Re: FAILED: patch "[PATCH] perf/core: Fix event cgroup tracking" failed to apply to 5.6-stable tree

[Sasha Levin <sashal@kernel.org>]

On Wed, Apr 15, 2020 at 01:42:14PM +0200, gregkh@linuxfoundation.org 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@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From 33238c50451596be86db1505ab65fee5172844d0 Mon Sep 17 00:00:00 2001
>From: Peter Zijlstra <peterz@infradead.org>
>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@vger.kernel.org> # v5.5+
>Fixes: db0503e4f675 ("perf/core: Optimize perf_install_in_event()")
>Reported-by: Song Liu <songliubraving@fb.com>
>Tested-by: Song Liu <songliubraving@fb.com>
>Reviewed-by: Song Liu <songliubraving@fb.com>
>Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
>Signed-off-by: Ingo Molnar <mingo@kernel.org>
>Link: https://lkml.kernel.org/r/20200318193337.GB20760@hirez.programming.kicks-ass.net

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