On Wed, Apr 15, 2020 at 01:42:14PM +0200, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
The patch below does not apply to the 5.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 33238c50451596be86db1505ab65fee5172844d0 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Wed, 18 Mar 2020 20:33:37 +0100
Subject: [PATCH] perf/core: Fix event cgroup tracking
Song reports that installing cgroup events is broken since:
db0503e4f675 ("perf/core: Optimize perf_install_in_event()")
The problem being that cgroup events try to track cpuctx->cgrp even
for disabled events, which is pointless and actively harmful since the
above commit. Rework the code to have explicit enable/disable hooks
for cgroup events, such that we can limit cgroup tracking to active
events.
More specifically, since the above commit disabled events are no
longer added to their context from the 'right' CPU, and we can't
access things like the current cgroup for a remote CPU.
Cc: <stable@xxxxxxxxxxxxxxx> # v5.5+
Fixes: db0503e4f675 ("perf/core: Optimize perf_install_in_event()")
Reported-by: Song Liu <songliubraving@xxxxxx>
Tested-by: Song Liu <songliubraving@xxxxxx>
Reviewed-by: Song Liu <songliubraving@xxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200318193337.GB20760@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I've also grabbed ab6f824cfdf7 ("perf/core: Unify
{pinned,flexible}_sched_in()") and 2c2366c7548e ("perf/core: Remove
'struct sched_in_data'"), and queued both for 5.6 and 5.5.
--
Thanks,
Sasha
