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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88AC6C433EF for ; Thu, 23 Jun 2022 09:31:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229482AbiFWJb6 (ORCPT ); Thu, 23 Jun 2022 05:31:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229645AbiFWJb4 (ORCPT ); Thu, 23 Jun 2022 05:31:56 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7DEE48302; Thu, 23 Jun 2022 02:31:55 -0700 (PDT) Date: Thu, 23 Jun 2022 11:31:51 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1655976713; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rdy+QUhPkvFcFC80rvjevTMJhfdSl1qbxeO2CTdvv58=; b=NEhmq8viQ72FOh+cau9QybpV1lZZv76F0Y0skF4OQ3K33zgzmjPISWBUw8wZ8ejYmmzZtJ Za/VxomJ8D0EbRmyHsp9iIgo5KJtEtw8W01lx6LJFRXY7qpRtQEeftXKQrJEcY8hZzGlao KFURtbeaNG/jIDaSC6pLEds9Sjs2tQ+rHR0NN2Ab4xtI0Y5BCzxPZgxN0ZT2FcYK9XAvq7 gSwZLLW3g90EflW0hduk0fFEQjhbAh7nK+ixMY00pRCxuxyhm4XqHCAREYUSI49F4mfXAT T+c1qZC3PMNYcahuSC2DpV5oXODqczdVooKzp4pXQI/smcHSisXnnjHwclyScw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1655976713; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rdy+QUhPkvFcFC80rvjevTMJhfdSl1qbxeO2CTdvv58=; b=1tpp+G+oSQjiwNGLj9aUmHGzkXlmunN6sB7hmmrXtf56s+eH5ZchYT6PhUcvWW8snWnOb/ i9anyEfJ1+O1mHDQ== From: Sebastian Andrzej Siewior To: Valentin Schneider Cc: linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-rt-users@vger.kernel.org, Eric Biederman , Arnd Bergmann , Petr Mladek , Thomas Gleixner , Juri Lelli , "Luis Claudio R. Goncalves" Subject: Re: [PATCH v2] panic, kexec: Make __crash_kexec() NMI safe Message-ID: References: <20220620111520.1039685-1-vschneid@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <20220620111520.1039685-1-vschneid@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022-06-20 12:15:20 [+0100], Valentin Schneider wrote: > Attempting to get a crash dump out of a debug PREEMPT_RT kernel via an NMI > panic() doesn't work. The cause of that lies in the PREEMPT_RT definition > of mutex_trylock(): >=20 =E2=80=A6 > Fixes: 6ce47fd961fa ("rtmutex: Warn if trylock is called from hard/softir= q context") > Signed-off-by: Valentin Schneider Reviewed-by: Sebastian Andrzej Siewior > --- > v1 -> v2 > ++++++++ >=20 > o Changed from Peterson-like synchronization to simpler atomic_cmpxchg > (Petr) > o Slightly reworded changelog > o Added Fixes: tag. Technically should be up to since kexec can happen > in an NMI, but that isn't such a clear target RT-wise it would be needed for each release. There is also a mutex_unlock() in case an image is missing. This can go via the scheduler if there is a waiter which does not look good with the NMI in the picture. Sebastian 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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CB486C433EF for ; Thu, 23 Jun 2022 09:32:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=3WHGgXiwBbZwWi3ifLGKuXws0p3udyFUtZ4leAyrcXU=; b=N3HUZSqwG28md5 nonnpx3TqT8l0ddXzqhSz5rfaTL670+p0qbMw5wqrft21VAmu8FNFuZ9FBUBnsyfB4Aa3EalAdWg2 +MN6Kuv2HXEzssvOwnywQhnXhd5/r6QVGM52+F3tec+SAkNgbEWqeORJUSI/Pvk5eE1PUItsvzxlI 0XQUkRkbiO41FCEs31PPH/Xz0BP3D7vwHQN+fjC5IdEpiYKvO7lbBJisbxVKyT3+5zQM1D2HL1UFt K/2/I4gZHMoJfmvLADNiAzAEd8/YUdmh1b8V16hgstBIEAf6Dpg5TS7dAWlAk/jUqTTk419WUT4UF Tm/PLav7wcSUMmFsWocg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o4JC7-00EKvh-Kc; Thu, 23 Jun 2022 09:32:11 +0000 Received: from galois.linutronix.de ([2a0a:51c0:0:12e:550::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o4JC1-00EKu2-Pq for kexec@lists.infradead.org; Thu, 23 Jun 2022 09:32:07 +0000 Date: Thu, 23 Jun 2022 11:31:51 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1655976713; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rdy+QUhPkvFcFC80rvjevTMJhfdSl1qbxeO2CTdvv58=; b=NEhmq8viQ72FOh+cau9QybpV1lZZv76F0Y0skF4OQ3K33zgzmjPISWBUw8wZ8ejYmmzZtJ Za/VxomJ8D0EbRmyHsp9iIgo5KJtEtw8W01lx6LJFRXY7qpRtQEeftXKQrJEcY8hZzGlao KFURtbeaNG/jIDaSC6pLEds9Sjs2tQ+rHR0NN2Ab4xtI0Y5BCzxPZgxN0ZT2FcYK9XAvq7 gSwZLLW3g90EflW0hduk0fFEQjhbAh7nK+ixMY00pRCxuxyhm4XqHCAREYUSI49F4mfXAT T+c1qZC3PMNYcahuSC2DpV5oXODqczdVooKzp4pXQI/smcHSisXnnjHwclyScw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1655976713; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rdy+QUhPkvFcFC80rvjevTMJhfdSl1qbxeO2CTdvv58=; b=1tpp+G+oSQjiwNGLj9aUmHGzkXlmunN6sB7hmmrXtf56s+eH5ZchYT6PhUcvWW8snWnOb/ i9anyEfJ1+O1mHDQ== From: Sebastian Andrzej Siewior To: Valentin Schneider Cc: linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-rt-users@vger.kernel.org, Eric Biederman , Arnd Bergmann , Petr Mladek , Thomas Gleixner , Juri Lelli , "Luis Claudio R. Goncalves" Subject: Re: [PATCH v2] panic, kexec: Make __crash_kexec() NMI safe Message-ID: References: <20220620111520.1039685-1-vschneid@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220620111520.1039685-1-vschneid@redhat.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220623_023206_016423_97E83A2D X-CRM114-Status: GOOD ( 10.19 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org T24gMjAyMi0wNi0yMCAxMjoxNToyMCBbKzAxMDBdLCBWYWxlbnRpbiBTY2huZWlkZXIgd3JvdGU6 Cj4gQXR0ZW1wdGluZyB0byBnZXQgYSBjcmFzaCBkdW1wIG91dCBvZiBhIGRlYnVnIFBSRUVNUFRf UlQga2VybmVsIHZpYSBhbiBOTUkKPiBwYW5pYygpIGRvZXNuJ3Qgd29yay4gVGhlIGNhdXNlIG9m IHRoYXQgbGllcyBpbiB0aGUgUFJFRU1QVF9SVCBkZWZpbml0aW9uCj4gb2YgbXV0ZXhfdHJ5bG9j aygpOgo+IArigKYKCj4gRml4ZXM6IDZjZTQ3ZmQ5NjFmYSAoInJ0bXV0ZXg6IFdhcm4gaWYgdHJ5 bG9jayBpcyBjYWxsZWQgZnJvbSBoYXJkL3NvZnRpcnEgY29udGV4dCIpCj4gU2lnbmVkLW9mZi1i eTogVmFsZW50aW4gU2NobmVpZGVyIDx2c2NobmVpZEByZWRoYXQuY29tPgoKUmV2aWV3ZWQtYnk6 IFNlYmFzdGlhbiBBbmRyemVqIFNpZXdpb3IgPGJpZ2Vhc3lAbGludXRyb25peC5kZT4KCj4gLS0t Cj4gdjEgLT4gdjIKPiArKysrKysrKwo+IAo+IG8gQ2hhbmdlZCBmcm9tIFBldGVyc29uLWxpa2Ug c3luY2hyb25pemF0aW9uIHRvIHNpbXBsZXIgYXRvbWljX2NtcHhjaGcKPiAgIChQZXRyKQo+IG8g U2xpZ2h0bHkgcmV3b3JkZWQgY2hhbmdlbG9nCj4gbyBBZGRlZCBGaXhlczogdGFnLiBUZWNobmlj YWxseSBzaG91bGQgYmUgdXAgdG8gc2luY2Uga2V4ZWMgY2FuIGhhcHBlbgo+ICAgaW4gYW4gTk1J LCBidXQgdGhhdCBpc24ndCBzdWNoIGEgY2xlYXIgdGFyZ2V0CgpSVC13aXNlIGl0IHdvdWxkIGJl IG5lZWRlZCBmb3IgZWFjaCByZWxlYXNlLgpUaGVyZSBpcyBhbHNvIGEgbXV0ZXhfdW5sb2NrKCkg aW4gY2FzZSBhbiBpbWFnZSBpcyBtaXNzaW5nLiBUaGlzIGNhbiBnbwp2aWEgdGhlIHNjaGVkdWxl ciBpZiB0aGVyZSBpcyBhIHdhaXRlciB3aGljaCBkb2VzIG5vdCBsb29rIGdvb2Qgd2l0aCB0aGUK Tk1JIGluIHRoZSBwaWN0dXJlLgoKU2ViYXN0aWFuCgpfX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fXwprZXhlYyBtYWlsaW5nIGxpc3QKa2V4ZWNAbGlzdHMuaW5m cmFkZWFkLm9yZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2tl eGVjCg==