From: AKASHI Takahiro <takahiro.akashi@linaro.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: wangyufen@huawei.com, steve.capper@arm.com,
Chen Zhou <chenzhou10@huawei.com>,
will.deacon@arm.com, robin.murphy@arm.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [BUG] arm64: kdump: capture kernel boot failed when crashkernel above 4G
Date: Wed, 27 Mar 2019 13:55:16 +0900 [thread overview]
Message-ID: <20190327045514.GQ9937@linaro.org> (raw)
In-Reply-To: <20190325143505.lrgrxwkxxltpggf7@mbp>
On Mon, Mar 25, 2019 at 02:35:05PM +0000, Catalin Marinas wrote:
> Hi Chen,
>
> On Sat, Mar 23, 2019 at 06:34:31PM +0800, Chen Zhou wrote:
> > When i tested kdump on arm64 with crashkernel=Y@X, the capture kernel boot failed if the start
> > address is above 4G.
> >
> > My test steps:
> > 1. set crashkernel=1024M@0x2040000000 and boot with ACPI
> > 2. echo c > /proc/sysrq-trigger
> > 3. boot capture kernel, failed
> [...]
> > [2019/3/23 15:58:47] [ 0.000000] Call trace:
> > [2019/3/23 15:58:47] [ 0.000000] dump_backtrace+0x0/0x188
> > [2019/3/23 15:58:47] [ 0.000000] show_stack+0x24/0x30
> > [2019/3/23 15:58:47] [ 0.000000] dump_stack+0xa8/0xcc
> > [2019/3/23 15:58:47] [ 0.000000] panic+0x14c/0x31c
> > [2019/3/23 15:58:47] [ 0.000000] setup_arch+0x2b0/0x5e0
> > [2019/3/23 15:58:47] [ 0.000000] start_kernel+0x90/0x52c
> > [2019/3/23 15:58:47] [ 0.000000] ---[ end Kernel panic - not syncing: request_standard_resources: Failed to allocate 384 bytes ]---
> >
> > The root cause is:
> > In capture kernel, memblock_alloc_low alloced memory in range [MEMBLOCK_LOW_LIMIT, ARCH_LOW_ADDRESS_LIMIT].
> > CONFIG_ZONE_DMA32 is enabled, and ARCH_LOW_ADDRESS_LIMIT equals to max_zone_dma_phys() - 1.
> > The return value of function max_zone_dma_phys is 4G due to the existing "no-map" memory below 4G.
> > So memblock_alloc_low alloced memory in range [0, 4G) and failed.
>
> Does it work better if, in request_standard_resources(), we call
> memblock_alloc() instead of the _low variant? I doubt we need the
> *_low() call here.
I've been aware of this issue in my testing, but I supposed
that there must be a reason for *_low() here to prevent the kernel
booting from higher address space.
-Takahiro Akashi
> --
> Catalin
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next prev parent reply other threads:[~2019-03-27 4:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-23 10:34 [BUG] arm64: kdump: capture kernel boot failed when crashkernel above 4G Chen Zhou
2019-03-25 14:35 ` Catalin Marinas
2019-03-26 8:25 ` Chen Zhou
2019-03-26 14:12 ` Catalin Marinas
2019-03-27 4:55 ` AKASHI Takahiro [this message]
2019-03-27 18:10 ` Catalin Marinas
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