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=-2.2 required=3.0 tests=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 BDACFC432C3 for ; Thu, 21 Nov 2019 09:15:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96AA720748 for ; Thu, 21 Nov 2019 09:15:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727301AbfKUJPX (ORCPT ); Thu, 21 Nov 2019 04:15:23 -0500 Received: from mx2.suse.de ([195.135.220.15]:44446 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726132AbfKUJPX (ORCPT ); Thu, 21 Nov 2019 04:15:23 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 92B8CB11E; Thu, 21 Nov 2019 09:15:20 +0000 (UTC) Date: Thu, 21 Nov 2019 10:15:18 +0100 From: Petr Mladek To: Sergey Senozhatsky Cc: 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: <20191121091518.vcohlxzsri2gv4p3@pathway.suse.cz> References: <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> <20191121010527.GB191121@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191121010527.GB191121@google.com> User-Agent: NeoMutt/20170912 (1.9.0) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 2019-11-21 10:05:27, Sergey Senozhatsky wrote: > 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 I guess that all SCHED_WARN_ON() would stop working. I am not 100% sure but I think that all WARN_ON*() in set_task_cpu(), finish_task_switch(), migrate_tasks() are affected. I have seen many reports with the WARN() from native_smp_send_reschedule() about offline CPU. Best Regards, Petr