Commit 75ee64b3 authored by Miaohe Lin's avatar Miaohe Lin Committed by Linus Torvalds
Browse files

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 retry once 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/20220218090118.1105-5-linmiaohe@huawei.com


Signed-off-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Acked-by: default avatarNaoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 49775047

mm/memory-failure.c

+15 −5
Original line number Diff line number Diff line
@@ -1686,7 +1686,6 @@ int memory_failure(unsigned long pfn, int flags) 
{

	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 @@ int memory_failure(unsigned long pfn, int flags) 
		goto unlock_mutex;

	}



	orig_head = hpage = compound_head(p);

	hpage = compound_head(p);

	num_poisoned_pages_inc();



	/*
@@ -1813,10 +1812,21 @@ int memory_failure(unsigned long pfn, int flags) 
	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) {

	if (PageCompound(p)) {

		if (retry) {

			if (TestClearPageHWPoison(p))

				num_poisoned_pages_dec();

			unlock_page(p);

			put_page(p);

			flags &= ~MF_COUNT_INCREASED;

			retry = false;

			goto try_again;

		}

		action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);

		res = -EBUSY;

		goto unlock_page;