linux-kernel - [PATCH v5 03/14] mm/gup: return an error on migration failure

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: <20210119043920.155044-4-pasha.tatashin@soleen.com>
Date:   Mon, 18 Jan 2021 23:39:09 -0500
From:   Pavel Tatashin <pasha.tatashin@...een.com>
To:     pasha.tatashin@...een.com, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, akpm@...ux-foundation.org, vbabka@...e.cz,
        mhocko@...e.com, david@...hat.com, osalvador@...e.de,
        dan.j.williams@...el.com, sashal@...nel.org,
        tyhicks@...ux.microsoft.com, iamjoonsoo.kim@....com,
        mike.kravetz@...cle.com, rostedt@...dmis.org, mingo@...hat.com,
        jgg@...pe.ca, peterz@...radead.org, mgorman@...e.de,
        willy@...radead.org, rientjes@...gle.com, jhubbard@...dia.com,
        linux-doc@...r.kernel.org, ira.weiny@...el.com,
        linux-kselftest@...r.kernel.org
Subject: [PATCH v5 03/14] mm/gup: return an error on migration failure

When migration failure occurs, we still pin pages, which means
that we may pin CMA movable pages which should never be the case.

Instead return an error without pinning pages when migration failure
happens.

No need to retry migrating, because migrate_pages() already retries
10 times.

Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
---
 mm/gup.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 16f10d5a9eb6..88ce41f41543 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1557,7 +1557,6 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
 {
 	unsigned long i;
 	bool drain_allow = true;
-	bool migrate_allow = true;
 	LIST_HEAD(cma_page_list);
 	long ret = nr_pages;
 	struct page *prev_head, *head;
@@ -1608,17 +1607,15 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
 			for (i = 0; i < nr_pages; i++)
 				put_page(pages[i]);
 
-		if (migrate_pages(&cma_page_list, alloc_migration_target, NULL,
-			(unsigned long)&mtc, MIGRATE_SYNC, MR_CONTIG_RANGE)) {
-			/*
-			 * some of the pages failed migration. Do get_user_pages
-			 * without migration.
-			 */
-			migrate_allow = false;
-
+		ret = migrate_pages(&cma_page_list, alloc_migration_target,
+				    NULL, (unsigned long)&mtc, MIGRATE_SYNC,
+				    MR_CONTIG_RANGE);
+		if (ret) {
 			if (!list_empty(&cma_page_list))
 				putback_movable_pages(&cma_page_list);
+			return ret > 0 ? -ENOMEM : ret;
 		}
+
 		/*
 		 * We did migrate all the pages, Try to get the page references
 		 * again migrating any new CMA pages which we failed to isolate
@@ -1628,7 +1625,7 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
 						   pages, vmas, NULL,
 						   gup_flags);
 
-		if ((ret > 0) && migrate_allow) {
+		if (ret > 0) {
 			nr_pages = ret;
 			drain_allow = true;
 			goto check_again;
-- 
2.25.1