diff mbox series

mm: gup: fix infinite loop within __get_longterm_locked

Message ID 20250120092604.3590285-1-zhaoyang.huang@unisoc.com (mailing list archive)
State New
Headers show
Series mm: gup: fix infinite loop within __get_longterm_locked | expand

Commit Message

zhaoyang.huang Jan. 20, 2025, 9:26 a.m. UTC 
From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>

Infinite loop within __get_longterm_locked detected in an unique usage
of pin_user_pages where the VA's pages are all unpinnable(vm_ops->fault
function allocate pages via cma_alloc for hardware purpose and leave them
out of LRU). Fixing this by have 'collected' reflect the actual number
of pages in movable_folio_list.

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
---
 mm/gup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/mm/gup.c b/mm/gup.c
index 3b75e631f369..2231ce7221f9 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2341,8 +2341,6 @@  static unsigned long collect_longterm_unpinnable_folios(
 		if (folio_is_longterm_pinnable(folio))
 			continue;
 
-		collected++;
-
 		if (folio_is_device_coherent(folio))
 			continue;
 
@@ -2359,6 +2357,8 @@  static unsigned long collect_longterm_unpinnable_folios(
 		if (!folio_isolate_lru(folio))
 			continue;
 
+		collected++;
+
 		list_add_tail(&folio->lru, movable_folio_list);
 		node_stat_mod_folio(folio,
 				    NR_ISOLATED_ANON + folio_is_file_lru(folio),