From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 23C67218840 for ; Thu, 5 Dec 2024 13:12:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733404364; cv=none; b=GzG0+QQ6YNahpUUIQV0ShTNzjLyZBoj5Js+fp/b/zHp94ffCajomEEvjQiXN63uRbtMcVMSB9HbszGRLaspcmWp3I+oGJt6xEQYK9jpgVo2psQSt3atUpI6TMoEpj7MgpAq/rr3V0qPZ4YGJesNseUp0fI5G26vYaMHofAAB7XA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733404364; c=relaxed/simple; bh=zSAmUMikM9qyp2hwJeOchmUecjS3KRaaw3qokCCQvIE=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=S554j4rcJBiJ5Lf3h8s1kkTXlLYSshteMVqBSaeV50daE/Ukxa9XP3Qdn+XRp1FhnKVd/pSAq7XB4RDWd/d4dlwF7XWFzNqQy33Ne8P03ko+qv0eMDbWI49YV7ESIlHGqhEmV2nWJDXNYcmd48lUASRp51EwHpBTZDp9mVl8zfQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=UL/ChKsS; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=cas2wXUH; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="UL/ChKsS"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="cas2wXUH" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1733404360; 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: in-reply-to:in-reply-to:references:references; bh=wwZJaavYAts7b0KEi30IQ/HqLbi/kQzf73ZNMNUGUa8=; b=UL/ChKsSlIFDaowyD88bIOBwT+Gh7cKIruRWusTdh8WcwJvDYXLPC+bmTJMTfU0VxvOK5W y/WPH0mndhOqc6c3UMiNtpmcfgrpivDopfQ9ReqkTXP1g890p4RRK9QZVxi9m+WSMGnNa8 odGSaSc1YmNzm41mQTOkpTFq7HZSkDCN5T2MKcL6tSh/C7QAw3YA7giAxCLdMh47GoLyKv 0dD776A1AdVbrogwpYFrQjaoTyVD/1aYSxsUXmoNYcPy/9Zsi0aQxF279yOkZnG7RtYAsW moyZuLSWmHJPL5DZyY3jcFE3+L9DWHgt6G9uKX5wrgoI+YOZ2NJjaEsINzNDyg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1733404360; 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: in-reply-to:in-reply-to:references:references; bh=wwZJaavYAts7b0KEi30IQ/HqLbi/kQzf73ZNMNUGUa8=; b=cas2wXUHxwQknTqhaVHU4H4YBmOALDsseHoMBnfBZZw3FHLLkuYr2E7Jn1o3giUav+ykEm 9EB7t9yd5ZTJxIDQ== To: Waiman Long , Waiman Long , Ingo Molnar , Borislav Petkov , Dave Hansen , Peter Zijlstra Cc: x86@kernel.org, linux-kernel@vger.kernel.org, "H. Peter Anvin" Subject: Re: [PATCH v2] x86/nmi: Add an emergency handler in nmi_desc & use it in nmi_shootdown_cpus() In-Reply-To: <9765a61a-e832-4491-af02-97b8736411ef@redhat.com> References: <20241203150732.182065-1-longman@redhat.com> <87h67jsif0.ffs@tglx> <7aa93137-4b5e-474f-a99c-47acffdf71a3@redhat.com> <87zflbqqar.ffs@tglx> <59b254dc-acf6-4114-b6b4-a7ae517bfa06@redhat.com> <9765a61a-e832-4491-af02-97b8736411ef@redhat.com> Date: Thu, 05 Dec 2024 14:12:20 +0100 Message-ID: <87r06mqnnv.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Wed, Dec 04 2024 at 23:01, Waiman Long wrote: > On 12/4/24 2:28 PM, Waiman Long wrote: >>> I'm not convinced that this should be used as a general mechanism. It's >>> for emergency situations and that's where it stops. If the thing >>> returns, it's a bug IMO. >> >> OK, I am fine with that. I will put a BUG_ON() after that in the next >> version. > > Actually, crash_nmi_callback() can return in the case of the crashing > CPUs, though all the other CPUs will not return once called. So I > believe the current form is correct. I will update the comment to > reflect that. Why would you continue servicing the NMI on a CPU which just crashed?