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Wed, 24 Feb 2021 02:36:58 -0800 (PST) Subject: Re: [PATCH] io_uring: don't issue reqs in iopoll mode when ctx is dying From: Pavel Begunkov To: Jens Axboe , Xiaoguang Wang , io-uring@vger.kernel.org Cc: joseph.qi@linux.alibaba.com References: <20210206150006.1945-1-xiaoguang.wang@linux.alibaba.com> <3e3cb8da-d925-7ebd-11a0-f9e145861962@linux.alibaba.com> <754563ed-5b2b-075d-16f8-d980e51102e6@linux.alibaba.com> <215e12a6-1aa7-c56f-1349-bd3828b225f6@kernel.dk> <7f52ca3a-b456-582e-c3db-99d2d028042f@linux.alibaba.com> <6a09434b-f975-cc49-cc6a-a5d369be325b@kernel.dk> <1c3b911c-1013-4fe1-12e3-1a650b0e207f@gmail.com> 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: <60d77979-45ad-7202-2c92-1c2a24a7aea4@gmail.com> Date: Wed, 24 Feb 2021 10:33:06 +0000 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: <1c3b911c-1013-4fe1-12e3-1a650b0e207f@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 24/02/2021 09:59, Pavel Begunkov wrote: > On 24/02/2021 09:46, Pavel Begunkov wrote: >>> Are you sure? We just don't want to reissue it, we need to fail it. >>> Hence if we catch it at reissue time, that should be enough. But I'm >>> open to clue batting :-) >> >> Jens, IOPOLL can happen from a different task, so >> 1) we don't want to grab io_wq_work context from it. As always we can pass it >> through task_work, or should be solved with your io-wq patches. >> >> 2) it happens who knows when in time, so iovec may be gone already -- same >> reasoning why io_[read,write]() copy it before going to io-wq. > > The diff below should solve the second problem by failing them (not tested). > 1) can be left to the io-wq patches. We can even try to init it in io_complete_rw_iopoll() similarly to __io_complete_rw(). The tricky part for me is that "!inline exec" comment, i.e. to distinct io_complete_rw_iopoll() -EAGAIN'ed inline and from IRQ/etc. Jens? diff --git a/fs/io_uring.c b/fs/io_uring.c index bf9ad810c621..413bb4dd0a2f 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2610,8 +2610,11 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events, list_del(&req->inflight_entry); if (READ_ONCE(req->result) == -EAGAIN) { + bool reissue = req->async_data || + !io_op_defs[req->opcode].needs_async_data; + req->iopoll_completed = 0; - if (io_rw_reissue(req)) + if (reissue && io_rw_reissue(req)) continue; } @@ -2829,7 +2832,7 @@ static bool io_resubmit_prep(struct io_kiocb *req) } #endif -static bool io_rw_reissue(struct io_kiocb *req) +static bool io_rw_reissue_prep(struct io_kiocb *req) { #ifdef CONFIG_BLOCK umode_t mode = file_inode(req->file)->i_mode; @@ -2844,13 +2847,21 @@ static bool io_rw_reissue(struct io_kiocb *req) ret = io_sq_thread_acquire_mm_files(req->ctx, req); - if (!ret && io_resubmit_prep(req)) { + if (!ret && io_resubmit_prep(req)) + return true; + req_set_fail_links(req); +#endif + return false; + +} + +static bool io_rw_reissue(struct io_kiocb *req) +{ + if (io_rw_reissue_prep(req)) { refcount_inc(&req->refs); io_queue_async_work(req); return true; } - req_set_fail_links(req); -#endif return false; } @@ -2885,8 +2896,12 @@ static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2) if (kiocb->ki_flags & IOCB_WRITE) kiocb_end_write(req); - if (res != -EAGAIN && res != req->result) + if (req == -EAGAIN) { + if (/* !inline exec || */ !io_rw_reissue_prep(req)) + req_set_fail_links(req); + } else if (res != req->result) { req_set_fail_links(req); + } WRITE_ONCE(req->result, res); /* order with io_poll_complete() checking ->result */ -- Pavel Begunkov