Hi, On 2013/12/13 10:32, Naoya Horiguchi wrote:
> On Fri, Dec 13, 2013 at 09:09:52AM +0800, Jianguo Wu wrote: >> 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-horigu...@ah.jp.nec.com> >> Cc: sta...@vger.kernel.org >> Signed-off-by: Jianguo Wu <wujian...@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); > > Why don't you set PageHWPoison only on the error raw page instead > of the whole error hugepage, or is there some problem of doing so? > Oh, yes, we should only poison the error raw page. I will resend a new version. Thanks, Jianguo Wu > Thanks, > Naoya > >> + } >> + >> + atomic_long_add(nr_pages, &num_poisoned_pages); >> } >> return ret; >> } >> -- >> 1.8.2.2 >> >> >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to majord...@kvack.org. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: <a href=mailto:"d...@kvack.org"> em...@kvack.org </a> >> > > . > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/