From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Reply-To: xlpang@redhat.com Subject: Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section References: <1492688374-27903-1-git-send-email-xlpang@redhat.com> <20170426071916.GD5381@dhcp-128-65.nay.redhat.com> <59006DAB.8030908@redhat.com> <59007405.6070107@redhat.com> <20170427030607.GB10602@dhcp-128-65.nay.redhat.com> <590180AF.3030202@redhat.com> <20170427054409.GA14079@dhcp-128-65.nay.redhat.com> From: Xunlei Pang Message-ID: <59018AD6.5030403@redhat.com> Date: Thu, 27 Apr 2017 14:08:22 +0800 MIME-Version: 1.0 In-Reply-To: <20170427054409.GA14079@dhcp-128-65.nay.redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Dave Young , xlpang@redhat.com Cc: Juergen Gross , linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org, Baoquan He , Petr Tesarik , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Eric Biederman , Hari Bathini , akpm@linux-foundation.org, Michael Holzheu List-ID: On 04/27/2017 at 01:44 PM, Dave Young wrote: > 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. OK, I will use PAGE_SIZE then, thanks for your comments. > > Thanks > Dave > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec