From patchwork Thu Aug 17 22:05:01 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Dufour X-Patchwork-Id: 802921 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [103.22.144.68]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3xYL6b29sYz9t3f for ; Fri, 18 Aug 2017 08:12:07 +1000 (AEST) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3xYL6b1SfvzDrLf for ; Fri, 18 Aug 2017 08:12:07 +1000 (AEST) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3xYKzF0G9jzDrLt for ; Fri, 18 Aug 2017 08:05:44 +1000 (AEST) Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v7HM3shw110308 for ; Thu, 17 Aug 2017 18:05:42 -0400 Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) by mx0b-001b2d01.pphosted.com with ESMTP id 2cdg4qtqqq-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 17 Aug 2017 18:05:42 -0400 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Thu, 17 Aug 2017 23:05:33 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v7HM5XXH24444984; Thu, 17 Aug 2017 22:05:33 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 514A911C05C; Thu, 17 Aug 2017 23:02:21 +0100 (BST) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 72E4911C04C; Thu, 17 Aug 2017 23:02:19 +0100 (BST) Received: from nimbus.lab.toulouse-stg.fr.ibm.com (unknown [9.145.2.164]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 17 Aug 2017 23:02:19 +0100 (BST) From: Laurent Dufour To: 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, Matthew Wilcox , benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon Subject: [PATCH v2 02/20] mm: Prepare for FAULT_FLAG_SPECULATIVE Date: Fri, 18 Aug 2017 00:05:01 +0200 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1503007519-26777-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1503007519-26777-1-git-send-email-ldufour@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17081722-0012-0000-0000-0000057087B9 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17081722-0013-0000-0000-000018E8530B Message-Id: <1503007519-26777-3-git-send-email-ldufour@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-08-17_12:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1708170357 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, npiggin@gmail.com, linux-mm@kvack.org, Tim Chen , haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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] Signed-off-by: Laurent Dufour --- include/linux/mm.h | 1 + mm/memory.c | 55 ++++++++++++++++++++++++++++++++++++++---------------- 2 files changed, 40 insertions(+), 16 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 46b9ac5e8569..8763ec96dc78 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -286,6 +286,7 @@ extern pgprot_t protection_map[16]; #define FAULT_FLAG_USER 0x40 /* The fault originated in userspace */ #define FAULT_FLAG_REMOTE 0x80 /* faulting for non current tsk/mm */ #define FAULT_FLAG_INSTRUCTION 0x100 /* The fault was during an instruction fetch */ +#define FAULT_FLAG_SPECULATIVE 0x200 /* Speculative fault, not holding mmap_sem */ #define FAULT_FLAG_TRACE \ { FAULT_FLAG_WRITE, "WRITE" }, \ diff --git a/mm/memory.c b/mm/memory.c index 36609c082256..3ed1b00ca841 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2269,6 +2269,12 @@ static inline void wp_page_reuse(struct vm_fault *vmf) pte_unmap_unlock(vmf->pte, vmf->ptl); } +static 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 the case of a page which we actually need to copy to a new page. * @@ -2296,6 +2302,7 @@ 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; @@ -2323,7 +2330,11 @@ 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)) { + mem_cgroup_cancel_charge(new_page, memcg, false); + ret = VM_FAULT_RETRY; + goto oom_free_new; + } if (likely(pte_same(*vmf->pte, vmf->orig_pte))) { if (old_page) { if (!PageAnon(old_page)) { @@ -2411,7 +2422,7 @@ static int wp_page_copy(struct vm_fault *vmf) oom: if (old_page) put_page(old_page); - return VM_FAULT_OOM; + return ret; } /** @@ -2432,8 +2443,8 @@ 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. @@ -2551,8 +2562,11 @@ 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); @@ -2710,8 +2724,10 @@ int do_swap_page(struct vm_fault *vmf) * Back out 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); + return VM_FAULT_RETRY; + } if (likely(pte_same(*vmf->pte, vmf->orig_pte))) ret = VM_FAULT_OOM; delayacct_clear_flag(DELAYACCT_PF_SWAPIN); @@ -2767,8 +2783,11 @@ int do_swap_page(struct vm_fault *vmf) /* * Back out 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; + mem_cgroup_cancel_charge(page, memcg, false); + goto out_page; + } if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) goto out_nomap; @@ -2894,8 +2913,8 @@ 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; /* Deliver the page fault to userland, check inside PT lock */ @@ -2927,8 +2946,11 @@ 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_map_lock(vmf)) { + mem_cgroup_cancel_charge(page, memcg, false); + put_page(page); + return VM_FAULT_RETRY; + } if (!pte_none(*vmf->pte)) goto release; @@ -3048,8 +3070,9 @@ 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; }