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[2003:cb:c715:ef00:fa40:f6df:a68d:a0e4]) by smtp.gmail.com with ESMTPSA id t15-20020a0560001a4f00b00313f676832bsm6546696wry.93.2023.06.28.02.10.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Jun 2023 02:10:35 -0700 (PDT) Message-ID: Date: Wed, 28 Jun 2023 11:10:34 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH] mm: Keep memory type same on DEVMEM Page-Fault To: Andrew Morton , "buddy.zhang" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Venkatesh Pallipadi , Suresh Siddha , Juergen Gross , Dan Williams , Konstantin Khlebnikov References: <20230319033750.475200-1-buddy.zhang@biscuitos.cn> <20230412142236.407d6d0e6d90232da004980e@linux-foundation.org> <20230416113944.c9b50a76a98b9e7c974cfac9@linux-foundation.org> <20230619131417.42d4e73d1b7669162ea44e29@linux-foundation.org> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230619131417.42d4e73d1b7669162ea44e29@linux-foundation.org> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 71A5F12000C X-Stat-Signature: 8idhm1bex81uejrgcnso5f53owsu1hac X-Rspam-User: X-HE-Tag: 1687943442-580315 X-HE-Meta: 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 A8sebqok HeHNrYTLjPZM5XVd9dMvje81CmGkgZl41rKj3fPYJzM6zE1xffMcZhCaFFJA2kZkQwwXinQRcXnbqU+4DOv15/kmmXyiFM5BIIOAj4LlspNb0EWZ5n0Vb5nDH6bupT541AqvrQIADjpUAxcSBcoZZYoHicZ+9TX3NhIrxLx3B10UD5u7iIFTUmUw0TieG0UGe54wkibHaO5DE5Cq/xVELC4ZL7mT+muIXWBpjXLOaVezr6773Sty5qWdCmliz3cZYI8CCLazHXgHjZuqjlinHcE3D/I+1irLvIPDoQF6e6/60BoiILpJ87sbZMgFASyCv1OIPmhPU+c9sUfZImT0m8WTR83TXTKe+ikZfEBWT0O9uutJO2ZHehWES/0C7whqAAGjz2MVdGo7eGdzh+S+oVQTkFchTy0VfkF73z8kAe1s+vFd5syTZA8HozumvB26zn64u/CKflGSlwMVrznwrm8O3Q4msxJ8ZgvSs 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: On 19.06.23 22:14, Andrew Morton wrote: > On Sun, 16 Apr 2023 11:39:44 -0700 Andrew Morton wrote: > >> On Wed, 12 Apr 2023 14:22:36 -0700 Andrew Morton wrote: >> >>> On Sun, 19 Mar 2023 11:37:50 +0800 "buddy.zhang" wrote: >>> >>>> On X86 architecture, supports memory type on Page-table, such as >>>> PTE is PAT/PCD/PWD, which can setup up Memory Type as WC/WB/WT/UC etc. >>>> Then, Virtual address from userspace or kernel space can map to >>>> same physical page, if each page table has different memory type, >>>> then it's confused to have more memory type for same physical page. >>> >>> Thanks. Nobody has worked on this code for a long time. I'll cc a few >>> folks who may be able to comment. >>> >> >> Well that didn't go very well. >> >> Buddy, can you please explain what are the user-visible effects of the >> bug? Does the kernel crash? Memory corruption, etc? Thanks. >> > > Anyone? > With a clear problem description, ad requested by you, I could be motivated to review this and understand the details :) -- Cheers, David / dhildenb