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authorJiri Olsa <jolsa@kernel.org>2014-12-10 21:23:51 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-01-16 06:59:34 -0800
commitc8af8989238dd365808ddc3606dc458b089597d3 (patch)
tree01fd2486b99326ac440876a93ec5ff2401a7651b
parentec9c772a1cb7436c278da5eb0aadb2589a62b485 (diff)
downloadlinux-linaro-stable-c8af8989238dd365808ddc3606dc458b089597d3.tar.gz
perf: Fix events installation during moving group
commit 9fc81d87420d0d3fd62d5e5529972c0ad9eab9cc upstream. We allow PMU driver to change the cpu on which the event should be installed to. This happened in patch: e2d37cd213dc ("perf: Allow the PMU driver to choose the CPU on which to install events") This patch also forces all the group members to follow the currently opened events cpu if the group happened to be moved. This and the change of event->cpu in perf_install_in_context() function introduced in: 0cda4c023132 ("perf: Introduce perf_pmu_migrate_context()") forces group members to change their event->cpu, if the currently-opened-event's PMU changed the cpu and there is a group move. Above behaviour causes problem for breakpoint events, which uses event->cpu to touch cpu specific data for breakpoints accounting. By changing event->cpu, some breakpoints slots were wrongly accounted for given cpu. Vinces's perf fuzzer hit this issue and caused following WARN on my setup: WARNING: CPU: 0 PID: 20214 at arch/x86/kernel/hw_breakpoint.c:119 arch_install_hw_breakpoint+0x142/0x150() Can't find any breakpoint slot [...] This patch changes the group moving code to keep the event's original cpu. Reported-by: Vince Weaver <vince@deater.net> Signed-off-by: Jiri Olsa <jolsa@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Vince Weaver <vince@deater.net> Cc: Yan, Zheng <zheng.z.yan@intel.com> Link: http://lkml.kernel.org/r/1418243031-20367-3-git-send-email-jolsa@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--kernel/events/core.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4bbb27adf23d..69cffb46db17 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7240,11 +7240,11 @@ SYSCALL_DEFINE5(perf_event_open,
if (move_group) {
synchronize_rcu();
- perf_install_in_context(ctx, group_leader, event->cpu);
+ perf_install_in_context(ctx, group_leader, group_leader->cpu);
get_ctx(ctx);
list_for_each_entry(sibling, &group_leader->sibling_list,
group_entry) {
- perf_install_in_context(ctx, sibling, event->cpu);
+ perf_install_in_context(ctx, sibling, sibling->cpu);
get_ctx(ctx);
}
}