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b=RJpiXoFqyWKXsiRSbKurj/snbkWegxcRcdb5ipXFzmA+U2SVo7fEschQfzxsFsF5C GMawSuO/7erkzr53L8e4p5jTyXVqxw+Re+zRAxuqTn1yM3BH4ybYr9jbQIHMriq4ku 4p5HhU/JdZhsi6vBVG69PzBRl4njn7vGqaPEfRxg= Date: Sat, 7 Sep 2024 20:24:58 -0700 From: Andrew Morton To: Huang Ying Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, Dan Williams , David Hildenbrand , Davidlohr Bueso , Jonathan Cameron , Dave Jiang , Alison Schofield , Vishal Verma , Ira Weiny , Alistair Popple , Andy Shevchenko , Bjorn Helgaas , Baoquan He Subject: Re: [PATCH -v3 1/3] resource: Fix region_intersects() vs add_memory_driver_managed() Message-Id: <20240907202458.dfe90bfee071021706af91eb@linux-foundation.org> In-Reply-To: <20240906030713.204292-2-ying.huang@intel.com> References: <20240906030713.204292-1-ying.huang@intel.com> <20240906030713.204292-2-ying.huang@intel.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-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7B027180003 X-Stat-Signature: zw873bqwjyokgfirhzf7wyhpd38gkqxr X-HE-Tag: 1725765901-620793 X-HE-Meta: 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 Vam5Lvqt nvnbENBV8pv5crpDYWxbTVqnmOFK73iFTALm+qqC2fC0GtlLO5Qd9+JQ54SijIBQBdPf3MpTvmbkgHgCqM4+F46gJGn8r3hZL8NTUc89jpnzldgtgW9RXSGCfZH0GjkWAIh62jyItTIT/FCV4fLVS7i7wYxUCVyHIRx2QVZSfufvPIiQ1OG9fp/svyVrV0ktoT0y+6BCHJWJYnbwr3PRFLV7mt/Vo4x6qFozsrg3pqm4YLiTvxpJeQReLVH/f3umjY4+KHCkLe61GKlraj+2jyvqqbkrp+lIIcRJXVu3rcJsYsg4wEa7oiaSVJN+9+cRhsvTr X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 6 Sep 2024 11:07:11 +0800 Huang Ying wrote: > On a system with CXL memory, the resource tree (/proc/iomem) related > to CXL memory may look like something as follows. > > 490000000-50fffffff : CXL Window 0 > 490000000-50fffffff : region0 > 490000000-50fffffff : dax0.0 > 490000000-50fffffff : System RAM (kmem) > > Because drivers/dax/kmem.c calls add_memory_driver_managed() during > onlining CXL memory, which makes "System RAM (kmem)" a descendant of > "CXL Window X". This confuses region_intersects(), which expects all > "System RAM" resources to be at the top level of iomem_resource. This > can lead to bugs. > > ... > > Fixes: c221c0b0308f ("device-dax: "Hotplug" persistent memory for use like normal RAM") Do you believe this should be fixed in earlier (-stable) kernels?