Messages in this thread Patch in this message |  | | Date | Fri, 13 Dec 2013 09:09:52 +0800 | From | Jianguo Wu <> | Subject | [PATCH v2] mm/memory-failure.c: recheck PageHuge() after hugetlb page migrate successfully |
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After a successful hugetlb page migration by soft offline, the source page will either be freed into hugepage_freelists or buddy(over-commit page). If page is in buddy, page_hstate(page) will be NULL. It will hit a NULL pointer dereference in dequeue_hwpoisoned_huge_page().
[ 890.677918] BUG: unable to handle kernel NULL pointer dereference at 0000000000000058 [ 890.685741] IP: [<ffffffff81163761>] dequeue_hwpoisoned_huge_page+0x131/0x1d0 [ 890.692861] PGD c23762067 PUD c24be2067 PMD 0 [ 890.697314] Oops: 0000 [#1] SMP
So check PageHuge(page) after call migrate_pages() successfully.
Tested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: stable@vger.kernel.org Signed-off-by: Jianguo Wu <wujianguo@huawei.com> --- mm/memory-failure.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c index b7c1716..e5567f2 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1471,7 +1471,8 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags) static int soft_offline_huge_page(struct page *page, int flags) { - int ret; + int ret, i; + unsigned long nr_pages; unsigned long pfn = page_to_pfn(page); struct page *hpage = compound_head(page); LIST_HEAD(pagelist); @@ -1489,6 +1490,8 @@ static int soft_offline_huge_page(struct page *page, int flags) } unlock_page(hpage); + nr_pages = 1 << compound_order(hpage); + /* Keep page count to indicate a given hugepage is isolated. */ list_move(&hpage->lru, &pagelist); ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, @@ -1505,10 +1508,16 @@ static int soft_offline_huge_page(struct page *page, int flags) if (ret > 0) ret = -EIO; } else { - set_page_hwpoison_huge_page(hpage); - dequeue_hwpoisoned_huge_page(hpage); - atomic_long_add(1 << compound_order(hpage), - &num_poisoned_pages); + /* overcommit hugetlb page will be freed to buddy */ + if (PageHuge(page)) { + set_page_hwpoison_huge_page(hpage); + dequeue_hwpoisoned_huge_page(hpage); + } else { + for (i = 0; i < nr_pages; i++) + SetPageHWPoison(hpage + i); + } + + atomic_long_add(nr_pages, &num_poisoned_pages); } return ret; } -- 1.8.2.2
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