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Sat, 19 Dec 2020 18:00:48 -0800 (PST) To: Jens Axboe , Josef Cc: Norman Maurer , Dmitry Kadashev , 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> 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== Subject: Re: "Cannot allocate memory" on ring creation (not RLIMIT_MEMLOCK) Message-ID: Date: Sun, 20 Dec 2020 01:57:28 +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: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org 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. Josef, can you test the patch below instead? Following Jens' idea it cancels more aggressively when a task is killed or exits. It's based on [1] but would probably apply fine to for-next. [1] git://git.kernel.dk/linux-block branch io_uring-5.11, commit dd20166236953c8cd14f4c668bf972af32f0c6be diff --git a/fs/io_uring.c b/fs/io_uring.c index f3690dfdd564..3a98e6dd71c0 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -8919,8 +8919,6 @@ void __io_uring_files_cancel(struct files_struct *files) struct io_ring_ctx *ctx = file->private_data; io_uring_cancel_task_requests(ctx, files); - if (files) - io_uring_del_task_file(file); } atomic_dec(&tctx->in_idle); @@ -8960,6 +8958,8 @@ static s64 tctx_inflight(struct io_uring_task *tctx) void __io_uring_task_cancel(void) { struct io_uring_task *tctx = current->io_uring; + struct file *file; + unsigned long index; DEFINE_WAIT(wait); s64 inflight; @@ -8986,6 +8986,9 @@ void __io_uring_task_cancel(void) finish_wait(&tctx->wait, &wait); atomic_dec(&tctx->in_idle); + + xa_for_each(&tctx->xa, index, file) + io_uring_del_task_file(file); } static int io_uring_flush(struct file *file, void *data) diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h index 35b2d845704d..54925c74aa88 100644 --- a/include/linux/io_uring.h +++ b/include/linux/io_uring.h @@ -48,7 +48,7 @@ static inline void io_uring_task_cancel(void) static inline void io_uring_files_cancel(struct files_struct *files) { if (current->io_uring && !xa_empty(¤t->io_uring->xa)) - __io_uring_files_cancel(files); + __io_uring_task_cancel(); } static inline void io_uring_free(struct task_struct *tsk) { -- Pavel Begunkov