From mboxrd@z Thu Jan 1 00:00:00 1970 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C1DF410ED665 for ; Fri, 27 Mar 2026 12:23:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C20E66B0092; Fri, 27 Mar 2026 08:23:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BF8F56B0095; Fri, 27 Mar 2026 08:23:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B359D6B0096; Fri, 27 Mar 2026 08:23:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 9FD726B0092 for ; Fri, 27 Mar 2026 08:23:51 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id EE146E16AE for ; Fri, 27 Mar 2026 12:23:50 +0000 (UTC) X-FDA: 84591759420.07.E04A704 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf25.hostedemail.com (Postfix) with ESMTP id 87F5CA000E for ; Fri, 27 Mar 2026 12:23:49 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=F8g4lx3T; spf=pass (imf25.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774614229; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=x18/5Wyzdm/GZMICwYr/NVdnbQ5iOX9RD5EC5IJ5KpM=; b=7RTliHZ/uZUvGMZE5g5CK8TjgOZNlz4T+9Wa4xtIDunOaHE7shHdwGzHpd4fj4lOD4HQ3j qF+I0wNshJZhK6fDO4LSzeMscQlyTVWM8hRBh75i8rjpclwGxKRkzvX/c7Vw3nGk2mTGVq YtqtvN4LJpHcSQKDz+4jW6vUkne7X6w= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774614229; a=rsa-sha256; cv=none; b=Kogj+sT1pSFAX0RbpMLd84hliufBckzIIaKcUXvovGSOAfLYvhi9LaD2Z7QTP7xfMUodDz gkH9+2InB+n5VakOLaDCLi3i9+fHKL/Lbv2dyIAy/gLDUGAZRPyWD1q8x3XaPgbXP23Mag +Jle2Sd+ue/ymC1EXTdUAEzrOJ59ARU= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=F8g4lx3T; spf=pass (imf25.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 0B2A461344; Fri, 27 Mar 2026 12:23:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 43B8CC2BC87; Fri, 27 Mar 2026 12:23:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774614228; bh=V8sGUJvbBSQZ15CzkQaKkEa1Er8HddnCsDI3BKLTvtU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=F8g4lx3TiflLWf5tCAz6PYcHqfwkdC2OZT6fbVgng80WiGZeUSPvNUYNoJG8K5b1k ctE+Y9mi2tJbXfyDuDYpL+MLulBxdZdLTJ7hf9Gv3NjsRIyv2n3D02pKsxew980YrY 4+aAgDeHNXTwUC9zVA8rD9RTvSfLv0b6MeQipBsM5cx/SVt0thD2DT5zRNOUOiBohx XMc2WXmuFzojQexEc+KdEdDUrkHdVKh24ktJCp5ilaCqdqttDpFSYHjHh2i73tnbQz gfZfOymgqxXaJrXm1saxMePV2fv6gwfSo+frkerGCyGdg58aV7PsrIPFpK3l/AGZwr 7gLG979b4EszA== Date: Fri, 27 Mar 2026 12:23:46 +0000 From: "Lorenzo Stoakes (Oracle)" To: Zi Yan Cc: "Matthew Wilcox (Oracle)" , Song Liu , Chris Mason , David Sterba , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , David Hildenbrand , Baolin Wang , "Liam R. 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: Re: [PATCH v1 03/10] mm: fs: remove filemap_nr_thps*() functions and their users Message-ID: References: <20260327014255.2058916-1-ziy@nvidia.com> <20260327014255.2058916-4-ziy@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260327014255.2058916-4-ziy@nvidia.com> X-Rspamd-Queue-Id: 87F5CA000E X-Stat-Signature: tb4qazrydusmw6mdofik7ytsduwxh1qe X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1774614229-747099 X-HE-Meta: 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 pQA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 26, 2026 at 09:42:48PM -0400, Zi Yan wrote: > 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. Typo: PMD_ORDRE -> PMD_ORDER > > Signed-off-by: Zi Yan This looks obviously-correct since this stuff wouldn't have been invoked for large folio file systems before + they already had to handle it separately, and this function is only tied to CONFIG_READ_ONLY_THP_FOR_FS (+ a quick grep suggests you didn't miss anything), so: 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; > > - /* > - * 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: > 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 struct address_space *mapping) > 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); > > /** > 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_space *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 folio *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_struct *mm, unsigned long addr, > 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); > - } > - } > + if (!is_shmem && inode_is_open_for_write(mapping->host)) > + result = SCAN_FAIL; > > xa_locked: > xas_unlock_irq(&xas); > @@ -2296,19 +2284,6 @@ static enum scan_result collapse_file(struct mm_struct *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 == 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; > > -- > 2.43.0 > Cheers, Lorenzo