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 E9FDEC61DB9 for ; Thu, 27 Aug 2026 16:19:26 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6EA566B0088; Thu, 27 Aug 2026 12:19:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 69BA06B008A; Thu, 27 Aug 2026 12:19:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 562A56B008C; Thu, 27 Aug 2026 12:19:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 281CA6B0088 for ; Thu, 27 Aug 2026 12:19:25 -0400 (EDT) Received: from smtpin26.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id A03CD140109 for ; Thu, 27 Aug 2026 16:19:24 +0000 (UTC) X-FDA: 85147559448.26.87302E5 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf13.hostedemail.com (Postfix) with ESMTP id E07EB2000B for ; Thu, 27 Aug 2026 16:19:22 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=COSR07O1; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1787847562; 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=oQK9VCo/irKfPIXKEc3cGBdHJHvWvT42ZgRi4sLaCGA=; b=QyYYQJcWOXumwjpW56c/Lzt4jjXGkZe4znewku6IPZgEDvS+519pJeb9e4vqlws0EeVzxX /afNSnIFTh68oA3nhiXdKIML0quF//g480InE/+iJaHYdFXb0Qma7PN+e6gRXSmwtSL+5g P1tTabuJNu2t2c/0IQD+iiXw29rW1U0= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787847562; b=jL6MDTAuY+XkboiFkfJr4dz69BctQLBAqfAvF8S6ANgjZcNOflm6TuSzyMJIh50BY5lPD+ lthiVHogK5C2aqaOx/DSF9kPSVsHeOWdyMYKvtYwRt4zAF85TCXPP/IxibqrL1tJSe1ICe yXtv+NbylrGZbRMerK+2ZvJ+oNbCu4s= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=COSR07O1; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 2B2C8600D3; Thu, 27 Aug 2026 16:19:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95C251F000E9; Thu, 27 Aug 2026 16:19:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787847561; bh=oQK9VCo/irKfPIXKEc3cGBdHJHvWvT42ZgRi4sLaCGA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=COSR07O1y9vXawm8HIwW9LxygFma/VKVqoPNcX145+K96FfaBJInTFBOjhATg/CN2 Nnjs63s5nnC1BdacteJ+YgvU0mjd28gfSShjoncowGKxW+T9m+i1cBpNsR6G6WzgeC 3IHZ+allCqPbZfG5YNxccc5PKxmLNfIAIUmqXu1ooE2P6GUXc2DItVJln8nL9bBTjH mOKMyCB1fU/szqNcRxBTNRwx2D770iE3Xxx2bE5Gi7au9IE/sujSsBI8tG8SI3xfJJ mh2fmjGxb+4zqGMe1C7ya/Vgz/o/hNb1aRrgA50HG7wFXK5Zl+C4rhzReORrBo01hS 4KykD3YYV9H6Q== Message-ID: Date: Thu, 27 Aug 2026 18:19:14 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 04/18] mm/huge_memory: split the routine for splitting anon and file folio To: kasong@tencent.com, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Chris Li , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , Shivam Kalra , Kairui Song References: <20260821-swap-thp-cleanup-v3-0-9b43f5163238@tencent.com> <20260821-swap-thp-cleanup-v3-4-9b43f5163238@tencent.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260821-swap-thp-cleanup-v3-4-9b43f5163238@tencent.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: E07EB2000B X-Stat-Signature: ib8xpjsw84g16ag5igkfix94q61wa9gi X-HE-Tag: 1787847562-632477 X-HE-Meta: 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 0KzBy1aL y7/Y4m1V9FicnQup+YGEfvQD/sBO3uRCWh2Qk/thOzRm+Ng/l2nIkqiV44Tynr57RikqhslKK9VJrPN1XQageUBDSGC4XdzuscuRATyvkamNqIs5Tzry/qcCr6al0Jx6eg2BXHB33WnuIp5n0gwWGk1JHsiu2OCyChNNMsdK2DJAd7cia9pAcA1l8IXznfymHdWPDeKuWsvDfY4jsXLEXMiFQr04zCr5nftbvzn4ldHggkHIgeXRUfdIPHRuGRygI2I82u2myWj6sZuqub0RCEL9VNUwwuEflXkLzdk/SouoBs4HXKse0zOeJRBhJ5EPi8cJcRM3rqcV+GQA6f41QnanWHR1J5b7JssIETqCHf2mI1AaX5vED0zShB8A41f69PUZqFO9O2w//bFW41dRD5vDzgQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/20/26 20:55, Kairui Song via B4 Relay wrote: > From: Kairui Song > > No functional change intended. Before adding more logic, split > __folio_freeze_and_split_unmapped() into an anon and a file variant so > each path can evolve independently. The two paths shared little beyond > the folio freeze call, the LRU locking, and the unfreeze skeleton, but > differed in all other per-folio bookkeeping and routines. Splitting that up makes sense. > > While splitting, some cleanups become easy to apply, and helped drop a > few now-redundant checks. Also introduce a folio iteration helper to > avoid a common pitfall of iterating post-split sub-folios: a sub folio > might get freed mid-iteration as pointed out by Zi [1]. > > Link: https://lore.kernel.org/linux-mm/DKJSFCLP967N.YBR4DNK1NM2N@nvidia.com/ [1] > Signed-off-by: Kairui Song > --- > mm/huge_memory.c | 119 +++++++++++++++++++++++++++++++++++-------------------- > 1 file changed, 75 insertions(+), 44 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 7fb603ac500f..c3fd6757c14c 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -3933,11 +3933,9 @@ static unsigned int folio_cache_ref_count(const struct folio *folio) > return folio_nr_pages(folio); > } > > -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, > - struct list_head *list, enum split_type split_type, > - pgoff_t end, int *nr_shmem_dropped) > +static int __folio_freeze_split_unmapped_anon(struct folio *folio, unsigned int new_order, > + struct page *split_at, bool do_lru, > + struct list_head *list, enum split_type split_type) Switch to double tab indentation instead while at it. Same for the other function. > { > struct folio *end_folio = folio_next(folio); > struct swap_cluster_info *ci = NULL; > @@ -3948,7 +3946,6 @@ static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int n > bool dequeue_deferred; > int ret = 0; > > - VM_WARN_ON_ONCE(!mapping && end); > /* > * If this folio can be on the deferred split queue, lock out > * the shrinker before freezing the ref. If the shrinker sees > @@ -3956,7 +3953,7 @@ static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int n > * lock and must clean up the LRU state - the same dequeue we > * will do below as part of the split. > */ > - dequeue_deferred = folio_test_anon(folio) && old_order > 1; > + dequeue_deferred = old_order > 1; > if (dequeue_deferred) { > struct mem_cgroup *memcg; > > @@ -3986,24 +3983,72 @@ static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int n > rcu_read_unlock(); > } > > - if (mapping) { > + if (folio_test_swapcache(folio)) > + ci = swap_cluster_get_and_lock(folio); > + > + if (do_lru) > + lruvec = folio_lruvec_lock(folio); > + > + ret = __split_unmapped_folio(folio, new_order, split_at, NULL, > + NULL, split_type); > + > + /* > + * Unfreeze the post-split folios and put them back to the right Why call it "post-split" here when it's "after-split" in the other comment? > + * place. Keep the head @folio frozen until the end: sub entries > + * in swap cache must be updated first, so a concurrent > + * swap_cache_get_folio() cannot return the head folio for a sub > + * entry (folio_try_get() will fail on the head @folio until unfreeze). > + */ > + for (new_folio = folio_next(folio); new_folio != end_folio; > + new_folio = next) { > + next = folio_next(new_folio); > + zone_device_private_split_cb(folio, new_folio); > + folio_ref_unfreeze(new_folio, > + folio_cache_ref_count(new_folio) + 1); > + if (do_lru) > + lru_add_split_folio(folio, new_folio, lruvec, list); > + if (ci) > + __swap_cache_replace_folio(ci, folio, new_folio); > + } This smells like duplicate code now. That should better be factored out? [...] > - zone_device_private_split_cb(folio, NULL); > /* > * Unfreeze @folio only after all page cache entries, which > * used to point to it, have been updated with new folios. > @@ -4075,8 +4105,6 @@ static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int n > > if (do_lru) > lruvec_unlock(lruvec); > - if (ci) > - swap_cluster_unlock(ci); > > return ret; > } > @@ -4230,10 +4258,14 @@ static int __folio_split(struct folio *folio, unsigned int new_order, > ret = -EAGAIN; > goto fail; > } > + ret = __folio_freeze_split_unmapped_file(folio, new_order, split_at, &xas, mapping, > + true, list, split_type, end, > + &nr_shmem_dropped); > + } else { > + ret = __folio_freeze_split_unmapped_anon(folio, new_order, split_at, true, > + list, split_type); > } I was briefly wondering whether shmem folios in the swapcache would now go through __folio_freeze_split_unmapped_anon(). But folio_check_splittable() rejects them. I think we should consider changing all the "if (mapping)" checks there to "is_anon" instead. is_anon implies no mapping and !is_anon implies that we need a mapping. This patch LGTM, but I think we should clean up __folio_split() further. Maybe taht happens in the next patches in this series :) Acked-by: David Hildenbrand (Arm) -- Cheers, David