From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 314C13AB29D for ; Mon, 18 May 2026 22:21:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779142917; cv=none; b=k1ex+mHiwGzcGhgajbSgAP2Y1Y3IJItgaG7jhW25BFhwp7BvHBeT83dG7EPMubRsm3ZAYOQHAgU26CZJqO+sVqeN8s4IiIXEh556GRgdxtz3lobUgVa/mbqMJ3o8MXm3XUkk19T54EllZPsCfu8f0RPCotkH14R+39uaNjHB+os= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779142917; c=relaxed/simple; bh=t5kQqKk55rmzfA7VHm5NXYycy57AhPJuOdJuFADYTrE=; h=Date:To:From:Subject:Message-Id; b=pwQyZy0zcjXp0aMyP43bfR8LToFpgHmq9TB1y9jXwr4sn+VP5VD/wj2Xhyy3KE00Msu8achACcMgDg45yQfFbOXGRGczbIQOCk4E0m+m6etMU/00egz0rNIWf+CcYGLxpg5jjx+G+Y72GMPPiFzfI2lTrpJHUbX13IUuW/FnSF0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=EENAFV8T; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="EENAFV8T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD044C2BCB7; Mon, 18 May 2026 22:21:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1779142916; bh=t5kQqKk55rmzfA7VHm5NXYycy57AhPJuOdJuFADYTrE=; h=Date:To:From:Subject:From; b=EENAFV8TEjZNxBEMPQ6Hx0QIwYVJGZ1NWyfjwJj4qTp8XfDMH0WPhiYZGCdz27FS6 2TxUUmJzRouUQn8aV4VmQtrzpRAt0b3WBOdr5yQz2CSQ8pH2Bp36BpZp072oHMfnyA HZAycv0tj39CcFXWS3kOzR/FQzpj3Rhz+m8XHZn8= Date: Mon, 18 May 2026 15:21:56 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-fs-remove-filemap_nr_thps-functions-and-their-users.patch added to mm-unstable branch Message-Id: <20260518222156.BD044C2BCB7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: fs: remove filemap_nr_thps*() functions and their users has been added to the -mm mm-unstable branch. Its filename is mm-fs-remove-filemap_nr_thps-functions-and-their-users.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fs-remove-filemap_nr_thps-functions-and-their-users.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Zi Yan Subject: mm: fs: remove filemap_nr_thps*() functions and their users Date: Sun, 17 May 2026 09:54:08 -0400 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_ORDER. READ_ONLY_THP_FOR_FS was using mapping->nr_thps, inode->i_writecount, and smp_mb() to prevent writes to a read-only THP and collapsing writable folios into a THP. In collapse_file(), mapping->nr_thps is increased, then smp_mb(), and if inode->i_writecount > 0, collapse is stopped, while do_dentry_open() first increases inode->i_writecount, then a full memory fence, and if mapping->nr_thps > 0, all read-only THPs are truncated. Now this mechanism can be removed along with READ_ONLY_THP_FOR_FS code, since a dirty folio check has been added after try_to_unmap() in collapse_file() to prevent dirty folios from being collapsed as clean. Link: https://lore.kernel.org/20260517135416.1434539-7-ziy@nvidia.com Signed-off-by: Zi Yan Reviewed-by: Matthew Wilcox (Oracle) Acked-by: David Hildenbrand (Arm) Reviewed-by: Baolin Wang Reviewed-by: Lance Yang Cc: Al Viro Cc: Barry Song Cc: Chris Mason Cc: Christian Brauner Cc: David Sterba Cc: Dev Jain Cc: Jan Kara Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Nico Pache Cc: Ryan Roberts Cc: Shuah Khan Cc: Song Liu Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- fs/open.c | 27 --------------------------- include/linux/pagemap.h | 29 ----------------------------- mm/filemap.c | 1 - mm/huge_memory.c | 1 - mm/khugepaged.c | 28 ---------------------------- 5 files changed, 86 deletions(-) --- a/fs/open.c~mm-fs-remove-filemap_nr_thps-functions-and-their-users +++ a/fs/open.c @@ -968,33 +968,6 @@ static int do_dentry_open(struct file *f if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT)) return -EINVAL; - /* - * 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 = 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; cleanup_all: --- a/include/linux/pagemap.h~mm-fs-remove-filemap_nr_thps-functions-and-their-users +++ a/include/linux/pagemap.h @@ -546,35 +546,6 @@ static inline size_t mapping_max_folio_s return PAGE_SIZE << mapping_max_folio_order(mapping); } -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) == 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) == 0); -#endif -} - struct address_space *folio_mapping(const struct folio *folio); /** --- a/mm/filemap.c~mm-fs-remove-filemap_nr_thps-functions-and-their-users +++ a/mm/filemap.c @@ -189,7 +189,6 @@ static void filemap_unaccount_folio(stru 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), --- a/mm/huge_memory.c~mm-fs-remove-filemap_nr_thps-functions-and-their-users +++ a/mm/huge_memory.c @@ -3951,7 +3951,6 @@ static int __folio_freeze_and_split_unma } else { lruvec_stat_mod_folio(folio, NR_FILE_THPS, -nr); - filemap_nr_thps_dec(mapping); } } } --- a/mm/khugepaged.c~mm-fs-remove-filemap_nr_thps-functions-and-their-users +++ a/mm/khugepaged.c @@ -2477,21 +2477,6 @@ out_unlock: goto xa_unlocked; } - 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 = SCAN_FAIL; - filemap_nr_thps_dec(mapping); - } - } - xa_locked: xas_unlock_irq(&xas); xa_unlocked: @@ -2669,19 +2654,6 @@ rollback: 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 == 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(); - } new_folio->mapping = NULL; _ Patches currently in -mm which might be from ziy@nvidia.com are mm-khugepaged-remove-read_only_thp_for_fs-check.patch mm-khugepaged-add-folio-dirty-check-after-try_to_unmap.patch mm-huge_memory-remove-read_only_thp_for_fs-from-file_thp_enabled.patch mm-khugepaged-remove-read_only_thp_for_fs-check-in-hugepage_enabled.patch mm-remove-read_only_thp_for_fs-kconfig-option.patch mm-fs-remove-filemap_nr_thps-functions-and-their-users.patch fs-remove-nr_thps-from-struct-address_space.patch mm-huge_memory-remove-folio-split-check-for-read_only_thp_for_fs.patch mm-truncate-use-folio_split-in-truncate_inode_partial_folio.patch fs-btrfs-remove-a-comment-referring-to-read_only_thp_for_fs.patch selftests-mm-remove-read_only_thp_for_fs-in-khugepaged.patch selftests-mm-remove-read_only_thp_for_fs-code-from-guard-regions.patch mm-khugepaged-enable-clean-pagecache-folio-collapse-for-writable-files.patch selftests-mm-add-writable-file-collapse-tests-for-khugepaged.patch