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b=bT4QUioTDP72vZZdzqwyLTZBnHJH4Tg/T7PX9xgGBWYjW9OVZAclnsWCx8AG2buLV nB3gJr6ceVCx6jDUCQiuvEBiNHhmerKizMXaW1e8ogakRTG338G1s6e3Q5fvyeNf+u fipYsjTEknR07ulhAJz9zwWI5Q2nEbEoko4ipvNAmywL87xv96CUSOs22rn+3Uld96 Ribf7uyDFNheHzgQMEnBJyy53Zi8KycN65nqdItpYGBPOyUsUE+hRuGpbRE83mAhw9 sOmOhZbpfFR/yy4R4HN6tUXAbRE8bQfSI6g3BD4fj9yRBbdWIzSLkMUeVKKuk4yy35 cL/HJHypNyR/Q== From: Christian Brauner To: Mateusz Guzik Cc: Christian Brauner , viro@zeniv.linux.org.uk, jack@suse.cz, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, tavianator@tavianator.com, linux-mm@kvack.org, akpm@linux-foundation.org Subject: Re: [RESEND PATCH] fs: avoid mmap sem relocks when coredumping with many missing pages Date: Mon, 20 Jan 2025 15:51:15 +0100 Message-ID: <20250120-knabbern-aufwiegen-82ec233f99dd@brauner> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250119103205.2172432-1-mjguzik@gmail.com> References: <20250119103205.2172432-1-mjguzik@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Developer-Signature: v=1; a=openpgp-sha256; l=1280; i=brauner@kernel.org; h=from:subject:message-id; bh=kXveLa76z/4LC7xZq/+gX3pqLdFejmJGWqWhQczZNrg=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMaT3JT1/95drgdWdY7M93+/2a5l2UmXGAe9VmxbnLz6fv btYulDuTEcpC4MYF4OsmCKLQ7tJuNxynorNRpkaMHNYmUCGMHBxCsBEtrxkZOjxyJ4SJ6dx91p4 E6vrRsWZSU1fbqS7nVmzXZexe5rWbBeGv2Kyvtrhdyf+Wu4kuti197pjiNS05C9h+5budAySWin xlAkA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 178D780012 X-Stat-Signature: k8miuan1ipt34g3mrygc4fn6y38w41tk X-HE-Tag: 1737384687-67499 X-HE-Meta: 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 gs/PAaSU X9TOa60KlmxyEUS3qKWhQ43kk83qVhR/ncGUOzpFPYB9qLdRUukJdGLK0l4W4sh49sXMgXr0hGxhyeFWvEpRzPbyioOr/3vrK76wBbuImaJMcMk2R1dG85W9A641+MQRbEhs6rzlnDhiA9blTVmrb+9kwwqNtdkMfmLPnUiu9VttUE3e4o7I4HRN81HVpTrLyWaUTHX2rDUks/lAXqeawEN3VRPDk+oK2n4cpxEBkf+6VX5zTf6+VvPYAvgcCK0M7I2KgP3MZsOGtZq8+pgDzvat+1H0hEE73tV60 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: On Sun, 19 Jan 2025 11:32:05 +0100, Mateusz Guzik wrote: > Dumping processes with large allocated and mostly not-faulted areas is > very slow. > > Borrowing a test case from Tavian Barnes: > > int main(void) { > char *mem = mmap(NULL, 1ULL << 40, PROT_READ | PROT_WRITE, > MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE, -1, 0); > printf("%p %m\n", mem); > if (mem != MAP_FAILED) { > mem[0] = 1; > } > abort(); > } > > [...] Applied to the vfs-6.15.misc branch of the vfs/vfs.git tree. Patches in the vfs-6.15.misc branch should appear in linux-next soon. Please report any outstanding bugs that were missed during review in a new review to the original patch series allowing us to drop it. It's encouraged to provide Acked-bys and Reviewed-bys even though the patch has now been applied. If possible patch trailers will be updated. Note that commit hashes shown below are subject to change due to rebase, trailer updates or similar. If in doubt, please check the listed branch. tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git branch: vfs-6.15.misc [1/1] fs: avoid mmap sem relocks when coredumping with many missing pages https://git.kernel.org/vfs/vfs/c/dbdd2935ed48