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[2620:137:e000::3:4]) by mx.google.com with ESMTPS id ls6-20020a17090b350600b0027763b64ea1si3856340pjb.44.2023.10.07.13.51.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Oct 2023 13:51:50 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:4 as permitted sender) client-ip=2620:137:e000::3:4; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20230601 header.b=Ru+OOEp9; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:4 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by howler.vger.email (Postfix) with ESMTP id C6A748062283; Sat, 7 Oct 2023 13:51:46 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at howler.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344185AbjJGUvT (ORCPT + 17 others); Sat, 7 Oct 2023 16:51:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344151AbjJGUvN (ORCPT ); Sat, 7 Oct 2023 16:51:13 -0400 Received: from mail-wr1-x431.google.com (mail-wr1-x431.google.com [IPv6:2a00:1450:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7761095; Sat, 7 Oct 2023 13:51:11 -0700 (PDT) Received: by mail-wr1-x431.google.com with SMTP id ffacd0b85a97d-3248aa5cf4eso3225180f8f.1; Sat, 07 Oct 2023 13:51:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1696711870; x=1697316670; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=3Eqt+lFhGqyhgA/GIcCG4Sd1WLEsHw06nfkpMalVsW4=; b=Ru+OOEp90ZxWbfQzr2tymGylhyaTuLX2Eu0LjuozDBlltxaJqqvME9fPpc7GmyWXIi nFSXmB3DnPT/ZAjVg9pYowUpeR3FPny4d+MvP5z5OIRtUPfb3ymIInbNhvtMziT4c9iG xqDz7LGy+G/zsROsLfur+ukqskhSW83xPPbdC4bYnVYO+MIhB+67RO7CTggMmRAjVFRJ /IubIvMIuh/un2lP28NBpQnVAuHeN05slSna+7GJLjQT9qXJa6fzXVw+iniY2W5ri8bD EzuLvYlH08S/STbXb1VWcxsWlFXBAKcn/03JnsxgTzea46TDRezVTTU2EIlFl6gX8k5R dWZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696711870; x=1697316670; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=3Eqt+lFhGqyhgA/GIcCG4Sd1WLEsHw06nfkpMalVsW4=; b=rylqF+l5ao+etdiSPKBMd6oEIKzWGXmDwK6UZ+7vcg4Dz8xt8XvL6eh/Ju0ICPGSgz vHO7Oyre/ArhcH2qglvDmhZw7/C2NTRJueBzxadzghbPnNChRWZiSnTGAkHa3Ygg7vp1 FYPYCcgy4tN9r39o79HAp7vgfYHoj3yU53oUW5b4LsvXOhWlg3IvK555mVD/ZB3EMSsg 7i+tj6pd5DvxjO1VA8ZcQGFJMn0E1eP+5EIyH59BsQULYkdNs89BKlHU70EprtogcSzy YlX0OFPZKyV8sIr9FijiTYnsJBvRAixVIKCRh0u02uoV3z2OX/zwz7indx/OS4Klnf6G kcLQ== X-Gm-Message-State: AOJu0YwJvIerH44n6Q2S/TPUyRHDpiiwzbAimg0ewzH/gbw5gje5GgeZ 8eiVwcPzW9oXqWLvGD/1ogg= X-Received: by 2002:a5d:4c8a:0:b0:313:ecd3:7167 with SMTP id z10-20020a5d4c8a000000b00313ecd37167mr9918903wrs.42.1696711869667; Sat, 07 Oct 2023 13:51:09 -0700 (PDT) Received: from lucifer.home ([2a00:23c5:dc8c:8701:1663:9a35:5a7b:1d76]) by smtp.googlemail.com with ESMTPSA id g7-20020adfe407000000b003232d122dbfsm5120550wrm.66.2023.10.07.13.51.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Oct 2023 13:51:08 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton Cc: Mike Kravetz , Muchun Song , Alexander Viro , Christian Brauner , Matthew Wilcox , Hugh Dickins , Andy Lutomirski , Jan Kara , linux-fsdevel@vger.kernel.org, bpf@vger.kernel.org, Lorenzo Stoakes Subject: [PATCH v3 1/3] mm: drop the assumption that VM_SHARED always implies writable Date: Sat, 7 Oct 2023 21:50:59 +0100 Message-ID: X-Mailer: git-send-email 2.42.0 In-Reply-To: References: MIME-Version: 1.0 X-Spam-Status: No, score=3.0 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_SBL_CSS, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on howler.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (howler.vger.email [0.0.0.0]); Sat, 07 Oct 2023 13:51:46 -0700 (PDT) X-Spam-Level: ** X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1779131388112321921 X-GMAIL-MSGID: 1779131388112321921 There is a general assumption that VMAs with the VM_SHARED flag set are writable. If the VM_MAYWRITE flag is not set, then this is simply not the case. Update those checks which affect the struct address_space->i_mmap_writable field to explicitly test for this by introducing [vma_]is_shared_maywrite() helper functions. This remains entirely conservative, as the lack of VM_MAYWRITE guarantees that the VMA cannot be written to. Suggested-by: Andy Lutomirski Signed-off-by: Lorenzo Stoakes --- include/linux/fs.h | 4 ++-- include/linux/mm.h | 11 +++++++++++ kernel/fork.c | 2 +- mm/filemap.c | 2 +- mm/madvise.c | 2 +- mm/mmap.c | 12 ++++++------ 6 files changed, 22 insertions(+), 11 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 92a9c6157de1..e9c03fb00d5c 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -454,7 +454,7 @@ extern const struct address_space_operations empty_aops; * It is also used to block modification of page cache contents through * memory mappings. * @gfp_mask: Memory allocation flags to use for allocating pages. - * @i_mmap_writable: Number of VM_SHARED mappings. + * @i_mmap_writable: Number of VM_SHARED, VM_MAYWRITE mappings. * @nr_thps: Number of THPs in the pagecache (non-shmem only). * @i_mmap: Tree of private and shared mappings. * @i_mmap_rwsem: Protects @i_mmap and @i_mmap_writable. @@ -557,7 +557,7 @@ static inline int mapping_mapped(struct address_space *mapping) /* * Might pages of this file have been modified in userspace? - * Note that i_mmap_writable counts all VM_SHARED vmas: do_mmap + * Note that i_mmap_writable counts all VM_SHARED, VM_MAYWRITE vmas: do_mmap * marks vma as VM_SHARED if it is shared, and the file was opened for * writing i.e. vma may be mprotected writable even if now readonly. * diff --git a/include/linux/mm.h b/include/linux/mm.h index a7b667786cde..c9e9628addc4 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -937,6 +937,17 @@ static inline bool vma_is_accessible(struct vm_area_struct *vma) return vma->vm_flags & VM_ACCESS_FLAGS; } +static inline bool is_shared_maywrite(vm_flags_t vm_flags) +{ + return (vm_flags & (VM_SHARED | VM_MAYWRITE)) == + (VM_SHARED | VM_MAYWRITE); +} + +static inline bool vma_is_shared_maywrite(struct vm_area_struct *vma) +{ + return is_shared_maywrite(vma->vm_flags); +} + static inline struct vm_area_struct *vma_find(struct vma_iterator *vmi, unsigned long max) { diff --git a/kernel/fork.c b/kernel/fork.c index e45a4457ba83..1e6c656e0857 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -733,7 +733,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, get_file(file); i_mmap_lock_write(mapping); - if (tmp->vm_flags & VM_SHARED) + if (vma_is_shared_maywrite(tmp)) mapping_allow_writable(mapping); flush_dcache_mmap_lock(mapping); /* insert tmp into the share list, just after mpnt */ diff --git a/mm/filemap.c b/mm/filemap.c index 48cd16c54e86..ad559f94e125 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3637,7 +3637,7 @@ int generic_file_mmap(struct file *file, struct vm_area_struct *vma) */ int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma) { - if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) + if (vma_is_shared_maywrite(vma)) return -EINVAL; return generic_file_mmap(file, vma); } diff --git a/mm/madvise.c b/mm/madvise.c index a4a20de50494..5c74fb645de8 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -999,7 +999,7 @@ static long madvise_remove(struct vm_area_struct *vma, return -EINVAL; } - if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE)) + if (!vma_is_shared_maywrite(vma)) return -EACCES; offset = (loff_t)(start - vma->vm_start) diff --git a/mm/mmap.c b/mm/mmap.c index 673429ee8a9e..6f6856b3267a 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -107,7 +107,7 @@ void vma_set_page_prot(struct vm_area_struct *vma) static void __remove_shared_vm_struct(struct vm_area_struct *vma, struct file *file, struct address_space *mapping) { - if (vma->vm_flags & VM_SHARED) + if (vma_is_shared_maywrite(vma)) mapping_unmap_writable(mapping); flush_dcache_mmap_lock(mapping); @@ -384,7 +384,7 @@ static unsigned long count_vma_pages_range(struct mm_struct *mm, static void __vma_link_file(struct vm_area_struct *vma, struct address_space *mapping) { - if (vma->vm_flags & VM_SHARED) + if (vma_is_shared_maywrite(vma)) mapping_allow_writable(mapping); flush_dcache_mmap_lock(mapping); @@ -2767,7 +2767,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr, vma->vm_pgoff = pgoff; if (file) { - if (vm_flags & VM_SHARED) { + if (is_shared_maywrite(vm_flags)) { error = mapping_map_writable(file->f_mapping); if (error) goto free_vma; @@ -2842,7 +2842,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr, mm->map_count++; if (vma->vm_file) { i_mmap_lock_write(vma->vm_file->f_mapping); - if (vma->vm_flags & VM_SHARED) + if (vma_is_shared_maywrite(vma)) mapping_allow_writable(vma->vm_file->f_mapping); flush_dcache_mmap_lock(vma->vm_file->f_mapping); @@ -2859,7 +2859,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr, /* Once vma denies write, undo our temporary denial count */ unmap_writable: - if (file && vm_flags & VM_SHARED) + if (file && is_shared_maywrite(vm_flags)) mapping_unmap_writable(file->f_mapping); file = vma->vm_file; ksm_add_vma(vma); @@ -2907,7 +2907,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr, unmap_region(mm, &vmi.mas, vma, prev, next, vma->vm_start, vma->vm_end, vma->vm_end, true); } - if (file && (vm_flags & VM_SHARED)) + if (file && is_shared_maywrite(vm_flags)) mapping_unmap_writable(file->f_mapping); free_vma: vm_area_free(vma); From patchwork Sat Oct 7 20:51:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenzo Stoakes X-Patchwork-Id: 149650 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:a888:0:b0:403:3b70:6f57 with SMTP id x8csp1099101vqo; Sat, 7 Oct 2023 13:52:45 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFW5F517ylPyo7E4BUDMQZnVhgCCpkq1bPcn7I8R6y9LHA3SYeoxz2hqkDF9k5ocnJFXJLg X-Received: by 2002:a17:902:8343:b0:1c2:82e:32de with SMTP id z3-20020a170902834300b001c2082e32demr11345498pln.0.1696711965122; Sat, 07 Oct 2023 13:52:45 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1696711965; cv=none; d=google.com; s=arc-20160816; b=iUMBrDhYHM5KpKPHukVxI/kHoRj9EUT7EFu+U2cKXc1q89soeAU0IPHwcD+N65FdRu +8LGR+/pvmq9tQbMoIhoHEPdaJGGEX4Kro6m+iqq9Mhw5qlcEQQeKDF0jh7LCWOmVg7p L6Mg6QTfQ6n9gABgVFG3GMatAN54vWDJBfGooJtYhXCxROsUwH3gUCC/79TkyNGaz3mx KlIJOCa2jCWIskn1k5WUVC5AjV0ngp/A4Rd/+nE90DeiGJKFvL5vhghoxBXexnA1Aqmd 2HssqomkLfgG2VhpZ5pnHndEG32JRd6JXrYQ7ejAxoO0x0kXQsZxYZT/xWtBIJ/DtYVP UH6g== ARC-Message-Signature: i=1; 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The F_SEAL_WRITE flag is not checked here, as that is handled via the mapping->i_mmap_writable mechanism and so any attempt at a mapping would fail before this could be run. However we intend to change this, meaning this check can be performed for F_SEAL_WRITE mappings also. The logic here is equally applicable to both flags, so update this function to accommodate both and rename it accordingly. Signed-off-by: Lorenzo Stoakes --- fs/hugetlbfs/inode.c | 2 +- include/linux/mm.h | 15 ++++++++------- mm/shmem.c | 2 +- 3 files changed, 10 insertions(+), 9 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 06693bb1153d..5c333373dcc9 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -112,7 +112,7 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) vm_flags_set(vma, VM_HUGETLB | VM_DONTEXPAND); vma->vm_ops = &hugetlb_vm_ops; - ret = seal_check_future_write(info->seals, vma); + ret = seal_check_write(info->seals, vma); if (ret) return ret; diff --git a/include/linux/mm.h b/include/linux/mm.h index c9e9628addc4..51a217ed4d1b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4027,25 +4027,26 @@ static inline void mem_dump_obj(void *object) {} #endif /** - * seal_check_future_write - Check for F_SEAL_FUTURE_WRITE flag and handle it + * seal_check_write - Check for F_SEAL_WRITE or F_SEAL_FUTURE_WRITE flags and + * handle them. * @seals: the seals to check * @vma: the vma to operate on * - * Check whether F_SEAL_FUTURE_WRITE is set; if so, do proper check/handling on - * the vma flags. Return 0 if check pass, or <0 for errors. + * Check whether F_SEAL_WRITE or F_SEAL_FUTURE_WRITE are set; if so, do proper + * check/handling on the vma flags. Return 0 if check pass, or <0 for errors. */ -static inline int seal_check_future_write(int seals, struct vm_area_struct *vma) +static inline int seal_check_write(int seals, struct vm_area_struct *vma) { - if (seals & F_SEAL_FUTURE_WRITE) { + if (seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) { /* * New PROT_WRITE and MAP_SHARED mmaps are not allowed when - * "future write" seal active. + * write seals are active. */ if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE)) return -EPERM; /* - * Since an F_SEAL_FUTURE_WRITE sealed memfd can be mapped as + * Since an F_SEAL_[FUTURE_]WRITE sealed memfd can be mapped as * MAP_SHARED and read-only, take care to not allow mprotect to * revert protections on such mappings. Do this only for shared * mappings. For private mappings, don't need to mask diff --git a/mm/shmem.c b/mm/shmem.c index 6503910b0f54..cab053831fea 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2405,7 +2405,7 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma) struct shmem_inode_info *info = SHMEM_I(inode); int ret; - ret = seal_check_future_write(info->seals, vma); + ret = seal_check_write(info->seals, vma); if (ret) return ret; From patchwork Sat Oct 7 20:51:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenzo Stoakes X-Patchwork-Id: 149649 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:a888:0:b0:403:3b70:6f57 with SMTP id x8csp1098952vqo; Sat, 7 Oct 2023 13:52:10 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEmQWUOb601uasiglff70L/D3aulJK4vMrryfhf4UtqlIkoUwM7kS6v/wcwuqeNgSp+OtRR X-Received: by 2002:a05:6a20:258a:b0:161:aef5:6395 with SMTP id k10-20020a056a20258a00b00161aef56395mr13417304pzd.24.1696711930640; Sat, 07 Oct 2023 13:52:10 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1696711930; cv=none; d=google.com; s=arc-20160816; b=cKaEkyPdTHl55yI/Zb9g7C2kDLtLJoEyyU3zPhZeHtNLGBOeWkFZAIJ/THMomrmfVZ mCbEEAmq4UrGjclCzsGkXKLoGYa9c5Gl1Xdao21GSdJo+WthSBxH6B0Jldu7PVqSedf+ S9SRNY7YYFvcCgzBJOW7xNGzzoQrdIwALhtYWXUzww37sz6F8dqU0J9FEiBMaJ+srTBj jhxrwY7YFibuBRMMp9MYsVu6ZRf6R1c/R4NLiDE1PC/0UZLCA82Y12+M0ad7MM0PX2IM JXRmfCwi9JqRwIkae4TAKbYJJjSHcG00N3SZym1pnMNcxa9bFdQNQUrVuHMJiB+L7yhC lcvw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=2R/SPrp+9X8K4zqdkQ2nu1IGtJt6e/ubH1aV+LRG8uo=; fh=On8i7MftmLnii/x6szJvRZF6tmYBE7/T6K0SDqpksdA=; b=gyQqaGpdsQB+0wzREHapt9zMbAeA+v6EKBT4rGSvgWpTzpykrBvBEdGHRc/ygAwfL9 v1/qzT5xsmopoigwEbPbgfKUU3ZEO6zjAVP4mpEmUCV5jxsmbSzhsqNvG7jWRn1krQiM VRcZue8V43zfNNguGmt4lEy6ExhitGocndm2D/REEKPZOiYmhPH5exC8UDfgGuZ3Bht8 IoO6fopeknGRe2ujwqgMkFyzrRpeCgvIYH3rOC/ktcpWO5NKZ5sMthoKXFde4XpnlHxB 1pMux+ButXNEFi1SNgMyPBEJRY5Y2aF97C9NXWlnAcQfib/jGk7HXrNl4gxrNGWg6rL4 x+3w== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20230601 header.b="cZfbV49/"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from pete.vger.email (pete.vger.email. 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We would otherwise fail the mapping_map_writable() check before we had the opportunity to clear VM_MAYWRITE. However, the existing logic in mmap_region() performs this check BEFORE calling call_mmap() (which invokes file->f_ops->mmap()). We must enforce this check AFTER the function call. In order to avoid any risk of breaking call_mmap() handlers which assume this will have been done first, we continue to mark the file writable first, simply deferring enforcement of it failing until afterwards. This enables mmap(..., PROT_READ, MAP_SHARED, fd, 0) mappings for memfd's sealed via F_SEAL_WRITE to succeed, whereas previously they were not permitted. Link: https://bugzilla.kernel.org/show_bug.cgi?id=217238 Signed-off-by: Lorenzo Stoakes --- mm/mmap.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 6f6856b3267a..9fbee92aaaee 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2767,17 +2767,25 @@ unsigned long mmap_region(struct file *file, unsigned long addr, vma->vm_pgoff = pgoff; if (file) { - if (is_shared_maywrite(vm_flags)) { - error = mapping_map_writable(file->f_mapping); - if (error) - goto free_vma; - } + int writable_error = 0; + + if (vma_is_shared_maywrite(vma)) + writable_error = mapping_map_writable(file->f_mapping); vma->vm_file = get_file(file); error = call_mmap(file, vma); if (error) goto unmap_and_free_vma; + /* + * call_mmap() may have changed VMA flags, so retry this check + * if it failed before. + */ + if (writable_error && vma_is_shared_maywrite(vma)) { + error = writable_error; + goto close_and_free_vma; + } + /* * Expansion is handled above, merging is handled below. * Drivers should not alter the address of the VMA.