From: Hari Bathini <hbathini@linux.ibm.com>
To: Pingfan Liu <kernelfans@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: kexec@lists.infradead.org
Subject: Re: [PATCHv4] powerpc/crashkernel: take "mem=" option into account
Date: Thu, 2 Apr 2020 00:06:01 +0530 [thread overview]
Message-ID: <2bfddcda-1187-5718-ce13-0c30d25337a9@linux.ibm.com> (raw)
In-Reply-To: <1585749644-4148-1-git-send-email-kernelfans@gmail.com>
On 01/04/20 7:30 PM, Pingfan Liu wrote:
> 'mem=" option is an easy way to put high pressure on memory during some
> test. Hence after applying the memory limit, instead of total mem, the
> actual usable memory should be considered when reserving mem for
> crashkernel. Otherwise the boot up may experience OOM issue.
>
> E.g. it would reserve 4G prior to the change and 512M afterward, if passing
> crashkernel="2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G", and
> mem=5G on a 256G machine.
>
> This issue is powerpc specific because it puts higher priority on fadump
> and kdump reservation than on "mem=". Referring the following code:
> if (fadump_reserve_mem() == 0)
> reserve_crashkernel();
> ...
> /* Ensure that total memory size is page-aligned. */
> limit = ALIGN(memory_limit ?: memblock_phys_mem_size(), PAGE_SIZE);
> memblock_enforce_memory_limit(limit);
>
> While on other arches, the effect of "mem=" takes a higher priority and pass
> through memblock_phys_mem_size() before calling reserve_crashkernel().
>> Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
> To: linuxppc-dev@lists.ozlabs.org
> Cc: Hari Bathini <hbathini@linux.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: kexec@lists.infradead.org
> ---
> v3 -> v4: fix total_mem_sz based on adjusted memory_limit
Thanks for the update.
Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
next prev parent reply other threads:[~2020-04-01 18:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-19 14:18 [PATCHv3] powerpc/crashkernel: take "mem=" option into account Pingfan Liu
2020-03-26 7:48 ` Hari Bathini
2020-04-01 14:00 ` [PATCHv4] " Pingfan Liu
2020-04-01 18:36 ` Hari Bathini [this message]
2020-06-09 5:28 ` Michael Ellerman
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