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 C22CACD8C85 for ; Tue, 9 Jun 2026 07:35:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DEACC6B0088; Tue, 9 Jun 2026 03:35:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DC1F96B008A; Tue, 9 Jun 2026 03:35:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CFECB6B008C; Tue, 9 Jun 2026 03:35:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id C2B166B0088 for ; Tue, 9 Jun 2026 03:35:42 -0400 (EDT) Received: from smtpin04.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 694C3A047C for ; Tue, 9 Jun 2026 07:35:42 +0000 (UTC) X-FDA: 84859564524.04.B4D8C61 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf10.hostedemail.com (Postfix) with ESMTP id BF7B2C0008 for ; Tue, 9 Jun 2026 07:35:40 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=QKM7zKoO; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf10.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1780990540; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=y7BX3CVcz1NCkcZ9VRBH6DdOLwzw/KIRmNNQBjRMkfQ=; b=GGfmna8G5Nf2B7npRmeeLTtNj4s4DhzMj6afi5lI/CbF0Q95NAVnfqbeoY/DvvBbOM9jc4 kdr4629FU/dkxyBcgoN4XxoHPKyuCQakBSEM2EIuqBQp5L5e/OGjmjejZK4hpOJrdxvF5w wM6A2A3rx2tqK/DMxxKsDUCqfTILc/Q= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=QKM7zKoO; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf10.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1780990540; b=ubsTRYgHVCLoXcG6oZ1cyYXNriRcsNJLoEO6RZjqBaPJSX1e0AORfJl3uPpzV0+V37T2a9 LnXi5eu/fmx6fdcSdxW3Yb4+lnBmVkAdVkkuFZ1qXSOGjIOmYHYs6KWNN6wAT2/I07XjBI NFQbX5rq+QDk7bul6DPbc7WxtP71Mvw= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id A511541856; Tue, 9 Jun 2026 07:35:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46D521F00893; Tue, 9 Jun 2026 07:35:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780990539; bh=y7BX3CVcz1NCkcZ9VRBH6DdOLwzw/KIRmNNQBjRMkfQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=QKM7zKoOEGCmMOgjqz22FaKfmugoiB47u0nOGoRF+NOmN4l3nOkdpksy+GKxK4DWw 4WYMWzVXJI9bMUCaTElKkEpgWpCvycuMhBRMi9/Kyc7WnxI/o0F1HEYfT4OJPt2gwV riQ4+si0ZdaOzfmaT5XiUDCG1nF3cyT2H8LjMY2KxQcEhxAM6gjWI59jaAgMxBsZMd /J7YJBXZnPGAhxBqBCDJXfiw3gGo+Y6FCNaomGkb9Yt1KNyfICXjtq8UOOz61RIsXN SCVTcDdXsg9MUCvSC5qXuq6jKSFtShI3F19CxxVnfKCdj013Dw2LsQ4QuwouEHROp4 QJSRvJNsI0rbw== Date: Tue, 9 Jun 2026 08:35:29 +0100 From: Lorenzo Stoakes To: Lance Yang Cc: hannes@cmpxchg.org, baolin.wang@linux.alibaba.com, akpm@linux-foundation.org, david@kernel.org, shakeel.butt@linux.dev, mhocko@kernel.org, david@fromorbit.com, roman.gushchin@linux.dev, muchun.song@linux.dev, qi.zheng@linux.dev, yosry.ahmed@linux.dev, ziy@nvidia.com, liam@infradead.org, usama.arif@linux.dev, kas@kernel.org, vbabka@kernel.org, ryncsn@gmail.com, zaslonko@linux.ibm.com, gor@linux.ibm.com, baohua@kernel.org, dev.jain@arm.com, npache@redhat.com, ryan.roberts@arm.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 9/9] mm: switch deferred split shrinker to list_lru Message-ID: References: <20260609032058.23770-1-lance.yang@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260609032058.23770-1-lance.yang@linux.dev> X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: BF7B2C0008 X-Stat-Signature: afrki8up5ibb3j1nxnb5afhsc88sktqt X-HE-Tag: 1780990540-886482 X-HE-Meta: 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 5+Hc9GBD Q/v9eywjnwyyQrBX6Ep1hPDze5jCCBSBPFkYLO1PgdVS2uvd8ta+KXNa0yE19wT+BHABeMl2s8F8XOsSrd0cMU1oNv9thODXo6m2//F+L2CcTI3O2Hyiw0yKo7DW5kIJSU2GeKnVk5pHKveNw4AMGxhXbwxnpnPMdZAwroSegaqQ9wbeMzJaNXh2KvHZk0uxarsWw1doECrka/jL+IfgX/HT2YytpdqvsSN6O7Tcazra6xOrATW7XWQ/vhMyXcEv10js1Yeg0WUL5mgYqv+IJU4R50QvTHejXoOZZTOguloNEiMRM5TQAarkftJdxui7ZdTKw Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jun 09, 2026 at 11:20:58AM +0800, Lance Yang wrote: > > On Mon, Jun 01, 2026 at 02:17:28PM -0400, Johannes Weiner wrote: > >On Mon, Jun 01, 2026 at 09:21:35PM +0800, Lance Yang wrote: > >> > >> On Wed, May 27, 2026 at 04:45:16PM -0400, Johannes Weiner wrote: > >> [...] > >> >diff --git a/mm/swap_state.c b/mm/swap_state.c > >> >index 04f5ce992401..9c3a5cf99778 100644 > >> >--- a/mm/swap_state.c > >> >+++ b/mm/swap_state.c > >> >@@ -465,6 +465,16 @@ static struct folio *__swap_cache_alloc(struct swap_cluster_info *ci, > >> > return ERR_PTR(-ENOMEM); > >> > } > >> > > >> > >> Shouldn't this be limited to anon swapin? > >> > >> e.g. vmf && vma_is_anonymous(vmf->vma) > >> > >> >+ if (order > 1 && folio_memcg_alloc_deferred(folio)) { > >> > >> __swap_cache_alloc() is also used by shmem direct swapin, so shmem can > >> get here too when handling a large swap entry: > >> > >> shmem_get_folio_gfp() > >> shmem_swapin_folio() > >> shmem_swap_alloc_folio() > >> swapin_sync() > >> swap_cache_alloc_folio() > >> __swap_cache_alloc() > >> folio_memcg_alloc_deferred() > > > >Good catch, I think you're right. I shouldn't have dismissed that > >branch due to "/* Direct swapin skipping swap cache & readahead */" > > > >> @Baolin please correct me if I got it wrong :) > >> > >> folio_memcg_alloc_deferred() itself doesn't filter shmem out either; it > >> only allocates the memcg list_lru metadata for deferred_split_lru: > >> > >> int folio_memcg_alloc_deferred(struct folio *folio) > >> { > >> if (mem_cgroup_disabled()) > >> return 0; > >> return folio_memcg_list_lru_alloc(folio, &deferred_split_lru, GFP_KERNEL); > >> } > >> > >> Since deferred_split_lru only queues anon large folios, doing this for > >> shmem swapin doesn't buy us anything :) > > > >Yes, agreed. I don't think it's a big deal / show stopper in terms of > >user-visible effect, but of course still worth fixing. > > > >I'll send a follow-up patch. > > Thanks. > > Looks like this has already landed in mm-stable. If you're okay with it, > I can send the follow-up. > > From: Lance Yang > Date: Tue, 9 Jun 2026 10:56:45 +0800 > Subject: [PATCH] mm: prepare deferred split metadata only for anon swapin > > __swap_cache_alloc() prepares deferred split metadata for large swapcache > folios. > > That also covers shmem swapin, because shmem_swap_alloc_folio() can call > swapin_sync() with a large order[1]. But shmem folios are not queued on > the deferred split queue, so preparing the metadata doesn't buy us > anything there. > > So let's limit it to anon swapin. > > [1] https://lore.kernel.org/all/20260601132135.14272-1-lance.yang@linux.dev/ > > Signed-off-by: Lance Yang > --- > mm/swap_state.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/swap_state.c b/mm/swap_state.c > index 9c3a5cf99778..7adac957c2b8 100644 > --- a/mm/swap_state.c > +++ b/mm/swap_state.c > @@ -465,7 +465,8 @@ static struct folio *__swap_cache_alloc(struct swap_cluster_info *ci, > return ERR_PTR(-ENOMEM); > } > > - if (order > 1 && folio_memcg_alloc_deferred(folio)) { > + if (order > 1 && vma && vma_is_anonymous(vma) && A folio can be anon for a non-shmem file-backed VMA though? E.g. MAP_PRIVATE-mapped file-backed mappings? Not sure if that's something that'd be a factor here/meaningful though. > + folio_memcg_alloc_deferred(folio)) { > spin_lock(&ci->lock); > __swap_cache_do_del_folio(ci, folio, entry, shadow); > spin_unlock(&ci->lock); > -- > 2.39.3 (Apple Git-146) Cheers, Lorenzo