Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60E7BC05027 for ; Thu, 26 Jan 2023 19:38:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232330AbjAZTit (ORCPT ); Thu, 26 Jan 2023 14:38:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232536AbjAZTi0 (ORCPT ); Thu, 26 Jan 2023 14:38:26 -0500 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4562936FF7 for ; Thu, 26 Jan 2023 11:38:11 -0800 (PST) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5028c723d28so31178837b3.15 for ; Thu, 26 Jan 2023 11:38:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=ZiBPU+eDHOqkXMrsDufSC0gz6UzIoIV8gCa/IcOfB+E=; b=m73DxO9jMvetXVPEszi0Jq7mi01vVVgt0BZIvBznYhv6ivS8hm7+23OxZRlC61JcUZ BHwUuqPCw+b5nazQInMzzi3+biojKImVBuXc30nFSw1PLF1kt5V7xEaZCKfimLJL93+9 TVAzPsoC/CDsJzMhAqE/M7vA04soveCg9rschI+7VItGY4S7zAYu3W7Gmg5yVd0plpnO wz0yONbTGqZ76kWnjIRpBT4RqBUiZM9/aVjX1vovX5GCHpHkfG3oBQGTqt4kRKcg15yB xy9oqMlpTp7XCjAgCH87WkHAOrFK2I8Q2mUGM8JqhUbfsRh7aHMWsVJQdO5n/1nFv+h0 54Aw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=ZiBPU+eDHOqkXMrsDufSC0gz6UzIoIV8gCa/IcOfB+E=; b=G3L+7C62uVmua/pZEMFG07lWZtr2vpHh3dybMWFOk8cGZxd/OsgucdR4JG+NR5KxJ5 0+uLqUYdMZKrvGHaRTM7kCGy0wHD28Jocx23nYXqQ1+m9tB1lpgVxK7ODJT5e55TuO5y u5bba7I7SHXEUrnoMEvL1iZXQ+q0Rj4htv3mNTDUl3VeKfxDuoO0t4pkaOKEcchwWmUG 5lkFB58QK5/+bjoKYa/mJvlOXWfpfzYxepm1CMETSnFQpCaPo5kQdH4jKKNltma2tTkm /6/62pmcbGUNund6BiJCDFyNCYRLAeSZKbCelV0qqkFbnLXbT8WY1+el0YbpIPlJ2f8x LHRw== X-Gm-Message-State: AFqh2kr7Bxh62TcBViMOslO+80+j4OyWkwnQ3oyUCzd3T46Le9IzPlOL ObQtu3eTX0gRz0kAdbCxyTOEDKxYxuk= X-Google-Smtp-Source: AMrXdXt20QRkRihGWlEdRJDhT+YO7v3lUpepK3uuj9V92kEGUFyRzloVkr71qHyKbWGH8sK+KSDR5LyhftY= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:d774:88af:bab3:648d]) (user=surenb job=sendgmr) by 2002:a5b:684:0:b0:804:cc8:dea3 with SMTP id j4-20020a5b0684000000b008040cc8dea3mr2587550ybq.451.1674761890401; Thu, 26 Jan 2023 11:38:10 -0800 (PST) Date: Thu, 26 Jan 2023 11:37:51 -0800 In-Reply-To: <20230126193752.297968-1-surenb@google.com> Mime-Version: 1.0 References: <20230126193752.297968-1-surenb@google.com> X-Mailer: git-send-email 2.39.1.456.gfc5497dd1b-goog Message-ID: <20230126193752.297968-7-surenb@google.com> Subject: [PATCH v4 6/7] mm: introduce __vm_flags_mod and use it in untrack_pfn From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, paulmck@kernel.org, mingo@redhat.com, will@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, rppt@kernel.org, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, surenb@google.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There are scenarios when vm_flags can be modified without exclusive mmap_lock, such as: - after VMA was isolated and mmap_lock was downgraded or dropped - in exit_mmap when there are no other mm users and locking is unnecessary Introduce __vm_flags_mod to avoid assertions when the caller takes responsibility for the required locking. Pass a hint to untrack_pfn to conditionally use __vm_flags_mod for flags modification to avoid assertion. Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko --- arch/x86/mm/pat/memtype.c | 10 +++++++--- include/linux/mm.h | 14 ++++++++++++-- include/linux/pgtable.h | 5 +++-- mm/memory.c | 13 +++++++------ mm/memremap.c | 4 ++-- mm/mmap.c | 16 ++++++++++------ 6 files changed, 41 insertions(+), 21 deletions(-) diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c index 6ca51b1aa5d9..691bf8934b6f 100644 --- a/arch/x86/mm/pat/memtype.c +++ b/arch/x86/mm/pat/memtype.c @@ -1046,7 +1046,7 @@ void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, pfn_t pfn) * can be for the entire vma (in which case pfn, size are zero). */ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, - unsigned long size) + unsigned long size, bool mm_wr_locked) { resource_size_t paddr; unsigned long prot; @@ -1065,8 +1065,12 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, size = vma->vm_end - vma->vm_start; } free_pfn_range(paddr, size); - if (vma) - vm_flags_clear(vma, VM_PAT); + if (vma) { + if (mm_wr_locked) + vm_flags_clear(vma, VM_PAT); + else + __vm_flags_mod(vma, 0, VM_PAT); + } } /* diff --git a/include/linux/mm.h b/include/linux/mm.h index 3c7fc3ecaece..a00fdeb4492d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -656,6 +656,16 @@ static inline void vm_flags_clear(struct vm_area_struct *vma, ACCESS_PRIVATE(vma, __vm_flags) &= ~flags; } +/* + * Use only if VMA is not part of the VMA tree or has no other users and + * therefore needs no locking. + */ +static inline void __vm_flags_mod(struct vm_area_struct *vma, + vm_flags_t set, vm_flags_t clear) +{ + vm_flags_init(vma, (vma->vm_flags | set) & ~clear); +} + /* * Use only when the order of set/clear operations is unimportant, otherwise * use vm_flags_{set|clear} explicitly. @@ -664,7 +674,7 @@ static inline void vm_flags_mod(struct vm_area_struct *vma, vm_flags_t set, vm_flags_t clear) { mmap_assert_write_locked(vma->vm_mm); - vm_flags_init(vma, (vma->vm_flags | set) & ~clear); + __vm_flags_mod(vma, set, clear); } static inline void vma_set_anonymous(struct vm_area_struct *vma) @@ -2102,7 +2112,7 @@ static inline void zap_vma_pages(struct vm_area_struct *vma) } void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt, struct vm_area_struct *start_vma, unsigned long start, - unsigned long end); + unsigned long end, bool mm_wr_locked); struct mmu_notifier_range; diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 5fd45454c073..c63cd44777ec 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1185,7 +1185,8 @@ static inline int track_pfn_copy(struct vm_area_struct *vma) * can be for the entire vma (in which case pfn, size are zero). */ static inline void untrack_pfn(struct vm_area_struct *vma, - unsigned long pfn, unsigned long size) + unsigned long pfn, unsigned long size, + bool mm_wr_locked) { } @@ -1203,7 +1204,7 @@ extern void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, pfn_t pfn); extern int track_pfn_copy(struct vm_area_struct *vma); extern void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, - unsigned long size); + unsigned long size, bool mm_wr_locked); extern void untrack_pfn_moved(struct vm_area_struct *vma); #endif diff --git a/mm/memory.c b/mm/memory.c index a6316cda0e87..7a04a1130ec1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1613,7 +1613,7 @@ void unmap_page_range(struct mmu_gather *tlb, static void unmap_single_vma(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long start_addr, unsigned long end_addr, - struct zap_details *details) + struct zap_details *details, bool mm_wr_locked) { unsigned long start = max(vma->vm_start, start_addr); unsigned long end; @@ -1628,7 +1628,7 @@ static void unmap_single_vma(struct mmu_gather *tlb, uprobe_munmap(vma, start, end); if (unlikely(vma->vm_flags & VM_PFNMAP)) - untrack_pfn(vma, 0, 0); + untrack_pfn(vma, 0, 0, mm_wr_locked); if (start != end) { if (unlikely(is_vm_hugetlb_page(vma))) { @@ -1675,7 +1675,7 @@ static void unmap_single_vma(struct mmu_gather *tlb, */ void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt, struct vm_area_struct *vma, unsigned long start_addr, - unsigned long end_addr) + unsigned long end_addr, bool mm_wr_locked) { struct mmu_notifier_range range; struct zap_details details = { @@ -1689,7 +1689,8 @@ void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt, start_addr, end_addr); mmu_notifier_invalidate_range_start(&range); do { - unmap_single_vma(tlb, vma, start_addr, end_addr, &details); + unmap_single_vma(tlb, vma, start_addr, end_addr, &details, + mm_wr_locked); } while ((vma = mas_find(&mas, end_addr - 1)) != NULL); mmu_notifier_invalidate_range_end(&range); } @@ -1723,7 +1724,7 @@ void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, * unmap 'address-end' not 'range.start-range.end' as range * could have been expanded for hugetlb pmd sharing. */ - unmap_single_vma(&tlb, vma, address, end, details); + unmap_single_vma(&tlb, vma, address, end, details, false); mmu_notifier_invalidate_range_end(&range); tlb_finish_mmu(&tlb); } @@ -2492,7 +2493,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, err = remap_pfn_range_notrack(vma, addr, pfn, size, prot); if (err) - untrack_pfn(vma, pfn, PAGE_ALIGN(size)); + untrack_pfn(vma, pfn, PAGE_ALIGN(size), true); return err; } EXPORT_SYMBOL(remap_pfn_range); diff --git a/mm/memremap.c b/mm/memremap.c index 08cbf54fe037..2f88f43d4a01 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -129,7 +129,7 @@ static void pageunmap_range(struct dev_pagemap *pgmap, int range_id) } mem_hotplug_done(); - untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range)); + untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range), true); pgmap_array_delete(range); } @@ -276,7 +276,7 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params, if (!is_private) kasan_remove_zero_shadow(__va(range->start), range_len(range)); err_kasan: - untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range)); + untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range), true); err_pfn_remap: pgmap_array_delete(range); return error; diff --git a/mm/mmap.c b/mm/mmap.c index 3d9b14d5f933..429e42c8fccc 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -78,7 +78,7 @@ core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644); static void unmap_region(struct mm_struct *mm, struct maple_tree *mt, struct vm_area_struct *vma, struct vm_area_struct *prev, struct vm_area_struct *next, unsigned long start, - unsigned long end); + unsigned long end, bool mm_wr_locked); static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags) { @@ -2136,14 +2136,14 @@ static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas) static void unmap_region(struct mm_struct *mm, struct maple_tree *mt, struct vm_area_struct *vma, struct vm_area_struct *prev, struct vm_area_struct *next, - unsigned long start, unsigned long end) + unsigned long start, unsigned long end, bool mm_wr_locked) { struct mmu_gather tlb; lru_add_drain(); tlb_gather_mmu(&tlb, mm); update_hiwater_rss(mm); - unmap_vmas(&tlb, mt, vma, start, end); + unmap_vmas(&tlb, mt, vma, start, end, mm_wr_locked); free_pgtables(&tlb, mt, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, next ? next->vm_start : USER_PGTABLES_CEILING); tlb_finish_mmu(&tlb); @@ -2391,7 +2391,11 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma, mmap_write_downgrade(mm); } - unmap_region(mm, &mt_detach, vma, prev, next, start, end); + /* + * We can free page tables without write-locking mmap_lock because VMAs + * were isolated before we downgraded mmap_lock. + */ + unmap_region(mm, &mt_detach, vma, prev, next, start, end, !downgrade); /* Statistics and freeing VMAs */ mas_set(&mas_detach, start); remove_mt(mm, &mas_detach); @@ -2704,7 +2708,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr, /* Undo any partial mapping done by a device driver. */ unmap_region(mm, &mm->mm_mt, vma, prev, next, vma->vm_start, - vma->vm_end); + vma->vm_end, true); } if (file && (vm_flags & VM_SHARED)) mapping_unmap_writable(file->f_mapping); @@ -3031,7 +3035,7 @@ void exit_mmap(struct mm_struct *mm) tlb_gather_mmu_fullmm(&tlb, mm); /* update_hiwater_rss(mm) here? but nobody should be looking */ /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */ - unmap_vmas(&tlb, &mm->mm_mt, vma, 0, ULONG_MAX); + unmap_vmas(&tlb, &mm->mm_mt, vma, 0, ULONG_MAX, false); mmap_read_unlock(mm); /* -- 2.39.1