Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area

From	Mark Rutland <mark.rutland@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area
Date	2016-01-15 12:30 +0100
Message-ID	<qRaJQ-5m5-7@gated-at.bofh.it> (permalink)
References	(2 earlier) <qQbHY-4HB-13@gated-at.bofh.it> <qQp8e-5ru-19@gated-at.bofh.it> <qQu7U-vr-3@gated-at.bofh.it> <qQVhM-2GT-23@gated-at.bofh.it> <qR9kK-4iA-11@gated-at.bofh.it>
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On Fri, Jan 15, 2016 at 10:54:26AM +0100, Ard Biesheuvel wrote:
> On 14 January 2016 at 19:57, Mark Rutland <mark.rutland@arm.com> wrote:
> > On Wed, Jan 13, 2016 at 01:51:10PM +0000, Mark Rutland wrote:
> >> On Wed, Jan 13, 2016 at 09:39:41AM +0100, Ard Biesheuvel wrote:
> >> > If I remove the rounding, I get false positive kasan errors which I
> >> > have not quite diagnosed yet, but are probably due to the fact that
> >> > the rounding performed by vmemmap_populate() goes in the wrong
> >> > direction.
> >
> > As far as I can see, it implicitly rounds the base down and end up to
> > SWAPPER_BLOCK_SIZE granularity.
> >
> > I can see that it might map too much memory, but I can't see why that
> > should trigger KASAN failures. Regardless of what was mapped KASAN
> > should stick to the region it cares about, and everything else should
> > stay out of that.
> >
> > When do you see the failures, and are they in any way consistent?
> >
> > Do you have an example to hand?
> >
> 
> For some reason, this issue has evaporated, i.e., I can no longer
> reproduce it on my WIP v4 branch.
> So I will remove the rounding.

Ok.

I'll let you know if I stumble across anything that looks like a
potential cause of the KASAN failures, and I'll try to give v4 a go at
some point soon.

Thanks,
Mark.

Thread

[PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-01-11 14:20 +0100
  Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Mark Rutland <mark.rutland@arm.com> - 2016-01-12 19:20 +0100
    Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-01-13 09:40 +0100
      Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-01-13 11:00 +0100
        Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Mark Rutland <mark.rutland@arm.com> - 2016-01-13 12:20 +0100
          Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-01-13 12:20 +0100
      Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Mark Rutland <mark.rutland@arm.com> - 2016-01-13 15:00 +0100
        Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-01-13 17:00 +0100
          Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Mark Rutland <mark.rutland@arm.com> - 2016-01-13 17:30 +0100
        Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Mark Rutland <mark.rutland@arm.com> - 2016-01-14 20:00 +0100
          Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-01-15 11:00 +0100
            Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Mark Rutland <mark.rutland@arm.com> - 2016-01-15 12:30 +0100
              Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-01-27 15:40 +0100

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