From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from e06smtp14.uk.ibm.com ([195.75.94.110]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Uz7Jq-000886-Pd for kexec@lists.infradead.org; Tue, 16 Jul 2013 15:37:41 +0000 Received: from /spool/local by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 16 Jul 2013 16:29:04 +0100 Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 6D5422190023 for ; Tue, 16 Jul 2013 16:41:11 +0100 (BST) Received: from d06av12.portsmouth.uk.ibm.com (d06av12.portsmouth.uk.ibm.com [9.149.37.247]) by b06cxnps4075.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r6GFb0G457737444 for ; Tue, 16 Jul 2013 15:37:00 GMT Received: from d06av12.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av12.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id r6GFbAMi002590 for ; Tue, 16 Jul 2013 09:37:11 -0600 Date: Tue, 16 Jul 2013 17:37:09 +0200 From: Michael Holzheu Subject: Re: [PATCH v6 3/5] vmcore: Introduce remap_oldmem_pfn_range() Message-ID: <20130716173709.3fed4c42@holzheu> In-Reply-To: <20130716140418.GB4005@redhat.com> References: <1372707159-10425-1-git-send-email-holzheu@linux.vnet.ibm.com> <1372707159-10425-4-git-send-email-holzheu@linux.vnet.ibm.com> <20130702154214.GC22603@redhat.com> <20130715154451.02a3a767@holzheu> <20130715142708.GB23772@redhat.com> <20130716112527.35decf17@holzheu> <20130716140418.GB4005@redhat.com> Mime-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: Vivek Goyal Cc: kexec@lists.infradead.org, Heiko Carstens , linux-kernel@vger.kernel.org, Jan Willeke , HATAYAMA Daisuke , Martin Schwidefsky , Andrew Morton On Tue, 16 Jul 2013 10:04:18 -0400 Vivek Goyal wrote: > On Tue, Jul 16, 2013 at 11:25:27AM +0200, Michael Holzheu wrote: > > [..] > > > > Hello Vivek and Andrew, > > > > > > > > We just realized that Hatayama's mmap patches went into v3.11-rc1. This currently > > > > breaks s390 kdump because of the following two issues: > > > > > > > > 1) The copy_oldmem_page() is now used for copying to vmalloc memory > > > > 2) The mmap() implementation is not compatible with the current > > > > s390 crashkernel swap: > > > > See: http://marc.info/?l=kexec&m=136940802511603&w=2 > > > > > > > > The "kdump: Introduce ELF header in new memory feature" patch series will > > > > fix both issues for s390. > > > > > > > > There is the one small open discussion left: > > > > > > > > http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg464856.html > > > > > > > > But once we have finished that, would it be possible to get the > > > > patches in 3.11? > > > > > > How about taking mmap() fault handler patches in 3.12. And in 3.11, deny > > > mmap() on s390 forcing makedumpfile to fall back on read() interface. That > > > way there will be no regression and mmap() related speedup will show up > > > in next release on s390. > > > > Hello Vivek and Hatayama, > > > > But then we still would have to somehow fix the copy_oldmem_page() issue (1). > > > > We would prefer to add the current patch series with "#ifndef CONFIG_S390" in > > the fault handler. > > > > @Vivek: > > > > Since you are the kdump maintainer, could you tell us which of the both > > variants you would like to have? > > > > static int mmap_vmcore_fault(struct vm_area_struct *vma, struct vm_fault *vmf) > > { > > ... > > > > #ifndef CONFIG_S390 > > return VM_FAULT_SIGBUS; > > #endif > > I think let us use this one. Kill the process on non-s390 arch if it goes > into mmap() fault handler. > > copy_oldmem_page() using real mode in s390 is an issue for vmalloc region. > I think post the series again and let us see if Andrew is comfortable > with it. Ok great, I will send Andrew the current patch series. Let's see what happens... > I suspect it is late. > IIUC, we do copying in real mode only to cope with HSA region in zfcpdump > case. The problem is that with the mmap patches we now use copy_oldmem_page() to copy the notes from oldmem into the notes_buf which has been allocated with vmalloc. The s390 version of copy_oldmem_page() bypasses the page tables and uses real copy. And this does not work on vmalloc memory. Best Regards, Michael _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec