Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753873AbdHQWFy (ORCPT ); Thu, 17 Aug 2017 18:05:54 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:51413 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753523AbdHQWFv (ORCPT ); Thu, 17 Aug 2017 18:05:51 -0400 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 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, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: [PATCH v2 04/20] mm: VMA sequence count Date: Fri, 18 Aug 2017 00:05:03 +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: 17081722-0040-0000-0000-000003D17CE6 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17081722-0041-0000-0000-000025D1A0FF Message-Id: <1503007519-26777-5-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 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3803 Lines: 120 From: Peter Zijlstra Wrap the VMA modifications (vma_adjust/unmap_page_range) with sequence counts such that we can easily test if a VMA is changed. The unmap_page_range() one allows us to make assumptions about page-tables; when we find the seqcount hasn't changed we can assume page-tables are still valid. The flip side is that we cannot distinguish between a vma_adjust() and the unmap_page_range() -- where with the former we could have re-checked the vma bounds against the address. Signed-off-by: Peter Zijlstra (Intel) [Port to 4.12 kernel] [Fix lock dependency between mapping->i_mmap_rwsem and vma->vm_sequence] Signed-off-by: Laurent Dufour --- include/linux/mm_types.h | 1 + mm/memory.c | 2 ++ mm/mmap.c | 21 ++++++++++++++++++--- 3 files changed, 21 insertions(+), 3 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 3cadee0a3508..642aad26b32f 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -342,6 +342,7 @@ struct vm_area_struct { struct mempolicy *vm_policy; /* NUMA policy for the VMA */ #endif struct vm_userfaultfd_ctx vm_userfaultfd_ctx; + seqcount_t vm_sequence; } __randomize_layout; struct core_thread { diff --git a/mm/memory.c b/mm/memory.c index fa598889eb0e..4a2736fe2ef6 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1408,6 +1408,7 @@ void unmap_page_range(struct mmu_gather *tlb, unsigned long next; BUG_ON(addr >= end); + write_seqcount_begin(&vma->vm_sequence); tlb_start_vma(tlb, vma); pgd = pgd_offset(vma->vm_mm, addr); do { @@ -1417,6 +1418,7 @@ void unmap_page_range(struct mmu_gather *tlb, next = zap_p4d_range(tlb, vma, pgd, addr, next, details); } while (pgd++, addr = next, addr != end); tlb_end_vma(tlb, vma); + write_seqcount_end(&vma->vm_sequence); } diff --git a/mm/mmap.c b/mm/mmap.c index f19efcf75418..140b22136cb7 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -557,6 +557,8 @@ void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, else mm->highest_vm_end = vm_end_gap(vma); + seqcount_init(&vma->vm_sequence); + /* * vma->vm_prev wasn't known when we followed the rbtree to find the * correct insertion point for that vma. As a result, we could not @@ -798,6 +800,11 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, } } + write_seqcount_begin(&vma->vm_sequence); + if (next && next != vma) + write_seqcount_begin_nested(&next->vm_sequence, + SINGLE_DEPTH_NESTING); + anon_vma = vma->anon_vma; if (!anon_vma && adjust_next) anon_vma = next->anon_vma; @@ -902,6 +909,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, mm->map_count--; mpol_put(vma_policy(next)); kmem_cache_free(vm_area_cachep, next); + write_seqcount_end(&next->vm_sequence); /* * In mprotect's case 6 (see comments on vma_merge), * we must remove another next too. It would clutter @@ -931,11 +939,14 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, if (remove_next == 2) { remove_next = 1; end = next->vm_end; + write_seqcount_end(&vma->vm_sequence); goto again; - } - else if (next) + } else if (next) { + if (next != vma) + write_seqcount_begin_nested(&next->vm_sequence, + SINGLE_DEPTH_NESTING); vma_gap_update(next); - else { + } else { /* * If remove_next == 2 we obviously can't * reach this path. @@ -961,6 +972,10 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, if (insert && file) uprobe_mmap(insert); + if (next && next != vma) + write_seqcount_end(&next->vm_sequence); + write_seqcount_end(&vma->vm_sequence); + validate_mm(mm); return 0; -- 2.7.4