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 048B2C79FA0 for ; Tue, 8 Sep 2026 09:25:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E5EE56B00AE; Tue, 8 Sep 2026 05:25:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E36466B00AF; Tue, 8 Sep 2026 05:25:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D4BE56B00B0; Tue, 8 Sep 2026 05:25:20 -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 B5CDA6B00AE for ; Tue, 8 Sep 2026 05:25:20 -0400 (EDT) Received: from smtpin15.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 248A8120493 for ; 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a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788859515; b=BheFZgnKFYnA3XgbFa6kYf4FnqOJhXnIe9LdwuSqFEzr/5ynwvA16Tw6qmUVKN/oE79uaG VuKTd5OaPtXD8RcV9j+U9LUVy1HZ+743rLk/jBslSJgHfYiHiMBej+aan8Pr78DQ/3T4DE 4r+VZReLl4ivfZTeT/HsWamxfq/OE/4= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf20.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 1874E60A97; Tue, 8 Sep 2026 09:25:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B5F51F00A3F; Tue, 8 Sep 2026 09:25:10 +0000 (UTC) Date: Tue, 8 Sep 2026 10:25:07 +0100 From: "Lorenzo Stoakes (ARM)" To: Kiryl Shutsemau Cc: akpm@linux-foundation.org, david@kernel.org, ziy@nvidia.com, hannes@cmpxchg.org, usama.arif@linux.dev, lance.yang@linux.dev, baolin.wang@linux.alibaba.com, liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, kasong@tencent.com, hughd@google.com, balbirs@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, "Kiryl Shutsemau (Meta)" Subject: Re: [PATCH] mm/huge_memory: add folio_reset_partially_mapped() Message-ID: References: <20260907183340.1446132-1-kirill@shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260907183340.1446132-1-kirill@shutemov.name> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 86E671C0006 X-Stat-Signature: c9a3d6y3s6r4fd4zu6ujc9r4ta9una9q X-Rspam-User: X-HE-Tag: 1788859515-824705 X-HE-Meta: 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 yLSo0Agd IUG7rsxuTotk5O+P2tTYXJ3CMG+pUngNfZi7cjWnHnqCjJ2waHEY2UkjeDAzVL2NLqL2XvTJqAJ0ORBLrnNJg0S7I3iHKPvcRycy0t73aXbZC8wKfcdEHzez/xlrH3MU6Xusp2ZdK2mTDIrt2DE6LGbRyxiY3GQm3Cbtj4K8PLydO8sUzbhWGMfZqyFrbbwimPv6ag29jarfzb5mQANq8mQfR5FS74h9qcfms9HiLasMLztOzKnR0JGULsg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 07, 2026 at 07:33:40PM +0100, Kiryl Shutsemau wrote: > From: "Kiryl Shutsemau (Meta)" > > __folio_unqueue_deferred_split() and __folio_freeze_and_split_unmapped() > both clear PG_partially_mapped and take the folio out of > MTHP_STAT_NR_ANON_PARTIALLY_MAPPED with the same five lines. > > Move the block into folio_reset_partially_mapped() and call it from both > places. > > The helper asserts what both callers rely on: the folio is frozen, so > deferred_split_folio() cannot set the flag again under it, and the folio > is already off the deferred split queue. The list check sits behind the > flag test because order-1 folios have no _deferred_list. > > folio_order() is safe to use at this point in the split process: it > still shows the pre-split order. > > Suggested-by: David Hildenbrand (Arm) > Assisted-by: Claude-Code:claude-fable-5-1 Note that policy has changed on Assisted-by tags so this should be: Assisted-by: LLM https://docs.kernel.org/process/coding-assistants.html > Signed-off-by: Kiryl Shutsemau (Meta) One nit above and below, with those addressed LGTM, so: Reviewed-by: Lorenzo Stoakes (ARM) > --- > mm/huge_memory.c | 31 ++++++++++++++++++++----------- > 1 file changed, 20 insertions(+), 11 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index dd66c6ad5af1..23ef22c2b5db 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -3972,6 +3972,24 @@ static unsigned int folio_cache_ref_count(const struct folio *folio) > return folio_nr_pages(folio); > } > > +static void folio_reset_partially_mapped(struct folio *folio) > +{ > + VM_WARN_ON_FOLIO(folio_ref_count(folio), folio); NIT: I wonder if we could have a folio_is_frozen() that'd make this self-documenting? As trivial as it'd be :) If not, then a comment like: /* Folio must be frozen. */ Would be helpful. > + > + if (!folio_test_partially_mapped(folio)) > + return; > + > + /* > + * Order-1 folios have no _deferred_list. The flag is only ever set > + * on folios that do, so the list can be checked after the flag. > + */ > + VM_WARN_ON_FOLIO(!list_empty(&folio->_deferred_list), folio); > + > + folio_clear_partially_mapped(folio); > + mod_mthp_stat(folio_order(folio), > + MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); > +} > + > static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int new_order, > struct page *split_at, struct xa_state *xas, > struct address_space *mapping, bool do_lru, > @@ -3980,7 +3998,6 @@ static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int n > { > struct folio *end_folio = folio_next(folio); > struct folio *new_folio, *next; > - int old_order = folio_order(folio); > int ret = 0; > > VM_WARN_ON_ONCE(!mapping && end); > @@ -3998,11 +4015,7 @@ static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int n > * leaves PG_partially_mapped set. > * Clear it here: the flag does not survive the split. > */ > - if (folio_test_partially_mapped(folio)) { > - folio_clear_partially_mapped(folio); > - mod_mthp_stat(old_order, > - MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); > - } > + folio_reset_partially_mapped(folio); > > if (mapping) { > int nr = folio_nr_pages(folio); > @@ -4516,11 +4529,7 @@ bool __folio_unqueue_deferred_split(struct folio *folio) > memcg = folio_memcg(folio); > lru = list_lru_lock_irqsave(&deferred_split_lru, nid, &memcg, &flags); > if (__list_lru_del(&deferred_split_lru, lru, &folio->_deferred_list, nid)) { > - if (folio_test_partially_mapped(folio)) { > - folio_clear_partially_mapped(folio); > - mod_mthp_stat(folio_order(folio), > - MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); > - } > + folio_reset_partially_mapped(folio); Nice bit of red :) > unqueued = true; > } > list_lru_unlock_irqrestore(lru, &flags); > > base-commit: e3fc12b08aadde9cec7b3799ac0e0c9a1aa245c4 > -- > 2.54.0 > -- Cheers, Lorenzo