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Tue, 07 May 2024 10:04:56 -0700 (PDT) Received: from www.outflux.net ([198.0.35.241]) by smtp.gmail.com with ESMTPSA id sj16-20020a17090b2d9000b002b27eb61901sm11927831pjb.21.2024.05.07.10.04.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 May 2024 10:04:56 -0700 (PDT) From: Kees Cook To: linux-fsdevel@vger.kernel.org, Allen Pais Cc: Kees Cook , linux-kernel@vger.kernel.org, linux-mm@kvack.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, ebiederm@xmission.com, mcgrof@kernel.org, j.granados@samsung.com, allen.lkml@gmail.com Subject: Re: [PATCH v4] fs/coredump: Enable dynamic configuration of max file note size Date: Tue, 7 May 2024 10:02:53 -0700 Message-Id: <171510137055.3977159.13112533071742599257.b4-ty@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240506193700.7884-1-apais@linux.microsoft.com> References: <20240506193700.7884-1-apais@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-Stat-Signature: pup7b6nyp978uknqd3td5fqwqojisy1e X-Rspam-User: X-Rspamd-Queue-Id: 19757C000A X-Rspamd-Server: rspam05 X-HE-Tag: 1715101498-485634 X-HE-Meta: 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 D9NAA8UA Rx3pRH4KgUn1Ip1lvdLOV4cwIiGnOt3dNFDNBHcAMkOsBV7ilzaZ8jLnvL7zgsAq0lrIbxTjsZX1rCiTqDKj0/c/3/8lVRSzQ+CfAPUJBX5ouJ1PnHb8Vq18ieFyIxPPWQ8Be/D3yUm6HKR1ByLDo6hNV9By1x+HCT4Bnqzya7HcGmgrJ1LlOuIMOhPXxBXPsoyTu5fY4gWY8cvP5J//c6y9YkkP2Xz0UJIHm2GOvPJvnk26HJcQA1TKGu7wSewCqs1fCZc8uty271f8iy88GK8+CDbM64uvn9PnDftXsne3X64kbiNwvKNzXTozCLoMppRQ9irZ+u8aQAitp4fdOzya91aybZBXkeZQWgiHk+pbsB2D3/hWx/oqWcdl6qbrVRFwwl8GCRkusaoNCiv0cbu2jnjMlvZbDTOKQ7tfSllNmujTNBKrpNNcUrbXrXyiV9WZeadbJk9zVf2uAwVYABsgunDQimxpsxOA4sOC6oCTUGXY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.020340, 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 Mon, 06 May 2024 19:37:00 +0000, Allen Pais wrote: > Introduce the capability to dynamically configure the maximum file > note size for ELF core dumps via sysctl. > > Why is this being done? > We have observed that during a crash when there are more than 65k mmaps > in memory, the existing fixed limit on the size of the ELF notes section > becomes a bottleneck. The notes section quickly reaches its capacity, > leading to incomplete memory segment information in the resulting coredump. > This truncation compromises the utility of the coredumps, as crucial > information about the memory state at the time of the crash might be > omitted. > > [...] I adjusted file names, but put it in -next. I had given some confusing feedback on v3, but I didn't realize until later; apologies for that! The end result is the sysctl is named kernel.core_file_note_size_limit and the internal const min/max variables have the _min and _max suffixes. Applied to for-next/execve, thanks! [1/1] fs/coredump: Enable dynamic configuration of max file note size https://git.kernel.org/kees/c/81e238b1299e Take care, -- Kees Cook