From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f49.google.com (mail-oa1-f49.google.com [209.85.160.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 84BF2344058 for ; Wed, 17 Dec 2025 14:36:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765982193; cv=none; b=TgE7f9ZIhogVu43+xXHLoGWyDBdxBPx8vCRD47+P18SGTuXum5/XXP87ZSyGn1Wcma6zrf5Lw/wSjvL+N/RBDeo0q6VZvTSPQSenroHm9n/wF1a5jPqHyBGPtqAX30rZ+VxrR6W23M4qDyWZdGZnBm7ZOU0wraoaR6sC+0Y0PYI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765982193; c=relaxed/simple; bh=94ycW3lgyjdSORnztV6EHe59jRLi4KhAVL3am8BaQ+0=; h=From:To:Cc:In-Reply-To:References:Subject:Message-Id:Date: MIME-Version:Content-Type; b=VPTsrhGabGL+5TT4RAFyDr5tppdaZxOsARQk1ivd1JrvPO6I2NI5yOH70F6kY/vE3vDP8WDHJ18xzrZm8igHMPgSA1qYX7MI6Nv5R0kNy5/R01gj5JJtNP83b6KrCSVMGsccimhgGXI347m3ty3ozxM3jjwOUXLYkOSC3a8zzHI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk; spf=pass smtp.mailfrom=kernel.dk; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b=Eckikt03; arc=none smtp.client-ip=209.85.160.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kernel.dk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b="Eckikt03" Received: by mail-oa1-f49.google.com with SMTP id 586e51a60fabf-3f4f9ea26aaso4375055fac.0 for ; Wed, 17 Dec 2025 06:36:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20230601.gappssmtp.com; s=20230601; t=1765982181; x=1766586981; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:date:message-id:subject :references:in-reply-to:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Ld6T8UtWouDR3xKdn1TrtGxRAlGZmoqNloVepqhEues=; b=Eckikt03DpREGa7a2kyvI0Gr8Ynn1TZERqKAHFlkmDP3gRwvszuVwLoM2G2P+dae3G vCnnoUFwVmjp0fMEasy0JVdIxQ6IYlgBbvTgYlw2c8XtUdgH4cN4yzfghoGne4Yt5cHV Ev+n6ic9eIMRvNKcggHxXAZ0P97B+sE0NSPBhcl7q+1EvZfBAD5ANCkSbsQB9UdQ4afO 7vuWLoJ6cHmFxW6FRutyOUgXCFDoyq6D+aAfb+kGklk/2KM4UfAxtWk9s3mxMz8XhzcM XytPgySzVzFaQ1Sn84nXs5BV/MZGZtdN1QUUqSA7fwjrXMYxVCqVzoVcenCq8f83+atB Ty9A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765982181; x=1766586981; h=content-transfer-encoding:mime-version:date:message-id:subject :references:in-reply-to:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=Ld6T8UtWouDR3xKdn1TrtGxRAlGZmoqNloVepqhEues=; b=hk+SlFMbJ7iVXlzo0/c3g3q0Q5+SZUra+UZ4UmRnpOb2hGiaV1LD7XCRusQaqp8TOn LUAJC4B4aRaBJfNpDdmuHKb8kc5SlvjH50VPPzxFxgAvoRKuxnsYkaUB0ALTHy1Guiw3 t6rDZzuplNTLJC63htGecCasUsv5CqQQL1fcLvP1PKBHkPjHu5tnXcai0Fm9P5hORcPd 2lKM1+naLTWMd9mbdFDQAZkiIKyB5g0gd3/VOnY/F5ruSarHUHC7qwzDrdGfNf+r2Iu5 rLTbKhXSxW5RM9Zt/Tum9s0RSwm99oRR4S/TMRWtx7960jYMtY0R9+J+0ht+IuMLuMpa 1NqA== X-Forwarded-Encrypted: i=1; AJvYcCXmMERu57L+jbmHBiuC4PIVC04cIT10xYPWabGBr85KmgDnzD5akfYY/dn/B6UJT7OYehTrtry22MWIlOs=@vger.kernel.org X-Gm-Message-State: AOJu0Yw/7rGeU5bZn38QqNUND42B9VlOTh2wSzgEgjsk80AsGBs+K5Tr f78kVyGSZVd2YsKZWWmSS3H5Ah5efy5G+p3lYobNFs7zoIKn0IyFx6Qf5q/gU8frJlA= X-Gm-Gg: AY/fxX72aynKBGzXlj15X+OrLi1YxMvdJH4ycCnMiHkmJrq0d7ZpmH+y/O95X8i2Mfa JkWho87nuZUkqCbBRfqA6D1sXscDP7rx1t1NVfEzj/nWFkthpDHj7+KS8yGt2hQe2V1NFu5Y6rs Jg3Y6OYidZpRbEt+LRGLay0kBZiQ4nWNx2Z5XvVYqVIdVJWf7E24dzSx8Je3knAA4bgUNCgDwpb 1pOFWIotjn0tqi6KHtERU90W5CN+kZu/xJ9dBCkv/oeqWL9tk82Adxt9fULG45yYj+DgpBmcELL zupm113N/B8B9Zl7dwB+eT46e7t8jE/E+UHpIreE0Yq0J2lYKSAUvHPD7cjoFhIgrJTdwBQGKk9 myDb298XcblQKXj8bisMwu/vDBuW4ETAMoqS0dc3Eju25tzZ8ACIn82d9aQ+IwcXCH6XvxflZ91 FfEiw= X-Google-Smtp-Source: AGHT+IFYryRICuUu40ewcf2L22LVn1aCV+6k+Edu2uvw+mN9u3Yo7M43WfwfxSDL8NCOVtBigpLq5g== X-Received: by 2002:a05:6820:1b07:b0:659:9a49:901a with SMTP id 006d021491bc7-65b4529c619mr7323246eaf.71.1765982181125; Wed, 17 Dec 2025 06:36:21 -0800 (PST) Received: from [127.0.0.1] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-65b867ae255sm2141700eaf.1.2025.12.17.06.36.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 06:36:17 -0800 (PST) From: Jens Axboe To: csander@purestorage.com, huang-jl Cc: io-uring@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ming.lei@redhat.com In-Reply-To: <20251217062632.113983-1-huang-jl@deepseek.com> References: <20251217062632.113983-1-huang-jl@deepseek.com> Subject: Re: [PATCH v2] io_uring: fix nr_segs calculation in io_import_kbuf Message-Id: <176598217718.7122.7321090942996172863.b4-ty@kernel.dk> Date: Wed, 17 Dec 2025 07:36:17 -0700 Precedence: bulk X-Mailing-List: linux-kernel@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-Mailer: b4 0.14.3 On Wed, 17 Dec 2025 14:26:32 +0800, huang-jl wrote: > io_import_kbuf() calculates nr_segs incorrectly when iov_offset is > non-zero after iov_iter_advance(). It doesn't account for the partial > consumption of the first bvec. > > The problem comes when meet the following conditions: > 1. Use UBLK_F_AUTO_BUF_REG feature of ublk. > 2. The kernel will help to register the buffer, into the io uring. > 3. Later, the ublk server try to send IO request using the registered > buffer in the io uring, to read/write to fuse-based filesystem, with > O_DIRECT. > > [...] Applied, thanks! [1/1] io_uring: fix nr_segs calculation in io_import_kbuf commit: 114ea9bbaf7681c4d363e13b7916e6fef6a4963a Best regards, -- Jens Axboe