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[210.143.35.52]) by mx.google.com with ESMTPS id k2si5049588oem.62.2015.07.15.18.42.56 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 15 Jul 2015 18:42:56 -0700 (PDT) From: Naoya Horiguchi Subject: [PATCH v1 4/4] mm/memory-failure: check __PG_HWPOISON separately from PAGE_FLAGS_CHECK_AT_* Date: Thu, 16 Jul 2015 01:41:56 +0000 Message-ID: <1437010894-10262-5-git-send-email-n-horiguchi@ah.jp.nec.com> References: <1437010894-10262-1-git-send-email-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1437010894-10262-1-git-send-email-n-horiguchi@ah.jp.nec.com> Content-Language: ja-JP Content-Type: text/plain; charset="iso-2022-jp" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Andi Kleen , Dean Nelson , Tony Luck , "Kirill A. Shutemov" , Hugh Dickins , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Naoya Horiguchi The race condition addressed in commit add05cecef80 ("mm: soft-offline: don= 't free target page in successful page migration") was not closed completely, because that can happen not only for soft-offline, but also for hard-offlin= e. Consider that a slab page is about to be freed into buddy pool, and then an uncorrected memory error hits the page just after entering __free_one_page(= ), then VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP) is triggered, despite the fact that it's not necessary because the data on the affected page is not consumed. To solve it, this patch drops __PG_HWPOISON from page flag checks at allocation/free time. I think it's justified because __PG_HWPOISON flags is defined to prevent the page from being reused and setting it outside the page's alloc-free cycle is a designed behavior (not a bug.) And the patch reverts most of the changes from commit add05cecef80 about the new refcounting rule of soft-offlined pages, which is no longer necessa= ry. Signed-off-by: Naoya Horiguchi --- include/linux/page-flags.h | 10 +++++++--- mm/huge_memory.c | 7 +------ mm/memory-failure.c | 6 +++++- mm/migrate.c | 9 +++------ mm/page_alloc.c | 4 ++++ 5 files changed, 20 insertions(+), 16 deletions(-) diff --git v4.2-rc2.orig/include/linux/page-flags.h v4.2-rc2/include/linux/= page-flags.h index f34e040b34e9..53400f101f2d 100644 --- v4.2-rc2.orig/include/linux/page-flags.h +++ v4.2-rc2/include/linux/page-flags.h @@ -631,15 +631,19 @@ static inline void ClearPageSlabPfmemalloc(struct pag= e *page) 1 << PG_private | 1 << PG_private_2 | \ 1 << PG_writeback | 1 << PG_reserved | \ 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \ - 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \ + 1 << PG_unevictable | __PG_MLOCKED | \ __PG_COMPOUND_LOCK) =20 /* * Flags checked when a page is prepped for return by the page allocator. - * Pages being prepped should not have any flags set. It they are set, + * Pages being prepped should not have these flags set. It they are set, * there has been a kernel bug or struct page corruption. + * + * __PG_HWPOISON is exceptional because it need to be kept beyond page's + * alloc-free cycle to prevent from reusing the page. */ -#define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1) +#define PAGE_FLAGS_CHECK_AT_PREP \ + (((1 << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON) =20 #define PAGE_FLAGS_PRIVATE \ (1 << PG_private | 1 << PG_private_2) diff --git v4.2-rc2.orig/mm/huge_memory.c v4.2-rc2/mm/huge_memory.c index c107094f79ba..097c7a4bfbd9 100644 --- v4.2-rc2.orig/mm/huge_memory.c +++ v4.2-rc2/mm/huge_memory.c @@ -1676,12 +1676,7 @@ static void __split_huge_page_refcount(struct page *= page, /* after clearing PageTail the gup refcount can be released */ smp_mb__after_atomic(); =20 - /* - * retain hwpoison flag of the poisoned tail page: - * fix for the unsuitable process killed on Guest Machine(KVM) - * by the memory-failure. - */ - page_tail->flags &=3D ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON; + page_tail->flags &=3D ~PAGE_FLAGS_CHECK_AT_PREP; page_tail->flags |=3D (page->flags & ((1L << PG_referenced) | (1L << PG_swapbacked) | diff --git v4.2-rc2.orig/mm/memory-failure.c v4.2-rc2/mm/memory-failure.c index 421d7c9b30f4..755f87e4ec64 100644 --- v4.2-rc2.orig/mm/memory-failure.c +++ v4.2-rc2/mm/memory-failure.c @@ -1723,6 +1723,9 @@ int soft_offline_page(struct page *page, int flags) =20 get_online_mems(); =20 + if (get_pageblock_migratetype(page) !=3D MIGRATE_ISOLATE) + set_migratetype_isolate(page, true); + ret =3D get_any_page(page, pfn, flags); put_online_mems(); if (ret > 0) { /* for in-use pages */ @@ -1730,7 +1733,7 @@ int soft_offline_page(struct page *page, int flags) ret =3D soft_offline_huge_page(page, flags); else ret =3D __soft_offline_page(page, flags); - } else if (ret =3D=3D 0) { /* for free pages */ + } else if (ret =3D=3D 0) { if (PageHuge(page)) { set_page_hwpoison_huge_page(hpage); if (!dequeue_hwpoisoned_huge_page(hpage)) @@ -1741,5 +1744,6 @@ int soft_offline_page(struct page *page, int flags) atomic_long_inc(&num_poisoned_pages); } } + unset_migratetype_isolate(page, MIGRATE_MOVABLE); return ret; } diff --git v4.2-rc2.orig/mm/migrate.c v4.2-rc2/mm/migrate.c index ee401e4e5ef1..c37d5772767b 100644 --- v4.2-rc2.orig/mm/migrate.c +++ v4.2-rc2/mm/migrate.c @@ -918,8 +918,7 @@ static int __unmap_and_move(struct page *page, struct p= age *newpage, static ICE_noinline int unmap_and_move(new_page_t get_new_page, free_page_t put_new_page, unsigned long private, struct page *page, - int force, enum migrate_mode mode, - enum migrate_reason reason) + int force, enum migrate_mode mode) { int rc =3D 0; int *result =3D NULL; @@ -950,8 +949,7 @@ static ICE_noinline int unmap_and_move(new_page_t get_n= ew_page, list_del(&page->lru); dec_zone_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); - if (reason !=3D MR_MEMORY_FAILURE) - putback_lru_page(page); + putback_lru_page(page); } =20 /* @@ -1124,8 +1122,7 @@ int migrate_pages(struct list_head *from, new_page_t = get_new_page, pass > 2, mode); else rc =3D unmap_and_move(get_new_page, put_new_page, - private, page, pass > 2, mode, - reason); + private, page, pass > 2, mode); =20 switch(rc) { case -ENOMEM: diff --git v4.2-rc2.orig/mm/page_alloc.c v4.2-rc2/mm/page_alloc.c index 506eac8b38af..e32d58ce5d2f 100644 --- v4.2-rc2.orig/mm/page_alloc.c +++ v4.2-rc2/mm/page_alloc.c @@ -1287,6 +1287,10 @@ static inline int check_new_page(struct page *page) bad_reason =3D "non-NULL mapping"; if (unlikely(atomic_read(&page->_count) !=3D 0)) bad_reason =3D "nonzero _count"; + if (unlikely(page->flags & __PG_HWPOISON)) { + bad_reason =3D "HWPoisoned (hardware-corrupted)"; + bad_flags =3D __PG_HWPOISON; + } if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_PREP)) { bad_reason =3D "PAGE_FLAGS_CHECK_AT_PREP flag set"; bad_flags =3D PAGE_FLAGS_CHECK_AT_PREP; --=20 2.4.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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