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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 739A5C1B0F1 for ; Wed, 20 Jun 2018 01:58:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2FBC0205C9 for ; Wed, 20 Jun 2018 01:58:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pykxUcjy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2FBC0205C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754168AbeFTB6m (ORCPT ); Tue, 19 Jun 2018 21:58:42 -0400 Received: from mail-pg0-f67.google.com ([74.125.83.67]:33553 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752836AbeFTB6j (ORCPT ); Tue, 19 Jun 2018 21:58:39 -0400 Received: by mail-pg0-f67.google.com with SMTP id e11-v6so717687pgq.0; Tue, 19 Jun 2018 18:58:39 -0700 (PDT) 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=Ydd0dgh985AQJdrjnGD2UXBBJc2Ji6+DAGILhnLi4NE=; b=pykxUcjyHyVEP1rhbRmPuIoASOWvL/Dwv6M210pQeusfawo367+E0f6TgRtxNZFfQq KYDJaqeR8Lj8sZOjn6GL5LVZgXu15d6jL3iPlhFzT2LKYyiCNDPzlsfYktg4939B+vvs ZjfTk58CkAYKdFHwb1DJ8K0aLeVBovZgs8nsuSLxdMb8+2YxfhooT86pbAtOY6bRMA+M ZgUQ7Dn+aKZo0CjJLZYPqkpwObXgD9BFCv8bpgLJJqYIKNdi5Gc0cJcegt1UD4gYPtgQ /q3yEdsot5Q47/K/nkttI75NNGX6+6gOdBwZvEZmVv9/Iynq9u0aBhKYqui3zD2HScjn F9bg== 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=Ydd0dgh985AQJdrjnGD2UXBBJc2Ji6+DAGILhnLi4NE=; b=iPoD97XARPPVR5PdnnCFRMOkjf3h3noO6QgNO3YHZdMNcZ661SD4b+vfMvEBdbMAoc oZGMp3O9atnhihHs++mG9xxQX3zD0UO6pO6I9iQsY4deXDdzcKs7Pc1FUyuBgP5deRU4 BDzxF6LcI+sjh5zRbDfyXXbg5Hy091WhfGjJC3XzVaBvg4f4QdZpa2RKHjxL/bM8y8W5 eRjXT5Gm2PRB73gqekOJZPoVEcrW0pPYgQWgKQs40JzSSsCJ0i9aD6Vh19OqOl7TYpm6 1BR2iD7f2BmXP4D13Zny4PKxIrVhBTZNcdOwj8mnU+24PL0syiOek9AlVc1ofv22+L0i hs0Q== X-Gm-Message-State: APt69E2w+fAgcw+wawPC9UkDwnZDin4a5gH89djIxBmE9lc5s3sOYKJ9 tlnwRgzVOgnAwANF1/T4/Ba+HDJ2 X-Google-Smtp-Source: ADUXVKIjhE7PcDDqnUVzACBjMNaTYXETryW8BYF7oyfT0ki1koYBy/NqCgplbgZkLsqmM+cg3WVeTA== X-Received: by 2002:a65:4587:: with SMTP id o7-v6mr16756466pgq.386.1529459919145; Tue, 19 Jun 2018 18:58:39 -0700 (PDT) Received: from localhost ([110.70.59.159]) by smtp.gmail.com with ESMTPSA id y20-v6sm872249pge.46.2018.06.19.18.58.37 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 19 Jun 2018 18:58:37 -0700 (PDT) Date: Wed, 20 Jun 2018 10:58:34 +0900 From: Sergey Senozhatsky To: Steven Rostedt Cc: Sergey Senozhatsky , Petr Mladek , Sergey Senozhatsky , Peter Zijlstra , Tetsuo Handa , linux-kernel@vger.kernel.org, "4 . 13+" Subject: Re: [PATCH] printk/nmi: Prevent deadlock when serializing NMI backtraces Message-ID: <20180620015834.GD650@jagdpanzerIV> References: <20180605124729.3vix5nlkjpjzdljx@pathway.suse.cz> <20180606051029.GA19211@tigerII.localdomain> <20180606103356.GB19211@tigerII.localdomain> <20180608104825.e7xoxteelaxnwx66@pathway.suse.cz> <20180618063738.GC27996@jagdpanzerIV> <20180618093917.qeaatnlqh5if6t3r@pathway.suse.cz> <20180618100718.GA555@jagdpanzerIV> <20180619075219.iq7ztwu43bn4uua7@pathway.suse.cz> <20180619082716.GD405@jagdpanzerIV> <20180619092304.6b6ba390@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180619092304.6b6ba390@gandalf.local.home> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (06/19/18 09:23), Steven Rostedt wrote: > > On (06/19/18 09:52), Petr Mladek wrote: > > > On Mon 2018-06-18 19:07:18, Sergey Senozhatsky wrote: > > > > On (06/18/18 11:39), Petr Mladek wrote: > > > > [..] > > > > > > > > Hmm. Can't answer right now :) > > > > > > Please, let me know what name you would like ;-) > > > > :) Wow, it's hard. Maybe we can derive some bits from the ftrace_dump() > > function name? Dunno... Does printk_dump_nmi_enter() sound terrible? > > > > Maybe Steven has some opinions on this? > > > > What exactly is the question? Which one of these you'd prefer to see in ftrace_dump(): - printk_nmi_direct_enter() / printk_nmi_direct_exit() - printk_chatty_nmi_enter() / printk_chatty_nmi_exit() - printk_large_nmi_enter() / printk_large_nmi_exit() - printk_dump_nmi_enter() / printk_dump_nmi_exit() > Also, from a previous email in this thread, if you have to risk > interleaved output to solve a deadlock, then just do that. Yep. -ss