+ mm-vmwgfx-simplify-pmd-pud-mapping-dirty-helpers.patch added to mm-unstable branch

+ mm-vmwgfx-simplify-pmd-pud-mapping-dirty-helpers.patch added to mm-unstable branch

[Andrew Morton]

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The patch titled
     Subject: mm/vmwgfx: simplify pmd & pud mapping dirty helpers
has been added to the -mm mm-unstable branch.  Its filename is
     mm-vmwgfx-simplify-pmd-pud-mapping-dirty-helpers.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmwgfx-simplify-pmd-pud-mapping-dirty-helpers.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Hugh Dickins <hughd@google.com>
Subject: mm/vmwgfx: simplify pmd & pud mapping dirty helpers
Date: Thu, 8 Jun 2023 18:20:04 -0700 (PDT)

wp_clean_pmd_entry() need not check pmd_trans_unstable() or pmd_none(),
wp_clean_pud_entry() need not check pud_trans_unstable() or pud_none():
it's just the ACTION_CONTINUE when trans_huge or devmap that's needed to
prevent splitting, and we're hoping to remove pmd_trans_unstable().  Is
that PUD #ifdef necessary?  Maybe some configs are missing a stub.

Link: https://lkml.kernel.org/r/d3379c7-65db-26d3-1764-8e866490925f@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mapping_dirty_helpers.c |   34 +++++++++-------------------------
 1 file changed, 9 insertions(+), 25 deletions(-)

--- a/mm/mapping_dirty_helpers.c~mm-vmwgfx-simplify-pmd-pud-mapping-dirty-helpers
+++ a/mm/mapping_dirty_helpers.c
@@ -128,19 +128,11 @@ static int wp_clean_pmd_entry(pmd_t *pmd
 {
 	pmd_t pmdval = pmdp_get_lockless(pmd);
 
-	if (!pmd_trans_unstable(&pmdval))
-		return 0;
-
-	if (pmd_none(pmdval)) {
-		walk->action = ACTION_AGAIN;
-		return 0;
-	}
-
-	/* Huge pmd, present or migrated */
-	walk->action = ACTION_CONTINUE;
-	if (pmd_trans_huge(pmdval) || pmd_devmap(pmdval))
+	/* Do not split a huge pmd, present or migrated */
+	if (pmd_trans_huge(pmdval) || pmd_devmap(pmdval)) {
 		WARN_ON(pmd_write(pmdval) || pmd_dirty(pmdval));
-
+		walk->action = ACTION_CONTINUE;
+	}
 	return 0;
 }
 
@@ -156,23 +148,15 @@ static int wp_clean_pmd_entry(pmd_t *pmd
 static int wp_clean_pud_entry(pud_t *pud, unsigned long addr, unsigned long end,
 			      struct mm_walk *walk)
 {
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 	pud_t pudval = READ_ONCE(*pud);
 
-	if (!pud_trans_unstable(&pudval))
-		return 0;
-
-	if (pud_none(pudval)) {
-		walk->action = ACTION_AGAIN;
-		return 0;
-	}
-
-#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
-	/* Huge pud */
-	walk->action = ACTION_CONTINUE;
-	if (pud_trans_huge(pudval) || pud_devmap(pudval))
+	/* Do not split a huge pud */
+	if (pud_trans_huge(pudval) || pud_devmap(pudval)) {
 		WARN_ON(pud_write(pudval) || pud_dirty(pudval));
+		walk->action = ACTION_CONTINUE;
+	}
 #endif
-
 	return 0;
 }
 
_

Patches currently in -mm which might be from hughd@google.com are

arm-allow-pte_offset_map-to-fail.patch
arm64-allow-pte_offset_map-to-fail.patch
arm64-hugetlb-pte_alloc_huge-pte_offset_huge.patch
ia64-hugetlb-pte_alloc_huge-pte_offset_huge.patch
m68k-allow-pte_offset_map-to-fail.patch
microblaze-allow-pte_offset_map-to-fail.patch
mips-update_mmu_cache-can-replace-__update_tlb.patch
mips-update_mmu_cache-can-replace-__update_tlb-fix.patch
parisc-add-pte_unmap-to-balance-get_ptep.patch
parisc-unmap_uncached_pte-use-pte_offset_kernel.patch
parisc-hugetlb-pte_alloc_huge-pte_offset_huge.patch
powerpc-kvmppc_unmap_free_pmd-pte_offset_kernel.patch
powerpc-allow-pte_offset_map-to-fail.patch
powerpc-hugetlb-pte_alloc_huge.patch
riscv-hugetlb-pte_alloc_huge-pte_offset_huge.patch
s390-allow-pte_offset_map_lock-to-fail.patch
s390-gmap-use-pte_unmap_unlock-not-spin_unlock.patch
sh-hugetlb-pte_alloc_huge-pte_offset_huge.patch
sparc-hugetlb-pte_alloc_huge-pte_offset_huge.patch
sparc-allow-pte_offset_map-to-fail.patch
sparc-iounit-and-iommu-use-pte_offset_kernel.patch
x86-allow-get_locked_pte-to-fail.patch
x86-sme_populate_pgd-use-pte_offset_kernel.patch
xtensa-add-pte_unmap-to-balance-pte_offset_map.patch
mm-use-pmdp_get_lockless-without-surplus-barrier.patch
mm-migrate-remove-cruft-from-migration_entry_waits.patch
mm-pgtable-kmap_local_page-instead-of-kmap_atomic.patch
mm-pgtable-allow-pte_offset_map-to-fail.patch
mm-filemap-allow-pte_offset_map_lock-to-fail.patch
mm-page_vma_mapped-delete-bogosity-in-page_vma_mapped_walk.patch
mm-page_vma_mapped-reformat-map_pte-with-less-indentation.patch
mm-page_vma_mapped-pte_offset_map_nolock-not-pte_lockptr.patch
mm-pagewalkers-action_again-if-pte_offset_map_lock-fails.patch
mm-pagewalk-walk_pte_range-allow-for-pte_offset_map.patch
mm-vmwgfx-simplify-pmd-pud-mapping-dirty-helpers.patch
mm-vmalloc-vmalloc_to_page-use-pte_offset_kernel.patch
mm-hmm-retry-if-pte_offset_map-fails.patch
mm-userfaultfd-retry-if-pte_offset_map-fails.patch
mm-userfaultfd-allow-pte_offset_map_lock-to-fail.patch
mm-debug_vm_pgtablepage_table_check-warn-pte-map-fails.patch
mm-various-give-up-if-pte_offset_map-fails.patch
mm-mprotect-delete-pmd_none_or_clear_bad_unless_trans_huge.patch
mm-mremap-retry-if-either-pte_offset_map_lock-fails.patch
mm-madvise-clean-up-pte_offset_map_lock-scans.patch
mm-madvise-clean-up-force_shm_swapin_readahead.patch
mm-swapoff-allow-pte_offset_map-to-fail.patch
mm-mglru-allow-pte_offset_map_nolock-to-fail.patch
mm-migrate_device-allow-pte_offset_map_lock-to-fail.patch
mm-gup-remove-foll_split_pmd-use-of-pmd_trans_unstable.patch
mm-huge_memory-split-huge-pmd-under-one-pte_offset_map.patch
mm-khugepaged-allow-pte_offset_map-to-fail.patch
mm-memory-allow-pte_offset_map-to-fail.patch
mm-memory-handle_pte_fault-use-pte_offset_map_nolock.patch
mm-pgtable-delete-pmd_trans_unstable-and-friends.patch
mm-swap-swap_vma_readahead-do-the-pte_offset_map.patch
perf-core-allow-pte_offset_map-to-fail.patch