From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-173.mta1.migadu.com (out-173.mta1.migadu.com [95.215.58.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0136337D10A for ; Tue, 14 Jul 2026 02:10:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783995016; cv=none; b=q5w78aYgoxVQPsJ81+lO5ztjCr6usTDH8myo7ljJxHqmNGq9+ZPhpqhUquXrxhNTuzodHV6xy/3/NmXy148aD90z4+e5VJIMU9FVbXHtleKPrt5ksUPTv4Gt8rUiQFFJkPL2q7eL4mtWfJXGLtB5vl8kIGguh6MtGDrSmCbGlpA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783995016; c=relaxed/simple; bh=b1VaFDW/vJ6wqPMInCCKdkHSqzW6apkl8NBOxKd9a6c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=R1tpcWOvUOHjbZjsPFdiUVdOf99EoAn1M8I0y+GF8UMLJyFAiuQTY33GvH+xeNJM701f+e4StmJRFVeQ0nTmjwk0Gt9Wz3YR/7ZTG1mK8PALoXuK05LQS+HAc+HaBKq50VqQpbgIBkW6udotYuqX4oeSl2TxtTbazv32W/dsfYM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=pOTIrFDv; arc=none smtp.client-ip=95.215.58.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="pOTIrFDv" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1783994996; 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=Oe29OFRdQWxJG3Qa1xsqDVWRullOweBuH8zwQOt47ZU=; b=pOTIrFDv42shfz0GqiuCI0/zTy5N++vrqD4K3ff7oohYi86VnOG9XBajIscXw1p+JVsfbO 0X1+teKSyDwqVoKUvlT4KGfdQHHrzM7cMtJy5FntL1v+23Hjb491lk9x1zAlbb6iHwMMl5 mAiHSfrz4kFTtflqlSt/VVu2EBvFe+g= Date: Tue, 14 Jul 2026 10:09:26 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH] fs/super: skip non-memcg-aware nr_cached_objects in memcg slab shrink 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: <20260609123047.1948242-1-usama.arif@linux.dev> <4752c658-7b61-4636-ab5b-bd172e11a42c@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT 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, > Usama