[merged] mm-take-i_mmap_lock-in-unmap_mapping_range-for-dax.patch removed from -mm tree

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The patch titled
     Subject: mm: take i_mmap_lock in unmap_mapping_range() for DAX
has been removed from the -mm tree.  Its filename was
     mm-take-i_mmap_lock-in-unmap_mapping_range-for-dax.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: mm: take i_mmap_lock in unmap_mapping_range() for DAX

DAX is not so special: we need i_mmap_lock to protect mapping->i_mmap.

__dax_pmd_fault() uses unmap_mapping_range() shoot out zero page from all
mappings.  We need to drop i_mmap_lock there to avoid lock deadlock.

Re-aquiring the lock should be fine since we check i_size after the
point.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 fs/dax.c    |   35 +++++++++++++++++++----------------
 mm/memory.c |   11 ++---------
 2 files changed, 21 insertions(+), 25 deletions(-)

diff -puN fs/dax.c~mm-take-i_mmap_lock-in-unmap_mapping_range-for-dax fs/dax.c
--- a/fs/dax.c~mm-take-i_mmap_lock-in-unmap_mapping_range-for-dax
+++ a/fs/dax.c
@@ -554,6 +554,25 @@ int __dax_pmd_fault(struct vm_area_struc
 	if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE)
 		goto fallback;
 
+	if (buffer_unwritten(&bh) || buffer_new(&bh)) {
+		int i;
+		for (i = 0; i < PTRS_PER_PMD; i++)
+			clear_page(kaddr + i * PAGE_SIZE);
+		count_vm_event(PGMAJFAULT);
+		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+		result |= VM_FAULT_MAJOR;
+	}
+
+	/*
+	 * If we allocated new storage, make sure no process has any
+	 * zero pages covering this hole
+	 */
+	if (buffer_new(&bh)) {
+		i_mmap_unlock_write(mapping);
+		unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0);
+		i_mmap_lock_write(mapping);
+	}
+
 	/*
 	 * If a truncate happened while we were allocating blocks, we may
 	 * leave blocks allocated to the file that are beyond EOF.  We can't
@@ -568,13 +587,6 @@ int __dax_pmd_fault(struct vm_area_struc
 	if ((pgoff | PG_PMD_COLOUR) >= size)
 		goto fallback;
 
-	/*
-	 * If we allocated new storage, make sure no process has any
-	 * zero pages covering this hole
-	 */
-	if (buffer_new(&bh))
-		unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0);
-
 	if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) {
 		spinlock_t *ptl;
 		pmd_t entry;
@@ -605,15 +617,6 @@ int __dax_pmd_fault(struct vm_area_struc
 		if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR))
 			goto fallback;
 
-		if (buffer_unwritten(&bh) || buffer_new(&bh)) {
-			int i;
-			for (i = 0; i < PTRS_PER_PMD; i++)
-				clear_page(kaddr + i * PAGE_SIZE);
-			count_vm_event(PGMAJFAULT);
-			mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
-			result |= VM_FAULT_MAJOR;
-		}
-
 		result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
 	}
 
diff -puN mm/memory.c~mm-take-i_mmap_lock-in-unmap_mapping_range-for-dax mm/memory.c
--- a/mm/memory.c~mm-take-i_mmap_lock-in-unmap_mapping_range-for-dax
+++ a/mm/memory.c
@@ -2426,17 +2426,10 @@ void unmap_mapping_range(struct address_
 	if (details.last_index < details.first_index)
 		details.last_index = ULONG_MAX;
 
-
-	/*
-	 * DAX already holds i_mmap_lock to serialise file truncate vs
-	 * page fault and page fault vs page fault.
-	 */
-	if (!IS_DAX(mapping->host))
-		i_mmap_lock_write(mapping);
+	i_mmap_lock_write(mapping);
 	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
 		unmap_mapping_range_tree(&mapping->i_mmap, &details);
-	if (!IS_DAX(mapping->host))
-		i_mmap_unlock_write(mapping);
+	i_mmap_unlock_write(mapping);
 }
 EXPORT_SYMBOL(unmap_mapping_range);
 
_

Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are

page-flags-trivial-cleanup-for-pagetrans-helpers.patch
page-flags-introduce-page-flags-policies-wrt-compound-pages.patch
page-flags-define-pg_locked-behavior-on-compound-pages.patch
page-flags-define-behavior-of-fs-io-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-lru-related-flags-on-compound-pages.patch
page-flags-define-behavior-slb-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-xen-related-flags-on-compound-pages.patch
page-flags-define-pg_reserved-behavior-on-compound-pages.patch
page-flags-define-pg_swapbacked-behavior-on-compound-pages.patch
page-flags-define-pg_swapcache-behavior-on-compound-pages.patch
page-flags-define-pg_mlocked-behavior-on-compound-pages.patch
page-flags-define-pg_uncached-behavior-on-compound-pages.patch
page-flags-define-pg_uptodate-behavior-on-compound-pages.patch
page-flags-look-on-head-page-if-the-flag-is-encoded-in-page-mapping.patch
mm-sanitize-page-mapping-for-tail-pages.patch
mm-mark-most-vm_operations_struct-const.patch
mm-make-sure-all-file-vmas-have-vm_ops-set.patch
mm-use-vma_is_anonymous-in-create_huge_pmd-and-wp_huge_pmd.patch
mm-madvise-use-vma_is_anonymous-to-check-for-anon-vma.patch

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