Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755650Ab3FKNUY (ORCPT ); Tue, 11 Jun 2013 09:20:24 -0400 Received: from mail-vb0-f43.google.com ([209.85.212.43]:53654 "EHLO mail-vb0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752170Ab3FKNUX (ORCPT ); Tue, 11 Jun 2013 09:20:23 -0400 MIME-Version: 1.0 In-Reply-To: <20130610173739.4d88d4ec@holzheu> References: <1370624161-2298-1-git-send-email-holzheu@linux.vnet.ibm.com> <1370624161-2298-4-git-send-email-holzheu@linux.vnet.ibm.com> <20130610173739.4d88d4ec@holzheu> Date: Tue, 11 Jun 2013 22:20:22 +0900 Message-ID: Subject: Re: [PATCH v5 3/5] vmcore: Introduce remap_oldmem_pfn_range() From: HATAYAMA Daisuke To: Michael Holzheu Cc: Vivek Goyal , Jan Willeke , Martin Schwidefsky , Heiko Carstens , linux-kernel@vger.kernel.org, kexec@lists.infradead.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3230 Lines: 90 2013/6/11 Michael Holzheu : > On Mon, 10 Jun 2013 22:40:24 +0900 > HATAYAMA Daisuke wrote: > >> 2013/6/8 Michael Holzheu : >> >> > @@ -225,6 +251,56 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer, >> > return acc; >> > } >> > >> > +static ssize_t read_vmcore(struct file *file, char __user *buffer, >> > + size_t buflen, loff_t *fpos) >> > +{ >> > + return __read_vmcore(buffer, buflen, fpos, 1); >> > +} >> > + >> > +/* >> > + * The vmcore fault handler uses the page cache and fills data using the >> > + * standard __vmcore_read() function. >> > + */ >> > +static int mmap_vmcore_fault(struct vm_area_struct *vma, struct vm_fault *vmf) >> > +{ >> > + struct address_space *mapping = vma->vm_private_data; >> > + pgoff_t index = vmf->pgoff; >> > + struct page *page; >> > + loff_t src; >> > + char *buf; >> > + int rc; >> > + >> > +find_page: >> > + page = find_lock_page(mapping, index); >> > + if (page) { >> > + unlock_page(page); >> > + rc = VM_FAULT_MINOR; >> > + } else { >> > + page = page_cache_alloc_cold(mapping); >> > + if (!page) >> > + return VM_FAULT_OOM; >> > + rc = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL); >> > + if (rc) { >> > + page_cache_release(page); >> > + if (rc == -EEXIST) >> > + goto find_page; >> > + /* Probably ENOMEM for radix tree node */ >> > + return VM_FAULT_OOM; >> > + } >> > + buf = (void *) (page_to_pfn(page) << PAGE_SHIFT); >> > + src = index << PAGE_CACHE_SHIFT; >> > + __read_vmcore(buf, PAGE_SIZE, &src, 0); >> > + unlock_page(page); >> > + rc = VM_FAULT_MAJOR; >> > + } >> > + vmf->page = page; >> > + return rc; >> > +} >> >> How about reusing find_or_create_page()? > > The function would then look like the following: > > static int mmap_vmcore_fault(struct vm_area_struct *vma, struct vm_fault *vmf) > { > struct address_space *mapping = vma->vm_private_data; > pgoff_t index = vmf->pgoff; > struct page *page; > loff_t src; > char *buf; > > page = find_or_create_page(mapping, index, GFP_KERNEL); > if (!page) > return VM_FAULT_OOM; > src = index << PAGE_CACHE_SHIFT; > buf = (void *) (page_to_pfn(page) << PAGE_SHIFT); > __read_vmcore(buf, PAGE_SIZE, &src, 0); You should check return value of __read_vmcore() since this can fail. Then, I think returning VM_FAULT_SIGBUS is correct. > unlock_page(page); > vmf->page = page; > return 0; > } Thanks. HATAYAMA, Daisuke -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/