linux-kernel - [PATCH 5.15 219/230] Revert "mm/memory-failure.c: fix race with changing page compound again"

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Date:   Mon, 11 Jul 2022 11:07:55 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Naoya Horiguchi <naoya.horiguchi@....com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Yang Shi <shy828301@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 5.15 219/230] Revert "mm/memory-failure.c: fix race with changing page compound again"

From: Naoya Horiguchi <naoya.horiguchi@....com>

commit 2ba2b008a8bf5fd268a43d03ba79e0ad464d6836 upstream.

Reverts commit 888af2701db7 ("mm/memory-failure.c: fix race with changing
page compound again") because now we fetch the page refcount under
hugetlb_lock in try_memory_failure_hugetlb() so that the race check is no
longer necessary.

Link: https://lkml.kernel.org/r/20220408135323.1559401-4-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>
Suggested-by: Miaohe Lin <linmiaohe@...wei.com>
Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>
Cc: Miaohe Lin <linmiaohe@...wei.com>
Cc: Yang Shi <shy828301@...il.com>
Cc: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 include/linux/mm.h      |    1 -
 include/ras/ras_event.h |    1 -
 mm/memory-failure.c     |   11 -----------
 3 files changed, 13 deletions(-)

--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3175,7 +3175,6 @@ enum mf_action_page_type {
 	MF_MSG_BUDDY_2ND,
 	MF_MSG_DAX,
 	MF_MSG_UNSPLIT_THP,
-	MF_MSG_DIFFERENT_PAGE_SIZE,
 	MF_MSG_UNKNOWN,
 };
 
--- a/include/ras/ras_event.h
+++ b/include/ras/ras_event.h
@@ -376,7 +376,6 @@ TRACE_EVENT(aer_event,
 	EM ( MF_MSG_BUDDY_2ND, "free buddy page (2nd try)" )		\
 	EM ( MF_MSG_DAX, "dax page" )					\
 	EM ( MF_MSG_UNSPLIT_THP, "unsplit thp" )			\
-	EM ( MF_MSG_DIFFERENT_PAGE_SIZE, "different page size" )	\
 	EMe ( MF_MSG_UNKNOWN, "unknown page" )
 
 /*
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -741,7 +741,6 @@ static const char * const action_page_ty
 	[MF_MSG_BUDDY_2ND]		= "free buddy page (2nd try)",
 	[MF_MSG_DAX]			= "dax page",
 	[MF_MSG_UNSPLIT_THP]		= "unsplit thp",
-	[MF_MSG_DIFFERENT_PAGE_SIZE]	= "different page size",
 	[MF_MSG_UNKNOWN]		= "unknown page",
 };
 
@@ -1526,16 +1525,6 @@ retry:
 		return res == MF_RECOVERED ? 0 : -EBUSY;
 	}
 
-	/*
-	 * The page could have changed compound pages due to race window.
-	 * If this happens just bail out.
-	 */
-	if (!PageHuge(p) || compound_head(p) != head) {
-		action_result(pfn, MF_MSG_DIFFERENT_PAGE_SIZE, MF_IGNORED);
-		res = -EBUSY;
-		goto out;
-	}
-
 	page_flags = head->flags;
 
 	/*