Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751342AbeAPOsE (ORCPT + 1 other); Tue, 16 Jan 2018 09:48:04 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:44194 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750750AbeAPOsC (ORCPT ); Tue, 16 Jan 2018 09:48:02 -0500 Subject: Re: [PATCH v6 22/24] mm: Speculative page fault handler return VMA To: Matthew Wilcox Cc: paulmck@linux.vnet.ibm.com, peterz@infradead.org, akpm@linux-foundation.org, kirill@shutemov.name, ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , Andrea Arcangeli , Alexei Starovoitov , kemi.wang@intel.com, sergey.senozhatsky.work@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, bsingharora@gmail.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org References: <1515777968-867-1-git-send-email-ldufour@linux.vnet.ibm.com> <1515777968-867-23-git-send-email-ldufour@linux.vnet.ibm.com> <20180112190251.GC7590@bombadil.infradead.org> <20180113042354.GA24241@bombadil.infradead.org> From: Laurent Dufour Date: Tue, 16 Jan 2018 15:47:51 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20180113042354.GA24241@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18011614-0012-0000-0000-000005A458CD X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18011614-0013-0000-0000-0000191FCB47 Message-Id: <6d958348-bece-2c21-e8dc-4e5a65e82f9b@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-01-16_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1801160205 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 13/01/2018 05:23, Matthew Wilcox wrote: > On Fri, Jan 12, 2018 at 11:02:51AM -0800, Matthew Wilcox wrote: >> On Fri, Jan 12, 2018 at 06:26:06PM +0100, Laurent Dufour wrote: >>> @@ -1354,7 +1354,10 @@ extern int handle_mm_fault(struct vm_area_struct *vma, unsigned long address, >>> unsigned int flags); >>> #ifdef CONFIG_SPF >>> extern int handle_speculative_fault(struct mm_struct *mm, >>> + unsigned long address, unsigned int flags, >>> + struct vm_area_struct **vma); >> >> I think this shows that we need to create 'struct vm_fault' on the stack >> in the arch code and then pass it to handle_speculative_fault(), followed >> by handle_mm_fault(). That should be quite a nice cleanup actually. >> I know that's only 30+ architectures to change ;-) > > Of course, we don't need to change them all. Try this: That would be good candidate for a clean up but I'm not sure this should be part of this already too long series. If you don't mind, unless a global agreement is stated on that, I'd prefer to postpone such a change once the initial series is accepted. Cheers, Laurent. > Subject: [PATCH] Add vm_handle_fault > > For the speculative fault handler, we want to create the struct vm_fault > on the stack in the arch code and pass it into the generic mm code. > To avoid changing 30+ architectures, leave handle_mm_fault with its > current function signature and move its guts into the new vm_handle_fault > function. Even this saves a nice 172 bytes on the random x86-64 .config > I happen to have around. > > Signed-off-by: Matthew Wilcox > > diff --git a/mm/memory.c b/mm/memory.c > index 5eb3d2524bdc..403934297a3d 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3977,36 +3977,28 @@ static int handle_pte_fault(struct vm_fault *vmf) > * The mmap_sem may have been released depending on flags and our > * return value. See filemap_fault() and __lock_page_or_retry(). > */ > -static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address, > - unsigned int flags) > +static int __handle_mm_fault(struct vm_fault *vmf) > { > - struct vm_fault vmf = { > - .vma = vma, > - .address = address & PAGE_MASK, > - .flags = flags, > - .pgoff = linear_page_index(vma, address), > - .gfp_mask = __get_fault_gfp_mask(vma), > - }; > - unsigned int dirty = flags & FAULT_FLAG_WRITE; > - struct mm_struct *mm = vma->vm_mm; > + unsigned int dirty = vmf->flags & FAULT_FLAG_WRITE; > + struct mm_struct *mm = vmf->vma->vm_mm; > pgd_t *pgd; > p4d_t *p4d; > int ret; > > - pgd = pgd_offset(mm, address); > - p4d = p4d_alloc(mm, pgd, address); > + pgd = pgd_offset(mm, vmf->address); > + p4d = p4d_alloc(mm, pgd, vmf->address); > if (!p4d) > return VM_FAULT_OOM; > > - vmf.pud = pud_alloc(mm, p4d, address); > - if (!vmf.pud) > + vmf->pud = pud_alloc(mm, p4d, vmf->address); > + if (!vmf->pud) > return VM_FAULT_OOM; > - if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) { > - ret = create_huge_pud(&vmf); > + if (pud_none(*vmf->pud) && transparent_hugepage_enabled(vmf->vma)) { > + ret = create_huge_pud(vmf); > if (!(ret & VM_FAULT_FALLBACK)) > return ret; > } else { > - pud_t orig_pud = *vmf.pud; > + pud_t orig_pud = *vmf->pud; > > barrier(); > if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) { > @@ -4014,50 +4006,51 @@ static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address, > /* NUMA case for anonymous PUDs would go here */ > > if (dirty && !pud_access_permitted(orig_pud, WRITE)) { > - ret = wp_huge_pud(&vmf, orig_pud); > + ret = wp_huge_pud(vmf, orig_pud); > if (!(ret & VM_FAULT_FALLBACK)) > return ret; > } else { > - huge_pud_set_accessed(&vmf, orig_pud); > + huge_pud_set_accessed(vmf, orig_pud); > return 0; > } > } > } > > - vmf.pmd = pmd_alloc(mm, vmf.pud, address); > - if (!vmf.pmd) > + vmf->pmd = pmd_alloc(mm, vmf->pud, vmf->address); > + if (!vmf->pmd) > return VM_FAULT_OOM; > - if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) { > - ret = create_huge_pmd(&vmf); > + if (pmd_none(*vmf->pmd) && transparent_hugepage_enabled(vmf->vma)) { > + ret = create_huge_pmd(vmf); > if (!(ret & VM_FAULT_FALLBACK)) > return ret; > } else { > - pmd_t orig_pmd = *vmf.pmd; > + pmd_t orig_pmd = *vmf->pmd; > > barrier(); > if (unlikely(is_swap_pmd(orig_pmd))) { > VM_BUG_ON(thp_migration_supported() && > !is_pmd_migration_entry(orig_pmd)); > if (is_pmd_migration_entry(orig_pmd)) > - pmd_migration_entry_wait(mm, vmf.pmd); > + pmd_migration_entry_wait(mm, vmf->pmd); > return 0; > } > if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) { > - if (pmd_protnone(orig_pmd) && vma_is_accessible(vma)) > - return do_huge_pmd_numa_page(&vmf, orig_pmd); > + if (pmd_protnone(orig_pmd) && > + vma_is_accessible(vmf->vma)) > + return do_huge_pmd_numa_page(vmf, orig_pmd); > > if (dirty && !pmd_access_permitted(orig_pmd, WRITE)) { > - ret = wp_huge_pmd(&vmf, orig_pmd); > + ret = wp_huge_pmd(vmf, orig_pmd); > if (!(ret & VM_FAULT_FALLBACK)) > return ret; > } else { > - huge_pmd_set_accessed(&vmf, orig_pmd); > + huge_pmd_set_accessed(vmf, orig_pmd); > return 0; > } > } > } > > - return handle_pte_fault(&vmf); > + return handle_pte_fault(vmf); > } > > /* > @@ -4066,9 +4059,10 @@ static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address, > * The mmap_sem may have been released depending on flags and our > * return value. See filemap_fault() and __lock_page_or_retry(). > */ > -int handle_mm_fault(struct vm_area_struct *vma, unsigned long address, > - unsigned int flags) > +int vm_handle_fault(struct vm_fault *vmf) > { > + unsigned int flags = vmf->flags; > + struct vm_area_struct *vma = vmf->vma; > int ret; > > __set_current_state(TASK_RUNNING); > @@ -4092,9 +4086,9 @@ int handle_mm_fault(struct vm_area_struct *vma, unsigned long address, > mem_cgroup_oom_enable(); > > if (unlikely(is_vm_hugetlb_page(vma))) > - ret = hugetlb_fault(vma->vm_mm, vma, address, flags); > + ret = hugetlb_fault(vma->vm_mm, vma, vmf->address, flags); > else > - ret = __handle_mm_fault(vma, address, flags); > + ret = __handle_mm_fault(vmf); > > if (flags & FAULT_FLAG_USER) { > mem_cgroup_oom_disable(); > @@ -4110,6 +4104,26 @@ int handle_mm_fault(struct vm_area_struct *vma, unsigned long address, > > return ret; > } > + > +/* > + * By the time we get here, we already hold the mm semaphore > + * > + * The mmap_sem may have been released depending on flags and our > + * return value. See filemap_fault() and __lock_page_or_retry(). > + */ > +int handle_mm_fault(struct vm_area_struct *vma, unsigned long address, > + unsigned int flags) > +{ > + struct vm_fault vmf = { > + .vma = vma, > + .address = address & PAGE_MASK, > + .flags = flags, > + .pgoff = linear_page_index(vma, address), > + .gfp_mask = __get_fault_gfp_mask(vma), > + }; > + > + return vm_handle_fault(&vmf); > +} > EXPORT_SYMBOL_GPL(handle_mm_fault); > > #ifndef __PAGETABLE_P4D_FOLDED >