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[2003:cb:c723:4c00:5c85:5575:c321:cea3]) by smtp.gmail.com with ESMTPSA id z10-20020a1c4c0a000000b003fe2397c17fsm2352867wmf.17.2023.07.31.12.24.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 Jul 2023 12:24:51 -0700 (PDT) Message-ID: <32b8c5e4-c8e3-0244-1b1a-ca33bd44f38a@redhat.com> Date: Mon, 31 Jul 2023 21:24:50 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v8 1/4] fs/proc/kcore: avoid bounce buffer for ktext data To: Lorenzo Stoakes Cc: Baoquan He , Jiri Olsa , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Uladzislau Rezki , Matthew Wilcox , Liu Shixin , Jens Axboe , Alexander Viro References: <86fd0ccb-f460-651f-8048-1026d905a2d6@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: 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-Stat-Signature: e9436rczndarz6tpm8ha5kjn6r7gazug X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: BEC5640013 X-Rspam-User: X-HE-Tag: 1690831495-664085 X-HE-Meta: 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 Gb06Ba7a wS2WvGM4SZf7+5yI1LGAXvyF9YoiHO0Ri9HGyB5jrnT8Aq0nA3Qe+bJi22rKgUMhMiCUHhF/nUK2bgh+VdBnQLbq7Kf9ncXsNe7WngHJ37xwTjMh7vZJzSwx2nXaEFQjRHTNcWOmm0cYI9nfPDvtwyvQxrHWReRxVvBw9owVo12OLTFhOAqtu0GNUEpl4qkx+EpJ5oUvXeqd49+kZ5inrMdh4XhlHdLaaTk1LqO9QdLfuJSlO3yXGGGL2BYJW562Bwp0EjldTdseE8AqDYIPFM5sRP2CTa1MQkU26MjgubL4/ekuD1YM1KVk+rpqyriSIPfQ/6ruiWUpANEKr1k4h6GGrJRNUIPGk+mwVYJaTo6XhsI9/JF99MGUF+vnN5nbMDjXf/Mf7NnEclB/TK944hVV4ZEfDOH1Nw+VoQDJuqISYJ2BDD09r5WC2HU0iaXxbM4/z 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 31.07.23 21:21, Lorenzo Stoakes wrote: > On Mon, Jul 24, 2023 at 08:23:55AM +0200, David Hildenbrand wrote: >> Hi, >> >>> >>> I met this too when I executed below command to trigger a kcore reading. >>> I wanted to do a simple testing during system running and got this. >>> >>> makedumpfile --mem-usage /proc/kcore >>> >>> Later I tried your above objdump testing, it corrupted system too. >>> >> >> What do you mean with "corrupted system too" -- did it not only fail to >> dump the system, but also actually harmed the system? >> >> @Lorenzo do you plan on reproduce + fix, or should we consider reverting >> that change? >> >> -- >> Cheers, >> >> David / dhildenb >> > > Apologies I mised this, I have been very busy lately not least with book :) > > Concerning, I will take a look as I get a chance. I think the whole series > would have to be reverted which would be... depressing... as other patches > in series eliminates the bounce buffer altogether. > I spotted https://lkml.kernel.org/r/069dd40aa71e634b414d07039d72467d051fb486.camel@gmx.de today, maybe that's related. -- Cheers, David / dhildenb