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X-CSE-ConnectionGUID: NLJgoMABRvKvcJBmnqDNPA== X-CSE-MsgGUID: DD4KsXH7Q62YUlKbb4e8+A== X-IronPort-AV: E=McAfee;i="6700,10204,11189"; a="13433166" X-IronPort-AV: E=Sophos;i="6.10,213,1719903600"; d="scan'208";a="13433166" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Sep 2024 18:01:17 -0700 X-CSE-ConnectionGUID: NdfFDBWRRW6RUDsVFOZwZQ== X-CSE-MsgGUID: IY2cAeqqTEuJRe1/9/hxWA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.10,213,1719903600"; d="scan'208";a="66296717" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Sep 2024 18:01:14 -0700 From: "Huang, Ying" To: Andrew Morton 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() In-Reply-To: <20240907202458.dfe90bfee071021706af91eb@linux-foundation.org> (Andrew Morton's message of "Sat, 7 Sep 2024 20:24:58 -0700") References: <20240906030713.204292-1-ying.huang@intel.com> <20240906030713.204292-2-ying.huang@intel.com> <20240907202458.dfe90bfee071021706af91eb@linux-foundation.org> Date: Mon, 09 Sep 2024 08:57:40 +0800 Message-ID: <87le011w57.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Stat-Signature: 38odaq7djoq3w95twq973atrhd4qqyfe X-Rspamd-Queue-Id: AEA37140003 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1725843678-859042 X-HE-Meta: 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 L+5Lx4tu WCiHvzCXoBvm/nNM/7xunnqLsaafGfx4OXsdkyjpW5CJPBA0U+xJhK2aaoShJkV2aNE2gEYF5cyAqf4r19TC56apfJlKQDdA9j6cYE4RdM7wguSQr4TfsfCFltjbBG5FEsioZnxzASHu06KYvBJB8PijvY+lpD4oWVQQh9ib4gFXJwE0+FjUfe1tr62l3pAf0J7GZ2GSuu58zagygPOpiLqp1z4srskuD7dVofe8INVJhk7S/yM4MB/xa9p5XGt/w8ivLjmtfvbrHuRxPPomp+PwFTifIUwx+XPPVteBl66hfI70= 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: Andrew Morton writes: > 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? Yes. I think that we should fix this in -stable kernels. Although no severe bug will be triggered on x86 in the earlier kernels, it may be a real bug for some other architectures. -- Best Regards, Huang, Ying