+ mm-memory-failurec-fix-race-with-changing-page-more-robustly.patch added to -mm tree

* + mm-memory-failurec-fix-race-with-changing-page-more-robustly.patch added to -mm tree
@ 2022-02-17  3:02 Andrew Morton
  0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2022-02-17  3:02 UTC (permalink / raw)
  To: mm-commits, naoya.horiguchi, linmiaohe, akpm


The patch titled
     Subject: mm/memory-failure.c: fix race with changing page more robustly
has been added to the -mm tree.  Its filename is
     mm-memory-failurec-fix-race-with-changing-page-more-robustly.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-memory-failurec-fix-race-with-changing-page-more-robustly.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-memory-failurec-fix-race-with-changing-page-more-robustly.patch

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm/memory-failure.c: fix race with changing page more robustly

We're only intended to deal with the non-Compound page after we split thp
in memory_failure.  However, the page could have changed compound pages
due to race window.  If this happens, we could try again to hopefully
handle the page next round.  Also remove unneeded orig_head.  It's always
equal to the hpage.  So we can use hpage directly and remove this
redundant one.

Link: https://lkml.kernel.org/r/20220216091431.39406-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory-failure.c |   20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

--- a/mm/memory-failure.c~mm-memory-failurec-fix-race-with-changing-page-more-robustly
+++ a/mm/memory-failure.c
@@ -1686,7 +1686,6 @@ int memory_failure(unsigned long pfn, in
 {
 	struct page *p;
 	struct page *hpage;
-	struct page *orig_head;
 	struct dev_pagemap *pgmap;
 	int res = 0;
 	unsigned long page_flags;
@@ -1732,7 +1731,7 @@ try_again:
 		goto unlock_mutex;
 	}
 
-	orig_head = hpage = compound_head(p);
+	hpage = compound_head(p);
 	num_poisoned_pages_inc();
 
 	/*
@@ -1813,13 +1812,18 @@ try_again:
 	lock_page(p);
 
 	/*
-	 * The page could have changed compound pages during the locking.
-	 * If this happens just bail out.
+	 * We're only intended to deal with the non-Compound page here.
+	 * However, the page could have changed compound pages due to
+	 * race window. If this happens, we could try again to hopefully
+	 * handle the page next round.
 	 */
-	if (PageCompound(p) && compound_head(p) != orig_head) {
-		action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
-		res = -EBUSY;
-		goto unlock_page;
+	if (PageCompound(p)) {
+		if (TestClearPageHWPoison(p))
+			num_poisoned_pages_dec();
+		unlock_page(p);
+		put_page(p);
+		flags &= ~MF_COUNT_INCREASED;
+		goto try_again;
 	}
 
 	/*
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-memremap-avoid-calling-kasan_remove_zero_shadow-for-device-private-memory.patch
filemap-remove-find_get_pages.patch
mm-sparse-make-mminit_validate_memmodel_limits-static.patch
mm-vmalloc-remove-unneeded-function-forward-declaration.patch
mm-mmzoneh-remove-unused-macros.patch
mm-memory-failurec-minor-clean-up-for-memory_failure_dev_pagemap.patch
mm-memory-failurec-catch-unexpected-efault-from-vma_address.patch
mm-memory-failurec-rework-the-signaling-logic-in-kill_proc.patch
mm-memory-failurec-fix-race-with-changing-page-more-robustly.patch
mm-memory-failurec-remove-pageslab-check-in-hwpoison_filter_dev.patch
mm-memory-failurec-rework-the-try_to_unmap-logic-in-hwpoison_user_mappings.patch
mm-memory-failurec-remove-obsolete-comment-in-__soft_offline_page.patch
mm-memory-failurec-remove-unnecessary-pagetranstail-check.patch
mm-balloon_compaction-make-balloon-page-compaction-callbacks-static.patch
mm-memory_hotplug-remove-obsolete-comment-of-__add_pages.patch
mm-memory_hotplug-avoid-calling-zone_intersects-for-zone_normal.patch
mm-memory_hotplug-clean-up-try_offline_node.patch
mm-memory_hotplug-fix-misplaced-comment-in-offline_pages.patch
mm-highmem-remove-unnecessary-done-label.patch
mm-hmmc-remove-unneeded-local-variable-ret.patch


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