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[2001:1ae9:1c2:4c00:726e:c10f:8833:ff22]) by smtp.gmail.com with ESMTPSA id kg8-20020a17090776e800b0099329b3ab67sm6337302ejc.71.2023.07.24.01.18.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jul 2023 01:18:51 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Mon, 24 Jul 2023 10:18:48 +0200 To: Baoquan He Cc: David Hildenbrand , Jiri Olsa , Lorenzo Stoakes , 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 Subject: Re: [PATCH v8 1/4] fs/proc/kcore: avoid bounce buffer for ktext data Message-ID: References: <86fd0ccb-f460-651f-8048-1026d905a2d6@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Stat-Signature: 9uwm9q9qreagu95n8kjiszeab7soiwqf X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 00E96160019 X-HE-Tag: 1690186733-394254 X-HE-Meta: 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 ddgUXGvM RA8qNjls2mskUFKohv6+YoMlVtOWVdXQr7nAROmwEcBqrjjhJDRCkizrEePjzJHnkQGVgMIFmt/OmHzUvbRKbX9XYXtk9fLFwjtlx1PiLm+r/hR6RsyxodErYp4nEO3Bdxy8B4hY7EmjEaYxOzHlntvf6lgbhUC1SFvYTkxVr0P7aFT3ip5CGw7hqAdIkJQw2Rqt53++PzZV/NROYBI2Tf8LU092HneKnNFvq5+BZyBjOlJ10DKPb/6kCu+XbL3eZI/rne/H/dVM6TiiSWHNJF51I5nBRCTdFEnJ8AuQWFPR8Aeq69eL95p8MJabwrchYomOihVPSyZvOk0PUrRfbiKpgkLOC8adN99FME9Pk0h/UeqazUh0omjWJtbJL2HCCBIQ+rQED80qTMu53XOuwgBxXjyyG9DsL9uhG 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 Mon, Jul 24, 2023 at 04:08:41PM +0800, Baoquan He wrote: > On 07/24/23 at 08:23am, 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? > > From my testing, reading kcore will cause system panic, then reboot. Not > sure if Jiri saw the same phenomenon. it did not crash for me, just the read error could you get console output from that? jirka > > > > > @Lorenzo do you plan on reproduce + fix, or should we consider reverting > > that change? > > When tested on a arm64 system, the reproducution is stable. I will have > a look too to see if I have some finding this week. >