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From: Oscar Salvador <osalvador@suse.de>
To: akpm@linux-foundation.org
Cc: mhocko@suse.com, linux-mm@kvack.org, mike.kravetz@oracle.com,
	david@redhat.com, aneesh.kumar@linux.vnet.ibm.com,
	naoya.horiguchi@nec.com, linux-kernel@vger.kernel.org,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Oscar Salvador <osalvador@suse.com>
Subject: [PATCH v4 03/15] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED
Date: Thu, 16 Jul 2020 14:37:57 +0200	[thread overview]
Message-ID: <20200716123810.25292-4-osalvador@suse.de> (raw)
In-Reply-To: <20200716123810.25292-1-osalvador@suse.de>

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

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

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Oscar Salvador <osalvador@suse.com>
---
 mm/madvise.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index a16dba21cdf6..1fe89a5b8d33 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -910,16 +910,24 @@ static int madvise_inject_error(int behavior,
 		 */
 		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))
 			continue;
-		}
 
 		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;
 			continue;
@@ -927,14 +935,6 @@ 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;
-- 
2.26.2


  parent reply	other threads:[~2020-07-16 12:38 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-16 12:37 [PATCH v4 00/15] Hwpoison soft-offline rework Oscar Salvador
2020-07-16 12:37 ` [PATCH v4 01/15] mm,hwpoison: cleanup unused PageHuge() check Oscar Salvador
2020-07-16 12:37 ` [PATCH v4 02/15] mm, hwpoison: remove recalculating hpage Oscar Salvador
2020-07-16 12:37 ` Oscar Salvador [this message]
2020-07-16 23:15   ` [PATCH v4 03/15] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED Mike Kravetz
2020-07-16 12:37 ` [PATCH v4 04/15] mm,madvise: Refactor madvise_inject_error Oscar Salvador
2020-07-16 12:37 ` [PATCH v4 05/15] mm,hwpoison-inject: don't pin for hwpoison_filter Oscar Salvador
2020-07-16 12:38 ` [PATCH v4 06/15] mm,hwpoison: Un-export get_hwpoison_page and make it static Oscar Salvador
2020-07-16 12:38 ` [PATCH v4 07/15] mm,hwpoison: Kill put_hwpoison_page Oscar Salvador
2020-07-16 12:38 ` [PATCH v4 08/15] mm,hwpoison: remove MF_COUNT_INCREASED Oscar Salvador
2020-07-16 12:38 ` [PATCH v4 09/15] mm,hwpoison: remove flag argument from soft offline functions Oscar Salvador
2020-07-16 12:38 ` [PATCH v4 10/15] mm,hwpoison: Unify THP handling for hard and soft offline Oscar Salvador
2020-07-16 12:38 ` [PATCH v4 11/15] mm,hwpoison: Rework soft offline for free pages Oscar Salvador
2020-07-16 12:38 ` [PATCH v4 12/15] mm,hwpoison: Rework soft offline for in-use pages Oscar Salvador
2020-07-17  6:55   ` HORIGUCHI NAOYA(堀口 直也)
     [not found]   ` <f7387d64d0024d15a1bc821a8e19b8f0@DB7PR04MB5180.eurprd04.prod.outlook.com>
2020-07-20  8:27     ` osalvador
2020-07-22  8:08       ` osalvador
2020-07-23 10:19         ` Oscar Salvador
2020-07-16 12:38 ` [PATCH v4 13/15] mm,hwpoison: Refactor soft_offline_huge_page and __soft_offline_page Oscar Salvador
2020-07-16 12:38 ` [PATCH v4 14/15] mm,hwpoison: Return 0 if the page is already poisoned in soft-offline Oscar Salvador
2020-07-16 12:38 ` [PATCH v4 15/15] mm,hwpoison: introduce MF_MSG_UNSPLIT_THP Oscar Salvador
2020-07-16 12:38 ` [PATCH] x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support Oscar Salvador
2020-07-16 12:43   ` osalvador
2020-07-17 14:49 ` [PATCH v4 00/15] Hwpoison soft-offline rework Qian Cai

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