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b=geQjXpnkhLCLWNLZMlbB0uJh57q6izf7cWViOO2F3QNL/ezvbGLWlZ6EfPWvlc2My rHe05QmuTuqLIidP4pipPlO48mWH7ktnfqpKLeeojkdVldgxvD7AaTKnc6uKPaXwIS ga3EUvvp6X7PGXDi+/0ClVy9SKTfFIrn4XXbPiPPy5b7Ktwd2JKbsetGBzUa3xElwx dd+7LrfnacEwWzKg9sfLTrUx2oHYSLZQJ1q/Tbb+sf7Kmt9ZGhbTzsUIslJc40j3zC f0bWxHKeluIzDMEMuQUUD5l7BGPRYAg3ihn1LbR3xYyrdCik1B+gSzMB+629x65BkD LE4h18DRFoGEw== Date: Fri, 17 Jan 2025 18:48:55 +0000 From: Jaegeuk Kim To: Matthew Wilcox Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 0/2 v6] add ioctl/sysfs to donate file-backed pages Message-ID: References: <20250117164350.2419840-1-jaegeuk@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: s3wzzadj3zsu1jhjxcmo4bypks164145 X-Rspamd-Queue-Id: 28F77120007 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1737139737-954038 X-HE-Meta: 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 QwznGsua Q8mHJR2JrEnQPaYGbJUTBArQ1uhMtxP+vJ1Z8BAMC1X0QvoW6XTczssu3lDiPF6se5MQb1E7tjZdgY6uuUETMMQmvcGYg/A/SRpwFSw24B2vUCWaO0p5nZGx9U0Jtz4XNZFt4ba/v2wYy3tQCVzCjXEx/WquWXb5U927959Hsja7Eduzkdn2ZLPY6PCFyJhiY1axDH3jabMXtMLOWY1j4HGWtZNIqEuH/yPer7hzpoRXyJ7UPrSTSQTnk1L0BJgZ68XUZtf5OLUMJsbLoABM/Jx2e5egNKb/Pci9v 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 01/17, Matthew Wilcox wrote: > On Fri, Jan 17, 2025 at 04:41:16PM +0000, Jaegeuk Kim wrote: > > If users clearly know which file-backed pages to reclaim in system view, they > > can use this ioctl() to register in advance and reclaim all at once later. > > > > To MM and others, > > > > I'd like to propose this API in F2FS only, since > > 1) the use-case is quite limited in Android at the moment. Once it's generall > > accepted with more use-cases, happy to propose a generic API such as fadvise. > > Please chime in, if there's any needs. > > > > 2) it's file-backed pages which requires to maintain the list of inode objects. > > I'm not sure this fits in MM tho, also happy to listen to any feedback. > > You didn't cc the patches to linux-mm, so that's a bad start. Because #1. > > I don't understand how this is different from MADV_COLD. Please > explain. MADV_COLD is a vma range, while this is a file range. So, it's more close to fadvise(POSIX_FADV_DONTNEED) which tries to reclaim the file-backed pages at the time when it's called. The idea is to keep the hints only, and try to reclaim all later when admin expects system memory pressure soon.