 goto out; 4494 } 4495 } 4496 4497 out: 4498 /* 4499 * Memory allocation/reclaim might be called from a WQ context and the 4500 * current implementation of the WQ concurrency control doesn't 4501 * recognize that a particular WQ is congested if the worker thread is 4502 * looping without ever sleeping. Therefore we have to do a short sleep 4503 * here rather than calling cond_resched(). 4504 */ 4505 if (current->flags & PF_WQ_WORKER) 4506 schedule_timeout_uninterruptible(1); 4507 else 4508 cond_resched(); 4509 return ret; 4510 } 4511 4512 static inline bool 4513 check_retry_cpuset(int cpuset_mems_cookie, struct alloc_context *ac) 4514 { 4515 /* 4516 * It's possible that cpuset's mems_allowed and the nodemask from 4517 * mempolicy don't intersect. This should be normally dealt with by 4518 * policy_nodemask(), but it's possible to race with cpuset update in 4519 * such a way the check therein was true, and then it became false 4520 * before we got our cpuset_mems_cookie here. 4521 * This assumes that for all allocations, ac->nodemask can come only 4522 * from MPOL_BIND mempolicy (whose documented semantics is to be ignored 4523 * when it does not intersect with the cpuset restrictions) or the 4524 * caller can deal with a violated nodemask. 4525 */ 4526 if (cpusets_enabled() && ac->nodemask && 4527 !cpuset_nodemask_valid_mems_allowed(ac->nodemask)) { 4528 ac->nodemask = NULL; 4529 return true; 4530 } 4531 4532 /* 4533 * When updating a task's mems_allowed or mempolicy nodemask, it is 4534 * possible to race with parallel threads in such a way that our 4535 * allocation can fail while the mask is being updated. If we are about 4536 * to fail, check if the cpuset changed during allocation and if so, 4537 * retry. 4538 */ 4539 if (read_mems_allowed_retry(cpuset_mems_cookie)) 4540 return true; 4541 4542 return false; 4543 } 4544 4545 static inline struct page * 4546 __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, 4547 struct alloc_context *ac) 4548 { 4549 bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM; 4550 const bool costly_order = order > PAGE_ALLOC_COSTLY_ORDER; 4551 struct page *page = NULL; 4552 unsigned int alloc_flags; 4553 unsigned long did_some_progress; 4554 enum compact_priority compact_priority; 4555 enum compact_result compact_result; > 4556 int compaction_retries; 4557 int no_progress_loops; 4558 unsigned int cpuset_mems_cookie; 4559 int reserve_flags; 4560 4561 /* 4562 * We also sanity check to catch abuse of atomic reserves being used by 4563 * callers that are not in atomic context. 4564 */ 4565 if (WARN_ON_ONCE((gfp_mask & (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM)) == 4566 (__GFP_ATOMIC|__GFP_DIRECT_RECLAIM))) 4567 gfp_mask &= ~__GFP_ATOMIC; 4568 4569 retry_cpuset: 4570 compaction_retries = 0; 4571 no_progress_loops = 0; 4572 compact_priority = DEF_COMPACT_PRIORITY; 4573 cpuset_mems_cookie = read_mems_allowed_begin(); 4574 4575 /* 4576 * The fast path uses conservative alloc_flags to succeed only until 4577 * kswapd needs to be woken up, and to avoid the cost of setting up 4578 * alloc_flags precisely. So we do that now. 4579 */ 4580 alloc_flags = gfp_to_alloc_flags(gfp_mask); 4581 4582 /* 4583 * We need to recalculate the starting point for the zonelist iterator 4584 * because we might have used different nodemask in the fast path, or 4585 * there was a cpuset modification and we are retrying - otherwise we 4586 * could end up iterating over non-eligible zones endlessly. 4587 */ 4588 ac->preferred_zoneref = first_zones_zonelist(ac->zonelist, 4589 ac->highest_zoneidx, ac->nodemask); 4590 if (!ac->preferred_zoneref->zone) 4591 goto nopage; 4592 4593 if (alloc_flags & ALLOC_KSWAPD) 4594 wake_all_kswapds(order, gfp_mask, ac); 4595 4596 /* 4597 * The adjusted alloc_flags might result in immediate success, so try 4598 * that first 4599 */ 4600 page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac); 4601 if (page) 4602 goto got_pg; 4603 4604 /* 4605 * For costly allocations, try direct compaction first, as it's likely 4606 * that we have enough base pages and don't need to reclaim. For non- 4607 * movable high-order allocations, do that as well, as compaction will 4608 * try prevent permanent fragmentation by migrating from blocks of the 4609 * same migratetype. 4610 * Don't try this for allocations that are allowed to ignore 4611 * watermarks, as the ALLOC_NO_WATERMARKS attempt didn't yet happen. 4612 */ 4613 if (can_direct_reclaim && 4614 (costly_order || 4615 (order > 0 && ac->migratetype != MIGRATE_MOVABLE)) 4616 && !gfp_pfmemalloc_allowed(gfp_mask)) { 4617 page = __alloc_pages_direct_compact(gfp_mask, order, 4618 alloc_flags, ac, 4619 INIT_COMPACT_PRIORITY, 4620 &compact_result); 4621 if (page) 4622 goto got_pg; 4623 4624 /* 4625 * Checks for costly allocations with __GFP_NORETRY, which 4626 * includes some THP page fault allocations 4627 */ 4628 if (costly_order && (gfp_mask & __GFP_NORETRY)) { 4629 /* 4630 * If allocating entire pageblock(s) and compaction 4631 * failed because all zones are below low watermarks 4632 * or is prohibited because it recently failed at this 4633 * order, fail immediately unless the allocator has 4634 * requested compaction and reclaim retry. 4635 * 4636 * Reclaim is 4637 * - potentially very expensive because zones are far 4638 * below their low watermarks or this is part of very 4639 * bursty high order allocations, 4640 * - not guaranteed to help because isolate_freepages() 4641 * may not iterate over freed pages as part of its 4642 * linear scan, and 4643 * - unlikely to make entire pageblocks free on its 4644 * own. 4645 */ 4646 if (compact_result == COMPACT_SKIPPED || 4647 compact_result == COMPACT_DEFERRED) 4648 goto nopage; 4649 4650 /* 4651 * Looks like reclaim/compaction is worth trying, but 4652 * sync compaction could be very expensive, so keep 4653 * using async compaction. 4654 */ 4655 compact_priority = INIT_COMPACT_PRIORITY; 4656 } 4657 } 4658 4659 retry: 4660 /* Ensure kswapd doesn't accidentally go to sleep as long as we loop */ 4661 if (alloc_flags & ALLOC_KSWAPD) 4662 wake_all_kswapds(order, gfp_mask, ac); 4663 4664 reserve_flags = __gfp_pfmemalloc_flags(gfp_mask); 4665 if (reserve_flags) 4666 alloc_flags = current_alloc_flags(gfp_mask, reserve_flags); 4667 4668 /* 4669 * Reset the nodemask and zonelist iterators if memory policies can be 4670 * ignored. These allocations are high priority and system rather than 4671 * user oriented. 4672 */ 4673 if (!(alloc_flags & ALLOC_CPUSET) || reserve_flags) { 4674 ac->nodemask = NULL; 4675 ac->preferred_zoneref = first_zones_zonelist(ac->zonelist, 4676 ac->highest_zoneidx, ac->nodemask); 4677 } 4678 4679 /* Attempt with potentially adjusted zonelist and alloc_flags */ 4680 page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac); 4681 if (page) 4682 goto got_pg; 4683 4684 /* Caller is not willing to reclaim, we can't balance anything */ 4685 if (!can_direct_reclaim) 4686 goto nopage; 4687 4688 /* Avoid recursion of direct reclaim */ 4689 if (current->flags & PF_MEMALLOC) 4690 goto nopage; 4691 4692 /* Try direct reclaim and then allocating */ 4693 page = __alloc_pages_direct_reclaim(gfp_mask, order, alloc_flags, ac, 4694 &did_some_progress); 4695 if (page) 4696 goto got_pg; 4697 4698 /* Try direct compaction and then allocating */ 4699 page = __alloc_pages_direct_compact(gfp_mask, order, alloc_flags, ac, 4700 compact_priority, &compact_result); 4701 if (page) 4702 goto got_pg; 4703 4704 /* Do not loop if specifically requested */ 4705 if (gfp_mask & __GFP_NORETRY) 4706 goto nopage; 4707 4708 /* 4709 * Do not retry costly high order allocations unless they are 4710 * __GFP_RETRY_MAYFAIL 4711 */ 4712 if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL)) 4713 goto nopage; 4714 4715 if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags, 4716 did_some_progress > 0, &no_progress_loops)) 4717 goto retry; 4718 4719 if (should_try_oom(no_progress_loops, compact_result)) 4720 goto oom: 4721 /* 4722 * It doesn't make any sense to retry for the compaction if the order-0 4723 * reclaim is not able to make any progress because the current 4724 * implementation of the compaction depends on the sufficient amount 4725 * of free memory (see __compaction_suitable) 4726 */ 4727 if (did_some_progress > 0 && 4728 should_compact_retry(ac, order, alloc_flags, 4729 compact_result, &compact_priority, 4730 &compaction_retries)) 4731 goto retry; 4732 4733 4734 /* Deal with possible cpuset update races before we start OOM killing */ 4735 if (check_retry_cpuset(cpuset_mems_cookie, ac)) 4736 goto retry_cpuset; 4737 4738 oom: 4739 /* Reclaim has failed us, start killing things */ 4740 page = __alloc_pages_may_oom(gfp_mask, order, ac, &did_some_progress); 4741 if (page) 4742 goto got_pg; 4743 4744 /* Avoid allocations with no watermarks from looping endlessly */ 4745 if (tsk_is_oom_victim(current) && 4746 (alloc_flags & ALLOC_OOM || 4747 (gfp_mask & __GFP_NOMEMALLOC))) 4748 goto nopage; 4749 4750 /* Retry as long as the OOM killer is making progress */ 4751 if (did_some_progress) { 4752 no_progress_loops = 0; 4753 goto retry; 4754 } 4755 4756 nopage: 4757 /* Deal with possible cpuset update races before we fail */ 4758 if (check_retry_cpuset(cpuset_mems_cookie, ac)) 4759 goto retry_cpuset; 4760 4761 /* 4762 * Make sure that __GFP_NOFAIL request doesn't leak out and make sure 4763 * we always retry 4764 */ 4765 if (gfp_mask & __GFP_NOFAIL) { 4766 /* 4767 * All existing users of the __GFP_NOFAIL are blockable, so warn 4768 * of any new users that actually require GFP_NOWAIT 4769 */ 4770 if (WARN_ON_ONCE(!can_direct_reclaim)) 4771 goto fail; 4772 4773 /* 4774 * PF_MEMALLOC request from this context is rather bizarre 4775 * because we cannot reclaim anything and only can loop waiting 4776 * for somebody to do a work for us 4777 */ 4778 WARN_ON_ONCE(current->flags & PF_MEMALLOC); 4779 4780 /* 4781 * non failing costly orders are a hard requirement which we 4782 * are not prepared for much so let's warn about these users 4783 * so that we can identify them and convert them to something 4784 * else. 4785 */ 4786 WARN_ON_ONCE(order > PAGE_ALLOC_COSTLY_ORDER); 4787 4788 /* 4789 * Help non-failing allocations by giving them access to memory 4790 * reserves but do not use ALLOC_NO_WATERMARKS because this 4791 * could deplete whole memory reserves which would just make 4792 * the situation worse 4793 */ 4794 page = __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_HARDER, ac); 4795 if (page) 4796 goto got_pg; 4797 4798 cond_resched(); 4799 goto retry; 4800 } 4801 fail: 4802 warn_alloc(gfp_mask, ac->nodemask, 4803 "page allocation failure: order:%u", order); 4804 got_pg: 4805 return page; 4806 } 4807 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
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