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Thu, 06 Feb 2020 12:01:21 -0800 (PST) Received: from [192.168.43.191] ([109.126.145.62]) by smtp.gmail.com with ESMTPSA id cm24sm38600edb.59.2020.02.06.12.01.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 Feb 2020 12:01:20 -0800 (PST) Subject: Re: [PATCH] io_uring: fix deferred req iovec leak To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org References: <6e7207b6-95c4-4287-5872-fb05abf60e88@kernel.dk> From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Message-ID: <4f7f61d3-b3f9-43db-ad32-ee502dc06c8b@gmail.com> Date: Thu, 6 Feb 2020 23:00:41 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <6e7207b6-95c4-4287-5872-fb05abf60e88@kernel.dk> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="lNrp9eOjsQH0WL1w9H3roSOwYDJAm3gBL" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --lNrp9eOjsQH0WL1w9H3roSOwYDJAm3gBL Content-Type: multipart/mixed; boundary="kAZLiVDR40gLonqaP1CHysU7AraRdk9LJ"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <4f7f61d3-b3f9-43db-ad32-ee502dc06c8b@gmail.com> Subject: Re: [PATCH] io_uring: fix deferred req iovec leak References: <6e7207b6-95c4-4287-5872-fb05abf60e88@kernel.dk> In-Reply-To: <6e7207b6-95c4-4287-5872-fb05abf60e88@kernel.dk> --kAZLiVDR40gLonqaP1CHysU7AraRdk9LJ Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 06/02/2020 22:56, Jens Axboe wrote: > On 2/6/20 10:16 AM, Pavel Begunkov wrote: >> On 06/02/2020 20:04, Pavel Begunkov wrote: >>> On 06/02/2020 19:51, Pavel Begunkov wrote: >>>> After defer, a request will be prepared, that includes allocating io= vec >>>> if needed, and then submitted through io_wq_submit_work() but not cu= stom >>>> handler (e.g. io_rw_async()/io_sendrecv_async()). However, it'll lea= k >>>> iovec, as it's in io-wq and the code goes as follows: >>>> >>>> io_read() { >>>> if (!io_wq_current_is_worker()) >>>> kfree(iovec); >>>> } >>>> >>>> Put all deallocation logic in io_{read,write,send,recv}(), which wil= l >>>> leave the memory, if going async with -EAGAIN. >>>> >>> Interestingly, this will fail badly if it returns -EAGAIN from io-wq = context. >>> Apparently, I need to do v2. >>> >> Or not... >> Jens, can you please explain what's with the -EAGAIN handling in >> io_wq_submit_work()? Checking the code, it seems neither of >> read/write/recv/send can return -EAGAIN from async context (i.e. >> force_nonblock=3Dfalse). Are there other ops that can do it? >=20 > Nobody should return -EAGAIN with force_nonblock=3Dfalse, they should > end the io_kiocb inline for that. >=20 If so for those 4, then the patch should work well. --=20 Pavel Begunkov --kAZLiVDR40gLonqaP1CHysU7AraRdk9LJ-- --lNrp9eOjsQH0WL1w9H3roSOwYDJAm3gBL Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl48cGkACgkQWt5b1Glr +6UlOQ/8C07MHg79xSZfDRsCvoXFmBYemEBszWwSW7uZ/h/+/I9fxcjygxisu/Oa cLxxFD3sukWyBu0zN+dCKoGp7RRQZP+jZK3CppAGntxsE5ogZuRsRCHgh2U61YDp oiDdxdnx2D2YrW6kZEij/0rw6FaaUGSljiQPVk8vzwwVjdH34unC+1+2POdM2z+d Nn4V+cbdd74GYUdMMD0ExtDSapZ7xmWj6gskO5sIs7rJmkzrczf/8fduzGv12Gzu oxAU8WuiN7VESnU8kKtUQw7FN+Y1v6KczeNzCg2KGdOvrov4FXHulHaLUdOvW4Pr F0zWQymRmx3G6/DVq+cl8x9cDrEpj9OpTDIi3vmSNk3q/F2VF8ygBlhKCPz2s0WI 9fy9ul/dLiQNHDqEF1Am93RTuJ6GS8qp9f8yvA55Oogz1g+E+21FxB9V7XsD5qVm BjnwEvejlWWq3R9CTprILZacamYIP7vzk0yjkYDEotpar1x4uDKwaXq/+4KFVXVE 612Ic2UX4HJUsZU50aqj/BCetuRkWx+35C7xL4adL7VxDCRpRKuWmjlWEHY1AsxF icS2VAH7Kjn0zt5RDcgVNpMt22XJSG814MIpRgUd+X51ngWCmAavPt5HndxjgXQR Jm8L2YY/Ppo+aXwtOYYQXqfgs3aS6HPor9xkcaCOLm9DOC/GLBM= =wZkY -----END PGP SIGNATURE----- --lNrp9eOjsQH0WL1w9H3roSOwYDJAm3gBL--