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 63508370D7C; Mon, 11 May 2026 11:58:43 +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=1778500723; cv=none; b=f8OgH0hMbTTH2rgpIW5JxKFz241DYRv/VCQ5vnXmv7m/PPFk+XPRGT0sFNFSdHyLpDmGivoi4wYUedNobEMLy9r9rrL4yooi1b1BYiW1flkaOttqOjOkxNkfMHSUCLK+4G5XY5/fO4LQ99g5rJegf0VH6OE8mm02ul0cftSm0ZQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778500723; c=relaxed/simple; bh=vzbSctaA6rDHZ0Wddj3/2akgAPlm5EoTM+A96NJEf+I=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=HhBbBp+1F9nnu17NvljGuXCrU2a+tKacbQQd62199QDfpCpDtUUpCjm88TOzVXdH3qMyvokYAYiZAonUF9qX1foJvuB8Y8QGbCl7MTf/v7vXd/yY98L0WAbaFGGQErw8UgTyAzv+o6cZrNauASC6taMulRXL2aWBV1ImyHx43BI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BcDbZEb2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BcDbZEb2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 409DCC2BCB0; Mon, 11 May 2026 11:58:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778500723; bh=vzbSctaA6rDHZ0Wddj3/2akgAPlm5EoTM+A96NJEf+I=; h=From:Subject:Date:To:Cc:From; b=BcDbZEb2314PR0jE6xKZa8a7PwI8Sj64t/sUXhQtUxdx/8F4KucT1wTtx1OXD/KYo clvEB1Z2+9We80sSiwNPlN0E3S9fneZys1Y+vtTn96QSHGMfBxiRtpmJq+OQub2lF9 grKKyeXEJRVPMBJyEEv9l6c6mWourhcVOadOfK/hcD1Oq3M9i1poKGHuwKU0kW5jQu FxGucI91mimy440r4oNCrM9zgJVyIAbdg37FNbCCJFJAYych3ZJ2nRFe2nxsh7aA22 XCmmqv13a7pGycgvUOLREiB+iiYqXeZgTS9QMAo2eYWuEG78FM3bwcsYk97XlC7www 1SbU9xGF/t+3g== From: Jeff Layton Subject: [PATCH v7 0/3] mm: improve write performance with RWF_DONTCACHE Date: Mon, 11 May 2026 07:58:26 -0400 Message-Id: <20260511-dontcache-v7-0-2848ddce8090@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAAAAAAAC/23Qy07EMAwF0F8ZZU1QXnZaVvwHYpGHM41ALUpHF WjUf8czGzIqyxv5XFu5ipVapVW8nK6i0VbXuswc/NNJpCnMZ5I1cxZGGVROaZmX+ZJCmkjCoDW V7CkUK3j+q1Gp3/eut3fOU10vS/u5V2/69vpfy6alkrqAd1hCdD68flCb6fN5aWdxq9lMT4eeG qajGzIlTR4wHqjtqMGeWqZ+pGh9DiM4f6Duj8LjwY4pZCDMyesU7YFCT11PganTyhIMkVcft2J PoafIFNGhHRTkjI/ftO/7L5G6tbDKAQAA X-Change-ID: 20260401-dontcache-5811efd7eaf3 To: Alexander Viro , Christian Brauner , Jan Kara , "Matthew Wilcox (Oracle)" , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Mike Snitzer , Jens Axboe , Ritesh Harjani , Chuck Lever Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, Jeff Layton X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=3839; i=jlayton@kernel.org; h=from:subject:message-id; bh=vzbSctaA6rDHZ0Wddj3/2akgAPlm5EoTM+A96NJEf+I=; b=owEBbQKS/ZANAwAKAQAOaEEZVoIVAcsmYgBqAcRpYaCPni00FFvtxSVSnnmM/vy+6GNFafFcn CWVlf9dxH+JAjMEAAEKAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCagHEaQAKCRAADmhBGVaC FQqhD/40SlOmg1H8CUFB1b8oL5Qk5tCaRTKWcDOv5SEo7KZsR3xzUhkGO33w454UNXg2fQYXIri ulXqUf1WuS4/ONecC4Bsf+e7+nMGXriBWYxpwn54azH3jbir0rLR6q9oTPVGH41l8lDw1KgbbSr AKsK7ifiGLEHZWosRMUQz0jsdAv0JRWocf1Vwcp3xnwYARHXnlAid5vLojTqWmQPXrLASStTI3c LhoJU1TThSCHqNOefg6rMsTUy8S0uHQLuRx5Zq9WKnDNXqSn8gzCIQh+yH/fkeovMygWRRVy4hB HKLGXKrOjqs3WFHexoU1PF3I+BiOh6orFB4RGYFjsVdJCkl2/ATCVCGYBX6VSnVlhcHJHjcf5Aw zrPeB0fzg4vtOYRzYmR21SAghIfAbbIZ8B8wCBKIr0g0QMeojFP3/hwy1G8ERHlxr1DF5Zax/Hl bVtg+9lM6Wk2Hot+aLOll8CJczXm7KU5WBcL8YtprH0iC33G3R9EHj0JbbXTI7NCp9GAJqyNJr8 eUKzUxpZshuymphkO90a1Ti13tNWQ7Qu/I6dwc7MkdQKL6F4xfwLPl5m+9GE0oXFreT5U1Oh8vv bAWDnj8o7CJio4O3qS0Ahf08LIFpQr4+2wAQJ4PMiU43vdYPuZtJIMf+ok6z4U1DFvZyZbqybIN 11sjAss4sqWxSLQ== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 This patch series is intended to improve write performance with RWF_DONTCACHE. This version fixes additional stat accounting issues found during review: integer promotion on 32-bit, cgroup writeback domain migration, folio split flag preservation, and a UAF that could occur in filemap_dontcache_kick_writeback(). Because there are substantive changes in this set, I've dropped the R-b's. Please resend them if you're OK with this version. Christian, please consider these for v7.2. Thanks, Signed-off-by: Jeff Layton --- Changes in v7: - Fix integer promotion bug on 32-bit: store folio_nr_pages() in signed long before negating, matching existing patterns in page-writeback.c - Transfer WB_DONTCACHE_DIRTY in inode_do_switch_wbs() alongside WB_RECLAIMABLE so the stat migrates with the inode on cgroup wb switch - Preserve PG_dropbehind in __split_folio_to_order() so tail folios retain the flag and are properly accounted when cleaned - Take reference to wb around unlocked_inode_to_wb_end() to avoid UAF - Link to v6: https://lore.kernel.org/r/20260505-dontcache-v6-0-66463805dd6a@kernel.org Changes in v6: - Use atomic folio_test_clear_dropbehind() in __filemap_get_folio_mpol() to prevent double-decrement of WB_DONTCACHE_DIRTY by concurrent readers - Add mapping_can_writeback() guard before decrementing WB_DONTCACHE_DIRTY in __filemap_get_folio_mpol() to match the increment path - Use wb_stat_sum() instead of wb_stat() in wb_check_start_dontcache() so small writes below the percpu batch threshold are visible to the flusher - Use test_and_clear_bit for WB_start_dontcache before starting writeback to prevent lost wakeups from concurrent DONTCACHE writers - Move wb_wakeup() outside the unlocked_inode_to_wb_begin/end section in filemap_dontcache_kick_writeback() to avoid spin_unlock_irq() re-enabling interrupts while the i_pages xa_lock is held during cgroup writeback switch - Drop Reviewed-by tags due to substantive changes - Link to v5: https://lore.kernel.org/r/20260504-dontcache-v5-0-4103e58bb377@kernel.org Changes in v5: - Flesh out comment over filemap_dontcache_kick_writeback() - Drop testcases from posting - Link to v4: https://lore.kernel.org/r/20260501-dontcache-v4-0-5d5e6dc71cb3@kernel.org Changes in v4: - Track DONTCACHE dirty pages per bdi_writeback - New benchmark for competing buffered and dontcache writers - New benchmark replicating Jens' original 32 concurrent writer test - Link to v3: https://lore.kernel.org/r/20260426-dontcache-v3-0-79eb37da9547@kernel.org Changes in v3: - Track dirty DONTCACHE pages in the VM - Have flusher write back a proportional number of pages after DONTCACHE write - Link to v2: https://lore.kernel.org/r/20260408-dontcache-v2-0-948dec1e756b@kernel.org Changes in v2: - kick flusher thread instead of initiating writeback inline - add mechanism to run 'perf lock' around the testcases - Link to v1: https://lore.kernel.org/r/20260401-dontcache-v1-0-1f5746fab47a@kernel.org --- Jeff Layton (3): mm: preserve PG_dropbehind flag during folio split mm: track DONTCACHE dirty pages per bdi_writeback mm: kick writeback flusher for IOCB_DONTCACHE with targeted dirty tracking fs/fs-writeback.c | 67 ++++++++++++++++++++++++++++++++++++++++ include/linux/backing-dev-defs.h | 3 ++ include/linux/fs.h | 6 ++-- include/trace/events/writeback.h | 3 +- mm/filemap.c | 15 +++++++-- mm/huge_memory.c | 1 + mm/page-writeback.c | 6 ++++ 7 files changed, 94 insertions(+), 7 deletions(-) --- base-commit: 7e2326f4275c11652e1fdaae11de06159fef1d90 change-id: 20260401-dontcache-5811efd7eaf3 Best regards, -- Jeff Layton