From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753368AbeDQOeG (ORCPT ); Tue, 17 Apr 2018 10:34:06 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41952 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753324AbeDQOd7 (ORCPT ); Tue, 17 Apr 2018 10:33:59 -0400 From: Laurent Dufour To: akpm@linux-foundation.org, mhocko@kernel.org, peterz@infradead.org, kirill@shutemov.name, ak@linux.intel.com, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , 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, Daniel Jordan , David Rientjes , Jerome Glisse , Ganesh Mahendran Cc: 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, paulmck@linux.vnet.ibm.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: [PATCH v10 04/25] mm: prepare for FAULT_FLAG_SPECULATIVE Date: Tue, 17 Apr 2018 16:33:10 +0200 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1523975611-15978-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1523975611-15978-1-git-send-email-ldufour@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18041714-0040-0000-0000-0000042FFFA3 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18041714-0041-0000-0000-000026340AEC Message-Id: <1523975611-15978-5-git-send-email-ldufour@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-17_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 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-1804170131 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra When speculating faults (without holding mmap_sem) we need to validate that the vma against which we loaded pages is still valid when we're ready to install the new PTE. Therefore, replace the pte_offset_map_lock() calls that (re)take the PTL with pte_map_lock() which can fail in case we find the VMA changed since we started the fault. Signed-off-by: Peter Zijlstra (Intel) [Port to 4.12 kernel] [Remove the comment about the fault_env structure which has been implemented as the vm_fault structure in the kernel] [move pte_map_lock()'s definition upper in the file] [move the define of FAULT_FLAG_SPECULATIVE later in the series] [review error path in do_swap_page(), do_anonymous_page() and wp_page_copy()] Signed-off-by: Laurent Dufour --- mm/memory.c | 87 ++++++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 58 insertions(+), 29 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index a1f990e33e38..4528bd584b7a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2288,6 +2288,13 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr, } EXPORT_SYMBOL_GPL(apply_to_page_range); +static inline bool pte_map_lock(struct vm_fault *vmf) +{ + vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, + vmf->address, &vmf->ptl); + return true; +} + /* * handle_pte_fault chooses page fault handler according to an entry which was * read non-atomically. Before making any commitment, on those architectures @@ -2477,25 +2484,26 @@ static int wp_page_copy(struct vm_fault *vmf) const unsigned long mmun_start = vmf->address & PAGE_MASK; const unsigned long mmun_end = mmun_start + PAGE_SIZE; struct mem_cgroup *memcg; + int ret = VM_FAULT_OOM; if (unlikely(anon_vma_prepare(vma))) - goto oom; + goto out; if (is_zero_pfn(pte_pfn(vmf->orig_pte))) { new_page = alloc_zeroed_user_highpage_movable(vma, vmf->address); if (!new_page) - goto oom; + goto out; } else { new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address); if (!new_page) - goto oom; + goto out; cow_user_page(new_page, old_page, vmf->address, vma); } if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false)) - goto oom_free_new; + goto out_free_new; __SetPageUptodate(new_page); @@ -2504,7 +2512,10 @@ static int wp_page_copy(struct vm_fault *vmf) /* * Re-check the pte - we dropped the lock */ - vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl); + if (!pte_map_lock(vmf)) { + ret = VM_FAULT_RETRY; + goto out_uncharge; + } if (likely(pte_same(*vmf->pte, vmf->orig_pte))) { if (old_page) { if (!PageAnon(old_page)) { @@ -2591,12 +2602,14 @@ static int wp_page_copy(struct vm_fault *vmf) put_page(old_page); } return page_copied ? VM_FAULT_WRITE : 0; -oom_free_new: +out_uncharge: + mem_cgroup_cancel_charge(new_page, memcg, false); +out_free_new: put_page(new_page); -oom: +out: if (old_page) put_page(old_page); - return VM_FAULT_OOM; + return ret; } /** @@ -2617,8 +2630,8 @@ static int wp_page_copy(struct vm_fault *vmf) int finish_mkwrite_fault(struct vm_fault *vmf) { WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED)); - vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address, - &vmf->ptl); + if (!pte_map_lock(vmf)) + return VM_FAULT_RETRY; /* * We might have raced with another page fault while we released the * pte_offset_map_lock. @@ -2736,8 +2749,11 @@ static int do_wp_page(struct vm_fault *vmf) get_page(vmf->page); pte_unmap_unlock(vmf->pte, vmf->ptl); lock_page(vmf->page); - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, - vmf->address, &vmf->ptl); + if (!pte_map_lock(vmf)) { + unlock_page(vmf->page); + put_page(vmf->page); + return VM_FAULT_RETRY; + } if (!pte_same(*vmf->pte, vmf->orig_pte)) { unlock_page(vmf->page); pte_unmap_unlock(vmf->pte, vmf->ptl); @@ -2944,11 +2960,15 @@ int do_swap_page(struct vm_fault *vmf) if (!page) { /* - * Back out if somebody else faulted in this pte - * while we released the pte lock. + * Back out if the VMA has changed in our back during + * a speculative page fault or if somebody else + * faulted in this pte while we released the pte lock. */ - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, - vmf->address, &vmf->ptl); + if (!pte_map_lock(vmf)) { + delayacct_clear_flag(DELAYACCT_PF_SWAPIN); + ret = VM_FAULT_RETRY; + goto out; + } if (likely(pte_same(*vmf->pte, vmf->orig_pte))) ret = VM_FAULT_OOM; delayacct_clear_flag(DELAYACCT_PF_SWAPIN); @@ -3001,10 +3021,13 @@ int do_swap_page(struct vm_fault *vmf) } /* - * Back out if somebody else already faulted in this pte. + * Back out if the VMA has changed in our back during a speculative + * page fault or if somebody else already faulted in this pte. */ - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, - &vmf->ptl); + if (!pte_map_lock(vmf)) { + ret = VM_FAULT_RETRY; + goto out_cancel_cgroup; + } if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) goto out_nomap; @@ -3082,8 +3105,9 @@ int do_swap_page(struct vm_fault *vmf) out: return ret; out_nomap: - mem_cgroup_cancel_charge(page, memcg, false); pte_unmap_unlock(vmf->pte, vmf->ptl); +out_cancel_cgroup: + mem_cgroup_cancel_charge(page, memcg, false); out_page: unlock_page(page); out_release: @@ -3134,8 +3158,8 @@ static int do_anonymous_page(struct vm_fault *vmf) !mm_forbids_zeropage(vma->vm_mm)) { entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address), vma->vm_page_prot)); - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, - vmf->address, &vmf->ptl); + if (!pte_map_lock(vmf)) + return VM_FAULT_RETRY; if (!pte_none(*vmf->pte)) goto unlock; ret = check_stable_address_space(vma->vm_mm); @@ -3170,14 +3194,16 @@ static int do_anonymous_page(struct vm_fault *vmf) if (vma->vm_flags & VM_WRITE) entry = pte_mkwrite(pte_mkdirty(entry)); - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, - &vmf->ptl); - if (!pte_none(*vmf->pte)) + if (!pte_map_lock(vmf)) { + ret = VM_FAULT_RETRY; goto release; + } + if (!pte_none(*vmf->pte)) + goto unlock_and_release; ret = check_stable_address_space(vma->vm_mm); if (ret) - goto release; + goto unlock_and_release; /* Deliver the page fault to userland, check inside PT lock */ if (userfaultfd_missing(vma)) { @@ -3199,10 +3225,12 @@ static int do_anonymous_page(struct vm_fault *vmf) unlock: pte_unmap_unlock(vmf->pte, vmf->ptl); return ret; +unlock_and_release: + pte_unmap_unlock(vmf->pte, vmf->ptl); release: mem_cgroup_cancel_charge(page, memcg, false); put_page(page); - goto unlock; + return ret; oom_free_page: put_page(page); oom: @@ -3295,8 +3323,9 @@ static int pte_alloc_one_map(struct vm_fault *vmf) * pte_none() under vmf->ptl protection when we return to * alloc_set_pte(). */ - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, - &vmf->ptl); + if (!pte_map_lock(vmf)) + return VM_FAULT_RETRY; + return 0; } -- 2.7.4