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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 6AEA0C43215 for ; Thu, 21 Nov 2019 01:05:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 428A220730 for ; Thu, 21 Nov 2019 01:05:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="CAUd8kFf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726573AbfKUBFc (ORCPT ); Wed, 20 Nov 2019 20:05:32 -0500 Received: from mail-pl1-f195.google.com ([209.85.214.195]:44892 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726202AbfKUBFc (ORCPT ); Wed, 20 Nov 2019 20:05:32 -0500 Received: by mail-pl1-f195.google.com with SMTP id az9so688530plb.11; Wed, 20 Nov 2019 17:05:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=+xan1UFVEC5bpc84JCNLbsM7TcNqUcHB/vTfYJqMW5Y=; b=CAUd8kFfzFjdlwIAqIpwfueKhe+Ro/GYclcICHkgUpZxyRwF35oQLu832eK4hDNQR/ QhQMxXBmwliCO+TOhJ9+8Kj5sHrYqKEw50kytv9PxzrSq9Du0jXbhaAmgjzLC665vp6+ f8LLezB+8AmzONND8zPgBxGQ9Atu8WGE8sv1mhAmdhnPjDDaAZ/Z3fnHic9UxKC4OwKf vMgkmpOTUpTDKijoSGuxemJRhJQO++KHE62QJwzt8xGroqoUq9LOcTETxN1QlEAh8EU4 ZI3yalo6niby9R7U3yqCPLJ1uOCjBJepnJTzgapdH8sgLFDKZSZfua+Q66q62BLq04K1 qh1Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=+xan1UFVEC5bpc84JCNLbsM7TcNqUcHB/vTfYJqMW5Y=; b=Hvc1hNlJEuvbT9aouX7dnLBo3tKCYWZpVVGnD1Va80CNJEHb45WvG/RrjX05fpY3XA pi6Sucq8eHWK/VmMhZRzKNUzhvapeMSzGySU1Mq/cXXfIrentF/2noecmg1OpM23tn/9 LVXzUR80yH6MVErGvlQIxON/grf6ayScjQQC+smTxD9ZuJHGZtx592z9xECt4+7jDhaM eMgNlc4EtGnU44qy3HqVFZqXpyP2RoA9M4BFsZfIREDAEJjT5WvBXYer0GsTI8ZbVVHy t2zzcYxFuCy1lgzTIGT8gj+n5eRY0UoHt69CNbOAskMpBRs/gQy3BilHeTwKRAzqwBqU L/vA== X-Gm-Message-State: APjAAAUeJH6a36+yGzJgWPCLBOIDwsL89xVxgM2G7yJ1X1PBLcHACx5U aq/B+VHnB/pPa8tT66+Gpww= X-Google-Smtp-Source: APXvYqwIOQvxYDL6qtI/37Fvl6/4sgevqF9opKFXOr+M5OHVMpi1YJPqWJ2EFY+hfzBjN928hEHTDA== X-Received: by 2002:a17:902:8d81:: with SMTP id v1mr5815296plo.289.1574298331187; Wed, 20 Nov 2019 17:05:31 -0800 (PST) Received: from localhost ([2401:fa00:8f:203:250d:e71d:5a0a:9afe]) by smtp.gmail.com with ESMTPSA id m6sm427110pgl.42.2019.11.20.17.05.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Nov 2019 17:05:30 -0800 (PST) Date: Thu, 21 Nov 2019 10:05:27 +0900 From: Sergey Senozhatsky To: Petr Mladek Cc: Sergey Senozhatsky , Sergey Senozhatsky , Qian Cai , Steven Rostedt , Michal Hocko , Eric Dumazet , davem@davemloft.net, netdev@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net/skbuff: silence warnings under memory pressure Message-ID: <20191121010527.GB191121@google.com> References: <1567599263.5576.72.camel@lca.pw> <20190904144850.GA8296@tigerII.localdomain> <1567629737.5576.87.camel@lca.pw> <20190905113208.GA521@jagdpanzerIV> <1573751570.5937.122.camel@lca.pw> <20191118152738.az364dczadskgimc@pathway.suse.cz> <20191119004119.GC208047@google.com> <20191119094134.6hzbjc7l5ite6bpg@pathway.suse.cz> <20191120013005.GA3191@tigerII.localdomain> <20191120161334.p63723g4jyk6k7p3@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191120161334.p63723g4jyk6k7p3@pathway.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On (19/11/20 17:13), Petr Mladek wrote: [..] > It is the first time that I hear about problem caused by the > irq_work(). But we deal with deadlocks caused by wake_up() for years. > It would be like replacing a lightly dripping tap with a heavily > dripping one. > > I see reports with WARN() from scheduler code from time to time. > I would get reports about silent death instead. Just curious, how many of those WARN() come under rq lock or pi_lock? // this is real question > RT guys are going to make printk() fully lockless. It would be > really great achievement. irq_work is lockless. While wake_up() > is not. > > There must be a better way how to break the infinite loop caused > by the irq_work. A lockless wake_up() would do :) -ss