sched/numa: Move up the access pid reset logic

Recent NUMA hinting faulting activity is reset approximately every
VMA_PID_RESET_PERIOD milliseconds. However, if the current task has not
accessed a VMA then the reset check is missed and the reset is potentially
deferred forever. Check if the PID activity information should be reset
before checking if the current task recently trapped a NUMA hinting fault.

[ mgorman@techsingularity.net: Rewrite changelog ]

Suggested-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231010083143.19593-5-mgorman@techsingularity.net

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 31cfdb0794fbcfc8a28bbf6abf1406f974233c35..ce36969625bdb5dfbf6aeaabee8fb44662283836 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3260,16 +3260,7 @@ static void task_numa_work(struct callback_head *work)
                        continue;
                }
 
-               /* Do not scan the VMA if task has not accessed */
-               if (!vma_is_accessed(vma)) {
-                       trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_PID_INACTIVE);
-                       continue;
-               }
-
-               /*
-                * RESET access PIDs regularly for old VMAs. Resetting after checking
-                * vma for recent access to avoid clearing PID info before access..
-                */
+               /* RESET access PIDs regularly for old VMAs. */
                if (mm->numa_scan_seq &&
                                time_after(jiffies, vma->numab_state->pids_active_reset)) {
                        vma->numab_state->pids_active_reset = vma->numab_state->pids_active_reset +
@@ -3278,6 +3269,12 @@ static void task_numa_work(struct callback_head *work)
                        vma->numab_state->pids_active[1] = 0;
                }
 
+               /* Do not scan the VMA if task has not accessed */
+               if (!vma_is_accessed(vma)) {
+                       trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_PID_INACTIVE);
+                       continue;
+               }
+
                do {
                        start = max(start, vma->vm_start);
                        end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE);