[merged mm-stable] mm-hugetlb-make-follow_hugetlb_page-safe-to-pmd-unshare.patch removed from -mm tree

[merged mm-stable] mm-hugetlb-make-follow_hugetlb_page-safe-to-pmd-unshare.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/hugetlb: make follow_hugetlb_page() safe to pmd unshare
has been removed from the -mm tree.  Its filename was
     mm-hugetlb-make-follow_hugetlb_page-safe-to-pmd-unshare.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Peter Xu <peterx@redhat.com>
Subject: mm/hugetlb: make follow_hugetlb_page() safe to pmd unshare
Date: Fri, 16 Dec 2022 10:52:23 -0500

Since follow_hugetlb_page() walks the pgtable, it needs the vma lock to
make sure the pgtable page will not be freed concurrently.

Link: https://lkml.kernel.org/r/20221216155223.2043727-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/mm/hugetlb.c~mm-hugetlb-make-follow_hugetlb_page-safe-to-pmd-unshare
+++ a/mm/hugetlb.c
@@ -6454,6 +6454,7 @@ long follow_hugetlb_page(struct mm_struc
 			break;
 		}
 
+		hugetlb_vma_lock_read(vma);
 		/*
 		 * Some archs (sparc64, sh*) have multiple pte_ts to
 		 * each hugepage.  We have to make sure we get the
@@ -6478,6 +6479,7 @@ long follow_hugetlb_page(struct mm_struc
 		    !hugetlbfs_pagecache_present(h, vma, vaddr)) {
 			if (pte)
 				spin_unlock(ptl);
+			hugetlb_vma_unlock_read(vma);
 			remainder = 0;
 			break;
 		}
@@ -6499,6 +6501,8 @@ long follow_hugetlb_page(struct mm_struc
 
 			if (pte)
 				spin_unlock(ptl);
+			hugetlb_vma_unlock_read(vma);
+
 			if (flags & FOLL_WRITE)
 				fault_flags |= FAULT_FLAG_WRITE;
 			else if (unshare)
@@ -6561,6 +6565,7 @@ long follow_hugetlb_page(struct mm_struc
 			remainder -= pages_per_huge_page(h);
 			i += pages_per_huge_page(h);
 			spin_unlock(ptl);
+			hugetlb_vma_unlock_read(vma);
 			continue;
 		}
 
@@ -6590,6 +6595,7 @@ long follow_hugetlb_page(struct mm_struc
 			if (WARN_ON_ONCE(!try_grab_folio(pages[i], refs,
 							 flags))) {
 				spin_unlock(ptl);
+				hugetlb_vma_unlock_read(vma);
 				remainder = 0;
 				err = -ENOMEM;
 				break;
@@ -6601,6 +6607,7 @@ long follow_hugetlb_page(struct mm_struc
 		i += refs;
 
 		spin_unlock(ptl);
+		hugetlb_vma_unlock_read(vma);
 	}
 	*nr_pages = remainder;
 	/*
_

Patches currently in -mm which might be from peterx@redhat.com are

selftests-vm-remove-__use_gnu-in-hugetlb-madvisec.patch