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 EEEF0CD8CAD for ; Tue, 9 Jun 2026 08:03:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5FEA26B0088; Tue, 9 Jun 2026 04:03:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5D55C6B0092; Tue, 9 Jun 2026 04:03:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4EB456B0093; Tue, 9 Jun 2026 04:03:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 3E1D56B0088 for ; Tue, 9 Jun 2026 04:03:11 -0400 (EDT) Received: from smtpin14.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id E0E1E1204D0 for ; Tue, 9 Jun 2026 08:03:10 +0000 (UTC) X-FDA: 84859633740.14.E333A33 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) by imf09.hostedemail.com (Postfix) with ESMTP id 4CB5C140007 for ; Tue, 9 Jun 2026 08:03:07 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="jRsT/4aB"; spf=pass (imf09.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.188 as permitted sender) smtp.mailfrom=lance.yang@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=1780992189; b=hcinwgnlYSTzFHbPZb+eusdzg5T6g/u2xqUQtDvvzMsyKm3mF35hMVsI/YcluTtRHu6LLF ygJ7XDHKCEHGR6iHB47C56ioXdbd9OdrYIcPabqXP6B35c1oGcomWynEQXwQ5dXcJ2z/Yf gQLaf3lCOvAeO0+5KP3zvMuepM+2338= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="jRsT/4aB"; spf=pass (imf09.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.188 as permitted sender) smtp.mailfrom=lance.yang@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=1780992189; 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=AUcVuWAo1N6d6dSjCQRntUYShy5LQAwX8omMTfd5mYY=; b=HrX5s1VnVHLHUVivfIlj7g67Qt6ew2dHdqB7lDXSuYC1Jn/YqYXJv27PJCrlS8jhKkG528 rncBkTDaixY2qwK8fPM4HfcQaFuQP6j9tt1ADartmVim9jobCerHdI3TkoM+2881VyxlnV fWC1BEmslrTJ1mr29is8cZigoB9NZMs= Message-ID: <3306b3b4-a063-43f9-a740-2311dd87be3c@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1780992180; 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=AUcVuWAo1N6d6dSjCQRntUYShy5LQAwX8omMTfd5mYY=; b=jRsT/4aBlYtkb7QyMASuQsaRCIGhVQN28SEQahPXRkP6GdrPmLYHyV3FPEJEvccUtoUjgS bqwbEEfE3urBD6PIGshjjfBeQMLGqIgDhPHFvxB1Pdzq/taY9MywfQfbiAgh8BaO4tcAgd CgI1a9LIBP+8p3ujctXEZz1NlV8s3XI= Date: Tue, 9 Jun 2026 16:02:46 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v5 9/9] mm: switch deferred split shrinker to list_lru To: Lorenzo Stoakes 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 References: <20260609032058.23770-1-lance.yang@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Lance Yang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 4CB5C140007 X-Rspam-User: X-Stat-Signature: hhd94bm3hq4xt8cxeufmekj88ncnxhyz X-HE-Tag: 1780992187-326999 X-HE-Meta: U2FsdGVkX19UTtxcdziP3T3EWOu5jXcQqEv6w1w5a6MRHVrnmJBkxJdxuB5rlw8SKcpoxGPNiFXKa5D8jSU0ikkd/ws/uP8EhVxI+eytM3cGmkNXv4KFHjurbj+T1R3XsANo2LRhMHZe4GmwlVLblbXrF7sr9dUMMBRlQSFGm+X3xMzRzjSemU8OhQIAtGWr+dSW7QYZZg6g1Nrwdaez/k/i5sQ6R6b6d6jqjbdds20C9/aL7v1fFiF2GKxOACeWPmx4nYHZ/7duiYIcTINCrfi1O2g6ydXM0SaZyFzKqL/r5ZdeKXkWwfS5/5PLSY/dgOoa2ZotOorNzIRUQDaEaVZKbAbrM/V/d2OhqtjVMLrbauht/oUxw012An2SvTJNKRubOaXIeQFSESOeF/4n5Y12a4/AZJ5wvFllSwuRpp83ul9V9UkCPwMrPIQgI/Fv/xYfoPzu3voYvet6TZ4gkrI4lFQSh7MFyAhocuR89ZsFm1XZKIjK0hpztk+cpyzDto/aqlg9I+VJMn12ygAx92SSkOe8dV+Jbz2v1/Z9sg3BmEZJB6W67x4YKiBghFHD8OcnkQ6dV3gCMMhfNHUnfAAVkkMT0/00LqKjWND+mBQ3qFngLeyENmvrBKzrWl/1AYjjzrc7cKSDHccPeEDx2zM4yXACU7AHDXQ6/fBKAIurrRtjyumgIPjYufcdLhgEIu/++tF1ma3Dy4Zemc3LU2RFHeCKTdsK7jg5QVxL5h5WftHvi2eaZnaEQhHmFESPC4IFoWT2ZYQ/nYTznMVLC5BV6cpWu9UsiB0bk1eXLYlcUaVwcckn5W/ISQZ71wS0utNqjMpca3b39CvAaqcPk6mWH+FnzkOq94pcarfl9BSrFqVa8nkH6l59TPTgJXGEtFKgiYPh2mU6IGItJt7oHT4p9Q3ZnRV25M4jH7en5kRGV66THL5SttwoVhuXwGTa7fYNaMtkxDSxnHp8gNG JBNKLE1e k5f1fdhioDTcbPGYb3P4lgVQsSMwMGcN67dNALGRFyzkYOGe/3o03Woqyv1MRjSsjhCXnrbOTNvQU7MUyBscFLyPoS3Z5HBfEJzkX8ngATcSg+dDEJJmwxS+kNCi1cfuROrzUARyHSD63zYnAavK2e/aBuV/szsCPhP3FhVn6c9RzqZOgCYDqasigK3+ic7CGXJmdq3DaXIGgcC0B8WNKiH9/EQs7iYaAM/Ze9eaOC64YgCizBR9lp/weuVLNn8HfzEkwuO8bnR8v4zVW8TvNgD3v/Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026/6/9 15:35, Lorenzo Stoakes wrote: > 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? Ah, good point! vma_is_anonymous() is too strong here ... Maybe use !vma_is_shmem(vma) instead? > 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