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b=p7+3HAptQoBy2YYTOS9pHN7GZaH/ozxVGuy+2xZ9Bf+W/uxMohWNOwt+rSUg7vzWg l6Vh9rdrWMaNbR55AbDN5U4LyJS4G/TP5iovSG1jMK2xBkTB7RTyiJ+5VxsXDt2jtL n7+WqVSXBcOLErC26vRXJtRtzScRUmqM5tM9Aspk= Date: Wed, 2 Sep 2026 14:40:39 -0700 From: Andrew Morton To: Gregory Price Cc: Liu Jing , david@kernel.org, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mempolicy: fix div-by-zero in alloc_pages_bulk_weighted_interleave Message-Id: <20260902144039.2824b7589e87dd185c92d67a@linux-foundation.org> In-Reply-To: References: <20260902090412.16445-1-liujing@cmss.chinamobile.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: 14pwk6qxg9i8fboyf1woh7ciq546sdwo X-Rspamd-Queue-Id: 28131140008 X-HE-Tag: 1788385241-703808 X-HE-Meta: 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 uxhcb9j1 Lihv4zvXKfHm+wKv6qrubb6aFyVUyjuy5ZBP/RJU9nUmNadf9BXZJFuxRSx1qIQ2JJIU2qwgtZ50+sZ7LSgrcBPow6MjE7W5nUAj3ulfQTJHzVp3B40WtZp1kKQvuBA3zoNYQXWNRs0yfSvene8XYboEFgCsg7vUHUMG8Z3QhdplwcIzg4ThaP1Gon4HGb9wwlMdrCoXyilWH4JN04AwxzerXUR/UjqkS4niobB/2YjKHckRopXlyVSWbO8sYtHCR6trCvwC8pKSyeGQTWhoKnbaBpF5t/2Gb2XVh1H7paLY6cU2TfZz/IRS0NlIdnoQK3SejHsNZSj341RmDNb7DnC2niGKfy3zY5TGCCqoxx4FuthBkbKLlvgZGL74asm9TfZMlZqtrPu+tnppDH/UG2DSmmyA0j51fKmENSzarfzxmZG5sYwWLm5zB3w== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 2 Sep 2026 09:57:35 -0400 Gregory Price wrote: > On Wed, Sep 02, 2026 at 05:04:12PM +0800, Liu Jing wrote: > > In alloc_pages_bulk_weighted_interleave(), if the iw_table contains > > all-zero weights for every node in the policy nodemask, weight_total > > sums to zero. The subsequent "rem_pages / weight_total" and > > "rem_pages % weight_total" trigger a divide-by-zero panic. > > > > weights can't be zero and we just fixed the rebind race So if the caller passes in me->weight==0 then we consider that caller to be buggy. In which case a div-by-zero is a perfectly acceptable way of reporting this bug, no code changes needed,