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 766EAC44501 for ; Tue, 14 Jul 2026 10:18:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 74DEC6B0088; Tue, 14 Jul 2026 06:18:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6D7036B0093; Tue, 14 Jul 2026 06:18:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 59EBA6B0095; Tue, 14 Jul 2026 06:18:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 2B97D6B0088 for ; Tue, 14 Jul 2026 06:18:05 -0400 (EDT) Received: from smtpin01.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 9AD57C0301 for ; Tue, 14 Jul 2026 10:18:04 +0000 (UTC) X-FDA: 84986981688.01.8E35C06 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) by imf27.hostedemail.com (Postfix) with ESMTP id 8497740003 for ; Tue, 14 Jul 2026 10:18:01 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="YPQmMD0/"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf27.hostedemail.com: domain of usama.arif@linux.dev designates 95.215.58.181 as permitted sender) smtp.mailfrom=usama.arif@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1784024281; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=EDiZS8zttT4a9O025kBB1zOShFsYsLLFK1SisQ6msEY=; b=YXRaHCDE4JvHkCVbrNov9BHMANZG8ekD5XnuK1dOA2D/fAH/Kr9+DnMP/9BPf3KZTQgpKV YIGMVE3KaE94VTX744oS3KuYQMLAXSfmuCTsM8Yc2wfX1kJZAeDNEKGqYlioHpjAHVmaDa QivF2SNpAG8oc1F34/ZOAaw8Lq5r6Sg= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="YPQmMD0/"; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf27.hostedemail.com: domain of usama.arif@linux.dev designates 95.215.58.181 as permitted sender) smtp.mailfrom=usama.arif@linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1784024281; b=aa2rRFceM9Y4OUmEQTSDuEnBFC1ss/cQOxc+xWjrApSB3nYntLfgEtuqksp3UMYiq5+kHx gH4lT2d3nxhPXNvK3R6D4oUgRnbmGxJwSSlOnR4g+GxG5OG+cj50YRg6uj2i6FTM1WUj2N pdN9svOIt32f181kLoyPceocGUcJaiU= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784024278; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EDiZS8zttT4a9O025kBB1zOShFsYsLLFK1SisQ6msEY=; b=YPQmMD0/zTCtgtqVy5SDNK+fsg0BTqTsor+JXyoKqwEfTjG7p9IsJgjJNVeLOLicga3pXM gP9//+7EcPmcJzR94Erhzir6snvi2gfkCwv0wOCWnsrLDd1Hd30WV/lxmMJyKojs/BGpkv I7T1czZ32Ibjv2lEpa1TLNGT4zPUUE8= From: Usama Arif To: Qi Zheng Cc: Usama Arif , brauner@kernel.org, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Al Viro , linux-mm@kvack.org, 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 Subject: Re: [PATCH] fs/super: skip non-memcg-aware nr_cached_objects in memcg slab shrink Date: Tue, 14 Jul 2026 03:17:38 -0700 Message-ID: <20260714101740.1270419-1-usama.arif@linux.dev> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 8497740003 X-Stat-Signature: y9fzy1yfkqp7p1qmufif66ax1wftuic1 X-HE-Tag: 1784024281-357846 X-HE-Meta: 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 PWMLT/BS lSPScJHZ5KZ9ejzb9wDUE2BrCPac/IGulEw+wqZEptthnfqQGhpYyxNTu94PVTyKva+EihlT5Pd+90IOD8j0/eml1NO+tbsEzlrymFCc11mCQt/Qm0cPyvebkcgkl/wEhFiOYcDQMDoMKx88IYo29W6OWwGjlb07pYY6YohbEdSPtSeVgHom3YsdigTspA/tZqlXtBNeE76GEMZ/X9h/xXc20LTSzuakjtt0AzcQYPH+r42zcWTZcd53BDXIMGmAEkL36120soGkGOJA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 14 Jul 2026 10:09:26 +0800 Qi Zheng wrote: > Hi Usama, > > On 7/13/26 11:34 PM, Usama Arif wrote: > > > > > > On 13/07/2026 14:12, Qi Zheng wrote: > >> Hi Usama, > >> > >> On 6/9/26 8:30 PM, Usama Arif wrote: > >>> The super_block shrinker is registered with SHRINKER_MEMCG_AWARE because its > >>> dentry and inode LRUs are memcg-aware (via list_lru). But the optional > >>> ->nr_cached_objects() hooks that the shrinker also drives are not memcg-aware: > >>> btrfs extent maps and xfs inode reclaim operate on filesystem-global > >>> state, and shmem's unused-huge shrinker walks a per-superblock shrinklist. > >>> None of them filter by sc->memcg. > >> > >> This makes sense for now, but how should we handle this if these > >> shrinkers are made memcg-aware in the future? > >> > >> I've recently been working on making the shmem huge shrinker > >> memcg-aware, but noticed my changes broke after rebasing onto the latest > >> tree, which led me to this patch. > >> > >> As for the shmem huge shrinker, I can work around this limitation by > >> making it a separate shrinker. But this feels more like an overall > >> design decision, effectively meaning that all nr_cached_objects are > >> precluded from being memcg-aware. > >> > >> Thanks, > >> Qi > >> > > > > > > Hi Qi, > > > > Thanks for raising this. I think the alternative is what I mentioned in > > https://lore.kernel.org/all/cfdb8620-ea55-4226-98bf-d006820e6270@linux.dev/ > > move this down to the fs own callbacks instead of here. Would that > > be better? > > Yes, I think this is a better approach. > > Later on, shrinkers that are converted to be memcg-aware can lift this > restriction themselves. > > Thanks, > Qi Thanks Qi, I have sent a patch to push it down to filesystems in [1]. No functional change inteneded in there. You would have to rebase your patch on top of that one and remove my code in shmem specifically. [1] https://lore.kernel.org/all/20260714101454.1202449-1-usama.arif@linux.dev/ > > > > > Thanks, > > Usama > >