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[49.179.0.65]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-20385fc6c26sm90399215ad.297.2024.08.27.21.11.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Aug 2024 21:11:45 -0700 (PDT) Received: from dave by dread.disaster.area with local (Exim 4.96) (envelope-from ) id 1sjA22-00FK14-2a; Wed, 28 Aug 2024 14:11:42 +1000 Date: Wed, 28 Aug 2024 14:11:42 +1000 From: Dave Chinner To: Michal Hocko Cc: Matthew Wilcox , Andrew Morton , Christoph Hellwig , Yafang Shao , Kent Overstreet , jack@suse.cz, Christian Brauner , Alexander Viro , Paul Moore , James Morris , "Serge E. Hallyn" , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-bcachefs@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] mm: drop PF_MEMALLOC_NORECLAIM Message-ID: References: <20240826085347.1152675-1-mhocko@kernel.org> <20240826085347.1152675-3-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: opzxoq7w119n65awybqb9xjydrbznmfj X-Rspam-User: X-Rspamd-Queue-Id: 7093B4000E X-Rspamd-Server: rspam02 X-HE-Tag: 1724818307-491928 X-HE-Meta: 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 ScsMfF9a jrjtIdv/ZkcBvwV83gmg4Zag0j4rUfpClsQcUcV4J9ouwzTvtc2v9SK53KYANEifcxVMrOmSN472lufhb5a+Qv9T/8zAxMyqChfauxGWoKVkxhD+qYA/muPylY6nN0M0SbaH+9UoY+HPhRoHqsFcQB6OPMUMEfQSSm+Ydpc8C808QrMy54FBlLdUvr5QeRbqWdoC7kGvIhcIbEuBEa1slAjuC99uQ3H+cJSIWyXi+vAmyE0X/YKSCtTI0VNRi/TESW+NIqmgqEsmx9O5zIByjjZ5VYgMZIYZYCccYsEpSDfoXCOJ6woi7Ucx66gyGlXlixHktsf2bjJojD7k3Nl+MA7Ni64ljffSETWyB/3TTm3KVPJuG70lwTZlvxcXlCZi45F5tppL55ZiHCAHjNIAJlYXIgbv/GPRwH9uS976RVme2yrq2d155ZC/FSvYA7gznHKSz7g+0DJOTFpoXBNMt1D8YC2S5jDlpSfYTDIMfcPP14IIiCW05hJadwsBn0IiJ51hMf5v8pquvgNQmI2QOxG0OpB7CDLMGVK6UhHfEKaZrbb1THIm4D5LIpATuilucaipXpGHnfBxGgMc9mRd3tRcm3FAzgJxaM7e1yYRuXEQE8Lo3+sFrVT/zGgxeYaWxqGREu5Xfy48TNGRolRHQbVwMCCD3lFXVz/xNWs0YtkIs6YA= 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 Mon, Aug 26, 2024 at 09:18:01PM +0200, Michal Hocko wrote: > On Mon 26-08-24 18:49:23, Matthew Wilcox wrote: > > On Mon, Aug 26, 2024 at 06:51:55PM +0200, Michal Hocko wrote: > [...] > > > If a plan revert is preferably, I will go with it. > > > > There aren't any other users of PF_MEMALLOC_NOWARN and it definitely > > seems like something you want at a callsite rather than blanket for every > > allocation below this point. We don't seem to have many PF_ flags left, > > so let's not keep it around if there's no immediate plans for it. > > Good point. What about this? > --- > From 923cd429d4b1a3520c93bcf46611ae74a3158865 Mon Sep 17 00:00:00 2001 > From: Michal Hocko > Date: Mon, 26 Aug 2024 21:15:02 +0200 > Subject: [PATCH] Revert "mm: introduce PF_MEMALLOC_NORECLAIM, > PF_MEMALLOC_NOWARN" > > This reverts commit eab0af905bfc3e9c05da2ca163d76a1513159aa4. > > There is no existing user of those flags. PF_MEMALLOC_NOWARN is > dangerous because a nested allocation context can use GFP_NOFAIL which > could cause unexpected failure. Such a code would be hard to maintain > because it could be deeper in the call chain. > > PF_MEMALLOC_NORECLAIM has been added even when it was pointed out [1] > that such a allocation contex is inherently unsafe if the context > doesn't fully control all allocations called from this context. > > While PF_MEMALLOC_NOWARN is not dangerous the way PF_MEMALLOC_NORECLAIM > is it doesn't have any user and as Matthew has pointed out we are > running out of those flags so better reclaim it without any real users. > > [1] https://lore.kernel.org/all/ZcM0xtlKbAOFjv5n@tiehlicka/ > > Signed-off-by: Michal Hocko Looks good to me. Reviewed-by: Dave Chinner -- Dave Chinner david@fromorbit.com