From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 458A13603C0; Sun, 19 Jul 2026 11:05:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784459115; cv=none; b=QqOmrDp16JsjEwt0GJwoOiBaIhki0wEZ9s2A2H1qHDWTyCVHJ1GcWIyeMI/U4GhY50eWdxcaJa0KNpLWM0p8KePPl1cA4eeKTksPbiWKoycOvxm+4mHe6sU6MITJ3VikIPbErzI4Ut8kCJ3xiaRz4J5Z5Dz8MEFlML2UqW25zck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784459115; c=relaxed/simple; bh=HzRnLzQRcq6hoUnenYNLfSMWsgm5yUI6AWR0vu8yZ8Y=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=RwVxp4ht37kurmSBdJgpJ32eN/AC2kHVx7wp9N/o5ESiIW+2nsV0iFVQLJ64nsCwtBBuSSq1uveJtBP3e7SrSmSRcet7KJdKyE3KnLG6a0sExRQRA3dSg+nBygC0vJwzuAI0F8QfvpzjaolT6scz/upP3WxykS3HLNY2vM2H77g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Su16s4mT; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Su16s4mT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B8DB1F000E9; Sun, 19 Jul 2026 11:05:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784459113; bh=oP7vvMFpRDPfDaszczWHJMC//8ZQkAMSWY/7STXwx7o=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=Su16s4mTynnplWcQruvVVYbvld7eRzHkbURZzBHSj2xTkiU9iq2sPWJZoPND10ZLG 36ASwTIStnSQqILBTijSq2p3WaLp1LRwzd7RzDPDNQr2D33sFBZrb2NkEGjHTfnx6H 9xuRIF/oY0Z5qqryVfDz3J731cXrZ87ozDT1NhoVGHqIUJ8EiACk7Mni0P4EMdC6Qy 4JlAVn/xBnbgb1rzZX3HDm19PB8g3dVjFk+Nah2IwgxSU0Hcci+HlWs4WTUGlpVZPN /7uE/OkxCI0jt8t3j+l6xDlLD7fC2LLQa36l9fdQRTNlAzWqCC8XCzfTdOvadtPRi7 eLRRrteKdhnyA== From: sashiko-bot@kernel.org Subject: Re: [PATCH v2 4/7] md/raid1: don't use write-behind for P2PDMA bios Reply-To: sashiko-reviews@lists.linux.dev To: "Mykola Marzhan" Cc: yukuai@fygo.io, linux-pci@vger.kernel.org, linux-raid@vger.kernel.org In-Reply-To: <20260719105327.864949-5-mykola@meshstor.io> References: <20260719105327.864949-1-mykola@meshstor.io> <20260719105327.864949-5-mykola@meshstor.io> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sun, 19 Jul 2026 11:05:13 +0000 Message-Id: <20260719110513.9B8DB1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > alloc_behind_master_bio() copies the bio's data with bio_copy_data(), > a CPU copy. P2PDMA pages are peer device (BAR) memory; generic code > must not assume CPU load/store access to them is safe or fast on > every architecture, and bouncing peer memory through the CPU defeats > the point of a peer-to-peer transfer. >=20 > Skip write-behind for P2PDMA bios: they are written directly to all > members, including write-mostly ones. Ordering against write-behind > I/O in flight to overlapping sectors is preserved: the non-behind > clone path serializes on CollisionCheck rdevs (see the preceding > fix), which covers these bios like any other write that bypasses > write-behind. >=20 > Fixes: 02666132403a ("md: propagate BLK_FEAT_PCI_P2PDMA from member devic= es to RAID device") > Assisted-by: Claude:claude-opus-4-8 > Signed-off-by: Mykola Marzhan Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260719105327.8649= 49-1-mykola@meshstor.io?part=3D4