From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 48EDB43DEC8 for ; Wed, 23 Sep 2026 22:32:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790202755; cv=none; b=YM6DLe2bdcgwZ6ntnh0/oELeyB8hcKx0Pjb7p1vThTdPLmXwjEnAgIuc+QFUW6SPcAZO9MkBIvse8hYR//CV443qNsGmZ/5nclyOEhzXip7IBJxviJwHMwiVm/ZFRqTJLBRC+e4JfD8DayZiGAaKTX1hM97prUN1SPy4MaoSrQc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790202755; c=relaxed/simple; bh=jaaUUiNFX5brIxx0H3MkJw9z0Jqu1GB0qY4e1WxD1dE=; h=Date:To:From:Subject:Message-Id; b=raknNJz8gZRzndrXGTaeDi+LzH5roSoeQVl4FHjmmQO1rRyCONFABxl4oHaSK0eBFVJyWUJK5O1l/KU62VdEzL7t4VFFLg9GDJSWrRQDK4Zw6/JRT/vGsRhXwtmuD5UdHeob9azFe743lCQW5aUAE+G7/v1CqzgE8bThXgssWVQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=xY/vxbzD; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="xY/vxbzD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6BED41F00898; Wed, 23 Sep 2026 22:32:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1790202750; bh=ic7RsW/DO7xvOIaCwtYt0naG1tdYWS80Gm3RVYOPYqk=; h=Date:To:From:Subject; b=xY/vxbzD6zyz6e1S70M1oTD5XdZPUvC5cZLxR2F4WLviVIBnqNMaMdPiu6/Ru7AQa JsYh6A+SsntZsv75VMIGN64i4M3U/RZaAFrcuQGaCOnz9tskj8zHZk/sGSlR/Sdy8M DRsimYM94ryNjj2qiCp9RvnWGEE9uTvuft470a0U= Date: Wed, 23 Sep 2026 15:32:30 -0700 To: mm-commits@vger.kernel.org,kasong@tencent.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-huge_memory-split-the-routine-for-splitting-anon-and-file-folio.patch added to mm-unstable branch Message-Id: <20260923223230.6BED41F00898@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/huge_memory: split the routine for splitting anon and file folio has been added to the -mm mm-unstable branch. Its filename is mm-huge_memory-split-the-routine-for-splitting-anon-and-file-folio.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-huge_memory-split-the-routine-for-splitting-anon-and-file-folio.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Kairui Song Subject: mm/huge_memory: split the routine for splitting anon and file folio Date: Wed, 23 Sep 2026 23:32:35 +0200 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. While splitting, some cleanups become easy to apply, and helped drop a few now-redundant checks. The zone_device_private_split_cb() calls are only kept in the anon variant, as device private folios can only back anonymous memory, and add a VM_WARN_ON_ONCE_FOLIO() at the entry of the file variant. Link: https://lore.kernel.org/20260923-swap-thp-cleanup-v6-4-ba1b4ba72c6f@tencent.com Signed-off-by: Kairui Song Signed-off-by: Andrew Morton Acked-by: David Hildenbrand (Arm) Reviewed-by: Zi Yan Reviewed-by: Yeoreum Yun Reviewed-by: Kiryl Shutsemau (Meta) Cc: Lorenzo Stoakes Cc: Baolin Wang Cc: Liam R. Howlett Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Lance Yang Cc: Usama Arif Cc: Vlastimil Babka Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Michal Hocko Cc: Chris Li Cc: Kemeng Shi Cc: Nhat Pham Cc: Baoquan He Cc: Barry Song Cc: Youngjun Park Cc: Shivam Kalra Cc: Kairui Song --- mm/huge_memory.c | 124 ++++++++++++++++++++++++++++----------------- 1 file changed, 78 insertions(+), 46 deletions(-) --- a/mm/huge_memory.c~mm-huge_memory-split-the-routine-for-splitting-anon-and-file-folio +++ a/mm/huge_memory.c @@ -4007,11 +4007,9 @@ static void folio_reset_partially_mapped 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, - struct list_head *list, enum split_type split_type, - pgoff_t end, int *nr_shmem_dropped) +static int __folio_freeze_split_anon(struct folio *folio, + unsigned int new_order, struct page *split_at, bool do_lru, + struct list_head *list, enum split_type split_type) { struct folio *end_folio = folio_next(folio); struct swap_cluster_info *ci = NULL; @@ -4019,8 +4017,6 @@ static int __folio_freeze_and_split_unma struct lruvec *lruvec; int ret = 0; - VM_WARN_ON_ONCE(!mapping && end); - if (!folio_ref_freeze(folio, folio_cache_ref_count(folio) + 1)) return -EAGAIN; @@ -4035,24 +4031,75 @@ static int __folio_freeze_and_split_unma */ folio_reset_partially_mapped(folio); - 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 after-split folios and put them back to the right + * 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); + } + + zone_device_private_split_cb(folio, NULL); + folio_ref_unfreeze(folio, folio_cache_ref_count(folio) + 1); + + if (do_lru) + lruvec_unlock(lruvec); + if (ci) + swap_cluster_unlock(ci); + + return ret; +} + +static int __folio_freeze_split_file(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) +{ + struct folio *end_folio = folio_next(folio); + struct folio *new_folio, *next; + struct lruvec *lruvec; + int ret; + + /* Currently device private folios can only back anonymous memory. */ + VM_WARN_ON_ONCE_FOLIO(folio_is_device_private(folio), folio); + + if (!folio_ref_freeze(folio, folio_cache_ref_count(folio) + 1)) + return -EAGAIN; + + if (folio_test_pmd_mappable(folio) && + new_order < HPAGE_PMD_ORDER) { int nr = folio_nr_pages(folio); - if (folio_test_pmd_mappable(folio) && - new_order < HPAGE_PMD_ORDER) { - if (folio_test_swapbacked(folio)) { - lruvec_stat_mod_folio(folio, - NR_SHMEM_THPS, -nr); - } else { - lruvec_stat_mod_folio(folio, - NR_FILE_THPS, -nr); - } + if (folio_test_swapbacked(folio)) { + lruvec_stat_mod_folio(folio, + NR_SHMEM_THPS, -nr); + } else { + lruvec_stat_mod_folio(folio, + NR_FILE_THPS, -nr); } } - if (folio_test_swapcache(folio)) - ci = swap_cluster_get_and_lock(folio); - /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ if (do_lru) lruvec = folio_lruvec_lock(folio); @@ -4062,7 +4109,7 @@ static int __folio_freeze_and_split_unma /* * Unfreeze after-split folios and put them back to the right - * list. @folio should be kept frozon until page cache + * list. @folio should be kept frozen until page cache * entries are updated with all the other after-split folios * to prevent others seeing stale page cache entries. * As a result, new_folio starts from the next folio of @@ -4072,29 +4119,15 @@ static int __folio_freeze_and_split_unma new_folio = next) { unsigned long nr_pages = folio_nr_pages(new_folio); + /* compute next before the folio can be freed below */ 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); - /* - * Anonymous folio with swap cache. - * NOTE: shmem in swap cache is not supported yet. - */ - if (ci) { - __swap_cache_replace_folio(ci, folio, new_folio); - continue; - } - - /* Anonymous folio without swap cache */ - if (!mapping) - continue; - /* Add the new folio to the page cache. */ if (new_folio->index < end) { __xa_store(&mapping->i_pages, new_folio->index, @@ -4113,7 +4146,6 @@ static int __folio_freeze_and_split_unma folio_put_refs(new_folio, nr_pages); } - 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. @@ -4125,9 +4157,6 @@ static int __folio_freeze_and_split_unma if (do_lru) lruvec_unlock(lruvec); - if (ci) - swap_cluster_unlock(ci); - return ret; } @@ -4269,7 +4298,10 @@ static int __folio_split(struct folio *f /* block interrupt reentry in xa_lock and spinlock */ local_irq_disable(); - if (mapping) { + if (is_anon) { + ret = __folio_freeze_split_anon(folio, new_order, split_at, + true, list, split_type); + } else { /* * Check if the folio is present in page cache. * We assume all tail are present too, if folio is there. @@ -4280,10 +4312,11 @@ static int __folio_split(struct folio *f ret = -EAGAIN; goto fail; } + ret = __folio_freeze_split_file(folio, new_order, split_at, &xas, mapping, + true, list, split_type, end, + &nr_shmem_dropped); } - ret = __folio_freeze_and_split_unmapped(folio, new_order, split_at, &xas, mapping, - true, list, split_type, end, &nr_shmem_dropped); fail: if (mapping) xas_unlock(&xas); @@ -4383,9 +4416,8 @@ int folio_split_unmapped(struct folio *f return -EAGAIN; local_irq_disable(); - ret = __folio_freeze_and_split_unmapped(folio, new_order, &folio->page, NULL, - NULL, false, NULL, SPLIT_TYPE_UNIFORM, - 0, NULL); + ret = __folio_freeze_split_anon(folio, new_order, &folio->page, + false, NULL, SPLIT_TYPE_UNIFORM); local_irq_enable(); return ret; } _ Patches currently in -mm which might be from kasong@tencent.com are mm-memcontrol-move-the-lru_zone_size-sanity-check-to-the-reader-side.patch mm-mglru-introduce-helpers-for-manipulating-gen-and-refs-flags.patch mm-migrate-copy-all-referenced-state-via-folio_migrate_lru_refs.patch mm-mglru-move-max_seq-read-into-walk_update_folio.patch mm-mglru-use-explicit-tier-range-in-read_ctrl_pos.patch mm-mglru-fix-potential-generation-folio-number-leak.patch mm-swap-fix-off-by-one-in-swap-cache-replace-sanity-check.patch mm-huge_memory-fix-rejection-of-swap-cache-folios-with-a-mapping.patch mm-huge_memory-invert-folio_ref_freeze-check-to-reduce-indentation.patch mm-huge_memory-split-the-routine-for-splitting-anon-and-file-folio.patch mm-huge_memory-rename-__split_unmapped_folio-to-__split_frozen_folio.patch mm-huge_memory-consolidate-irq-and-locking-for-folio-split.patch mm-huge_memory-move-eof-trimming-into-the-file-split-helper.patch mm-huge_memory-move-unmap-and-remap-into-the-split-helpers.patch mm-huge_memory-rename-remap_page-to-remap_anon_folio.patch mm-huge_memory-move-the-racy-refcount-check-into-unmap_folio.patch mm-huge_memory-move-filemap-management-into-the-file-split-helper.patch mm-huge_memory-move-anon_vma-handling-into-the-anon-split-helper.patch mm-huge_memory-move-memcg-switch-into-the-file-split-helper.patch mm-huge_memory-drop-the-unused-do_lru-argument-of-the-file-split-helper.patch mm-huge_memory-clean-up-after-split-folio-freeing-in-__folio_split.patch mm-huge_memory-count-only-swap-cache-refs-in-anon-folio-split.patch mm-huge_memory-drop-the-redundant-mapping-argument-of-__split_frozen_folio.patch