From: Dave Young <dyoung@redhat.com>
To: xlpang@redhat.com
Cc: Juergen Gross <jgross@suse.com>,
linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org,
Baoquan He <bhe@redhat.com>, Petr Tesarik <ptesarik@suse.cz>,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
Eric Biederman <ebiederm@xmission.com>,
Hari Bathini <hbathini@linux.vnet.ibm.com>,
akpm@linux-foundation.org,
Michael Holzheu <holzheu@linux.vnet.ibm.com>
Subject: Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section
Date: Thu, 27 Apr 2017 13:44:09 +0800 [thread overview]
Message-ID: <20170427054409.GA14079@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <590180AF.3030202@redhat.com>
Hi Xunlei,
On 04/27/17 at 01:25pm, Xunlei Pang wrote:
> On 04/27/2017 at 11:06 AM, Dave Young wrote:
> > [snip]
> >>>>>
> >>>>> static int __init crash_save_vmcoreinfo_init(void)
> >>>>> {
> >>>>> + /* One page should be enough for VMCOREINFO_BYTES under all archs */
> >>>> Can we add a comment in the VMCOREINFO_BYTES header file about the one
> >>>> page assumption?
> >>>>
> >>>> Or just define the VMCOREINFO_BYTES as PAGE_SIZE instead of 4096
> >>> Yes, I considered this before, but VMCOREINFO_BYTES is also used by VMCOREINFO_NOTE_SIZE
> >>> definition which is exported to sysfs, also some platform has larger page size(64KB), so
> >>> I didn't touch this 4096 value.
> >>>
> >>> I think I should use kmalloc() to allocate both of them, then move this comment to Patch3
> >>> kimage_crash_copy_vmcoreinfo().
> >> But on the other hand, using a separate page for them seems safer compared with
> >> using frequently-used slab, what's your opinion?
> > I feel current page based way is better.
> >
> > For 64k page the vmcore note size will increase it seems fine. Do you
> > have concern in mind?
>
> Since tools are supposed to acquire vmcoreinfo note size from sysfs, it should be safe to do so,
> except that there is some waste in memory for larger PAGE_SIZE.
Either way is fine to me, I think it is up to your implementation, if
choose page alloc then modify the macro with PAGE_SIZE looks better.
Thanks
Dave
next prev parent reply other threads:[~2017-04-27 5:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-20 11:39 [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section Xunlei Pang
2017-04-20 11:39 ` [PATCH v4 2/3] powerpc/fadump: Use the correct VMCOREINFO_NOTE_SIZE for phdr Xunlei Pang
2017-04-21 0:55 ` Xunlei Pang
2017-04-26 7:11 ` Dave Young
2017-04-27 7:38 ` Mahesh Jagannath Salgaonkar
2017-04-20 11:39 ` [PATCH v4 3/3] kdump: Protect vmcoreinfo data under the crash memory Xunlei Pang
2017-04-26 7:09 ` Dave Young
2017-04-26 9:21 ` Xunlei Pang
2017-04-27 2:56 ` Dave Young
2017-04-20 14:24 ` [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section Juergen Gross
2017-04-24 15:18 ` Michael Holzheu
2017-04-26 7:19 ` Dave Young
2017-04-26 9:51 ` Xunlei Pang
2017-04-26 10:18 ` Xunlei Pang
2017-04-27 3:06 ` Dave Young
2017-04-27 5:25 ` Xunlei Pang
2017-04-27 5:44 ` Dave Young [this message]
2017-04-27 6:08 ` Xunlei Pang
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