From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=193.142.43.55 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793780458; b=ZMNooxk/m+wTvEUczyVMAuA9RQb4SOAMBoYfVbcX8i0kC1ok6Zhf7zxhyhY9TbxXWY23 fm+W4JQfrJInJ7G1t0m2EP7rgU8SYvV+RIBlvlJpcwwS3cusoQ0u6cgEj7RyLjJ7PJiFW xrT7LkRZvwJGA0yZp9CHEdUgmBWoepW0XiF+9KJbZ4mXqseZR41CGcFyeIixkP+4I6/g8 N374/masXp0tfJ6TkPw/zTWgn/HE9sz4sSEhTCVVL8M8xbBmV2hOlzcZioY5qSBGG5Ow6 oPKKBswdZILw4CN9MVXeandlF1NbUUjv6RSMS79tIZDwXZ0gs6ZpYYISiECXXSpmWsA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793780458; h=DMARC-Filter:From:DKIM-Signature:DKIM-Signature:To:Cc:Subject: In-Reply-To:References:Date:Message-ID:MIME-Version:Content-Type; bh=lkIJPTF+rng+xUHUM1yRH1n6HfCu3188jQjR6cCCrnk=; b=VHb08p7YB3l64d/Br3G5y254h1MFqoGOyzbc2RFU7QtKQ4DAsL/ejjSUdwdYK6FBAUYZ qbyzDriTRKp0ovCwQzGcBnDJjM0gmWH4SvizfZqra6GfOtIuu2c/4jeD5BoJuC5+zR7mO v0j++i0o/alRXiX8rriTq/dg/brAkjnZh4HYTWnPG0xhD3B962bebP9o3341UBLdzuLdP byEb6rSbwxFKMW/WbKftwCzxq2PaVXWti/rkMO+C5vZxOWG0T+8HFjMcDhV9a8YluRCvr zjcfFtB1BHW6BBHgWz5Un2MpAYT3Vz/ng0GW3PbQWw9mvUWcJLcAnAn04mY+t8I3mrw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=ayzstiGI; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=0k+cdqhk; arc=none smtp.remote-ip=193.142.43.55 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5B8DF606A328 for ; Wed, 4 Nov 2026 08:20:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 5B8DF606A328 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, unprotected) header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=ayzstiGI; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=0k+cdqhk From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1793780456; 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=lkIJPTF+rng+xUHUM1yRH1n6HfCu3188jQjR6cCCrnk=; b=ayzstiGIpHElycU48fFZd4+l/X9fW2BRInWe3HqQDotl7y2lM36wDVG8eo9kMeRbdssafZ eNzOjeLjses+Uot5rMmMHny4PMuIkXPNKs9rv7Mc10wUW8S/cEL5NNgtWlWxeK1ghdJXUe 7PsSQbIWPwNxcfQYqrT205ik4eYpa5kukFVOot82And9zEb0ERimCbyYSumRvMAla4B8RH 3FXAoVaDcUEIsZD+gNz3J7XNKa/opEJyHE6t128QHpX1+aNjlvbUm9NoPv3aTc9F66Pacq ekxfUL/RbDq5plGQ5da7/sS6Z52rAFCQ9rxn4GEO0HNZyDmUaSrl5Onv9t+Hgg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1793780456; 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=lkIJPTF+rng+xUHUM1yRH1n6HfCu3188jQjR6cCCrnk=; b=0k+cdqhkA+nUcKXRkIDB51+uCSF1htbzJYUalY6So/iOiac6eulsW4ceyBDXDbG8jiF0SP 3KGlL8JUMAW/y9BQ== To: Breno Leitao , Andrew Morton , Alexander Potapenko , Andrey Ryabinin Cc: Marco Elver , Andrey Konovalov , Dmitry Vyukov , Vlastimil Babka , Petr Mladek , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, Breno Leitao , Toshiyuki Sato , Greg Kroah-Hartman Subject: Re: [PATCH] stackdepot: don't WARN when the depot runs out of pools In-Reply-To: <20261103-stackdepot-full-warn-v1-1-41f1fc651b64@debian.org> References: <20261103-stackdepot-full-warn-v1-1-41f1fc651b64@debian.org> Date: Wed, 04 Nov 2026 09:26:55 +0106 Message-ID: <87wlqtxb14.fsf@jogness.linutronix.de> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain On 2026-11-03, Breno Leitao wrote: > That deferral only applies to legacy consoles. ON nbcon WARN() puts the > CPU in emergency mode, and in emergency mode printk() flushes all > pending records to the nbcon consoles from the calling context. Yes. WARN() is supposed to be for critical issues. > With > a slow serial console (pl011 is an nbcon console) and a backlog of > messages, that flush can outlast the hard lockup threshold, all of it > with pool_lock held and IRQs disabled, while every other CPU that needs > to save a new stack trace spins on pool_lock. Several serial drivers call touch_nmi_watchdog() (such as 8250) to avoid this issue. Perhaps the pl011 should be doing this as well (at least for the write_atomic() path)? > Running out of depot space is an expected condition under heavy debug > load, not a kernel bug, so report it with pr_warn_once() instead. This is the key takeaway. WARN() is not appropriate here. Reviewed-by: John Ogness