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Fri, 29 Aug 2025 01:52:48 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id hpziOPAHsWg0EQAAD6G6ig (envelope-from ); Fri, 29 Aug 2025 01:52:48 +0000 Date: Fri, 29 Aug 2025 03:52:47 +0200 From: David Sterba To: Boris Burkov Cc: akpm@linux-foundation.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, kernel-team@fb.com, shakeel.butt@linux.dev, wqu@suse.com, willy@infradead.org, mhocko@kernel.org, muchun.song@linux.dev, roman.gushchin@linux.dev, hannes@cmpxchg.org Subject: Re: [PATCH v4 0/3] introduce kernel file mapped folios Message-ID: <20250829015247.GJ29826@twin.jikos.cz> Reply-To: dsterba@suse.cz References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: F204C1C0002 X-Stat-Signature: 5w3d8meordcce55ad9uzce1uyocmx63f X-Rspam-User: X-HE-Tag: 1756432370-803634 X-HE-Meta: U2FsdGVkX1+4wDazva7xbHw5AqgfTzogtpDIW86f/ERqxhNEkssbOkWw0uHYGm9tOuKXzZNUfMr0/Ae9tQq5AtfTwDRQQCv5FsMAYqORXl/UzTHGtRMtnbVEvN2pzg60JI0ombiq7OHGCbwoIyyiBULV9HMOW+eefikz4J31asyLvvZz4AjMEnIdg4Cj2S3p0Y13gWXCIvpYxih34s51d+jNAMzGWdKtqET49nEYPVLJy+MUsFdcgu69vWQdRtnRTeDjma/xsX5dXGNhp/sClsqHzxJ91SeSow++xarOMkjHcUKhxXyCdZSx6xqkJHm8oOvcaEebyHVdlJSRkcggaNYUof1dj2onMrixQTwfr1Rznw7clK0lUGCdafrSKAeeQhOejl2+8IN06U8cqiU+gbz3pPnIta8E9yUnS0TvllZSC2BM4tYtBdrPdbTxLKwE5OIAVPF8yc1+okqyC8ULRKh0u89+I4+ZwivOBSO7gOx9VwP//Yq387d/MdCaniiRbePrkmrYGSnOeZWinFSuWreNqYK8Tx6oyZ3R+/5izJQrNlGfjuusAoctDVRhcDBxvMO+ICpvRgeJ3DIW0G73Flnsc9wH06Zal7OqSosXM7MPhjPE6UMRE+rcV1Dxss4TphWfw2Cb+zmqjXvx++PgsbtriTh+xsg3pt021ixmbqM2beCDhbPLLViicIAOiWq3djhTG3Ox5XVA7MgW8u0KKoYhjqdI/6CSpbQTQedGCwOUtRssTIENVbKjoXnym4xLPrOWgHxnbzdZQg0OXHwzQIM80gZpehsDHNh30iL2h6wGqitZkYH2zayRkRwrjYDjeWNqjW3ItPjnGdhl1vtRvXjVHCos2aL1blgrW/jY8fpB2SkyDaJaL0YeRHS2QQZcLSTmkEp8DzsSwR6RaU+20RAiAbRtQDF/m/gVkTNIqL0AIE+VeZCGGrVIG7CVVngnmFLzkjcuh+6H1Drbhxs 0re5kujU 98/s/8Yda8keift5bcoh6DbKWPTMqSRaOSkjYNh9R4bXN4qY2W/HOysnK8gJCfLkEe+0rAnRU28iIJ2aD8E+7fFZtnwmCP/NtI2h3stf5PM7ifiW7qSBPHLXl4eO62hKP6Jf007e6dc7PT/sn6vPX9UILI84dJga7kvSHG/qaxP53nIMRbhnCQmJ3cfv6qhZFUawpZkzhzzph0tP/ul5no0WSVBXNZ5T1l+TM6KBgAuDZpMN5hAbnUsQjTjG+3cwg3iM8YiH99CKaYoVJrSghF+YK6INGbNYqnFEz4+vcBxNiCvtkzEkWYhshxM7hpAmwDJHWzwknTXdcQdVighIoBE2mrH0HmEIZ2mIcsYimISnX/hto97QWJlnOfBFxfSVHLq5osMPQxQhSk32pMOW6TxiDEj15pLrzYA0ogaRm2XDa2qD7cla+W3PzEA== 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 Thu, Aug 21, 2025 at 02:55:34PM -0700, Boris Burkov wrote: > I would like to revisit Qu's proposal to not charge btrfs extent_buffer > allocations to the user's cgroup. > > https://lore.kernel.org/linux-mm/b5fef5372ae454a7b6da4f2f75c427aeab6a07d6.1727498749.git.wqu@suse.com/ > > I believe it is detrimental to account these global pages to the cgroup > using them, basically at random. A bit more justification and explanation > in the patches themselves. > > --- > Changelog: > v4: > - change the concept from "uncharged" to "kernel_file" > - no longer violates the invariant that each mapped folio has a memcg > when CONFIG_MEMCG=y > - no longer really tied to memcg conceptually, so simplify build/helpers > v3: > - use mod_node_page_state since we will never count cgroup stats > - include Shakeel's patch that removes a WARNING triggered by this series > v2: > - switch from filemap_add_folio_nocharge() to AS_UNCHARGED on the > address_space. > - fix an interrupt safety bug in the vmstat patch. > - fix some foolish build errors for CONFIG_MEMCG=n > > > > Boris Burkov (3): > mm/filemap: add AS_KERNEL_FILE > mm: add vmstat for kernel_file pages > btrfs: set AS_KERNEL_FILE on the btree_inode > > fs/btrfs/disk-io.c | 1 + > include/linux/mmzone.h | 1 + > include/linux/pagemap.h | 2 ++ > mm/filemap.c | 13 +++++++++++++ > mm/vmstat.c | 1 + For the btrfs parts, Acked-by: David Sterba