From: Kan Liang <[email protected]> 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 valide. 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 <[email protected]> --- 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 89f0f16..a83581c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4423,7 +4423,7 @@ 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)) -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
