sched/numa: Move up the access pid reset logic

[ Upstream commit 2e2675db1906ac04809f5399bf1f5e30d56a6f3e ]

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
Stable-dep-of: f22cde4371f3 ("sched/numa: Fix the vma scan starving issue")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7c5f6e94b3cdc681f6c18524b05214301e2da19a..07363b73ccdcc5a1600094dc71992ed331e31fe0 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3335,16 +3335,7 @@ 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 +
@@ -3353,6 +3344,12 @@ 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);