[PATCH v14-fix 05/11] mm: multi-gen LRU: fix warning from seq_is_valid()

[Yu Zhao <yuzhao@google.com>]

v5 (link below) calls inc_min_seq() in the correct order but rewrites
in the later versions broke it.

WARNING: CPU: 0 PID: 0 at ./include/linux/mm_types.h:613 context_switch+0x375/0x3e0
 __schedule+0x443/0x610
 schedule_idle+0x27/0x40
 do_idle+0x322/0x360
 cpu_startup_entry+0x65/0x70
 rest_init+0x1e7/0x1f0
 start_kernel+0x529/0x5a0
 x86_64_start_reservations+0x13f/0x150
 x86_64_start_kernel+0x1f2/0x200
 secondary_startup_64+0xa6/0xb0

Link: https://lore.kernel.org/linux-mm/20211111041510.402534-7-yuzhao@google.com/
Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Yu Zhao <yuzhao@google.com>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8291808ec535..e509e896c019 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4307,7 +4307,7 @@ static void inc_max_seq(struct lruvec *lruvec, bool can_swap, bool force_scan)
 
 	VM_WARN_ON_ONCE(!seq_is_valid(lruvec));
 
-	for (type = 0; type < ANON_AND_FILE; type++) {
+	for (type = ANON_AND_FILE - 1; type >= 0; type--) {
 		if (get_nr_gens(lruvec, type) != MAX_NR_GENS)
 			continue;
 
-- 
2.37.3.968.ga6b4b080e4-goog