+ mm-thp-fix-wrong-cache-flush-in-remove_migration_pmd.patch added to -mm tree

* + mm-thp-fix-wrong-cache-flush-in-remove_migration_pmd.patch added to -mm tree
@ 2022-02-08 21:15 Andrew Morton
  0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2022-02-08 21:15 UTC (permalink / raw)
  To: mm-commits, ziy, willy, rientjes, mike.kravetz, lars.persson,
	kirill.shutemov, duanxiongchun, almasrymina, songmuchun, akpm


The patch titled
     Subject: mm: thp: fix wrong cache flush in remove_migration_pmd()
has been added to the -mm tree.  Its filename is
     mm-thp-fix-wrong-cache-flush-in-remove_migration_pmd.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-thp-fix-wrong-cache-flush-in-remove_migration_pmd.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-fix-wrong-cache-flush-in-remove_migration_pmd.patch

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------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm: thp: fix wrong cache flush in remove_migration_pmd()

The flush_cache_range() is supposed to be justified only if the page is
already placed in process page table, and that is done right after
flush_cache_range().  So using this interface is wrong.  And there is no
need to invalite cache since it was non-present before in
remove_migration_pmd().  So just to remove it.

Link: https://lkml.kernel.org/r/20220208073617.70342-2-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Lars Persson <lars.persson@axis.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mina Almasry <almasrymina@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/huge_memory.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/huge_memory.c~mm-thp-fix-wrong-cache-flush-in-remove_migration_pmd
+++ a/mm/huge_memory.c
@@ -3124,7 +3124,6 @@ void remove_migration_pmd(struct page_vm
 	if (pmd_swp_uffd_wp(*pvmw->pmd))
 		pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde));
 
-	flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
 	if (PageAnon(new))
 		page_add_anon_rmap(new, vma, mmun_start, true);
 	else
@@ -3132,6 +3131,8 @@ void remove_migration_pmd(struct page_vm
 	set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
 	if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
 		mlock_vma_page(new);
+
+	/* No need to invalidate - it was non-present before */
 	update_mmu_cache_pmd(vma, address, pvmw->pmd);
 }
 #endif
_

Patches currently in -mm which might be from songmuchun@bytedance.com are

mm-thp-fix-wrong-cache-flush-in-remove_migration_pmd.patch
mm-fix-missing-cache-flush-for-all-tail-pages-of-compound-page.patch
mm-hugetlb-fix-missing-cache-flush-in-copy_huge_page_from_user.patch
mm-hugetlb-fix-missing-cache-flush-in-hugetlb_mcopy_atomic_pte.patch
mm-replace-multiple-dcache-flush-with-flush_dcache_folio.patch
mm-hugetlb-free-the-2nd-vmemmap-page-associated-with-each-hugetlb-page.patch
mm-hugetlb-replace-hugetlb_free_vmemmap_enabled-with-a-static_key.patch
mm-sparsemem-use-page-table-lock-to-protect-kernel-pmd-operations.patch
selftests-vm-add-a-hugetlb-test-case.patch
mm-sparsemem-move-vmemmap-related-to-hugetlb-to-config_hugetlb_page_free_vmemmap.patch


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