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Subject: + mmmadvise-call-soft_offline_page-without-mf_count_increased.patch added to -mm tree
Date: Wed, 24 Jun 2020 12:19:26 -0700	[thread overview]
Message-ID: <> (raw)

The patch titled
     Subject: mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED
has been added to the -mm tree.  Its filename is

This patch should soon appear at
and later at

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From: Naoya Horiguchi <>
Subject: mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED

The call to get_user_pages_fast is only to get the pointer to a struct
page of a given address, pinning it is memory-poisoning handler's job, so
drop the refcount grabbed by get_user_pages_fast().

Note that the target page is still pinned after this put_page() because
the current process should have refcount from mapping.

Signed-off-by: Naoya Horiguchi <>
Signed-off-by: Oscar Salvador <>
Cc: "Aneesh Kumar K.V" <>
Cc: Aneesh Kumar K.V <>
Cc: Dave Hansen <>
Cc: David Hildenbrand <>
Cc: Dmitry Yakunin <>
Cc: Michal Hocko <>
Cc: Mike Kravetz <>
Cc: Tony Luck <>
Signed-off-by: Andrew Morton <>

 mm/madvise.c |   24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

--- a/mm/madvise.c~mmmadvise-call-soft_offline_page-without-mf_count_increased
+++ a/mm/madvise.c
@@ -893,16 +893,24 @@ static int madvise_inject_error(int beha
 		size = page_size(compound_head(page));
-		if (PageHWPoison(page)) {
-			put_page(page);
+		/*
+		 * The get_user_pages_fast() is just to get the pfn of the
+		 * given address, and the refcount has nothing to do with
+		 * what we try to test, so it should be released immediately.
+		 * This is racy but it's intended because the real hardware
+		 * errors could happen at any moment and memory error handlers
+		 * must properly handle the race.
+		 */
+		put_page(page);
+		if (PageHWPoison(page))
-		}
 		if (behavior == MADV_SOFT_OFFLINE) {
 			pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
 					pfn, start);
-			ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
+			ret = soft_offline_page(pfn, 0);
 			if (ret)
 				return ret;
@@ -910,14 +918,6 @@ static int madvise_inject_error(int beha
 		pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
 				pfn, start);

             reply	other threads:[~2020-06-24 19:19 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-24 19:19 akpm [this message]
2020-07-03 22:14 incoming Andrew Morton
2020-07-16 21:45 ` + mmmadvise-call-soft_offline_page-without-mf_count_increased.patch added to -mm tree Andrew Morton
2020-07-24  4:14 incoming Andrew Morton
2020-07-31 20:05 ` + mmmadvise-call-soft_offline_page-without-mf_count_increased.patch added to -mm tree Andrew Morton
2020-11-20 23:58 akpm

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