+ mm-huge_memory-add-a-common-exit-path-to-zap_huge_pmd.patch added to mm-new branch

+ mm-huge_memory-add-a-common-exit-path-to-zap_huge_pmd.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/huge_memory: add a common exit path to zap_huge_pmd()
has been added to the -mm mm-new branch.  Its filename is
     mm-huge_memory-add-a-common-exit-path-to-zap_huge_pmd.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-add-a-common-exit-path-to-zap_huge_pmd.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

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------------------------------------------------------
From: "Lorenzo Stoakes (Oracle)" <ljs@kernel.org>
Subject: mm/huge_memory: add a common exit path to zap_huge_pmd()
Date: Thu, 19 Mar 2026 13:00:11 +0000

Other than when we acquire the PTL, we always need to unlock the PTL, and
optionally need to flush on exit.

The code is currently very duplicated in this respect, so default
flush_needed to false, set it true in the case in which it's required,
then share the same logic for all exit paths.

This also makes flush_needed make more sense as a function-scope value (we
don't need to flush for the PFN map/mixed map, zero huge, error cases for
instance).

Link: https://lkml.kernel.org/r/f5d3d47da1bc1607fc01604c0e803c3248d8a1fb.1773924928.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand (ARM) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Kiryl Shutsemau <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/huge_memory.c |   15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

--- a/mm/huge_memory.c~mm-huge_memory-add-a-common-exit-path-to-zap_huge_pmd
+++ a/mm/huge_memory.c
@@ -2338,7 +2338,7 @@ bool zap_huge_pmd(struct mmu_gather *tlb
 		 pmd_t *pmd, unsigned long addr)
 {
 	struct folio *folio = NULL;
-	bool flush_needed = true;
+	bool flush_needed = false;
 	spinlock_t *ptl;
 	pmd_t orig_pmd;
 
@@ -2360,19 +2360,18 @@ bool zap_huge_pmd(struct mmu_gather *tlb
 	if (vma_is_special_huge(vma)) {
 		if (arch_needs_pgtable_deposit())
 			zap_deposited_table(tlb->mm, pmd);
-		spin_unlock(ptl);
-		return true;
+		goto out;
 	}
 	if (is_huge_zero_pmd(orig_pmd)) {
 		if (!vma_is_dax(vma) || arch_needs_pgtable_deposit())
 			zap_deposited_table(tlb->mm, pmd);
-		spin_unlock(ptl);
-		return true;
+		goto out;
 	}
 
 	if (pmd_present(orig_pmd)) {
 		struct page *page = pmd_page(orig_pmd);
 
+		flush_needed = true;
 		folio = page_folio(page);
 		folio_remove_rmap_pmd(folio, page, vma);
 		WARN_ON_ONCE(folio_mapcount(folio) < 0);
@@ -2381,14 +2380,12 @@ bool zap_huge_pmd(struct mmu_gather *tlb
 		const softleaf_t entry = softleaf_from_pmd(orig_pmd);
 
 		folio = softleaf_to_folio(entry);
-		flush_needed = false;
 
 		if (!thp_migration_supported())
 			WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
 	} else {
 		WARN_ON_ONCE(true);
-		spin_unlock(ptl);
-		return true;
+		goto out;
 	}
 
 	if (folio_test_anon(folio)) {
@@ -2415,10 +2412,10 @@ bool zap_huge_pmd(struct mmu_gather *tlb
 		folio_put(folio);
 	}
 
+out:
 	spin_unlock(ptl);
 	if (flush_needed)
 		tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE);
-
 	return true;
 }
 
_

Patches currently in -mm which might be from ljs@kernel.org are

mm-zswap-add-missing-kunmap_local.patch
mm-rmap-clear-vma-anon_vma-on-error.patch
mm-rename-vma-flag-helpers-to-be-more-readable.patch
mm-add-vma_desc_test_all-and-use-it.patch
mm-always-inline-__mk_vma_flags-and-invoked-functions.patch
mm-reintroduce-vma_flags_test-as-a-singular-flag-test.patch
mm-reintroduce-vma_desc_test-as-a-singular-flag-test.patch
tools-testing-vma-add-test-for-vma_flags_test-vma_desc_test.patch
tools-testing-vma-add-test-for-vma_flags_test-vma_desc_test-fix.patch
mm-mremap-correct-invalid-map-count-check.patch
mm-abstract-reading-sysctl_max_map_count-and-read_once.patch
mm-mremap-check-map-count-under-mmap-write-lock-and-abstract.patch
mm-vma-add-vma_flags_empty-vma_flags_and-vma_flags_diff_pair.patch
tools-testing-vma-add-unit-tests-flag-empty-diff_pair-and.patch
mm-vma-add-further-vma_flags_t-unions.patch
tools-testing-vma-convert-bulk-of-test-code-to-vma_flags_t.patch
mm-vma-use-new-vma-flags-for-sticky-flags-logic.patch
tools-testing-vma-fix-vma-flag-tests.patch
mm-vma-add-append_vma_flags-helper.patch
tools-testing-vma-add-simple-test-for-append_vma_flags.patch
mm-unexport-vm_brk_flags-and-eliminate-vm_flags-parameter.patch
mm-vma-introduce-vma_flags_same.patch
mm-vma-introduce-_to_-helpers.patch
tools-testing-vma-test-that-legacy-flag-helpers-work-correctly.patch
mm-vma-introduce-vma_test-and-make-inlining-consistent.patch
tools-testing-vma-update-vma-flag-tests-to-test-vma_test.patch
mm-introduce-vma_flags_count-and-vma_test_single_mask.patch
tools-testing-vma-test-vma_flags_countvma_test_single_mask.patch
mm-convert-do_brk_flags-to-use-vma_flags_t.patch
mm-update-vma_supports_mlock-to-use-new-vma-flags.patch
mm-vma-introduce-vma_clear_flags.patch
tools-testing-vma-update-vma-tests-to-test-vma_clear_flags.patch
mm-vma-convert-as-much-as-we-can-in-mm-vmac-to-vma_flags_t.patch
mm-vma-convert-vma_modify_flags-to-use-vma_flags_t.patch
mm-vma-convert-__mmap_region-to-use-vma_flags_t.patch
mm-various-small-mmap_prepare-cleanups.patch
mm-add-documentation-for-the-mmap_prepare-file-operation-callback.patch
mm-document-vm_operations_struct-open-the-same-as-close.patch
mm-add-vm_ops-mapped-hook.patch
fs-afs-correctly-drop-reference-count-on-mapping-failure.patch
mm-add-mmap_action_simple_ioremap.patch
misc-open-dice-replace-deprecated-mmap-hook-with-mmap_prepare.patch
hpet-replace-deprecated-mmap-hook-with-mmap_prepare.patch
mtdchar-replace-deprecated-mmap-hook-with-mmap_prepare-clean-up.patch
stm-replace-deprecated-mmap-hook-with-mmap_prepare.patch
staging-vme_user-replace-deprecated-mmap-hook-with-mmap_prepare.patch
mm-allow-handling-of-stacked-mmap_prepare-hooks-in-more-drivers.patch
drivers-hv-vmbus-replace-deprecated-mmap-hook-with-mmap_prepare.patch
uio-replace-deprecated-mmap-hook-with-mmap_prepare-in-uio_info.patch
mm-add-mmap_action_map_kernel_pages.patch
mm-on-remap-assert-that-input-range-within-the-proposed-vma.patch
mm-huge_memory-simplify-vma_is_specal_huge.patch
mm-huge-avoid-big-else-branch-in-zap_huge_pmd.patch
mm-huge_memory-have-zap_huge_pmd-return-a-boolean-add-kdoc.patch
mm-huge_memory-handle-buggy-pmd-entry-in-zap_huge_pmd.patch
mm-huge_memory-add-a-common-exit-path-to-zap_huge_pmd.patch
mm-huge_memory-remove-unnecessary-vm_bug_on_page.patch
mm-huge_memory-deduplicate-zap-deposited-table-call.patch
mm-huge_memory-deduplicate-zap_huge_pmd-further-by-tracking-state.patch
mm-huge_memory-have-zap_huge_pmd-use-vm_normal_folio_pmd.patch