On 2016/11/15 17:48, Ingo Molnar wrote:
* Takao Indoh <indou.ta...@jp.fujitsu.com> wrote:In rb_alloc_aux_page(), a page order is set to MAX_ORDER when order is greater than MAX_ORDER, but page order should be less than MAX_ORDER, therefore alloc_pages_node fails at least once. This patch fixes page order so that it can be always less than MAX_ORDER. Signed-off-by: Takao Indoh <indou.ta...@jp.fujitsu.com> --- kernel/events/ring_buffer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 257fa46..3f76fdd 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -502,8 +502,8 @@ static struct page *rb_alloc_aux_page(int node, int order) { struct page *page; - if (order > MAX_ORDER) - order = MAX_ORDER; + if (order >= MAX_ORDER) + order = MAX_ORDER - 1; do { page = alloc_pages_node(node, PERF_AUX_GFP, order);I'm wondering under what circumstances this allocation failure was seen in practice - why did others not hit this?
I found this when I ran perf with -m,2048. I think in the most cases users use default buffer size hence they does not notice. Thanks, Takao Indoh
