@@ -347,6 +347,7 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size,
bool truncated)
{
struct ring_buffer *rb = handle->rb;
+ bool wakeup = truncated;
unsigned long aux_head;
u64 flags = 0;
@@ -375,9 +376,16 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size,
aux_head = rb->user_page->aux_head = local_read(&rb->aux_head);
if (aux_head - local_read(&rb->aux_wakeup) >= rb->aux_watermark) {
- perf_output_wakeup(handle);
+ wakeup = true;
local_add(rb->aux_watermark, &rb->aux_wakeup);
}
+
+ if (wakeup) {
+ if (truncated)
+ handle->event->pending_disable = 1;
+ perf_output_wakeup(handle);
+ }
+
handle->event = NULL;
local_set(&rb->aux_nest, 0);
This is a note to let you know that I have just added a patch titled perf/core: Disable the event on a truncated AUX record to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt11. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From da94675f2421926235a2981e3af6d7838f937e18 Mon Sep 17 00:00:00 2001 From: Alexander Shishkin <alexander.shishkin@linux.intel.com> Date: Tue, 10 May 2016 16:18:33 +0300 Subject: perf/core: Disable the event on a truncated AUX record commit 9f448cd3cbcec8995935e60b27802ae56aac8cc0 upstream. When the PMU driver reports a truncated AUX record, it effectively means that there is no more usable room in the event's AUX buffer (even though there may still be some room, so that perf_aux_output_begin() doesn't take action). At this point the consumer still has to be woken up and the event has to be disabled, otherwise the event will just keep spinning between perf_aux_output_begin() and perf_aux_output_end() until its context gets unscheduled. Again, for cpu-wide events this means never, so once in this condition, they will be forever losing data. Fix this by disabling the event and waking up the consumer in case of a truncated AUX record. Reported-by: Markus Metzger <markus.t.metzger@intel.com> Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: vince@deater.net Link: http://lkml.kernel.org/r/1462886313-13660-3-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- kernel/events/ring_buffer.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) -- 2.7.4