This is a note to let you know that I've just added the patch titled perf: fix perf_event_context->time to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: perf-fix-perf_event_context-time.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit c953a2c5ed43f37c2de6b1a6ff9b8f56ff2d3b8d Author: Song Liu <song@xxxxxxxxxx> Date: Mon Mar 13 10:16:08 2023 -0700 perf: fix perf_event_context->time [ Upstream commit baf1b12a67f5b24f395baca03e442ce27cab0c18 ] Time readers rely on perf_event_context->[time|timestamp|timeoffset] to get accurate time_enabled and time_running for an event. The difference between ctx->timestamp and ctx->time is the among of time when the context is not enabled. __update_context_time(ctx, false) is used to increase timestamp, but not time. Therefore, it should only be called in ctx_sched_in() when EVENT_TIME was not enabled. Fixes: 09f5e7dc7ad7 ("perf: Fix perf_event_read_local() time") Signed-off-by: Song Liu <song@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20230313171608.298734-1-song@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/kernel/events/core.c b/kernel/events/core.c index 6c4e78cd7a8b5..2aa286b4151b3 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3830,7 +3830,7 @@ ctx_sched_in(struct perf_event_context *ctx, if (likely(!ctx->nr_events)) return; - if (is_active ^ EVENT_TIME) { + if (!(is_active & EVENT_TIME)) { /* start ctx time */ __update_context_time(ctx, false); perf_cgroup_set_timestamp(cpuctx);