* [PATCH] perf/core: Fix the WARN_ON_ONCE is out of lock protected region
@ 2025-06-26 13:54 Luo Gengkun
0 siblings, 0 replies; only message in thread
From: Luo Gengkun @ 2025-06-26 13:54 UTC (permalink / raw)
To: peterz
Cc: mingo, acme, namhyung, mark.rutland, alexander.shishkin, jolsa,
irogers, adrian.hunter, kan.liang, linux-perf-users, linux-kernel,
luogengkun
commit 3172fb986666 ("perf/core: Fix WARN in perf_cgroup_switch()") try to
fix a concurrency problem between perf_cgroup_switch and
perf_cgroup_event_disable. But it does not to move the WARN_ON_ONCE into
lock-protected region, so the warning is still be triggered.
Fixes: 3172fb986666 ("perf/core: Fix WARN in perf_cgroup_switch()")
Signed-off-by: Luo Gengkun <luogengkun@huaweicloud.com>
---
kernel/events/core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1f746469fda5..a35784d42c66 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -951,8 +951,6 @@ static void perf_cgroup_switch(struct task_struct *task)
if (READ_ONCE(cpuctx->cgrp) == NULL)
return;
- WARN_ON_ONCE(cpuctx->ctx.nr_cgroups == 0);
-
cgrp = perf_cgroup_from_task(task, NULL);
if (READ_ONCE(cpuctx->cgrp) == cgrp)
return;
@@ -964,6 +962,8 @@ static void perf_cgroup_switch(struct task_struct *task)
if (READ_ONCE(cpuctx->cgrp) == NULL)
return;
+ WARN_ON_ONCE(cpuctx->ctx.nr_cgroups == 0);
+
perf_ctx_disable(&cpuctx->ctx, true);
ctx_sched_out(&cpuctx->ctx, NULL, EVENT_ALL|EVENT_CGROUP);
--
2.34.1
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