Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965472AbeAMEY2 (ORCPT + 1 other); Fri, 12 Jan 2018 23:24:28 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:56578 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965407AbeAMEY0 (ORCPT ); Fri, 12 Jan 2018 23:24:26 -0500 Date: Fri, 12 Jan 2018 20:23:54 -0800 From: Matthew Wilcox To: Laurent Dufour 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 Subject: Re: [PATCH v6 22/24] mm: Speculative page fault handler return VMA Message-ID: <20180113042354.GA24241@bombadil.infradead.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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180112190251.GC7590@bombadil.infradead.org> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: 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: 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