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=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 3104EC433E1 for ; Sat, 22 Aug 2020 16:30:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0E2C420738 for ; Sat, 22 Aug 2020 16:30:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598113842; bh=T6qxWCdnx7yQWW539dupam4L5Gst5+melCCWJ5BWJIY=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=d1Zhr6WKnJ++75+5vvaIsSna2aYTJ1CEGfkt6bJ9XGDSlFpmvPCfwEbyzwslTEH0Q a8rVyQI9nuj1PTn0E1C8nFRJhEvGhfs/jKcqG4p65/lIm3y1aJQ29z+AxMFI9tFrjm NF/wXmoMvtL1R9YB5i66ZkNDGULEaVUrEwvgWBAU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728521AbgHVQak (ORCPT ); Sat, 22 Aug 2020 12:30:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728513AbgHVQai (ORCPT ); Sat, 22 Aug 2020 12:30:38 -0400 Received: from mail-il1-x141.google.com (mail-il1-x141.google.com [IPv6:2607:f8b0:4864:20::141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7C34C061573 for ; Sat, 22 Aug 2020 09:30:37 -0700 (PDT) Received: by mail-il1-x141.google.com with SMTP id f75so3617568ilh.3 for ; Sat, 22 Aug 2020 09:30:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=uJj5TK3G7MVm+VYBo5lqKGxPSR8A7s2q6tf5foLdof4=; b=S75MaG1vCkClffX2X3FaZOKUXo+pwYdtuLZc6ncCVkuF7BdPWJ13mqOgHl3iDTyGt1 ULyvbN3EPIMD26sIkvGpT8s0smqQ/4ky4VwJSoaH6CJcbOaDUgu2OfdWm1M77634TEeu mtteCanJgrirygtSakPKLI0b7KFcBW3CF8Ew0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=uJj5TK3G7MVm+VYBo5lqKGxPSR8A7s2q6tf5foLdof4=; b=WDhiL2hyElq/9HyBhvIcJQ0IHiqn/Wz0dyBeg05cuhpyynOzzIaSkCvZetSCsfsZGD gkRNYvN8Ut2rhoVgYPs+B7TiUzxiQ0Qjz9idZqWYN7htG2WRD+gjZBT/sF9hREMmcGdH 8Vv2JvfdX6bHyd2H2tmjI6DrpMlL2t20HzW+7aQltPgkDeskhCcQs1vA38y0glsA07QH /H8xG1jLqPeNZoGQpwQe68ev+msE9bx6rh/eY5164uMkOEEHDdm9UOiDAtLQWQ8Qh2j0 k4s7wvwYzNPY90sDbcanE4uwoyu7hKxMr19qAQ5dUbbQxMYHLh8zbPx23Lwkz+0ZDPQf sytg== X-Gm-Message-State: AOAM530LHaVFIb3kn2Abkyjk68Pwgy4I5cfUfN9quwxFAAl9TWmp2/4/ Ycm+LkrG308NYgfhdQdotAsT+kKWKG6YmD+cYND4nw== X-Google-Smtp-Source: ABdhPJzQYZ/z0hpLgPOSs8sPRZM4W0ZXC5611Jmeb9rkOBbf1q+BiabPCpGfL1YZ9sPLlsdfHTEd3UhZNYkdnb/4Hqg= X-Received: by 2002:a92:da49:: with SMTP id p9mr7196041ilq.233.1598113835616; Sat, 22 Aug 2020 09:30:35 -0700 (PDT) MIME-Version: 1.0 References: <00000000000045b3fe05abcced2f@google.com> <20200807053148.GA10409@redhat.com> <20200810192941.GA16925@redhat.com> <7ba35ca4-13c1-caa3-0655-50d328304462@i-love.sakura.ne.jp> In-Reply-To: <7ba35ca4-13c1-caa3-0655-50d328304462@i-love.sakura.ne.jp> From: Linus Torvalds Date: Sat, 22 Aug 2020 09:30:25 -0700 Message-ID: Subject: Re: [RFC PATCH] pipe: make pipe_release() deferrable. To: Tetsuo Handa Cc: Al Viro , Andrea Arcangeli , syzbot , syzkaller-bugs , linux-fsdevel , Linux Kernel Mailing List , Dmitry Vyukov , Andrew Morton Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 21, 2020 at 9:35 PM Tetsuo Handa wrote: > > Therefore, this patch tries to convert __pipe_lock() in pipe_release() to > killable, by deferring to a workqueue context when __pipe_lock_killable() > failed. I don't think this is an improvement. If somebody can delay the pipe unlock arbitrarily, you've now turned a user-visible blocking operation into blocking a workqueue instead. So it's still there, and now it possibly is much worse and blocks system_wq instead. Linus