From: Alexander Shishkin alexander.shishkin@linux.intel.com
mainline inclusion from mainline-v5.1 commit 26ae4f4406f88d82d79c85c11ac5fae18213cd38 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V CVE: NA
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commit 26ae4f4406f88d82d79c85c11ac5fae18213cd38 upstream.
This recent commit:
5768402fd9c6e87 ("perf/ring_buffer: Use high order allocations for AUX buffers optimistically")
overlooked the fact that the previous one page granularity of the AUX buffer provided an implicit double buffering capability to the PMU driver, which went away when the entire buffer became one high-order page.
Always make the full-trace mode AUX allocation at least two-part to preserve the previous behavior and allow the implicit double buffering to continue.
Reported-by: Ammy Yi ammy.yi@intel.com Signed-off-by: Alexander Shishkin alexander.shishkin@linux.intel.com Acked-by: Peter Zijlstra a.p.zijlstra@chello.nl Cc: Arnaldo Carvalho de Melo acme@redhat.com Cc: Jiri Olsa jolsa@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Stephane Eranian eranian@google.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Vince Weaver vincent.weaver@maine.edu Cc: adrian.hunter@intel.com Fixes: 5768402fd9c6e87 ("perf/ring_buffer: Use high order allocations for AUX buffers optimistically") Link: http://lkml.kernel.org/r/20190503085536.24119-2-alexander.shishkin@linux.int... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Shen, Xiaochen xiaochen.shen@intel.com Signed-off-by: Jackie Liu liuyun01@kylinos.cn Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Reviewed-by: Yang Jihong yangjihong1@huawei.com Reviewed-by: Xie XiuQi xiexiuqi@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- kernel/events/ring_buffer.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 12f351b253bb..34e1667e4254 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -630,8 +630,7 @@ int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event, * PMU requests more than one contiguous chunks of memory * for SW double buffering */ - if ((event->pmu->capabilities & PERF_PMU_CAP_AUX_SW_DOUBLEBUF) && - !overwrite) { + if (!overwrite) { if (!max_order) return -EINVAL;