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Mon, 21 Dec 2020 07:39:44 -0800 (PST) Subject: Re: "Cannot allocate memory" on ring creation (not RLIMIT_MEMLOCK) To: Dmitry Kadashev Cc: Jens Axboe , Josef , Norman Maurer , io-uring References: <4dc9c74b-249d-117c-debf-4bb9e0df2988@kernel.dk> <2B352D6C-4CA2-4B09-8751-D7BB8159072D@googlemail.com> <0fe708e2-086b-94a8-def4-e4ebd6e0b709@kernel.dk> <614f8422-3e0e-25b9-4cc2-4f1c07705ab0@kernel.dk> <986c85af-bb77-60d4-8739-49b662554157@gmail.com> <2e968c77-912d-6ae1-7000-5e34eb978ab5@gmail.com> 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: <91f7f69c-266d-5d02-85c4-31cd1b82c753@gmail.com> Date: Mon, 21 Dec 2020 15:36:23 +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: 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 21/12/2020 11:00, Dmitry Kadashev wrote: > On Mon, Dec 21, 2020 at 5:35 PM Dmitry Kadashev wrote: >> >> On Sun, Dec 20, 2020 at 7:59 AM Pavel Begunkov wrote: >>> >>> On 20/12/2020 00:25, Jens Axboe wrote: >>>> On 12/19/20 4:42 PM, Pavel Begunkov wrote: >>>>> On 19/12/2020 23:13, Jens Axboe wrote: >>>>>> On 12/19/20 2:54 PM, Jens Axboe wrote: >>>>>>> On 12/19/20 1:51 PM, Josef wrote: >>>>>>>>> And even more so, it's IOSQE_ASYNC on the IORING_OP_READ on an eventfd >>>>>>>>> file descriptor. You probably don't want/mean to do that as it's >>>>>>>>> pollable, I guess it's done because you just set it on all reads for the >>>>>>>>> test? >>>>>>>> >>>>>>>> yes exactly, eventfd fd is blocking, so it actually makes no sense to >>>>>>>> use IOSQE_ASYNC >>>>>>> >>>>>>> Right, and it's pollable too. >>>>>>> >>>>>>>> I just tested eventfd without the IOSQE_ASYNC flag, it seems to work >>>>>>>> in my tests, thanks a lot :) >>>>>>>> >>>>>>>>> In any case, it should of course work. This is the leftover trace when >>>>>>>>> we should be exiting, but an io-wq worker is still trying to get data >>>>>>>>> from the eventfd: >>>>>>>> >>>>>>>> interesting, btw what kind of tool do you use for kernel debugging? >>>>>>> >>>>>>> Just poking at it and thinking about it, no hidden magic I'm afraid... >>>>>> >>>>>> Josef, can you try with this added? Looks bigger than it is, most of it >>>>>> is just moving one function below another. >>>>> >>>>> Hmm, which kernel revision are you poking? Seems it doesn't match >>>>> io_uring-5.10, and for 5.11 io_uring_cancel_files() is never called with >>>>> NULL files. >>>>> >>>>> if (!files) >>>>> __io_uring_cancel_task_requests(ctx, task); >>>>> else >>>>> io_uring_cancel_files(ctx, task, files); >>>> >>>> Yeah, I think I messed up. If files == NULL, then the task is going away. >>>> So we should cancel all requests that match 'task', not just ones that >>>> match task && files. >>>> >>>> Not sure I have much more time to look into this before next week, but >>>> something like that. >>>> >>>> The problem case is the async worker being queued, long before the task >>>> is killed and the contexts go away. But from exit_files(), we're only >>>> concerned with canceling if we have inflight. Doesn't look right to me. >>> >>> In theory all that should be killed in io_ring_ctx_wait_and_kill(), >>> of course that's if the ring itself is closed. >>> >>> Guys, do you share rings between processes? Explicitly like sending >>> io_uring fd over a socket, or implicitly e.g. sharing fd tables >>> (threads), or cloning with copying fd tables (and so taking a ref >>> to a ring). >> >> We do not share rings between processes. Our rings are accessible from different >> threads (under locks), but nothing fancy. >> >>> In other words, if you kill all your io_uring applications, does it >>> go back to normal? >> >> I'm pretty sure it does not, the only fix is to reboot the box. But I'll find an >> affected box and double check just in case. > > So, I've just tried stopping everything that uses io-uring. No io_wq* processes > remained: > > $ ps ax | grep wq > 9 ? I< 0:00 [mm_percpu_wq] > 243 ? I< 0:00 [tpm_dev_wq] > 246 ? I< 0:00 [devfreq_wq] > 27922 pts/4 S+ 0:00 grep --colour=auto wq > $ > > But not a single ring (with size 1024) can be created afterwards anyway. > > Apparently the problem netty hit and this one are different? Yep, looks like it -- Pavel Begunkov