Subject: [merged] mm-thp-fix-infinite-loop-on-memcg-oom.patch removed from -mm tree To: kirill.shutemov@xxxxxxxxxxxxxxx,aarcange@xxxxxxxxxx,hannes@xxxxxxxxxxx,m.mizuma@xxxxxxxxxxxxxx,mhocko@xxxxxxx,rientjes@xxxxxxxxxx,stable@xxxxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Thu, 27 Feb 2014 12:23:50 -0800 The patch titled Subject: mm, thp: fix infinite loop on memcg OOM has been removed from the -mm tree. Its filename was mm-thp-fix-infinite-loop-on-memcg-oom.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Subject: mm, thp: fix infinite loop on memcg OOM Masayoshi Mizuma reported a bug with the hang of an application under the memcg limit. It happens on write-protection fault to huge zero page If we successfully allocate a huge page to replace zero page but hit the memcg limit we need to split the zero page with split_huge_page_pmd() and fallback to small pages. The other part of the problem is that VM_FAULT_OOM has special meaning in do_huge_pmd_wp_page() context. __handle_mm_fault() expects the page to be split if it sees VM_FAULT_OOM and it will will retry page fault handling. This causes an infinite loop if the page was not split. do_huge_pmd_wp_zero_page_fallback() can return VM_FAULT_OOM if it failed to allocate one small page, so fallback to small pages will not help. The solution for this part is to replace VM_FAULT_OOM with VM_FAULT_FALLBACK is fallback required. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reported-by: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx> Reviewed-by: Michal Hocko <mhocko@xxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/huge_memory.c | 9 ++++++--- mm/memory.c | 14 +++----------- 2 files changed, 9 insertions(+), 14 deletions(-) diff -puN mm/huge_memory.c~mm-thp-fix-infinite-loop-on-memcg-oom mm/huge_memory.c --- a/mm/huge_memory.c~mm-thp-fix-infinite-loop-on-memcg-oom +++ a/mm/huge_memory.c @@ -1166,8 +1166,10 @@ alloc: } else { ret = do_huge_pmd_wp_page_fallback(mm, vma, address, pmd, orig_pmd, page, haddr); - if (ret & VM_FAULT_OOM) + if (ret & VM_FAULT_OOM) { split_huge_page(page); + ret |= VM_FAULT_FALLBACK; + } put_page(page); } count_vm_event(THP_FAULT_FALLBACK); @@ -1179,9 +1181,10 @@ alloc: if (page) { split_huge_page(page); put_page(page); - } + } else + split_huge_page_pmd(vma, address, pmd); + ret |= VM_FAULT_FALLBACK; count_vm_event(THP_FAULT_FALLBACK); - ret |= VM_FAULT_OOM; goto out; } diff -puN mm/memory.c~mm-thp-fix-infinite-loop-on-memcg-oom mm/memory.c --- a/mm/memory.c~mm-thp-fix-infinite-loop-on-memcg-oom +++ a/mm/memory.c @@ -3704,7 +3704,6 @@ static int __handle_mm_fault(struct mm_s if (unlikely(is_vm_hugetlb_page(vma))) return hugetlb_fault(mm, vma, address, flags); -retry: pgd = pgd_offset(mm, address); pud = pud_alloc(mm, pgd, address); if (!pud) @@ -3742,20 +3741,13 @@ retry: if (dirty && !pmd_write(orig_pmd)) { ret = do_huge_pmd_wp_page(mm, vma, address, pmd, orig_pmd); - /* - * If COW results in an oom, the huge pmd will - * have been split, so retry the fault on the - * pte for a smaller charge. - */ - if (unlikely(ret & VM_FAULT_OOM)) - goto retry; - return ret; + if (!(ret & VM_FAULT_FALLBACK)) + return ret; } else { huge_pmd_set_accessed(mm, vma, address, pmd, orig_pmd, dirty); + return 0; } - - return 0; } } _ Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are origin.patch mm-close-pagetail-race.patch mm-page_alloc-make-first_page-visible-before-pagetail.patch mm-include-vm_mixedmap-flag-in-the-vm_special-list-to-avoid-munlocking.patch pagewalk-update-page-table-walker-core.patch pagewalk-add-walk_page_vma.patch smaps-redefine-callback-functions-for-page-table-walker.patch clear_refs-redefine-callback-functions-for-page-table-walker.patch pagemap-redefine-callback-functions-for-page-table-walker.patch numa_maps-redefine-callback-functions-for-page-table-walker.patch memcg-redefine-callback-functions-for-page-table-walker.patch madvise-redefine-callback-functions-for-page-table-walker.patch arch-powerpc-mm-subpage-protc-use-walk_page_vma-instead-of-walk_page_range.patch pagewalk-remove-argument-hmask-from-hugetlb_entry.patch mempolicy-apply-page-table-walker-on-queue_pages_range.patch mm-rename-__do_fault-do_fault.patch mm-do_fault-extract-to-call-vm_ops-do_fault-to-separate-function.patch mm-introduce-do_read_fault.patch mm-introduce-do_cow_fault.patch mm-introduce-do_shared_fault-and-drop-do_fault.patch mm-consolidate-code-to-call-vm_ops-page_mkwrite.patch mm-consolidate-code-to-call-vm_ops-page_mkwrite-fix.patch mm-consolidate-code-to-setup-pte.patch mm-thp-drop-do_huge_pmd_wp_zero_page_fallback.patch mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags.patch mm-thp-add-vm_init_def_mask-and-prctl_thp_disable.patch exec-kill-the-unnecessary-mm-def_flags-setting-in-load_elf_binary.patch mm-disable-split-page-table-lock-for-mmu.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html