From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79B44C4338F for ; Wed, 28 Jul 2021 09:35:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50A9760FD8 for ; Wed, 28 Jul 2021 09:35:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235384AbhG1Jfc (ORCPT ); Wed, 28 Jul 2021 05:35:32 -0400 Received: from proxmox-new.maurer-it.com ([94.136.29.106]:11082 "EHLO proxmox-new.maurer-it.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231256AbhG1Jfc (ORCPT ); Wed, 28 Jul 2021 05:35:32 -0400 X-Greylist: delayed 515 seconds by postgrey-1.27 at vger.kernel.org; Wed, 28 Jul 2021 05:35:31 EDT Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id B905640F58; Wed, 28 Jul 2021 11:26:54 +0200 (CEST) Subject: Re: [PATCH 2/2] io_uring: don't block level reissue off completion path To: Jens Axboe , io-uring@vger.kernel.org Cc: stable@vger.kernel.org References: <20210727165811.284510-1-axboe@kernel.dk> <20210727165811.284510-3-axboe@kernel.dk> From: Fabian Ebner Message-ID: <70b7b7b2-c6d5-8088-ee76-c1ffc53ac2a3@proxmox.com> Date: Wed, 28 Jul 2021 11:26:48 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210727165811.284510-3-axboe@kernel.dk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Am 27.07.21 um 18:58 schrieb Jens Axboe: > Some setups, like SCSI, can throw spurious -EAGAIN off the softirq > completion path. Normally we expect this to happen inline as part > of submission, but apparently SCSI has a weird corner case where it > can happen as part of normal completions. > > This should be solved by having the -EAGAIN bubble back up the stack > as part of submission, but previous attempts at this failed and we're > not just quite there yet. Instead we currently use REQ_F_REISSUE to > handle this case. > > For now, catch it in io_rw_should_reissue() and prevent a reissue > from a bogus path. > > Cc: stable@vger.kernel.org > Reported-by: Fabian Ebner > Signed-off-by: Jens Axboe > --- > fs/io_uring.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 6ba101cd4661..83f67d33bf67 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -2447,6 +2447,12 @@ static bool io_rw_should_reissue(struct io_kiocb *req) > */ > if (percpu_ref_is_dying(&ctx->refs)) > return false; > + /* > + * Play it safe and assume not safe to re-import and reissue if we're > + * not in the original thread group (or in task context). > + */ > + if (!same_thread_group(req->task, current) || !in_task()) > + return false; > return true; > } > #else > Hi, thank you for the fix! This does indeed prevent the panic (with 5.11.22) and hang (with 5.13.3) with my problematic workload. Best Regards, Fabian