mm/gup: return an error on migration failure

[ Upstream commit f0f4463837da17a89d965dcbe4e411629dbcf308 ]

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.

Link: https://lkml.kernel.org/r/20210215161349.246722-4-pasha.tatashin@soleen.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/mm/gup.c b/mm/gup.c
index 6530672131dbb5682194aacb5d7923110be32b4f..2b48c65e27cc6a52616c846744b93049c794fef6 100644 (file)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1553,7 +1553,6 @@ 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;
@@ -1604,17 +1603,15 @@ check_again:
                        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
@@ -1624,7 +1621,7 @@ check_again:
                                                   pages, vmas, NULL,
                                                   gup_flags);
 
-               if ((ret > 0) && migrate_allow) {
+               if (ret > 0) {
                        nr_pages = ret;
                        drain_allow = true;
                        goto check_again;