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 A030A57F726 for ; Wed, 23 Sep 2026 22:23:20 +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=1790202201; cv=none; b=mSOGy7nEFTVYtTCAQzQBAaXqNSXNBrBQoyVuDSlOZ3ncrkOmOUUK68iAhOI8/vEHuhrN3buSQR6dZDiGmxSlngrDPp/Z2DavD1T29RgOMlqkzXl7gNW56qB2E3tmL3dpzLls3xk7mtzveADhdTVw6X6ziRNwD52azZ95xkkvz6E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790202201; c=relaxed/simple; bh=Gd6aer2FbDUom4Wp+92AogIzgr/+HnmrJhEOHmlL/0U=; h=Date:To:From:Subject:Message-Id; b=NUflzWkSCygHM8wN7IVi8Y0Zz3wbBg1O8w9nfeo3nVJ8goQL5WWdbn/dMyNqj6G06wl+YNkydl7VTrYM6eGTvhQob57sAymvXXeoa0zPpza9zumHPwC4l2DAP6t+mheMRRaIJsID97oCsNUT9eWnmgPREwcVPrSh1qy1vPIkhLE= 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=mTB7U4FQ; 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="mTB7U4FQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 777091F000FF; Wed, 23 Sep 2026 22:23:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1790202200; bh=rWlz9FllOE2H47YcqNIIpVJFSdWbg7WqEs5em2L2v2w=; h=Date:To:From:Subject; b=mTB7U4FQ2cBZIQNjC/oBdc/7hvuG7iFst3rSdbmRPZzDcQl+bEOI8xQTFuXMk4eH2 GKq/m+p5BN3JPKnI4FWWWquBm3JjTmcilfmpFhAHipoyUHwjkQCeSYJKVMNspVqCJ6 3EvdguJlcb87AsSpxGVJDjIJpASggkB0uDaK1s3U= Date: Wed, 23 Sep 2026 15:23:20 -0700 To: mm-commits@vger.kernel.org,kasong@tencent.com,akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] mm-huge_memory-move-the-racy-refcount-check-into-unmap_folio.patch removed from -mm tree Message-Id: <20260923222320.777091F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/huge_memory: move the racy refcount check into unmap_folio() has been removed from the -mm tree. Its filename was mm-huge_memory-move-the-racy-refcount-check-into-unmap_folio.patch This patch was dropped because an updated version will be issued ------------------------------------------------------ From: Kairui Song Subject: mm/huge_memory: move the racy refcount check into unmap_folio() Date: Tue, 15 Sep 2026 01:14:51 +0800 The check only exists to avoid the expensive PMD-splitting unmap of a folio that cannot be split anyway. Move it from __folio_split() into unmap_folio(), right before the PMD split, so both the anon and file split helpers get the early check without repeating it. unmap_folio() now returns -EAGAIN if the check fails and the split helpers propagate the error. folio_split_unmapped() drops its own copy of the check: it works on already unmapped folios and the definitive folio_ref_freeze() in __folio_freeze_split_anon() still catches unexpected references. Link: https://lore.kernel.org/20260915-swap-thp-cleanup-v5-10-39878b37dfb0@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 | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) --- a/mm/huge_memory.c~mm-huge_memory-move-the-racy-refcount-check-into-unmap_folio +++ a/mm/huge_memory.c @@ -3538,13 +3538,17 @@ void vma_adjust_trans_huge(struct vm_are split_huge_pmd_if_needed(next, end); } -static void unmap_folio(struct folio *folio) +static int unmap_folio(struct folio *folio) { enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SYNC | TTU_BATCH_FLUSH; VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); + /* Racy check if we can split the page, before we split PMDs */ + if (folio_expected_ref_count(folio) != folio_ref_count(folio) - 1) + return -EAGAIN; + if (folio_test_pmd_mappable(folio)) ttu_flags |= TTU_SPLIT_HUGE_PMD; @@ -3559,6 +3563,8 @@ static void unmap_folio(struct folio *fo try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); try_to_unmap_flush(); + + return 0; } static bool __discard_anon_folio_pmd_locked(struct vm_area_struct *vma, @@ -4029,7 +4035,9 @@ static int __folio_freeze_split_anon(str if (folio_mapped(folio)) { need_remap = true; - unmap_folio(folio); + ret = unmap_folio(folio); + if (ret) + return ret; } local_irq_disable(); @@ -4123,7 +4131,9 @@ static int __folio_freeze_split_file(str if (shmem_mapping(mapping)) end = shmem_fallocend(mapping->host, end); - unmap_folio(folio); + ret = unmap_folio(folio); + if (ret) + return ret; xas_lock_irq(xas); @@ -4331,15 +4341,6 @@ static int __folio_split(struct folio *f i_mmap_lock_read(mapping); } - /* - * Racy check if we can split the page, before unmap_folio() will - * split PMDs - */ - if (folio_expected_ref_count(folio) != folio_ref_count(folio) - 1) { - ret = -EAGAIN; - goto out_unlock; - } - if (is_anon) ret = __folio_freeze_split_anon(folio, new_order, split_at, true, list, split_type); @@ -4378,7 +4379,6 @@ static int __folio_split(struct folio *f free_folio_and_swap_cache(new_folio); } -out_unlock: if (anon_vma) { anon_vma_unlock_write(anon_vma); put_anon_vma(anon_vma); @@ -4426,9 +4426,6 @@ int folio_split_unmapped(struct folio *f VM_WARN_ON_ONCE_FOLIO(!folio_test_large(folio), folio); VM_WARN_ON_ONCE_FOLIO(!folio_test_anon(folio), folio); - if (folio_expected_ref_count(folio) != folio_ref_count(folio) - 1) - return -EAGAIN; - 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-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