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Date: Mon, 2 Mar 2015 18:03:49 -0300 From: Arnaldo Carvalho de Melo <acme@...hat.com> To: kan.liang@...el.com Cc: Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org, xiakaixu@...wei.com, a.p.zijlstra@...llo.nl, ak@...ux.intel.com Subject: Re: [PATCH 1/1] Revert "perf: Remove the extra validity check on nr_pages" Em Mon, Mar 02, 2015 at 02:14:26AM -0500, kan.liang@...el.com escreveu: > From: Kan Liang <kan.liang@...el.com> > > 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! Yeah, my bad, we need to revert this, its just on tip/perf/core, will put the revert in my next pull request, thanks for spotting this! - Arnaldo > Signed-off-by: Kan Liang <kan.liang@...el.com> > --- > 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 majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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