diff mbox series

[v5,03/14] mm/gup: return an error on migration failure

Message ID 20210119043920.155044-4-pasha.tatashin@soleen.com (mailing list archive)
State New, archived
Headers show
Series prohibit pinning pages in ZONE_MOVABLE | expand

Commit Message

Pasha Tatashin Jan. 19, 2021, 4:39 a.m. UTC 
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@soleen.com>
---
 mm/gup.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

Comments

Jason Gunthorpe Jan. 19, 2021, 6:28 p.m. UTC | #1 
On Mon, Jan 18, 2021 at 11:39:09PM -0500, Pavel Tatashin wrote:
> 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@soleen.com>
>  mm/gup.c | 17 +++++++----------
>  1 file changed, 7 insertions(+), 10 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
diff mbox series

Patch

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;