| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.5 352/367] perf/cgroups: Install cgroup events to correct cpuctx | Date | Mon, 10 Feb 2020 04:34:25 -0800 |
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From: Song Liu <songliubraving@fb.com>
commit 07c5972951f088094776038006a0592a46d14bbc upstream.
cgroup events are always installed in the cpuctx. However, when it is not installed via IPI, list_update_cgroup_event() adds it to cpuctx of current CPU, which triggers list corruption:
[] list_add double add: new=ffff888ff7cf0db0, prev=ffff888ff7ce82f0, next=ffff888ff7cf0db0.
To reproduce this, we can simply run:
# perf stat -e cs -a & # perf stat -e cs -G anycgroup
Fix this by installing it to cpuctx that contains event->ctx, and the proper cgrp_cpuctx_list.
Fixes: db0503e4f675 ("perf/core: Optimize perf_install_in_event()") Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20200122195027.2112449-1-songliubraving@fb.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/events/core.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
--- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -951,9 +951,9 @@ list_update_cgroup_event(struct perf_eve /* * Because cgroup events are always per-cpu events, - * this will always be called from the right CPU. + * @ctx == &cpuctx->ctx. */ - cpuctx = __get_cpu_context(ctx); + cpuctx = container_of(ctx, struct perf_cpu_context, ctx); /* * Since setting cpuctx->cgrp is conditional on the current @cgrp @@ -979,7 +979,8 @@ list_update_cgroup_event(struct perf_eve cpuctx_entry = &cpuctx->cgrp_cpuctx_entry; if (add) - list_add(cpuctx_entry, this_cpu_ptr(&cgrp_cpuctx_list)); + list_add(cpuctx_entry, + per_cpu_ptr(&cgrp_cpuctx_list, event->cpu)); else list_del(cpuctx_entry); }
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