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 B38B42ED154 for ; Tue, 15 Sep 2026 00:45:04 +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=1789433107; cv=none; b=twRZajkYKgl4LaqwCy11MY/QZK4RQ6OPokP3izS6sKbLxcxi5l3yyRdQORcTwsFIBHUJYOEw/V9War0Rx6L7ioK4jj8aLY9PgbaQke3QmqF3GQq/VKLpKw6fBNQIeAwR3Cb8lZdifdje4xKog3klABgqB0HcSKxids+TTGaPwxo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789433107; c=relaxed/simple; bh=szYpvO/Y5PUoWd1BoTRrROgTol1/OHr+bGDrtFSHzAU=; h=Date:To:From:Subject:Message-Id; b=fKHJbCStIoVTqx2zI/cIKwPkZQuPMhXbdVkhDh/GkTCcfHDM87dyuK2JWpx6mPHhGBHysr54FKdMqN1hGN4a/p27fYTI5wwYv5G+UCrkcMd4YGsG7pChI8gV+76mSFHkGVFj4C2fPCmXAGt86zRlzCXTa3IiQEBRCE1e6qe0UPM= 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=STz5EG8i; 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="STz5EG8i" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B67F1F000FF; Tue, 15 Sep 2026 00:45:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789433104; bh=KQMW8EH5VGj4RR2Ehy6p1Aj66lKGQ5ycxSBfh342ATA=; h=Date:To:From:Subject; b=STz5EG8ieqLNM/BkwAptulHwyblTnhYfQC2dllnHOSbAO2tvroJTX0B492aes+giw Q9iYxqfqkMmYsHi22TY11o4pp0RogAfTrLMmUJsd9omPwOQ1FaZOTtVDhd2ajlDMAJ EuFjAiLh++5WVtFN6S9176aPAExTxdIg4Pnt5NTM= Date: Mon, 14 Sep 2026 17:45:03 -0700 To: mm-commits@vger.kernel.org,kasong@tencent.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-huge_memory-consolidate-irq-and-locking-for-folio-split.patch added to mm-new branch Message-Id: <20260915004504.3B67F1F000FF@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: consolidate irq and locking for folio split has been added to the -mm mm-new branch. Its filename is mm-huge_memory-consolidate-irq-and-locking-for-folio-split.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-consolidate-irq-and-locking-for-folio-split.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next 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: consolidate irq and locking for folio split Date: Tue, 15 Sep 2026 01:14:47 +0800 Let each split helper handle its own locking instead of relying on the caller, so both helpers manage their own irq and locking state. This lets __folio_split() drop its local irq handling and fail label, preparing for further cleanup. The file path now uses xas_lock_irq() instead of local_irq_disable() with xas_lock(). The two are equivalent on non-RT, and TRANSPARENT_HUGEPAGE cannot be enabled on RT anyway. This conversion also buys consistency: every other place in mm/ that freezes a folio while it is still reachable through the page cache already takes the lock this way. This was actually the last plain xas_lock() on mapping->i_pages left in mm. If we are going to support RT, spinning on frozen folio refs could be a problem, but it already exists in many places and should be fixed generically. The anon helper keeps a single local_irq_disable() as before, because it has to cover several plain spinlocks at once. The dropped xas_reset() was a no-op as the xa_state is not walked before the xas_load() under the lock. Link: https://lore.kernel.org/20260915-swap-thp-cleanup-v5-6-39878b37dfb0@tencent.com Signed-off-by: Kairui Song Signed-off-by: Andrew Morton Reviewed-by: Zi Yan Reviewed-by: Kiryl Shutsemau (Meta) Reviewed-by: Yeoreum Yun Acked-by: David Hildenbrand (Arm) Cc: Baolin Wang Cc: Baoquan He Cc: Barry Song Cc: Chris Li Cc: Dev Jain Cc: Kemeng Shi Cc: Lance Yang Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Nhat Pham Cc: Ryan Roberts Cc: Suren Baghdasaryan Cc: Vlastimil Babka --- mm/huge_memory.c | 58 ++++++++++++++++++++------------------------- 1 file changed, 27 insertions(+), 31 deletions(-) --- a/mm/huge_memory.c~mm-huge_memory-consolidate-irq-and-locking-for-folio-split +++ a/mm/huge_memory.c @@ -4021,8 +4021,12 @@ static int __folio_freeze_split_anon(str struct lruvec *lruvec; int ret = 0; - if (!folio_ref_freeze(folio, folio_cache_ref_count(folio) + 1)) + local_irq_disable(); + + if (!folio_ref_freeze(folio, folio_cache_ref_count(folio) + 1)) { + local_irq_enable(); return -EAGAIN; + } /* Take off the deferred split queue while frozen and memcg set */ folio_unqueue_deferred_split(folio); @@ -4070,6 +4074,7 @@ static int __folio_freeze_split_anon(str lruvec_unlock(lruvec); if (ci) swap_cluster_unlock(ci); + local_irq_enable(); return ret; } @@ -4088,8 +4093,21 @@ static int __folio_freeze_split_file(str /* 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; + xas_lock_irq(xas); + + /* + * Check if the folio is present in page cache. + * We assume all tail are present too, if folio is there. + */ + if (xas_load(xas) != folio) { + ret = -EAGAIN; + goto fail; + } + + if (!folio_ref_freeze(folio, folio_cache_ref_count(folio) + 1)) { + ret = -EAGAIN; + goto fail; + } if (folio_test_pmd_mappable(folio) && new_order < HPAGE_PMD_ORDER) { @@ -4161,6 +4179,8 @@ static int __folio_freeze_split_file(str if (do_lru) lruvec_unlock(lruvec); +fail: + xas_unlock_irq(xas); return ret; } @@ -4300,32 +4320,13 @@ static int __folio_split(struct folio *f unmap_folio(folio); - /* block interrupt reentry in xa_lock and spinlock */ - local_irq_disable(); - if (is_anon) { + 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. - */ - xas_lock(&xas); - xas_reset(&xas); - if (xas_load(&xas) != folio) { - ret = -EAGAIN; - goto fail; - } + else ret = __folio_freeze_split_file(folio, new_order, split_at, &xas, mapping, true, list, split_type, end, &nr_shmem_dropped); - } - -fail: - if (mapping) - xas_unlock(&xas); - - local_irq_enable(); if (nr_shmem_dropped) shmem_uncharge(mapping->host, nr_shmem_dropped); @@ -4409,8 +4410,6 @@ out_no_memcg: */ int folio_split_unmapped(struct folio *folio, unsigned int new_order) { - int ret = 0; - VM_WARN_ON_ONCE_FOLIO(folio_mapped(folio), folio); VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio); VM_WARN_ON_ONCE_FOLIO(!folio_test_large(folio), folio); @@ -4419,11 +4418,8 @@ int folio_split_unmapped(struct folio *f if (folio_expected_ref_count(folio) != folio_ref_count(folio) - 1) return -EAGAIN; - local_irq_disable(); - ret = __folio_freeze_split_anon(folio, new_order, &folio->page, - false, NULL, SPLIT_TYPE_UNIFORM); - local_irq_enable(); - return ret; + return __folio_freeze_split_anon(folio, new_order, &folio->page, + false, NULL, SPLIT_TYPE_UNIFORM); } /* _ 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