diff mbox series

[4/4] hugetlbfs: replace hugetlb_vma_lock with invalidate_lock

Message ID 20231006040020.3677377-5-riel@surriel.com
State New
Headers
Series hugetlbfs: close race between MADV_DONTNEED and page fault |

Commit Message

Rik van Riel Oct. 6, 2023, 3:59 a.m. UTC 
  From: Rik van Riel <riel@surriel.com>

Replace the custom hugetlbfs VMA locking code with the recently
introduced invalidate_lock. This greatly simplifies things.

However, this is a large enough change that it should probably go in
separately from the other changes.

Another question is whether this simplification hurts scalability
for certain workloads.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Rik van Riel <riel@surriel.com>
---
 fs/hugetlbfs/inode.c    |  71 ++----------
 include/linux/fs.h      |   6 +
 include/linux/hugetlb.h |  21 +---
 mm/hugetlb.c            | 237 ++++------------------------------------
 4 files changed, 35 insertions(+), 300 deletions(-)

Comments

Mike Kravetz Oct. 17, 2023, 12:52 a.m. UTC | #1 
On 10/05/23 23:59, riel@surriel.com wrote:
> From: Rik van Riel <riel@surriel.com>
> 
> Replace the custom hugetlbfs VMA locking code with the recently
> introduced invalidate_lock. This greatly simplifies things.
> 
> However, this is a large enough change that it should probably go in
> separately from the other changes.
> 
> Another question is whether this simplification hurts scalability
> for certain workloads.

Finally got around to running some performance tests on this.

As a reminder, the hugetlb specific vma lock was introduced as a result
of this report:
https://lore.kernel.org/linux-mm/43faf292-245b-5db5-cce9-369d8fb6bd21@infradead.org/

I do not have access to the database or applications to recreate the issues
originally reported.  However, while working the issue I did use a
simulated workload that showed the regression and improvements moving to a
vma specific lock.  Here is part of the commit log describing the testing
when the vma lock was introduced.


"The recent regression report [1] notes page fault and fork latency of
shared hugetlb mappings.  To measure this, I created two simple programs:
1) map a shared hugetlb area, write fault all pages, unmap area
   Do this in a continuous loop to measure faults per second
2) map a shared hugetlb area, write fault a few pages, fork and exit
   Do this in a continuous loop to measure forks per second
These programs were run on a 48 CPU VM with 320GB memory.  The shared
mapping size was 250GB.  For comparison, a single instance of the program
was run.  Then, multiple instances were run in parallel to introduce
lock contention.  Changing the locking scheme results in a significant
performance benefit.

test            instances       unmodified      revert          vma
--------------------------------------------------------------------------
faults per sec  1               393043          395680          389932
faults per sec  24               71405           81191           79048
forks per sec   1                 2802            2747            2725
forks per sec   24                 439             536             500
Combined faults 24                1621           68070           53662
Combined forks  24                 358              67             142

Combined test is when running both faulting program and forking program
simultaneously."

Ray Fucillo (on Cc) verified the performance regression was removed when
the vma lock was introduced.

I have run the same benchmark on this patch.

test            instances       before			after
--------------------------------------------------------------------------
faults per sec  1		385135			386253
faults per sec  24		 95922			 75665
forks per sec   1		  3392			  3207
forks per sec   24		   683			   704
Combined faults 24		 76004			 30407
Combined forks  24		   241			   278

The Combined faults number drops by over 50%.  This is not nearly as dramatic
as the changes originally seen.  However, I do expect that there will be
a noticeable performance regression.  Ray may be able to help running real
workloads on real applications and database.

I suggest we hold off on adding this change until further, more real world
analysis can be performed.  The simplification of the code is nice, but I
would hate to regress any workloads.
Rik van Riel Oct. 17, 2023, 1:47 p.m. UTC | #2 
On Mon, 2023-10-16 at 17:52 -0700, Mike Kravetz wrote:
> 
> The Combined faults number drops by over 50%.  This is not nearly as
> dramatic
> as the changes originally seen.  However, I do expect that there will
> be
> a noticeable performance regression.  Ray may be able to help running
> real
> workloads on real applications and database.
> 
> I suggest we hold off on adding this change until further, more real
> world
> analysis can be performed.  The simplification of the code is nice,
> but I
> would hate to regress any workloads.

Agreed. Thank you for running those tests.

Andrew, would it be possible to drop patch 4/4 from -mm?
diff mbox series

Patch

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 316c4cebd3f3..18a66632d789 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -485,7 +485,6 @@  static void hugetlb_unmap_file_folio(struct hstate *h,
 					struct folio *folio, pgoff_t index)
 {
 	struct rb_root_cached *root = &mapping->i_mmap;
-	struct hugetlb_vma_lock *vma_lock;
 	struct page *page = &folio->page;
 	struct vm_area_struct *vma;
 	unsigned long v_start;
@@ -495,9 +494,9 @@  static void hugetlb_unmap_file_folio(struct hstate *h,
 	start = index * pages_per_huge_page(h);
 	end = (index + 1) * pages_per_huge_page(h);
 
+	filemap_invalidate_lock(mapping);
 	i_mmap_lock_write(mapping);
-retry:
-	vma_lock = NULL;
+
 	vma_interval_tree_foreach(vma, root, start, end - 1) {
 		v_start = vma_offset_start(vma, start);
 		v_end = vma_offset_end(vma, end);
@@ -505,62 +504,12 @@  static void hugetlb_unmap_file_folio(struct hstate *h,
 		if (!hugetlb_vma_maps_page(vma, v_start, page))
 			continue;
 
-		if (!hugetlb_vma_trylock_write(vma)) {
-			vma_lock = vma->vm_private_data;
-			/*
-			 * If we can not get vma lock, we need to drop
-			 * immap_sema and take locks in order.  First,
-			 * take a ref on the vma_lock structure so that
-			 * we can be guaranteed it will not go away when
-			 * dropping immap_sema.
-			 */
-			kref_get(&vma_lock->refs);
-			break;
-		}
-
 		unmap_hugepage_range(vma, v_start, v_end, NULL,
 				     ZAP_FLAG_DROP_MARKER);
-		hugetlb_vma_unlock_write(vma);
 	}
 
+	filemap_invalidate_unlock(mapping);
 	i_mmap_unlock_write(mapping);
-
-	if (vma_lock) {
-		/*
-		 * Wait on vma_lock.  We know it is still valid as we have
-		 * a reference.  We must 'open code' vma locking as we do
-		 * not know if vma_lock is still attached to vma.
-		 */
-		down_write(&vma_lock->rw_sema);
-		i_mmap_lock_write(mapping);
-
-		vma = vma_lock->vma;
-		if (!vma) {
-			/*
-			 * If lock is no longer attached to vma, then just
-			 * unlock, drop our reference and retry looking for
-			 * other vmas.
-			 */
-			up_write(&vma_lock->rw_sema);
-			kref_put(&vma_lock->refs, hugetlb_vma_lock_release);
-			goto retry;
-		}
-
-		/*
-		 * vma_lock is still attached to vma.  Check to see if vma
-		 * still maps page and if so, unmap.
-		 */
-		v_start = vma_offset_start(vma, start);
-		v_end = vma_offset_end(vma, end);
-		if (hugetlb_vma_maps_page(vma, v_start, page))
-			unmap_hugepage_range(vma, v_start, v_end, NULL,
-					     ZAP_FLAG_DROP_MARKER);
-
-		kref_put(&vma_lock->refs, hugetlb_vma_lock_release);
-		hugetlb_vma_unlock_write(vma);
-
-		goto retry;
-	}
 }
 
 static void
@@ -578,20 +527,10 @@  hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end,
 		unsigned long v_start;
 		unsigned long v_end;
 
-		if (!hugetlb_vma_trylock_write(vma))
-			continue;
-
 		v_start = vma_offset_start(vma, start);
 		v_end = vma_offset_end(vma, end);
 
 		unmap_hugepage_range(vma, v_start, v_end, NULL, zap_flags);
-
-		/*
-		 * Note that vma lock only exists for shared/non-private
-		 * vmas.  Therefore, lock is not held when calling
-		 * unmap_hugepage_range for private vmas.
-		 */
-		hugetlb_vma_unlock_write(vma);
 	}
 }
 
@@ -725,10 +664,12 @@  static void hugetlb_vmtruncate(struct inode *inode, loff_t offset)
 	pgoff = offset >> PAGE_SHIFT;
 
 	i_size_write(inode, offset);
+	filemap_invalidate_lock(mapping);
 	i_mmap_lock_write(mapping);
 	if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
 		hugetlb_vmdelete_list(&mapping->i_mmap, pgoff, 0,
 				      ZAP_FLAG_DROP_MARKER);
+	filemap_invalidate_unlock(mapping);
 	i_mmap_unlock_write(mapping);
 	remove_inode_hugepages(inode, offset, LLONG_MAX);
 }
@@ -778,6 +719,7 @@  static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 		return -EPERM;
 	}
 
+	filemap_invalidate_lock(mapping);
 	i_mmap_lock_write(mapping);
 
 	/* If range starts before first full page, zero partial page. */
@@ -799,6 +741,7 @@  static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 				hole_end, offset + len);
 
 	i_mmap_unlock_write(mapping);
+	filemap_invalidate_unlock(mapping);
 
 	/* Remove full pages from the file. */
 	if (hole_end > hole_start)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4aeb3fa11927..b455a8913db4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -847,6 +847,12 @@  static inline void filemap_invalidate_lock(struct address_space *mapping)
 	down_write(&mapping->invalidate_lock);
 }
 
+static inline int filemap_invalidate_trylock(
+					struct address_space *mapping)
+{
+	return down_write_trylock(&mapping->invalidate_lock);
+}
+
 static inline void filemap_invalidate_unlock(struct address_space *mapping)
 {
 	up_write(&mapping->invalidate_lock);
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index d9ec500cfef9..2908c47e7bf2 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -60,7 +60,6 @@  struct resv_map {
 	long adds_in_progress;
 	struct list_head region_cache;
 	long region_cache_count;
-	struct rw_semaphore rw_sema;
 #ifdef CONFIG_CGROUP_HUGETLB
 	/*
 	 * On private mappings, the counter to uncharge reservations is stored
@@ -107,12 +106,6 @@  struct file_region {
 #endif
 };
 
-struct hugetlb_vma_lock {
-	struct kref refs;
-	struct rw_semaphore rw_sema;
-	struct vm_area_struct *vma;
-};
-
 extern struct resv_map *resv_map_alloc(void);
 void resv_map_release(struct kref *ref);
 
@@ -1277,17 +1270,9 @@  hugetlb_walk(struct vm_area_struct *vma, unsigned long addr, unsigned long sz)
 {
 #if defined(CONFIG_HUGETLB_PAGE) && \
 	defined(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) && defined(CONFIG_LOCKDEP)
-	struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-	/*
-	 * If pmd sharing possible, locking needed to safely walk the
-	 * hugetlb pgtables.  More information can be found at the comment
-	 * above huge_pte_offset() in the same file.
-	 *
-	 * NOTE: lockdep_is_held() is only defined with CONFIG_LOCKDEP.
-	 */
-	if (__vma_shareable_lock(vma))
-		WARN_ON_ONCE(!lockdep_is_held(&vma_lock->rw_sema) &&
+	if (vma->vm_file)
+		WARN_ON_ONCE(!lockdep_is_held(
+				 &vma->vm_file->f_mapping->invalidate_lock) &&
 			     !lockdep_is_held(
 				 &vma->vm_file->f_mapping->i_mmap_rwsem));
 #endif
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 552c2e3221bd..0dcaccc29e97 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -92,9 +92,6 @@  struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
 
 /* Forward declaration */
 static int hugetlb_acct_memory(struct hstate *h, long delta);
-static void hugetlb_vma_lock_free(struct vm_area_struct *vma);
-static void hugetlb_vma_lock_alloc(struct vm_area_struct *vma);
-static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma);
 static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
 		unsigned long start, unsigned long end);
 static struct resv_map *vma_resv_map(struct vm_area_struct *vma);
@@ -264,170 +261,41 @@  static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
  */
 void hugetlb_vma_lock_read(struct vm_area_struct *vma)
 {
-	if (__vma_shareable_lock(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-		down_read(&vma_lock->rw_sema);
-	} else if (__vma_private_lock(vma)) {
-		struct resv_map *resv_map = vma_resv_map(vma);
-
-		down_read(&resv_map->rw_sema);
-	}
+	if (vma->vm_file)
+		filemap_invalidate_lock_shared(vma->vm_file->f_mapping);
 }
 
 void hugetlb_vma_unlock_read(struct vm_area_struct *vma)
 {
-	if (__vma_shareable_lock(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-		up_read(&vma_lock->rw_sema);
-	} else if (__vma_private_lock(vma)) {
-		struct resv_map *resv_map = vma_resv_map(vma);
-
-		up_read(&resv_map->rw_sema);
-	}
+	if (vma->vm_file)
+		filemap_invalidate_unlock_shared(vma->vm_file->f_mapping);
 }
 
 void hugetlb_vma_lock_write(struct vm_area_struct *vma)
 {
-	if (__vma_shareable_lock(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-		down_write(&vma_lock->rw_sema);
-	} else if (__vma_private_lock(vma)) {
-		struct resv_map *resv_map = vma_resv_map(vma);
-
-		down_write(&resv_map->rw_sema);
-	}
+	if (vma->vm_file)
+		filemap_invalidate_lock(vma->vm_file->f_mapping);
 }
 
 void hugetlb_vma_unlock_write(struct vm_area_struct *vma)
 {
-	if (__vma_shareable_lock(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-		up_write(&vma_lock->rw_sema);
-	} else if (__vma_private_lock(vma)) {
-		struct resv_map *resv_map = vma_resv_map(vma);
-
-		up_write(&resv_map->rw_sema);
-	}
+	if (vma->vm_file)
+		filemap_invalidate_unlock(vma->vm_file->f_mapping);
 }
 
 int hugetlb_vma_trylock_write(struct vm_area_struct *vma)
 {
 
-	if (__vma_shareable_lock(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-		return down_write_trylock(&vma_lock->rw_sema);
-	} else if (__vma_private_lock(vma)) {
-		struct resv_map *resv_map = vma_resv_map(vma);
-
-		return down_write_trylock(&resv_map->rw_sema);
-	}
+	if (vma->vm_file)
+		return filemap_invalidate_trylock(vma->vm_file->f_mapping);
 
 	return 1;
 }
 
 void hugetlb_vma_assert_locked(struct vm_area_struct *vma)
 {
-	if (__vma_shareable_lock(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-		lockdep_assert_held(&vma_lock->rw_sema);
-	} else if (__vma_private_lock(vma)) {
-		struct resv_map *resv_map = vma_resv_map(vma);
-
-		lockdep_assert_held(&resv_map->rw_sema);
-	}
-}
-
-void hugetlb_vma_lock_release(struct kref *kref)
-{
-	struct hugetlb_vma_lock *vma_lock = container_of(kref,
-			struct hugetlb_vma_lock, refs);
-
-	kfree(vma_lock);
-}
-
-static void __hugetlb_vma_unlock_write_put(struct hugetlb_vma_lock *vma_lock)
-{
-	struct vm_area_struct *vma = vma_lock->vma;
-
-	/*
-	 * vma_lock structure may or not be released as a result of put,
-	 * it certainly will no longer be attached to vma so clear pointer.
-	 * Semaphore synchronizes access to vma_lock->vma field.
-	 */
-	vma_lock->vma = NULL;
-	vma->vm_private_data = NULL;
-	up_write(&vma_lock->rw_sema);
-	kref_put(&vma_lock->refs, hugetlb_vma_lock_release);
-}
-
-static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma)
-{
-	if (__vma_shareable_lock(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-		__hugetlb_vma_unlock_write_put(vma_lock);
-	} else if (__vma_private_lock(vma)) {
-		struct resv_map *resv_map = vma_resv_map(vma);
-
-		/* no free for anon vmas, but still need to unlock */
-		up_write(&resv_map->rw_sema);
-	}
-}
-
-static void hugetlb_vma_lock_free(struct vm_area_struct *vma)
-{
-	/*
-	 * Only present in sharable vmas.
-	 */
-	if (!vma || !__vma_shareable_lock(vma))
-		return;
-
-	if (vma->vm_private_data) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-		down_write(&vma_lock->rw_sema);
-		__hugetlb_vma_unlock_write_put(vma_lock);
-	}
-}
-
-static void hugetlb_vma_lock_alloc(struct vm_area_struct *vma)
-{
-	struct hugetlb_vma_lock *vma_lock;
-
-	/* Only establish in (flags) sharable vmas */
-	if (!vma || !(vma->vm_flags & VM_MAYSHARE))
-		return;
-
-	/* Should never get here with non-NULL vm_private_data */
-	if (vma->vm_private_data)
-		return;
-
-	vma_lock = kmalloc(sizeof(*vma_lock), GFP_KERNEL);
-	if (!vma_lock) {
-		/*
-		 * If we can not allocate structure, then vma can not
-		 * participate in pmd sharing.  This is only a possible
-		 * performance enhancement and memory saving issue.
-		 * However, the lock is also used to synchronize page
-		 * faults with truncation.  If the lock is not present,
-		 * unlikely races could leave pages in a file past i_size
-		 * until the file is removed.  Warn in the unlikely case of
-		 * allocation failure.
-		 */
-		pr_warn_once("HugeTLB: unable to allocate vma specific lock\n");
-		return;
-	}
-
-	kref_init(&vma_lock->refs);
-	init_rwsem(&vma_lock->rw_sema);
-	vma_lock->vma = vma;
-	vma->vm_private_data = vma_lock;
+	if (vma->vm_file)
+		lockdep_assert_held(&vma->vm_file->f_mapping->invalidate_lock);
 }
 
 /* Helper that removes a struct file_region from the resv_map cache and returns
@@ -1100,7 +968,6 @@  struct resv_map *resv_map_alloc(void)
 	kref_init(&resv_map->refs);
 	spin_lock_init(&resv_map->lock);
 	INIT_LIST_HEAD(&resv_map->regions);
-	init_rwsem(&resv_map->rw_sema);
 
 	resv_map->adds_in_progress = 0;
 	/*
@@ -1194,22 +1061,11 @@  void hugetlb_dup_vma_private(struct vm_area_struct *vma)
 	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
 	/*
 	 * Clear vm_private_data
-	 * - For shared mappings this is a per-vma semaphore that may be
-	 *   allocated in a subsequent call to hugetlb_vm_op_open.
-	 *   Before clearing, make sure pointer is not associated with vma
-	 *   as this will leak the structure.  This is the case when called
-	 *   via clear_vma_resv_huge_pages() and hugetlb_vm_op_open has already
-	 *   been called to allocate a new structure.
 	 * - For MAP_PRIVATE mappings, this is the reserve map which does
 	 *   not apply to children.  Faults generated by the children are
 	 *   not guaranteed to succeed, even if read-only.
 	 */
-	if (vma->vm_flags & VM_MAYSHARE) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-		if (vma_lock && vma_lock->vma != vma)
-			vma->vm_private_data = NULL;
-	} else
+	if (!(vma->vm_flags & VM_MAYSHARE))
 		vma->vm_private_data = NULL;
 }
 
@@ -4845,25 +4701,6 @@  static void hugetlb_vm_op_open(struct vm_area_struct *vma)
 		resv_map_dup_hugetlb_cgroup_uncharge_info(resv);
 		kref_get(&resv->refs);
 	}
-
-	/*
-	 * vma_lock structure for sharable mappings is vma specific.
-	 * Clear old pointer (if copied via vm_area_dup) and allocate
-	 * new structure.  Before clearing, make sure vma_lock is not
-	 * for this vma.
-	 */
-	if (vma->vm_flags & VM_MAYSHARE) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
-
-		if (vma_lock) {
-			if (vma_lock->vma != vma) {
-				vma->vm_private_data = NULL;
-				hugetlb_vma_lock_alloc(vma);
-			} else
-				pr_warn("HugeTLB: vma_lock already exists in %s.\n", __func__);
-		} else
-			hugetlb_vma_lock_alloc(vma);
-	}
 }
 
 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
@@ -4874,8 +4711,6 @@  static void hugetlb_vm_op_close(struct vm_area_struct *vma)
 	unsigned long reserve, start, end;
 	long gbl_reserve;
 
-	hugetlb_vma_lock_free(vma);
-
 	resv = vma_resv_map(vma);
 	if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
 		return;
@@ -5047,16 +4882,10 @@  int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 		mmu_notifier_invalidate_range_start(&range);
 		vma_assert_write_locked(src_vma);
 		raw_write_seqcount_begin(&src->write_protect_seq);
-	} else {
-		/*
-		 * For shared mappings the vma lock must be held before
-		 * calling hugetlb_walk() in the src vma. Otherwise, the
-		 * returned ptep could go away if part of a shared pmd and
-		 * another thread calls huge_pmd_unshare.
-		 */
-		hugetlb_vma_lock_read(src_vma);
 	}
 
+	hugetlb_vma_lock_read(src_vma);
+
 	last_addr_mask = hugetlb_mask_last_page(h);
 	for (addr = src_vma->vm_start; addr < src_vma->vm_end; addr += sz) {
 		spinlock_t *src_ptl, *dst_ptl;
@@ -5208,10 +5037,10 @@  int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 	if (cow) {
 		raw_write_seqcount_end(&src->write_protect_seq);
 		mmu_notifier_invalidate_range_end(&range);
-	} else {
-		hugetlb_vma_unlock_read(src_vma);
 	}
 
+	hugetlb_vma_unlock_read(src_vma);
+
 	return ret;
 }
 
@@ -5449,28 +5278,12 @@  void __hugetlb_zap_begin(struct vm_area_struct *vma,
 void __hugetlb_zap_end(struct vm_area_struct *vma,
 		       struct zap_details *details)
 {
-	zap_flags_t zap_flags = details ? details->zap_flags : 0;
-
 	if (!vma->vm_file)	/* hugetlbfs_file_mmap error */
 		return;
 
-	if (zap_flags & ZAP_FLAG_UNMAP) {	/* final unmap */
-		/*
-		 * Unlock and free the vma lock before releasing i_mmap_rwsem.
-		 * When the vma_lock is freed, this makes the vma ineligible
-		 * for pmd sharing.  And, i_mmap_rwsem is required to set up
-		 * pmd sharing.  This is important as page tables for this
-		 * unmapped range will be asynchrously deleted.  If the page
-		 * tables are shared, there will be issues when accessed by
-		 * someone else.
-		 */
-		__hugetlb_vma_unlock_write_free(vma);
-	} else {
-		hugetlb_vma_unlock_write(vma);
-	}
-
 	if (vma->vm_file)
 		i_mmap_unlock_write(vma->vm_file->f_mapping);
+	hugetlb_vma_unlock_write(vma);
 }
 
 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
@@ -6713,12 +6526,6 @@  bool hugetlb_reserve_pages(struct inode *inode,
 		return false;
 	}
 
-	/*
-	 * vma specific semaphore used for pmd sharing and fault/truncation
-	 * synchronization
-	 */
-	hugetlb_vma_lock_alloc(vma);
-
 	/*
 	 * Only apply hugepage reservation if asked. At fault time, an
 	 * attempt will be made for VM_NORESERVE to allocate a page
@@ -6841,7 +6648,6 @@  bool hugetlb_reserve_pages(struct inode *inode,
 	hugetlb_cgroup_uncharge_cgroup_rsvd(hstate_index(h),
 					    chg * pages_per_huge_page(h), h_cg);
 out_err:
-	hugetlb_vma_lock_free(vma);
 	if (!vma || vma->vm_flags & VM_MAYSHARE)
 		/* Only call region_abort if the region_chg succeeded but the
 		 * region_add failed or didn't run.
@@ -6913,13 +6719,10 @@  static unsigned long page_table_shareable(struct vm_area_struct *svma,
 	/*
 	 * match the virtual addresses, permission and the alignment of the
 	 * page table page.
-	 *
-	 * Also, vma_lock (vm_private_data) is required for sharing.
 	 */
 	if (pmd_index(addr) != pmd_index(saddr) ||
 	    vm_flags != svm_flags ||
-	    !range_in_vma(svma, sbase, s_end) ||
-	    !svma->vm_private_data)
+	    !range_in_vma(svma, sbase, s_end))
 		return 0;
 
 	return saddr;
@@ -6939,8 +6742,6 @@  bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr)
 	 */
 	if (!(vma->vm_flags & VM_MAYSHARE))
 		return false;
-	if (!vma->vm_private_data)	/* vma lock required for sharing */
-		return false;
 	if (!range_in_vma(vma, start, end))
 		return false;
 	return true;