From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 37F41C43458 for ; Tue, 14 Jul 2026 10:57:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3D4786B009B; Tue, 14 Jul 2026 06:57:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3AB3A6B009D; Tue, 14 Jul 2026 06:57:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2C2066B009E; Tue, 14 Jul 2026 06:57:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 075596B009B for ; Tue, 14 Jul 2026 06:57:06 -0400 (EDT) Received: from smtpin17.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 7A51B40369 for ; Tue, 14 Jul 2026 10:57:06 +0000 (UTC) X-FDA: 84987080052.17.D561577 Received: from out-189.mta0.migadu.com (out-189.mta0.migadu.com [91.218.175.189]) by imf16.hostedemail.com (Postfix) with ESMTP id 95368180003 for ; Tue, 14 Jul 2026 10:57:04 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Gc8GFZ+d; spf=pass (imf16.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.189 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1784026624; b=EHb4Y23UqPRKed5Zm4a1QWAwSNoFJqM63wKWaN0crWFzlD45IFne+eruiKqjDoi4XrvbKI yqV1dlKqiFifedqms4+EV9KJXckQKt8oiuVt82b+39QLo4m32e3mtOZEyG3ELxee22imLy rCLtUiHAvhUW4CnhMHfLVeoRBUwYj7A= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Gc8GFZ+d; spf=pass (imf16.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.189 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1784026624; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=b+/02nV5PKCig2GWCVlTdDIGXiyzApjtVUV59kIrcLM=; b=bM1/5gqYkD6bazJkYgYD2ZTHe0Quz5iK70PCCCZ0pdRpGjoKhfIbkGVwKegaEjnJExngbX cHoaxSQegYTK+JIpIhgiaab4Q5NEba3KsRIji3cP4XE/wcdUWY4LgFQ88UWHuV7N/wHUDX tXPGAwFXUPmp52b1Ih0umFMbD4OKehU= Message-ID: <3b85c8ec-f49a-45be-8e40-fe729c908e0f@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784026622; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=b+/02nV5PKCig2GWCVlTdDIGXiyzApjtVUV59kIrcLM=; b=Gc8GFZ+d3zpJbug2thf9FF6OZIE897xwN3vzOQlKoLCTS9pePGJ+vnyvp/ZqCoaevVxpL0 MABYh96Okw4r16h1lG84PA/X3/WsJLyqTYjIvO3ZWyboHtGV+FpE0REbcJaCFGqmtjZB8i U6IvaVO/osbGa73qzG0SU06B1xld1E0= Date: Tue, 14 Jul 2026 18:56:29 +0800 MIME-Version: 1.0 Subject: Re: [PATCH] fs: push nr_cached_objects memcg gating into individual filesystems To: Usama Arif , brauner@kernel.org, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Al Viro , linux-mm@kvack.org Cc: hughd@google.com, boris@bur.io, clm@fb.com, dsterba@suse.com, linux-btrfs@vger.kernel.org, cem@kernel.org, linux-xfs@vger.kernel.org, shakeel.butt@linux.dev, hannes@cmpxchg.org, riel@surriel.com, kernel-team@meta.com References: <20260714101454.1202449-1-usama.arif@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: <20260714101454.1202449-1-usama.arif@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 95368180003 X-Stat-Signature: 3g3er5j1grcbgygayt6oxs5scfg9zps6 X-HE-Tag: 1784026624-304413 X-HE-Meta: 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 cXc7DTDR Ozl7E3JxnEZmttvqPooASzZjMKsvUzm+2MBAiOObN53SkRPx7UJUxmd5eTI6y83KAuN4XFCcD+DczO0SJYXR6kMR/ilnH5+u0fOOHsyWxS7S2DxVlJF9zQh3yKM/xY3MAJelxS/chW+QpU0aTj2sm8XaaKR1yGqzK+zSZxV9bHVIlS2Ho92WzMDDDAOTz1tJIJtMS8Lv2HsQRCuT07cJvOx0e5g0DmgVL/PbcT7AfA+/01Q51guGcO71znvlDeRufK03n Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/14/26 6:14 PM, Usama Arif wrote: > Commit 0baad6f9b997 ("fs/super: skip non-memcg-aware nr_cached_objects > in memcg slab shrink") added a check in fs/super.c that skips the > ->nr_cached_objects() hook whenever the shrinker is invoked for a > non-root memcg, because none of the current implementations (btrfs, > xfs, shmem huge) honour sc->memcg. > > That policy is really a filesystem-owned property: fs/super.c should > not encode the assumption that these hooks are never memcg-aware, > since a future implementation might legitimately filter by sc->memcg. > Move the check into btrfs_nr_cached_objects(), xfs_fs_nr_cached_objects() > and shmem_unused_huge_count() so each filesystem can lift the > restriction independently once its underlying counters/scans become > memcg-aware, without needing a coordinated change to fs/super.c. > > Behaviour is unchanged: calls into these hooks from shrink_slab_memcg() > still early-return 0 for non-root memcg contexts, keeping the shrinker > bit clearable in each memcg's bitmap; the global (kswapd or root > direct reclaim) path still drives them as before. > > Signed-off-by: Usama Arif > --- > fs/btrfs/super.c | 11 +++++++++++ > fs/super.c | 19 ++----------------- > fs/xfs/xfs_super.c | 12 ++++++++++++ > mm/shmem.c | 11 +++++++++++ > 4 files changed, 36 insertions(+), 17 deletions(-) Looks reasonable to me. So Acked-by: Qi Zheng Thanks!