linux-kernel - Re: [PATCH 0/3 v3] Fix kdump failures with crashkernel=high

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Message-ID: <20150605132736.GF3679@pd.tnic>
Date:	Fri, 5 Jun 2015 15:27:36 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Joerg Roedel <joro@...tes.org>, "H. Peter Anvin" <hpa@...or.com>,
	Ingo Molnar <mingo@...hat.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	Dave Young <dyoung@...hat.com>, Baoquan He <bhe@...hat.com>,
	x86@...nel.org, kexec@...ts.infradead.org, jroedel@...e.de,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3 v3] Fix kdump failures with crashkernel=high

On Fri, Jun 05, 2015 at 12:29:59PM +0200, Joerg Roedel wrote:
> v2->v3
> 
> * Rebased to v4.1-rc6
> * Updated changelogs as requested and added outcome of
>   previous discussions
> * Added more Acked-bys
> 
> v1->v2:
> 
> * Updated comments based on feedback from Konrad
> * Added Acked-bys
> * Rebased to v3.19-rc3
> 
> Hi,
> 
> here is a patch-set to fix failed kdump kernel boots when
> the systems was booted with crashkernel=X,high. On those
> systems the kernel allocates only 72MiB of low-memory for
> DMA buffers, which showed to be too low on some systems.
> 
> The problem is that 64MiB of the low-memory is allocated by
> swiotlb, leaving 8MB for the page-allocator. But swiotlb
> tries to allocate DMA memory from the page-allocator first,
> which fails pretty fast in the boot sequence, causing
> warnings. This patch-set removes these warnings.
> 
> But even the 64MiB for swiotlb are eaten up on some systems,
> so that the default of low-memory allocated for the
> crash-kernel is increase from 72MB to 256MB (only changing
> the defaults, can still be overwritten by crashkernel=X,low).
> 
> This number comes from experiments on the affected systems,
> 128MiB low-memory was still not enough there, thus I set the
> value to 256MiB to fix the issues.
> 
> Any feedback appreciated.
> 
> Thanks,
> 
> 	Joerg
> 
> Joerg Roedel (3):
>   swiotlb: Warn on allocation failure in swiotlb_alloc_coherent
>   x86, swiotlb: Try coherent allocations with __GFP_NOWARN
>   x86, crash: Allocate enough low-mem when crashkernel=high
> 
>  arch/x86/kernel/pci-swiotlb.c |  7 +++++++
>  arch/x86/kernel/setup.c       |  5 ++++-
>  lib/swiotlb.c                 | 11 +++++++++--
>  3 files changed, 20 insertions(+), 3 deletions(-)

Looks simple enough, all applied, thanks.

hpa, Ingo, any concerns?

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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