The patch titled
Subject: mm/gup: return an error on migration failure
has been added to the -mm tree. Its filename is
mm-gup-return-an-error-on-migration-failure.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-gup-return-an-error-on-migration-failure.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-return-an-error-on-migration-failure.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Subject: 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.
Link: https://lkml.kernel.org/r/20210201153827.444374-4-pasha.tatashin@xxxxxxxxxx
Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sasha Levin <sashal@xxxxxxxxxx>
Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Cc: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
--- a/mm/gup.c~mm-gup-return-an-error-on-migration-failure
+++ a/mm/gup.c
@@ -1550,7 +1550,6 @@ static long check_and_migrate_cma_pages(
{
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;
@@ -1601,17 +1600,15 @@ 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
@@ -1621,7 +1618,7 @@ check_again:
pages, vmas, NULL,
gup_flags);
- if ((ret > 0) && migrate_allow) {
+ if (ret > 0) {
nr_pages = ret;
drain_allow = true;
goto check_again;
_
Patches currently in -mm which might be from pasha.tatashin@xxxxxxxxxx are
mm-gup-dont-pin-migrated-cma-pages-in-movable-zone.patch
mm-gup-check-every-subpage-of-a-compound-page-during-isolation.patch
mm-gup-return-an-error-on-migration-failure.patch
mm-gup-check-for-isolation-errors.patch
mm-cma-rename-pf_memalloc_nocma-to-pf_memalloc_pin.patch
mm-apply-per-task-gfp-constraints-in-fast-path.patch
mm-honor-pf_memalloc_pin-for-all-movable-pages.patch
mm-gup-do-not-migrate-zero-page.patch
mm-gup-migrate-pinned-pages-out-of-movable-zone.patch
memory-hotplugrst-add-a-note-about-zone_movable-and-page-pinning.patch
mm-gup-change-index-type-to-long-as-it-counts-pages.patch
mm-gup-longterm-pin-migration-cleanup.patch
selftests-vm-gup_test-fix-test-flag.patch
selftests-vm-gup_test-test-faulting-in-kernel-and-verify-pinnable-pages.patch
