From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 E0C223FEF for ; Sun, 4 Jan 2026 20:30:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767558657; cv=none; b=ZInAEop8dAxBahCOS029gP7iKMA97xp8nGRpoGbGgbxSZol23+xYwVWmKbAdazDW5pGZ/nd7db5frN6RCMKvDWtq+SL09lwdMPZJt3udFRsHoW8M/vTOaR+VBzBGl03bxwvVSBrreWttP3tLeJcQWNN5MUeyoIA6SOZBEE9drL0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767558657; c=relaxed/simple; bh=+KEvRDUkBjGVFlARiTeevHENz3gsYOF4LX/BQzQ4zYg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kVINwblrzN0lfupSSy0C4ytTye9ORz1T1niEIdBQvj9y+ePn58+nrnOylb3IFRTDgto30QAy3J/UsxOQ3MKkiUxgnogIj8X1GU5WLwpylCtYKzUhDaVo4qo4Q8V3xN1wXkq+f0wMFXFBdZAGM2rOfH6AzM6QRFUU8jZ9T7xjWiw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=bru356Lu; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bru356Lu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1767558654; 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=WDzrq9hE5fdY0BcHRlEsAqgMWnvVciiF8/N1x0jMVwk=; b=bru356LuchebIYmI9RPQUnanktPpvcIQ9QkRrAZM8Z2ksx3cyHXp75T8NZZT6mNWkMyD40 5j7XRO/l1wNjMqXJYjfk7z2uC57zyiZwQxTtOKW8fyGJq+4oo1JiXwW4lhED2AjJFYZ6Am +ODG20zzv20i+n9mwnD9lcSDuIdfnMk= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-549-iQWwHTVdNiuHBDrkK7C_Rw-1; Sun, 04 Jan 2026 15:30:49 -0500 X-MC-Unique: iQWwHTVdNiuHBDrkK7C_Rw-1 X-Mimecast-MFC-AGG-ID: iQWwHTVdNiuHBDrkK7C_Rw_1767558647 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5F24B18001D1; Sun, 4 Jan 2026 20:30:47 +0000 (UTC) Received: from fedora (unknown [10.45.224.28]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 365FF30001A2; Sun, 4 Jan 2026 20:30:40 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Sun, 4 Jan 2026 21:30:46 +0100 (CET) Date: Sun, 4 Jan 2026 21:30:39 +0100 From: Oleg Nesterov To: David Laight Cc: Xia Fukun , Peter Zijlstra , Ingo Molnar , "Li,Rongqing" , "linux-kernel@vger.kernel.org" , "vschneid@redhat.com" , "mgorman@suse.de" , "bsegall@google.com" , "rostedt@goodmis.org" , "dietmar.eggemann@arm.com" , "vincent.guittot@linaro.org" , "juri.lelli@redhat.com" , "Zhangqiao (2012 lab)" Subject: Re: [????] Re: divide error in x86 and cputime Message-ID: References: <78a0d7bb20504c0884d474868eccd858@baidu.com> <20250707220937.GA15787@redhat.com> <20250707223038.GB15787@redhat.com> <2ef88def90634827bac1874d90e0e329@baidu.com> <518a5712-3348-4acd-ae26-529621143ef7@huawei.com> <20260104181501.740884d5@pumpkin> 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: <20260104181501.740884d5@pumpkin> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On 01/04, David Laight wrote: > > On Sun, 4 Jan 2026 15:23:19 +0100 > Oleg Nesterov wrote: > > > Peter, Ingo, > > > > can you take > > > > [PATCH v3 0/2] x86/math64: handle #DE in mul_u64_u64_div_u64() > > https://lore.kernel.org/all/20250815164009.GA11676@redhat.com/ > > > > ? at least 1/2 which fixes the problem with #DE ... > ... > But this code needs a completely different fix. Of course, this is clear. The fix above doesn't even try to address the problems in cputime_adjust() paths. But. To me the fix above makes sense regardless. mul_u64_u64_div_u64() should nevet trigger #DE, and I thought that we already discussed this before. Do you agree? Oleg.