| From 07c5972951f088094776038006a0592a46d14bbc Mon Sep 17 00:00:00 2001 |
| From: Song Liu <songliubraving@fb.com> |
| Date: Wed, 22 Jan 2020 11:50:27 -0800 |
| Subject: perf/cgroups: Install cgroup events to correct cpuctx |
| |
| 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); |
| } |