From 2ed11312eb19506c027e7cac039994ad42a9cb2c Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Mon, 2 Mar 2015 02:14:26 -0500 Subject: [PATCH] Revert "perf: Remove the extra validity check on nr_pages" This reverts commit 74390aa55678 ("perf: Remove the extra validity check on nr_pages") nr_pages equals to number of pages - 1 in perf_mmap. So nr_pages = 0 is valid. So the nr_pages != 0 && !is_power_of_2(nr_pages) are all needed for checking. Otherwise, for example, perf test 6 failed. # perf test 6 6: x86 rdpmc test :Error: mmap() syscall returned with (Invalid argument) FAILED! Signed-off-by: Kan Liang Cc: Andi Kleen Cc: Kaixu Xia Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1425280466-7830-1-git-send-email-kan.liang@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index af924bc38121..8bb20cc39a92 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4446,7 +4446,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) * If we have rb pages ensure they're a power-of-two number, so we * can do bitmasks instead of modulo. */ - if (!is_power_of_2(nr_pages)) + if (nr_pages != 0 && !is_power_of_2(nr_pages)) return -EINVAL; if (vma_size != PAGE_SIZE * (1 + nr_pages)) -- 2.20.1