linux-kernel - [PATCH v8 3/3] Revert "mm/memory-failure.c: fix race with changing page compound again"

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Date:   Fri,  8 Apr 2022 22:53:23 +0900
From:   Naoya Horiguchi <naoya.horiguchi@...ux.dev>
To:     linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Yang Shi <shy828301@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v8 3/3] Revert "mm/memory-failure.c: fix race with changing page compound again"

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

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.

Suggested-by: Miaohe Lin <linmiaohe@...wei.com>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>
---
 include/linux/mm.h      |  1 -
 include/ras/ras_event.h |  1 -
 mm/memory-failure.c     | 11 -----------
 3 files changed, 13 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9f44254af8ce..d446e834a3e5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3251,7 +3251,6 @@ enum mf_action_page_type {
 	MF_MSG_BUDDY,
 	MF_MSG_DAX,
 	MF_MSG_UNSPLIT_THP,
-	MF_MSG_DIFFERENT_PAGE_SIZE,
 	MF_MSG_UNKNOWN,
 };
 
diff --git a/include/ras/ras_event.h b/include/ras/ras_event.h
index 1e694fd239b9..d0337a41141c 100644
--- a/include/ras/ras_event.h
+++ b/include/ras/ras_event.h
@@ -374,7 +374,6 @@ TRACE_EVENT(aer_event,
 	EM ( MF_MSG_BUDDY, "free buddy page" )				\
 	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" )
 
 /*
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b2e32cdc3823..e2674532678b 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -733,7 +733,6 @@ static const char * const action_page_types[] = {
 	[MF_MSG_BUDDY]			= "free buddy page",
 	[MF_MSG_DAX]			= "dax page",
 	[MF_MSG_UNSPLIT_THP]		= "unsplit thp",
-	[MF_MSG_DIFFERENT_PAGE_SIZE]	= "different page size",
 	[MF_MSG_UNKNOWN]		= "unknown page",
 };
 
@@ -1605,16 +1604,6 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
 		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;
 
 	/*
-- 
2.25.1