From: Mike Rapoport <rppt@linux.ibm.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Guillaume Tucker <guillaume.tucker@collabora.com>,
Andrew Morton <akpm@linux-foundation.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
kernelci-results-staging@groups.io,
"kernelci-results@groups.io" <kernelci-results@groups.io>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Mike Rapoport <rppt@kernel.org>, Baoquan He <bhe@redhat.com>
Subject: Re: kernelci/staging-next bisection: sleep.login on rk3288-rock2-square #2286-staging
Date: Tue, 5 Jan 2021 11:13:30 +0200 [thread overview]
Message-ID: <20210105091330.GD832698@linux.ibm.com> (raw)
In-Reply-To: <X/Ikalm2CLln2alz@redhat.com>
On Sun, Jan 03, 2021 at 03:09:14PM -0500, Andrea Arcangeli wrote:
> Hello Mike,
>
> On Sun, Jan 03, 2021 at 03:47:53PM +0200, Mike Rapoport wrote:
> > Thanks for the logs, it seems that implicitly adding reserved regions to
> > memblock.memory wasn't that bright idea :)
>
> Would it be possible to somehow clean up the hack then?
>
> The only difference between the clean solution and the hack is that
> the hack intended to achieved the exact same, but without adding the
> reserved regions to memblock.memory.
I didn't consider adding reserved regions to memblock.memory as a clean
solution, this was still a hack, but I didn't think that things are that
fragile.
I still think we cannot rely on memblock.reserved to detect
memory/zone/node sizes and the boot failure reported here confirms this.
> The comment on that problematic area says the reserved area cannot be
> used for DMA because of some unexplained hw issue, and that doing so
> prevents booting, but since the area got reserved, even with the clean
> solution, it shouldn't have never been used for DMA?
>
> So I can only imagine that the physical memory region is way more
> problematic than just for DMA. It sounds like that anything that
> touches it, including the CPU, will hang the system, not just DMA. It
> sounds somewhat similar to the other e820 direct mapping issue on x86?
My understanding is that the boot failed because when I implicitly added
the reserved region to memblock.memory the memory size seen by
free_area_init() jumped from 2G to 4G because the reserved area was close
to 4G. The very first allocation would get a chunk from slightly below of
4G and as there is no real memory there, the kernel would crash.
> If you want to test the hack on the arm board to check if it boots you
> can use the below commit:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git/commit/?id=c3ea2633015104ce0df33dcddbc36f57de1392bc
My take is your solution would boot with this memory configuration, but I
still don't think that using memblock.reserved for zone/node sizing is
correct.
> Thanks,
> Andrea
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2021-01-05 9:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <5fd3e5d9.1c69fb81.f9e69.5028@mx.google.com>
2020-12-11 21:53 ` kernelci/staging-next bisection: sleep.login on rk3288-rock2-square #2286-staging Guillaume Tucker
2020-12-13 8:23 ` Mike Rapoport
2020-12-18 21:59 ` Guillaume Tucker
2021-01-03 13:47 ` Mike Rapoport
2021-01-03 20:09 ` Andrea Arcangeli
2021-01-05 9:13 ` Mike Rapoport [this message]
2021-01-12 10:53 ` Guillaume Tucker
2021-01-12 11:10 ` Guillaume Tucker
2021-01-12 12:06 ` Mike Rapoport
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