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McKenney" , Matthew Wilcox , David Rientjes , Axel Rasmussen , Suren Baghdasaryan , Vlastimil Babka , Rik van Riel , Peter Zijlstra Subject: [PATCH v3 18/66] mm/mmap: Use advanced maple tree API for mmap_region() Thread-Topic: [PATCH v3 18/66] mm/mmap: Use advanced maple tree API for mmap_region() Thread-Index: AQHXuYiaG4rRVLdtWk65fIbdQSuKiw== Date: Tue, 5 Oct 2021 01:30:38 +0000 Message-ID: <20211005012959.1110504-19-Liam.Howlett@oracle.com> References: <20211005012959.1110504-1-Liam.Howlett@oracle.com> In-Reply-To: <20211005012959.1110504-1-Liam.Howlett@oracle.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: git-send-email 2.30.2 authentication-results: lists.infradead.org; dkim=none (message not signed) header.d=none;lists.infradead.org; dmarc=none action=none header.from=oracle.com; x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 472b1b20-f37f-4909-edfa-08d9879fbcf8 x-ms-traffictypediagnostic: BLAPR10MB5044: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:8882; 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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BL0PR10MB3011.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 472b1b20-f37f-4909-edfa-08d9879fbcf8 X-MS-Exchange-CrossTenant-originalarrivaltime: 05 Oct 2021 01:30:38.8136 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: YvlHKcww111+kgq0KCNtfTQzzz+wawEwC1WKrph4deIXkp82YAbpFOKyFCSbWgc6tAZitp/rjpVW0EldWH5NaA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BLAPR10MB5044 X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10127 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 adultscore=0 phishscore=0 malwarescore=0 bulkscore=0 mlxlogscore=999 mlxscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109230001 definitions=main-2110050007 X-Proofpoint-GUID: BQYoHGjdaohQZSf0Gc12AmaAhHmgDrKd X-Proofpoint-ORIG-GUID: BQYoHGjdaohQZSf0Gc12AmaAhHmgDrKd Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Liam R. Howlett" Changing mmap_region() to use the maple tree state and the advanced maple tree interface allows for a lot less tree walking. This change removes the last caller of munmap_vma_range(), so drop this unused function. Add vma_expand() to expand a VMA if possible by doing the necessary hugepage check, uprobe_munmap of files, dcache flush, modifications then undoing the detaches, etc. Add vma_mas_link() helper to add a VMA to the linked list and maple tree until the linked list is removed. Signed-off-by: Liam R. Howlett --- mm/mmap.c | 259 +++++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 207 insertions(+), 52 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 3b1de99d0ea0..747c69ec88de 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -501,28 +501,6 @@ static inline struct vm_area_struct *vma_next(struct m= m_struct *mm, return vma->vm_next; } =20 -/* - * munmap_vma_range() - munmap VMAs that overlap a range. - * @mm: The mm struct - * @start: The start of the range. - * @len: The length of the range. - * @pprev: pointer to the pointer that will be set to previous vm_area_str= uct - * - * Find all the vm_area_struct that overlap from @start to - * @end and munmap them. Set @pprev to the previous vm_area_struct. - * - * Returns: -ENOMEM on munmap failure or 0 on success. - */ -static inline int -munmap_vma_range(struct mm_struct *mm, unsigned long start, unsigned long = len, - struct vm_area_struct **pprev, struct list_head *uf) -{ - // Needs optimization. - while (range_has_overlap(mm, start, start + len, pprev)) - if (do_munmap(mm, start, len, uf)) - return -ENOMEM; - return 0; -} static unsigned long count_vma_pages_range(struct mm_struct *mm, unsigned long addr, unsigned long end) { @@ -600,6 +578,35 @@ void vma_mt_store(struct mm_struct *mm, struct vm_area= _struct *vma) GFP_KERNEL); } =20 +/* + * vma_mas_link() - Link a VMA into an mm + * @mm: The mm struct + * @vma: The VMA to link in + * @mas: The maple state + * + * Must hold the @mas lock. + */ +static void vma_mas_link(struct mm_struct *mm, struct vm_area_struct *vma, + struct ma_state *mas, struct vm_area_struct *prev) +{ + struct address_space *mapping =3D NULL; + + if (vma->vm_file) { + mapping =3D vma->vm_file->f_mapping; + i_mmap_lock_write(mapping); + } + + vma_mas_store(vma, mas); + __vma_link_list(mm, vma, prev); + __vma_link_file(vma); + + if (mapping) + i_mmap_unlock_write(mapping); + + mm->map_count++; + validate_mm(mm); +} + static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev) { @@ -634,6 +641,108 @@ static void __insert_vm_struct(struct mm_struct *mm, = struct vm_area_struct *vma) mm->map_count++; } =20 +/* + * vma_expand - Expand an existing VMA + * @mas: The maple state + * @vma: The vma to expand + * @start: The start of the vma + * @end: The exclusive end of the vma + * + * @mas must be locked + */ +inline int vma_expand(struct ma_state *mas, struct vm_area_struct *vma, + unsigned long start, unsigned long end, pgoff_t pgoff, + struct vm_area_struct *next) +{ + struct mm_struct *mm =3D vma->vm_mm; + struct address_space *mapping =3D NULL; + struct rb_root_cached *root =3D NULL; + struct anon_vma *anon_vma =3D vma->anon_vma; + struct file *file =3D vma->vm_file; + bool remove_next =3D false; + int error; + + if (next && (vma !=3D next) && (end =3D=3D next->vm_end)) { + remove_next =3D true; + if (next->anon_vma && !vma->anon_vma) { + vma->anon_vma =3D next->anon_vma; + error =3D anon_vma_clone(vma, next); + if (error) + return error; + } + } + + vma_adjust_trans_huge(vma, start, end, 0); + + if (file) { + mapping =3D file->f_mapping; + root =3D &mapping->i_mmap; + uprobe_munmap(vma, vma->vm_start, vma->vm_end); + i_mmap_lock_write(mapping); + } + + if (anon_vma) { + anon_vma_lock_write(anon_vma); + anon_vma_interval_tree_pre_update_vma(vma); + } + + if (file) { + flush_dcache_mmap_lock(mapping); + vma_interval_tree_remove(vma, root); + } + + vma->vm_start =3D start; + vma->vm_end =3D end; + vma->vm_pgoff =3D pgoff; + /* Note: mas must be pointing to the expanding VMA */ + vma_mas_store(vma, mas); + + if (file) { + vma_interval_tree_insert(vma, root); + flush_dcache_mmap_unlock(mapping); + } + + /* Expanding over the next vma */ + if (remove_next) { + /* Remove from mm linked list - also updates highest_vm_end */ + __vma_unlink_list(mm, next); + + /* Kill the cache */ + vmacache_invalidate(mm); + + if (file) + __remove_shared_vm_struct(next, file, mapping); + + } else if (!next) { + mm->highest_vm_end =3D vm_end_gap(vma); + } + + if (anon_vma) { + anon_vma_interval_tree_post_update_vma(vma); + anon_vma_unlock_write(anon_vma); + } + + if (file) { + i_mmap_unlock_write(mapping); + uprobe_mmap(vma); + } + + if (remove_next) { + if (file) { + uprobe_munmap(next, next->vm_start, next->vm_end); + fput(file); + } + if (next->anon_vma) + anon_vma_merge(vma, next); + mm->map_count--; + mpol_put(vma_policy(next)); + vm_area_free(next); + } + + validate_mm(mm); + return 0; +} + /* * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that * is already present in an i_mmap tree without adjusting the tree. @@ -1614,9 +1723,15 @@ unsigned long mmap_region(struct file *file, unsigne= d long addr, struct list_head *uf) { struct mm_struct *mm =3D current->mm; - struct vm_area_struct *vma, *prev, *merge; - int error; + struct vm_area_struct *vma =3D NULL; + struct vm_area_struct *prev, *next; + pgoff_t pglen =3D len >> PAGE_SHIFT; unsigned long charged =3D 0; + unsigned long end =3D addr + len; + unsigned long merge_start =3D addr, merge_end =3D end; + pgoff_t vm_pgoff; + int error; + MA_STATE(mas, &mm->mm_mt, addr, end - 1); =20 /* Check against address space limit. */ if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) { @@ -1626,16 +1741,17 @@ unsigned long mmap_region(struct file *file, unsign= ed long addr, * MAP_FIXED may remove pages of mappings that intersects with * requested mapping. Account for the pages it would unmap. */ - nr_pages =3D count_vma_pages_range(mm, addr, addr + len); + nr_pages =3D count_vma_pages_range(mm, addr, end); =20 if (!may_expand_vm(mm, vm_flags, (len >> PAGE_SHIFT) - nr_pages)) return -ENOMEM; } =20 - /* Clear old maps, set up prev and uf */ - if (munmap_vma_range(mm, addr, len, &prev, uf)) + /* Unmap any existing mapping in the area */ + if (do_munmap(mm, addr, len, uf)) return -ENOMEM; + /* * Private writable mapping: check memory availability */ @@ -1646,14 +1762,51 @@ unsigned long mmap_region(struct file *file, unsign= ed long addr, vm_flags |=3D VM_ACCOUNT; } =20 - /* - * Can we just expand an old mapping? - */ - vma =3D vma_merge(mm, prev, addr, addr + len, vm_flags, - NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX); - if (vma) - goto out; =20 + if (vm_flags & VM_SPECIAL) { + rcu_read_lock(); + prev =3D mas_prev(&mas, 0); + rcu_read_unlock(); + goto cannot_expand; + } + + /* Attempt to expand an old mapping */ + + /* Check next */ + rcu_read_lock(); + next =3D mas_next(&mas, ULONG_MAX); + rcu_read_unlock(); + if (next && next->vm_start =3D=3D end && vma_policy(next) && + can_vma_merge_before(next, vm_flags, NULL, file, pgoff+pglen, + NULL_VM_UFFD_CTX)) { + merge_end =3D next->vm_end; + vma =3D next; + vm_pgoff =3D next->vm_pgoff - pglen; + } + + /* Check prev */ + rcu_read_lock(); + prev =3D mas_prev(&mas, 0); + rcu_read_unlock(); + if (prev && prev->vm_end =3D=3D addr && !vma_policy(prev) && + can_vma_merge_after(prev, vm_flags, NULL, file, pgoff, + NULL_VM_UFFD_CTX)) { + merge_start =3D prev->vm_start; + vma =3D prev; + vm_pgoff =3D prev->vm_pgoff; + } + + + /* Actually expand, if possible */ + if (vma && + !vma_expand(&mas, vma, merge_start, merge_end, vm_pgoff, next)) { + khugepaged_enter_vma_merge(prev, vm_flags); + goto expanded; + } + + mas.index =3D addr; + mas.last =3D end - 1; +cannot_expand: /* * Determine the object being mapped and call the appropriate * specific mapper. the address has already been validated, but @@ -1666,7 +1819,7 @@ unsigned long mmap_region(struct file *file, unsigned= long addr, } =20 vma->vm_start =3D addr; - vma->vm_end =3D addr + len; + vma->vm_end =3D end; vma->vm_flags =3D vm_flags; vma->vm_page_prot =3D vm_get_page_prot(vm_flags); vma->vm_pgoff =3D pgoff; @@ -1687,8 +1840,6 @@ unsigned long mmap_region(struct file *file, unsigned= long addr, * * Answer: Yes, several device drivers can do it in their * f_op->mmap method. -DaveM - * Bug: If addr is changed, prev, rb_link, rb_parent should - * be updated for vma_link() */ WARN_ON_ONCE(addr !=3D vma->vm_start); =20 @@ -1697,23 +1848,31 @@ unsigned long mmap_region(struct file *file, unsign= ed long addr, /* If vm_flags changed after call_mmap(), we should try merge vma again * as we may succeed this time. */ - if (unlikely(vm_flags !=3D vma->vm_flags && prev)) { - merge =3D vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags= , - NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX); - if (merge) { + if (unlikely(vm_flags !=3D vma->vm_flags && prev && + prev->vm_end =3D=3D addr && !vma_policy(prev) && + can_vma_merge_after(prev, vm_flags, NULL, file, + pgoff, NULL_VM_UFFD_CTX))) { + merge_start =3D prev->vm_start; + vm_pgoff =3D prev->vm_pgoff; + if (!vma_expand(&mas, prev, merge_start, merge_end, + vm_pgoff, next)) { /* ->mmap() can change vma->vm_file and fput the original file. So * fput the vma->vm_file here or we would add an extra fput for file * and cause general protection fault ultimately. */ fput(vma->vm_file); vm_area_free(vma); - vma =3D merge; - /* Update vm_flags to pick up the change. */ + vma =3D prev; + /* Update vm_flags and possible addr to pick up the change. We don't + * warn here if addr changed as the vma is not linked by vma_link(). + */ + addr =3D vma->vm_start; vm_flags =3D vma->vm_flags; goto unmap_writable; } } =20 + mas_set(&mas, addr); vm_flags =3D vma->vm_flags; } else if (vm_flags & VM_SHARED) { error =3D shmem_zero_setup(vma); @@ -1732,20 +1891,20 @@ unsigned long mmap_region(struct file *file, unsign= ed long addr, goto free_vma; } =20 - vma_link(mm, vma, prev); + vma_mas_link(mm, vma, &mas, prev); /* Once vma denies write, undo our temporary denial count */ unmap_writable: if (file && vm_flags & VM_SHARED) mapping_unmap_writable(file->f_mapping); file =3D vma->vm_file; -out: +expanded: perf_event_mmap(vma); =20 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT); if (vm_flags & VM_LOCKED) { if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) || - is_vm_hugetlb_page(vma) || - vma =3D=3D get_gate_vma(current->mm)) + is_vm_hugetlb_page(vma) || + vma =3D=3D get_gate_vma(current->mm)) vma->vm_flags &=3D VM_LOCKED_CLEAR_MASK; else mm->locked_vm +=3D (len >> PAGE_SHIFT); @@ -2580,13 +2739,10 @@ int __do_munmap(struct mm_struct *mm, unsigned long= start, size_t len, vma =3D find_vma_intersection(mm, start, end); if (!vma) return 0; + prev =3D vma->vm_prev; /* we have start < vma->vm_end */ =20 - /* if it doesn't overlap, we have nothing.. */ - if (vma->vm_start >=3D end) - return 0; - /* * If we need to split any vma, do it now to save pain later. * @@ -2596,7 +2752,6 @@ int __do_munmap(struct mm_struct *mm, unsigned long s= tart, size_t len, */ if (start > vma->vm_start) { int error; - /* * Make sure that map_count on return from munmap() will * not exceed its limit; but let map_count go just above --=20 2.30.2