3.16.35-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Alexander Shishkin <[email protected]> commit 927a5570855836e5d5859a80ce7e91e963545e8f upstream. The error path in perf_event_open() is such that asking for a sampling event on a PMU that doesn't generate interrupts will end up in dropping the perf_sched_count even though it hasn't been incremented for this event yet. Given a sufficient amount of these calls, we'll end up disabling scheduler's jump label even though we'd still have active events in the system, thereby facilitating the arrival of the infernal regions upon us. I'm fixing this by moving account_event() inside perf_event_alloc(). Signed-off-by: Alexander Shishkin <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Vince Weaver <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/1456917854-29427-1-git-send-email-alexander.shish...@linux.intel.com Signed-off-by: Ingo Molnar <[email protected]> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- kernel/events/core.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6975,6 +6975,9 @@ perf_event_alloc(struct perf_event_attr } } + /* symmetric to unaccount_event() in _free_event() */ + account_event(event); + return event; err_pmu: @@ -7276,8 +7279,6 @@ SYSCALL_DEFINE5(perf_event_open, } } - account_event(event); - /* * Special case software events and allow them to be part of * any hardware group. @@ -7486,8 +7487,6 @@ perf_event_create_kernel_counter(struct goto err; } - account_event(event); - ctx = find_get_context(event->pmu, task, cpu); if (IS_ERR(ctx)) { err = PTR_ERR(ctx);
