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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 95813C433DF for ; Sat, 22 Aug 2020 12:33:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E65C207DF for ; Sat, 22 Aug 2020 12:33:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="nKgiiGbk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728018AbgHVMd1 (ORCPT ); Sat, 22 Aug 2020 08:33:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727975AbgHVMd0 (ORCPT ); Sat, 22 Aug 2020 08:33:26 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3C1EC061573 for ; Sat, 22 Aug 2020 05:33:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=kebkrhfhu6FPNViCpaO1wfA5wFtK+FeFG3araNR8KPY=; b=nKgiiGbkv1l/FNuGk5sC/nTGC8 Ba33e00rjGn5WJrhiUMLnb1YaOCdORtni4a2Lgi+QSVXXylHlKiM/WwiZUBIiAK7YM6B2jnp/EmtJ vw+FZr3SqKAINwoSc/qnGT+0y82lihEsBoH5AUREochGeGYKt/SxJ+FEvRRAGeyNQLq3munwv0v7K GwMp8grQRydiPeJNlAhDg9KwmdpCOXHAfpe2Tqr6fb8jaku6jO5QVuCguSuk6kJ7e0sXyz8ApO/OI 6rJfCepWL//v075Fz0Dxdlnc+05m+HZ9soBSYkOE/HEWbedIC1d+RaBUuTfhqG/BhRWTcVfqpAiL3 DKLQqOsg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1k9Shb-0002C5-4A; Sat, 22 Aug 2020 12:32:55 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 60D143003E1; Sat, 22 Aug 2020 14:32:52 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 4578A2363BF90; Sat, 22 Aug 2020 14:32:52 +0200 (CEST) Date: Sat, 22 Aug 2020 14:32:52 +0200 From: peterz@infradead.org To: Steven Rostedt Cc: Andrew Morton , Joerg Vehlow , Thomas Gleixner , Sebastian Andrzej Siewior , Huang Ying , linux-kernel@vger.kernel.org, Joerg Vehlow , dave@stgolabs.net Subject: Re: [BUG RT] dump-capture kernel not executed for panic in interrupt context Message-ID: <20200822123252.GQ1362448@hirez.programming.kicks-ass.net> References: <2c243f59-6d10-7abb-bab4-e7b1796cd54f@jv-coder.de> <20200528084614.0c949e8d@gandalf.local.home> <20200727163655.8c94c8e245637b62311f5053@linux-foundation.org> <20200821110848.6c3183d1@oasis.local.home> <20200821134753.9547695c9b782275be3c95b5@linux-foundation.org> <20200821170334.73b52fdd@oasis.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200821170334.73b52fdd@oasis.local.home> 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 05:03:34PM -0400, Steven Rostedt wrote: > > Sigh. Is it too hard to make mutex_trylock() usable from interrupt > > context? > > > That's a question for Thomas and Peter Z. You should really know that too, the TL;DR answer is it's fundamentally buggered, can't work. The problem is that RT relies on being able to PI boost the mutex owner. ISTR we had a thread about all this last year or so, let me see if I can find that. Here goes: https://lkml.kernel.org/r/20191218135047.GS2844@hirez.programming.kicks-ass.net Kexec even gets mentioned: https://lkml.kernel.org/r/20191219090535.GV2844@hirez.programming.kicks-ass.net