From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f68.google.com (mail-wm1-f68.google.com [209.85.128.68]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5B6F03EBF15 for ; Tue, 3 Feb 2026 17:24:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.68 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770139464; cv=none; b=IzADvEhPWunQsCr0l3NuyXPjTOqy86eSckG6CE8xCm89LmRHOJt6iX/621poBUTC5zi1iUsqP5D4C9cGztyAFGn7zdO5DLArZ1GrZtUWkl6j243CYxWZwz6qBjAsBznO+5gJwnO58jWaJImhcTbmdxmPHFLqRZQD52JL/rxhgBc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770139464; c=relaxed/simple; bh=HiQ6YXMpdlAnTPtAG9c0NFE/qlsBZf7eAK37MyklQbw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=rQnTAdxoxY4drfcXN7LlmPErV7Vb3qjmQ9iJJJAT+zKpyhvD+9qoN3datP+B6qCCyoeo/KX5Aeb6WahFxMiymtgbWEPQe0yn/SQCQEpO3hWTpCSpVIc2pwsQWjfpb9BIWCD1j54hSkHvbEp2QQhYaHKVSQBAX+EkpXI+uDrK4eM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=D2ME+g5w; arc=none smtp.client-ip=209.85.128.68 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="D2ME+g5w" Received: by mail-wm1-f68.google.com with SMTP id 5b1f17b1804b1-4806cc07ce7so59356755e9.1 for ; Tue, 03 Feb 2026 09:24:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1770139461; x=1770744261; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=r0v0GLllQmL/KRq8U4ajLDOV1RqqjTzamcBduCfw0/Q=; b=D2ME+g5wJ483DLMvLZgBt0HuJ+1kvQkKv7Ey/yQhb7ABhhZ8mW3bHcxDMEar7N9WTd gO7E1dtknMBFaFbuelJbpA9Dyv4RfzyuiP8i+XTx3Q6c+5m7LnuTlnZYg5oDp2U/UzxZ GMJ2l6GguFZ/A2pFksv5d0/zTOKfwiLEbwt67T7FpPlHJEQeZY+pKh3UijF+v6sRh7ww F+2vc34a9svIlAPY97yjoBpdDpF2xuEyyZsOM3s4Jv2t+y15l31ZlOwPI/05J9Xk5fjJ aOR/f5fAPMcLEpTjuhyWpEAD+9CA4nVKMNB1VuJlct9j2DSzzQyRqfTo/OH3vunGFsJm 1MlQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770139461; x=1770744261; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=r0v0GLllQmL/KRq8U4ajLDOV1RqqjTzamcBduCfw0/Q=; b=fbb8Y9rxqfZVRP50xDnDMSHEw24JkVxft86fEVTfbs9aKMWVmT2ULdJbwNZDAlYdzD 5QkIU/Be/IKGwCYBYALs5b6yDzr8CVMiPv/HIv/hxnjWq+MBglsKVbvkyHRzUVYcgj5U cK8NM3KoIyj5zXqFhTNx30LQcseS6XnZEqSi1Z1lggL2M81VLQUMpM/zCMidU4TlQ+O0 TFRO/nu0Tv0+TScRfG37PXz2HG5rRN2UyQoWaaIlAmj+L8WDmS5jdU6Qa7M3ICPus9De fM0K+XwUraNVjhviB2y19BYarmInidcatV7ChEiGUJ5xm/gLfayWR4gemW03xIMuVFOo lJjg== X-Forwarded-Encrypted: i=1; AJvYcCWdBOYpfjSqp41aA7KCp6WNRXN6RejkmP0/s6iPdoD1J6s07m1D9wfBebqEiFzV3f+CwNJXZhYsBcx9WRo=@vger.kernel.org X-Gm-Message-State: AOJu0YztWG/BEhOh3QMRSCFARMNoLrs+2BTUmYHogw/fgjWgfQ4brqkS N8DhUPtijRV2Wgx4xE98DFvoc7mHRFxLloMyNTFmhJQjLxJW3hImPlqxzlAawPWE81M= X-Gm-Gg: AZuq6aLNjGg98JlM+oN1aXYAajVeUuBF8+yqSHxwRuQG4Bi+/QuPxUItNDT3pUlvIVV hIiUcoOhXqv3B/DEsyk8A3ycWBjHC1BjGkiLsBtMrY1y6SkABHVl0lN1YuH2ZIjkuCYguAxhDHl lgsV8evcMHGV4+qFhtq6LBC+GX48BIcx8O8waryw26NuEbSrV/IBGS7iZ9MLhwH3aubI9VIekWS sYxEUtztgAFPWvsC/Bet8CNZvJEmQZKK/5RmlqQdF8uSZBasFzVdphgW12r5InB9l8RGTHhxge8 rMee23w5QSrn1qrua+oRes4aYX7STkr/reNqEvy/CXsfYxq6wlh3NsiHQ2dtt/9lwUGMtJ4/L+k lepnuqFYSpT2Bgoz4h74r6FLr0jHtmhmMXc5L7lfrXE+wXW4NDQh4Z+4FTL5/tTWq6PhF+3Q9Qh Pl0bSCF+eJfleLelxBps/fWFBx X-Received: by 2002:a05:600c:608a:b0:482:eec4:76d with SMTP id 5b1f17b1804b1-4830e987c44mr5135435e9.17.1770139460619; Tue, 03 Feb 2026 09:24:20 -0800 (PST) Received: from pathway.suse.cz ([176.114.240.130]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4830515381esm80061795e9.11.2026.02.03.09.24.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Feb 2026 09:24:20 -0800 (PST) Date: Tue, 3 Feb 2026 18:24:18 +0100 From: Petr Mladek To: "feng.zhou" Cc: john.ogness@linutronix.de, linux-kernel@vger.kernel.org, rostedt@goodmis.org, senozhatsky@chromium.org Subject: Re: [RESEND] Re: [PATCH] printk: Fix _DESCS_COUNT type for 64-bit systems Message-ID: References: <87o6m7fk4c.fsf@jogness.linutronix.de> <20260202150750.10985-1-realsummitzhou@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260202150750.10985-1-realsummitzhou@gmail.com> On Mon 2026-02-02 23:07:50, feng.zhou wrote: > Hi John and maintainers, > > (Resending to the list - apologies for the initial off-list reply) > > On Mon, Feb 2, 2026, John Ogness wrote: > > This is important to us as well! And we really do want those > > wrap-arounds to happen early. > > > Your v1 is certainly OK as-is. I just want to do some more investigating > > and testing. With your patch it will be the first time we experience > > descriptor ID wraps. > > > > As to the other U->UL conversion, I really have no preference. Let's > > just wait a bit in case Petr wants to comment. > > Thank you for the feedback! I understand v1 is acceptable and you're doing > additional testing. I'll wait for Petr's comments and your investigation > results before any further action. JFYI, this patch is on my radar. But the review might take some time: 1. I am a bit overloaded. 2. This patch has low priority. It helps to test a rather non-realistic scenario. 3. The review is far from easy because the macro _DESCS_COUNT() is used on many cricial parts of the lock-less code via DESC_COUNT() macro. > For the record, here's a summary of our off-list discussion: > > 1. Early wrap-around testing is important for the printk_ringbuffer design > itself, not just for matching documentation. > > 2. John noted this is interesting because it will be the first time descriptor > ID wraps are actually exercised in practice. > > 3. There's a similar issue with the text buffer array size definition using 1U, > but we agreed to wait for broader maintainer input on whether to address it > in the same patch or separately. This is another complicated problem. The printk log buffer size is limited to 2GB. I am not exactly sure why. Some clue can be found at https://lore.kernel.org/all/20181008135916.gg4kkmoki5bgtco5@pathway.suse.cz/ > I apologize for not using "Reply All" initially - I'm still learning the > kernel development process. I'll make sure all future communications stay > on-list. No problem. It happens. It is great that you are learning. > Thanks again for your patience and guidance! You are welcome. Please, have patience with us as well. Best Regards, Petr