linux-kernel - [PATCH v4 14/15] mm,hwpoison: Return 0 if the page is already poisoned in soft-offline

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200716123810.25292-15-osalvador@suse.de>
Date:   Thu, 16 Jul 2020 14:38:08 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     akpm@...ux-foundation.org
Cc:     mhocko@...e.com, linux-mm@...ck.org, mike.kravetz@...cle.com,
        david@...hat.com, aneesh.kumar@...ux.vnet.ibm.com,
        naoya.horiguchi@....com, linux-kernel@...r.kernel.org,
        Oscar Salvador <osalvador@...e.de>,
        Oscar Salvador <osalvador@...e.com>
Subject: [PATCH v4 14/15] mm,hwpoison: Return 0 if the page is already poisoned in soft-offline

Currently, there is an inconsistency when calling soft-offline from
different paths on a page that is already poisoned.

1) madvise:

        madvise_inject_error skips any poisoned page and continues
        the loop.
        If that was the only page to madvise, it returns 0.

2) /sys/devices/system/memory/:

        When calling soft_offline_page_store()->soft_offline_page(),
        we return -EBUSY in case the page is already poisoned.
        This is inconsistent with a) the above example and b)
        memory_failure, where we return 0 if the page was poisoned.

Fix this by dropping the PageHWPoison() check in madvise_inject_error,
and let soft_offline_page return 0 if it finds the page already poisoned.

Please, note that this represents a user-api change, since now the
return error when calling soft_offline_page_store()->soft_offline_page()
will be different.

Signed-off-by: Oscar Salvador <osalvador@...e.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@....com>
---
 mm/madvise.c        | 3 ---
 mm/memory-failure.c | 4 ++--
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 226f0fcf0828..7b5ca96108cd 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -920,9 +920,6 @@ static int madvise_inject_error(int behavior,
 		 */
 		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);
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index c6c83337708a..2b2aa5a76b9b 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1781,7 +1781,7 @@ static int __soft_offline_page(struct page *page)
 		unlock_page(page);
 		put_page(page);
 		pr_info("soft offline: %#lx page already poisoned\n", pfn);
-		return -EBUSY;
+		return 0;
 	}
 
 	if (!PageHuge(page))
@@ -1881,7 +1881,7 @@ int soft_offline_page(unsigned long pfn)
 
 	if (PageHWPoison(page)) {
 		pr_info("soft offline: %#lx page already poisoned\n", pfn);
-		return -EBUSY;
+		return 0;
 	}
 
 	get_online_mems();
-- 
2.26.2