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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: [PATCH v1 03/10] mm: fs: remove filemap_nr_thps*() functions and their users Date: Thu, 26 Mar 2026 21:42:48 -0400 Message-ID: <20260327014255.2058916-4-ziy@nvidia.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260327014255.2058916-1-ziy@nvidia.com> References: <20260327014255.2058916-1-ziy@nvidia.com> Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: BL1PR13CA0378.namprd13.prod.outlook.com (2603:10b6:208:2c0::23) To DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR12MB9473:EE_|LV8PR12MB9264:EE_ X-MS-Office365-Filtering-Correlation-Id: 4f5b485c-62a8-4932-266c-08de8ba2328f X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|7416014|376014|18002099003|56012099003|22082099003; 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charset="utf-8" They are used by READ_ONLY_THP_FOR_FS to handle writes to FSes without large folio support, so that read-only THPs created in these FSes are not seen by the FSes when the underlying fd becomes writable. Now read-only PMD THPs only appear in a FS with large folio support and the supported orders include PMD_ORDRE. Signed-off-by: Zi Yan Reviewed-by: Lance Yang Reviewed-by: Lorenzo Stoakes (Oracle) --- fs/open.c | 27 --------------------------- include/linux/pagemap.h | 29 ----------------------------- mm/filemap.c | 1 - mm/huge_memory.c | 1 - mm/khugepaged.c | 29 ++--------------------------- 5 files changed, 2 insertions(+), 85 deletions(-) diff --git a/fs/open.c b/fs/open.c index 91f1139591ab..cef382d9d8b8 100644 --- a/fs/open.c +++ b/fs/open.c @@ -970,33 +970,6 @@ static int do_dentry_open(struct file *f, if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT)) return -EINVAL; =20 - /* - * XXX: Huge page cache doesn't support writing yet. Drop all page - * cache for this file before processing writes. - */ - if (f->f_mode & FMODE_WRITE) { - /* - * Depends on full fence from get_write_access() to synchronize - * against collapse_file() regarding i_writecount and nr_thps - * updates. Ensures subsequent insertion of THPs into the page - * cache will fail. - */ - if (filemap_nr_thps(inode->i_mapping)) { - struct address_space *mapping =3D inode->i_mapping; - - filemap_invalidate_lock(inode->i_mapping); - /* - * unmap_mapping_range just need to be called once - * here, because the private pages is not need to be - * unmapped mapping (e.g. data segment of dynamic - * shared libraries here). - */ - unmap_mapping_range(mapping, 0, 0, 0); - truncate_inode_pages(mapping, 0); - filemap_invalidate_unlock(inode->i_mapping); - } - } - return 0; =20 cleanup_all: diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index ec442af3f886..dad3f8846cdc 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -530,35 +530,6 @@ static inline size_t mapping_max_folio_size(const stru= ct address_space *mapping) return PAGE_SIZE << mapping_max_folio_order(mapping); } =20 -static inline int filemap_nr_thps(const struct address_space *mapping) -{ -#ifdef CONFIG_READ_ONLY_THP_FOR_FS - return atomic_read(&mapping->nr_thps); -#else - return 0; -#endif -} - -static inline void filemap_nr_thps_inc(struct address_space *mapping) -{ -#ifdef CONFIG_READ_ONLY_THP_FOR_FS - if (!mapping_large_folio_support(mapping)) - atomic_inc(&mapping->nr_thps); -#else - WARN_ON_ONCE(mapping_large_folio_support(mapping) =3D=3D 0); -#endif -} - -static inline void filemap_nr_thps_dec(struct address_space *mapping) -{ -#ifdef CONFIG_READ_ONLY_THP_FOR_FS - if (!mapping_large_folio_support(mapping)) - atomic_dec(&mapping->nr_thps); -#else - WARN_ON_ONCE(mapping_large_folio_support(mapping) =3D=3D 0); -#endif -} - struct address_space *folio_mapping(const struct folio *folio); =20 /** diff --git a/mm/filemap.c b/mm/filemap.c index 2b933a1da9bd..4248e7cdecf3 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -189,7 +189,6 @@ static void filemap_unaccount_folio(struct address_spac= e *mapping, lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, -nr); } else if (folio_test_pmd_mappable(folio)) { lruvec_stat_mod_folio(folio, NR_FILE_THPS, -nr); - filemap_nr_thps_dec(mapping); } if (test_bit(AS_KERNEL_FILE, &folio->mapping->flags)) mod_node_page_state(folio_pgdat(folio), diff --git a/mm/huge_memory.c b/mm/huge_memory.c index b2a6060b3c20..c7873dbdc470 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3833,7 +3833,6 @@ static int __folio_freeze_and_split_unmapped(struct f= olio *folio, unsigned int n } else { lruvec_stat_mod_folio(folio, NR_FILE_THPS, -nr); - filemap_nr_thps_dec(mapping); } } } diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 45b12ffb1550..8004ab8de6d2 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2104,20 +2104,8 @@ static enum scan_result collapse_file(struct mm_stru= ct *mm, unsigned long addr, goto xa_unlocked; } =20 - if (!is_shmem) { - filemap_nr_thps_inc(mapping); - /* - * Paired with the fence in do_dentry_open() -> get_write_access() - * to ensure i_writecount is up to date and the update to nr_thps - * is visible. Ensures the page cache will be truncated if the - * file is opened writable. - */ - smp_mb(); - if (inode_is_open_for_write(mapping->host)) { - result =3D SCAN_FAIL; - filemap_nr_thps_dec(mapping); - } - } + if (!is_shmem && inode_is_open_for_write(mapping->host)) + result =3D SCAN_FAIL; =20 xa_locked: xas_unlock_irq(&xas); @@ -2296,19 +2284,6 @@ static enum scan_result collapse_file(struct mm_stru= ct *mm, unsigned long addr, folio_putback_lru(folio); folio_put(folio); } - /* - * Undo the updates of filemap_nr_thps_inc for non-SHMEM - * file only. This undo is not needed unless failure is - * due to SCAN_COPY_MC. - */ - if (!is_shmem && result =3D=3D SCAN_COPY_MC) { - filemap_nr_thps_dec(mapping); - /* - * Paired with the fence in do_dentry_open() -> get_write_access() - * to ensure the update to nr_thps is visible. - */ - smp_mb(); - } =20 new_folio->mapping =3D NULL; =20 --=20 2.43.0