lkml.org 
[lkml]   [2020]   [Jan]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip: perf/urgent] perf/cgroups: Install cgroup events to correct cpuctx
The following commit has been merged into the perf/urgent branch of tip:

Commit-ID: 07c5972951f088094776038006a0592a46d14bbc
Gitweb: https://git.kernel.org/tip/07c5972951f088094776038006a0592a46d14bbc
Author: Song Liu <songliubraving@fb.com>
AuthorDate: Wed, 22 Jan 2020 11:50:27 -08:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 28 Jan 2020 21:20:19 +01:00

perf/cgroups: Install cgroup events to correct cpuctx

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
---
kernel/events/core.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2d9aeba..fdb7f7e 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -951,9 +951,9 @@ list_update_cgroup_event(struct perf_event *event,

/*
* 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_event *event,

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);
}
\
 
 \ /
  Last update: 2020-01-29 12:34    [W:0.128 / U:0.168 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site