(added stable@xxxxxxxxxxxxxxx to CC) On Tue, 11 Feb 2014 12:35:54 -0800 akpm@xxxxxxxxxxxxxxxxxxxx wrote: > Subject: + mm-thp-fix-infinite-loop-on-memcg-oom.patch added to -mm tree > To: kirill.shutemov@xxxxxxxxxxxxxxx,aarcange@xxxxxxxxxx,hannes@xxxxxxxxxxx,m.mizuma@xxxxxxxxxxxxxx,mhocko@xxxxxxx,rientjes@xxxxxxxxxx > From: akpm@xxxxxxxxxxxxxxxxxxxx > Date: Tue, 11 Feb 2014 12:35:54 -0800 > > > The patch titled > Subject: mm, thp: fix infinite loop on memcg OOM > has been added to the -mm tree. Its filename is > mm-thp-fix-infinite-loop-on-memcg-oom.patch > > This patch should soon appear at > http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-fix-infinite-loop-on-memcg-oom.patch > and later at > http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-fix-infinite-loop-on-memcg-oom.patch > > Before you just go and hit "reply", please: > a) Consider who else should be cc'ed > b) Prefer to cc a suitable mailing list as well > c) Ideally: find the original patch on the mailing list and do a > reply-to-all to that, adding suitable additional cc's > > *** Remember to use Documentation/SubmitChecklist when testing your code *** > > The -mm tree is included into linux-next and is updated > there every 3-4 working days > > ------------------------------------------------------ > 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> > Cc: Michal Hocko <mhocko@xxxxxxx> > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> > Cc: David Rientjes <rientjes@xxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- I believe this patch should be backported to stable tree. Regards, Masayoshi Mizuma > > 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 > > mm-hwpoison-release-page-on-pagehwpoison-in-__do_fault.patch > mm-thp-fix-infinite-loop-on-memcg-oom.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-setup-pte.patch > mm-thp-drop-do_huge_pmd_wp_zero_page_fallback.patch > -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html