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From: Oscar Salvador <osalvador@suse.de>
To: n-horiguchi@ah.jp.nec.com
Cc: mhocko@kernel.org, mike.kravetz@oracle.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, Oscar Salvador <osalvador@suse.de>
Subject: [PATCH 02/10] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED
Date: Tue, 10 Sep 2019 12:30:08 +0200	[thread overview]
Message-ID: <20190910103016.14290-3-osalvador@suse.de> (raw)
In-Reply-To: <20190910103016.14290-1-osalvador@suse.de>

From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

Currently madvise_inject_error() pins the target via get_user_pages_fast.
The call to get_user_pages_fast is only to get the respective page
of a given address, but it is the job of the memory-poisoning handler
to deal with races, so drop the refcount grabbed by get_user_pages_fast.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
 mm/madvise.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 6e023414f5c1..fbe6d402232c 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -883,6 +883,16 @@ static int madvise_inject_error(int behavior,
 		ret = get_user_pages_fast(start, 1, 0, &page);
 		if (ret != 1)
 			return ret;
+		/*
+		 * 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);
+
 		pfn = page_to_pfn(page);
 
 		/*
@@ -892,16 +902,11 @@ static int madvise_inject_error(int behavior,
 		 */
 		order = compound_order(compound_head(page));
 
-		if (PageHWPoison(page)) {
-			put_page(page);
-			continue;
-		}
-
 		if (behavior == MADV_SOFT_OFFLINE) {
 			pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
 					pfn, start);
 
-			ret = soft_offline_page(page, MF_COUNT_INCREASED);
+			ret = soft_offline_page(page, 0);
 			if (ret)
 				return ret;
 			continue;
@@ -909,14 +914,6 @@ static int madvise_inject_error(int behavior,
 
 		pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
 				pfn, start);
-
-		/*
-		 * Drop the page reference taken by get_user_pages_fast(). In
-		 * the absence of MF_COUNT_INCREASED the memory_failure()
-		 * routine is responsible for pinning the page to prevent it
-		 * from being released back to the page allocator.
-		 */
-		put_page(page);
 		ret = memory_failure(pfn, 0);
 		if (ret)
 			return ret;
-- 
2.12.3


  parent reply	other threads:[~2019-09-10 10:31 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-10 10:30 [PATCH 00/10] Hwpoison soft-offline rework Oscar Salvador
2019-09-10 10:30 ` [PATCH 01/10] mm,hwpoison: cleanup unused PageHuge() check Oscar Salvador
2019-09-11 10:17   ` David Hildenbrand
2019-09-10 10:30 ` Oscar Salvador [this message]
2019-09-11 10:23   ` [PATCH 02/10] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED David Hildenbrand
2019-09-12  1:28     ` Naoya Horiguchi
2019-09-11 10:27   ` David Hildenbrand
2019-09-12  1:37     ` Naoya Horiguchi
2019-09-13  8:37       ` David Hildenbrand
2019-09-10 10:30 ` [PATCH 03/10] mm,hwpoison-inject: don't pin for hwpoison_filter Oscar Salvador
2019-09-16  7:41   ` David Hildenbrand
2019-09-10 10:30 ` [PATCH 04/10] mm,hwpoison: remove MF_COUNT_INCREASED Oscar Salvador
2019-09-11 10:24   ` David Hildenbrand
2019-09-10 10:30 ` [PATCH 05/10] mm: remove flag argument from soft offline functions Oscar Salvador
2019-09-11 10:24   ` David Hildenbrand
2019-09-10 10:30 ` [PATCH 06/10] mm,hwpoison: Unify THP handling for hard and soft offline Oscar Salvador
2019-09-10 10:30 ` [PATCH 07/10] mm,hwpoison: Rework soft offline for in-use pages Oscar Salvador
2019-09-10 10:30 ` [PATCH 08/10] mm,hwpoison: Refactor soft_offline_huge_page and __soft_offline_page Oscar Salvador
2019-09-10 10:30 ` [PATCH 09/10] mm,hwpoison: Rework soft offline for free pages Oscar Salvador
2019-09-10 10:30 ` [PATCH 10/10] mm,hwpoison: Use hugetlb_replace_page to replace free hugetlb pages Oscar Salvador
2019-09-10 10:32 ` [PATCH 00/10] Hwpoison soft-offline rework Oscar Salvador
2019-09-11  5:29 ` Naoya Horiguchi
2019-09-11  6:22   ` Naoya Horiguchi
2019-09-11  6:35     ` osalvador
2019-09-11  7:21       ` Naoya Horiguchi
2019-09-12 13:16         ` Oscar Salvador

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