Commit d344734b authored by Naoya Horiguchi's avatar Naoya Horiguchi Committed by Zheng Zengkai
Browse files

mm, hwpoison: fix condition in free hugetlb page path 

mainline inclusion
from mainline-v5.16-rc7
commit e37e7b0b
category: bugfix
bugzilla: https://e.gitee.com/open_euler/issues/list?issue=I4SJ2V
CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e37e7b0b3bd52ec4f8ab71b027bcec08f57f1b3b

--------------------------------

When a memory error hits a tail page of a free hugepage,
__page_handle_poison() is expected to be called to isolate the error in
4kB unit, but it's not called due to the outdated if-condition in
memory_failure_hugetlb().  This loses the chance to isolate the error in
the finer unit, so it's not optimal.  Drop the condition.

This "(p != head && TestSetPageHWPoison(head)" condition is based on the
old semantics of PageHWPoison on hugepage (where PG_hwpoison flag was
set on the subpage), so it's not necessray any more.  By getting to set
PG_hwpoison on head page for hugepages, concurrent error events on
different subpages in a single hugepage can be prevented by
TestSetPageHWPoison(head) at the beginning of memory_failure_hugetlb().
So dropping the condition should not reopen the race window originally
mentioned in commit b985194c ("hwpoison, hugetlb:
lock_page/unlock_page does not match for handling a free hugepage")

[naoya.horiguchi@linux.dev: fix "HardwareCorrupted" counter]
  Link: https://lkml.kernel.org/r/20211220084851.GA1460264@u2004

Link: https://lkml.kernel.org/r/20211210110208.879740-1-naoya.horiguchi@linux.dev


Signed-off-by: default avatarNaoya Horiguchi <naoya.horiguchi@nec.com>
Reported-by: default avatarFei Luo <luofei@unicloud.com>
Reviewed-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Cc: <stable@vger.kernel.org>	[5.14+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarBin Wang <wangbin224@huawei.com>
Reviewed-by: default avatarluo chunsheng <luochunsheng@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent 54fd15a0

mm/memory-failure.c

+4 −9
Original line number Diff line number Diff line
@@ -1163,18 +1163,13 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags) 
	num_poisoned_pages_inc();



	if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) {

		/*

		 * Check "filter hit" and "race with other subpage."

		 */

		lock_page(head);

		if (PageHWPoison(head)) {

			if ((hwpoison_filter(p) && TestClearPageHWPoison(p))

			    || (p != head && TestSetPageHWPoison(head))) {

		if (hwpoison_filter(p)) {

			if (TestClearPageHWPoison(head))

				num_poisoned_pages_dec();

			unlock_page(head);

			return 0;

		}

		}

		unlock_page(head);

		dissolve_free_huge_page(p);

		action_result(pfn, MF_MSG_FREE_HUGE, MF_DELAYED);