From 734df5ab549ca44f40de0f07af1c8803856dfb18 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Tue, 9 Jul 2013 17:44:10 +0200 Subject: [PATCH] perf: Clone child context from parent context pmu Currently when the child context for inherited events is created, it's based on the pmu object of the first event of the parent context. This is wrong for the following scenario: - HW context having HW and SW event - HW event got removed (closed) - SW event stays in HW context as the only event and its pmu is used to clone the child context The issue starts when the cpu context object is touched based on the pmu context object (__get_cpu_context). In this case the HW context will work with SW cpu context ending up with following WARN below. Fixing this by using parent context pmu object to clone from child context. Addresses the following warning reported by Vince Weaver: [ 2716.472065] ------------[ cut here ]------------ [ 2716.476035] WARNING: at kernel/events/core.c:2122 task_ctx_sched_out+0x3c/0x) [ 2716.476035] Modules linked in: nfsd auth_rpcgss oid_registry nfs_acl nfs locn [ 2716.476035] CPU: 0 PID: 3164 Comm: perf_fuzzer Not tainted 3.10.0-rc4 #2 [ 2716.476035] Hardware name: AOpen DE7000/nMCP7ALPx-DE R1.06 Oct.19.2012, BI2 [ 2716.476035] 0000000000000000 ffffffff8102e215 0000000000000000 ffff88011fc18 [ 2716.476035] ffff8801175557f0 0000000000000000 ffff880119fda88c ffffffff810ad [ 2716.476035] ffff880119fda880 ffffffff810af02a 0000000000000009 ffff880117550 [ 2716.476035] Call Trace: [ 2716.476035] [] ? warn_slowpath_common+0x5b/0x70 [ 2716.476035] [] ? task_ctx_sched_out+0x3c/0x5f [ 2716.476035] [] ? perf_event_exit_task+0xbf/0x194 [ 2716.476035] [] ? do_exit+0x3e7/0x90c [ 2716.476035] [] ? __do_fault+0x359/0x394 [ 2716.476035] [] ? do_group_exit+0x66/0x98 [ 2716.476035] [] ? get_signal_to_deliver+0x479/0x4ad [ 2716.476035] [] ? __perf_event_task_sched_out+0x230/0x2d1 [ 2716.476035] [] ? do_signal+0x3c/0x432 [ 2716.476035] [] ? ctx_sched_in+0x43/0x141 [ 2716.476035] [] ? perf_event_context_sched_in+0x7a/0x90 [ 2716.476035] [] ? __perf_event_task_sched_in+0x31/0x118 [ 2716.476035] [] ? mmdrop+0xd/0x1c [ 2716.476035] [] ? finish_task_switch+0x7d/0xa6 [ 2716.476035] [] ? do_notify_resume+0x20/0x5d [ 2716.476035] [] ? retint_signal+0x3d/0x78 [ 2716.476035] ---[ end trace 827178d8a5966c3d ]--- Reported-by: Vince Weaver Signed-off-by: Jiri Olsa Cc: Corey Ashford Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Namhyung Kim Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1373384651-6109-1-git-send-email-jolsa@redhat.com Signed-off-by: Ingo Molnar --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 1833bc5..1d1f030 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7465,7 +7465,7 @@ inherit_task_group(struct perf_event *event, struct task_struct *parent, * child. */ - child_ctx = alloc_perf_context(event->pmu, child); + child_ctx = alloc_perf_context(parent_ctx->pmu, child); if (!child_ctx) return -ENOMEM; -- 2.7.4