+ mm-page_vma_mapped-reformat-map_pte-with-less-indentation.patch added to mm-unstable branch

+ mm-page_vma_mapped-reformat-map_pte-with-less-indentation.patch added to mm-unstable branch

[Andrew Morton]

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The patch titled
     Subject: mm/page_vma_mapped: reformat map_pte() with less indentation
has been added to the -mm mm-unstable branch.  Its filename is
     mm-page_vma_mapped-reformat-map_pte-with-less-indentation.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_vma_mapped-reformat-map_pte-with-less-indentation.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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The -mm tree is included into linux-next via the mm-everything
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/page_vma_mapped: reformat map_pte() with less indentation
Date: Thu, 8 Jun 2023 18:14:12 -0700 (PDT)

No functional change here, but adjust the format of map_pte() so that the
following commit will be easier to read: separate out the PVMW_SYNC case
first, and remove two levels of indentation from the ZONE_DEVICE case.

Link: https://lkml.kernel.org/r/bf723f59-e3fc-6839-1cc3-c0631ee248bc@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/page_vma_mapped.c |   65 +++++++++++++++++++++--------------------
 1 file changed, 34 insertions(+), 31 deletions(-)

--- a/mm/page_vma_mapped.c~mm-page_vma_mapped-reformat-map_pte-with-less-indentation
+++ a/mm/page_vma_mapped.c
@@ -15,38 +15,41 @@ static inline bool not_found(struct page
 
 static bool map_pte(struct page_vma_mapped_walk *pvmw)
 {
-	pvmw->pte = pte_offset_map(pvmw->pmd, pvmw->address);
-	if (!(pvmw->flags & PVMW_SYNC)) {
-		if (pvmw->flags & PVMW_MIGRATION) {
-			if (!is_swap_pte(*pvmw->pte))
-				return false;
-		} else {
-			/*
-			 * We get here when we are trying to unmap a private
-			 * device page from the process address space. Such
-			 * page is not CPU accessible and thus is mapped as
-			 * a special swap entry, nonetheless it still does
-			 * count as a valid regular mapping for the page (and
-			 * is accounted as such in page maps count).
-			 *
-			 * So handle this special case as if it was a normal
-			 * page mapping ie lock CPU page table and returns
-			 * true.
-			 *
-			 * For more details on device private memory see HMM
-			 * (include/linux/hmm.h or mm/hmm.c).
-			 */
-			if (is_swap_pte(*pvmw->pte)) {
-				swp_entry_t entry;
+	if (pvmw->flags & PVMW_SYNC) {
+		/* Use the stricter lookup */
+		pvmw->pte = pte_offset_map_lock(pvmw->vma->vm_mm, pvmw->pmd,
+						pvmw->address, &pvmw->ptl);
+		return true;
+	}
 
-				/* Handle un-addressable ZONE_DEVICE memory */
-				entry = pte_to_swp_entry(*pvmw->pte);
-				if (!is_device_private_entry(entry) &&
-				    !is_device_exclusive_entry(entry))
-					return false;
-			} else if (!pte_present(*pvmw->pte))
-				return false;
-		}
+	pvmw->pte = pte_offset_map(pvmw->pmd, pvmw->address);
+	if (pvmw->flags & PVMW_MIGRATION) {
+		if (!is_swap_pte(*pvmw->pte))
+			return false;
+	} else if (is_swap_pte(*pvmw->pte)) {
+		swp_entry_t entry;
+		/*
+		 * Handle un-addressable ZONE_DEVICE memory.
+		 *
+		 * We get here when we are trying to unmap a private
+		 * device page from the process address space. Such
+		 * page is not CPU accessible and thus is mapped as
+		 * a special swap entry, nonetheless it still does
+		 * count as a valid regular mapping for the page
+		 * (and is accounted as such in page maps count).
+		 *
+		 * So handle this special case as if it was a normal
+		 * page mapping ie lock CPU page table and return true.
+		 *
+		 * For more details on device private memory see HMM
+		 * (include/linux/hmm.h or mm/hmm.c).
+		 */
+		entry = pte_to_swp_entry(*pvmw->pte);
+		if (!is_device_private_entry(entry) &&
+		    !is_device_exclusive_entry(entry))
+			return false;
+	} else if (!pte_present(*pvmw->pte)) {
+		return false;
 	}
 	pvmw->ptl = pte_lockptr(pvmw->vma->vm_mm, pvmw->pmd);
 	spin_lock(pvmw->ptl);
_

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