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=-5.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 A8D6CC433E0 for ; Sat, 20 Feb 2021 03:41:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7868664EE1 for ; Sat, 20 Feb 2021 03:41:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229934AbhBTDla (ORCPT ); Fri, 19 Feb 2021 22:41:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229765AbhBTDla (ORCPT ); Fri, 19 Feb 2021 22:41:30 -0500 Received: from mail-pl1-x636.google.com (mail-pl1-x636.google.com [IPv6:2607:f8b0:4864:20::636]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D662BC061786 for ; Fri, 19 Feb 2021 19:40:49 -0800 (PST) Received: by mail-pl1-x636.google.com with SMTP id e9so4444366plh.3 for ; Fri, 19 Feb 2021 19:40:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=6jt3gbYErGCzVqXwrw0j1MDwi/V+DbPwPhbFBvdatBQ=; b=QI5McYwyk5IxzUIodb0NsvibxF0lPDxPVuLZalTge8OpQMDC12Pf3nhM9tq8NanqF9 jSZzBKl2HVechPMkcqtaco8yMZ2iphW88WZX1sxIoQkag2lbuDMKzhamw5ifULchy/ik 2kK3NkUDTFgJS2Yp5XSVqbsI6KDvG+GH9CYx/gGCMcclTUfC8fbpI9rwcgDMY6DpApZy QYg28l0P1Slc3M/6OxQA2BOzn8vepmjawRxaHVfC9n1NlkShkiX3rEQmxa/FmVeZbv9I m+kHaebKsh6s95fZkJM3wE1Q00ONWXhDmcsTcsjEYBNTBiWiwvbLpKBY1vSqr6TcTIst CElg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=6jt3gbYErGCzVqXwrw0j1MDwi/V+DbPwPhbFBvdatBQ=; b=SHLAGU7OW8IsyR4hBOqwZt/NyUPfhiB78LhbE2xtH9yQfIuP2YKeDmzTB070GrsK8X fSqIwnMoKG/ETqunF5UjAHfCGmEe9Ir3E2MV1ZlYC73p5m3YSX/O3tejg3mX0WAlv2MQ 9wGp0JBjLAZaHho6acGJA/CYLCHSUvhSEzwHclPSF2WPm8Vv7+p4h+hO7GhU9+upBJ20 W0xnXY1Y9nFHZKoSeRGsZKS/v3F1z6BMU/VOMgR7HVFulqBgjN0sbQjZb4ODNKbPqDeQ boTLFFqr9itU2My+ll5bJ+kOK8hUR9Vvc9rvrEriy/p8f94AsIC7MeUAmerg/CwfZDJ2 exzw== X-Gm-Message-State: AOAM533lt2OA8je0KZIGK5f5JxzBVVV8piAIhILnsSkUglEVOJ37YotG TYEA5UloHJt7Mntxcd2VPir9Bw== X-Google-Smtp-Source: ABdhPJyRfz7ie9+qo2jZoSEjRvqrzJTBXcAo3gAKbhmJKB0GRGOVP/0SqXAnUkUV+BF9iixr+xriEg== X-Received: by 2002:a17:90b:224f:: with SMTP id hk15mr12194864pjb.31.1613792449316; Fri, 19 Feb 2021 19:40:49 -0800 (PST) Received: from [192.168.1.134] ([66.219.217.173]) by smtp.gmail.com with ESMTPSA id y23sm10837002pfo.50.2021.02.19.19.40.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 19 Feb 2021 19:40:48 -0800 (PST) Subject: Re: [PATCH 1/2] io_uring: wait potential ->release() on resurrect To: Pavel Begunkov , io-uring@vger.kernel.org Cc: stable@vger.kernel.org References: <75e1c94aff46a5bc409f50e50207f4d9a01ff9a0.1613785076.git.asml.silence@gmail.com> From: Jens Axboe Message-ID: <914848f1-f30e-4d3a-ab40-9db78e1321b7@kernel.dk> Date: Fri, 19 Feb 2021 20:40:46 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <75e1c94aff46a5bc409f50e50207f4d9a01ff9a0.1613785076.git.asml.silence@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 2/19/21 6:39 PM, Pavel Begunkov wrote: > There is a short window where percpu_refs are already turned zero, but > we try to do resurrect(). Play nicer and wait for all users to leave RCU > section. We need to do something better than synchronize_rcu() here, that can take a long time on a loaded box. I'll try and think about this one. -- Jens Axboe