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 -------------------------------- 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 12f351b253bbb..34e1667e42549 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; -- 2.25.1