[merged mm-stable] mm-mmap-prevent-pagefault-handler-from-racing-with-mmu_notifier-registration.patch removed from -mm tree

[merged mm-stable] mm-mmap-prevent-pagefault-handler-from-racing-with-mmu_notifier-registration.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/mmap: prevent pagefault handler from racing with mmu_notifier registration
has been removed from the -mm tree.  Its filename was
     mm-mmap-prevent-pagefault-handler-from-racing-with-mmu_notifier-registration.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: Suren Baghdasaryan <surenb@google.com>
Subject: mm/mmap: prevent pagefault handler from racing with mmu_notifier registration
Date: Mon, 27 Feb 2023 09:36:20 -0800

Page fault handlers might need to fire MMU notifications while a new
notifier is being registered.  Modify mm_take_all_locks to write-lock all
VMAs and prevent this race with page fault handlers that would hold VMA
locks.  VMAs are locked before i_mmap_rwsem and anon_vma to keep the same
locking order as in page fault handlers.

Link: https://lkml.kernel.org/r/20230227173632.3292573-22-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mmap.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/mm/mmap.c~mm-mmap-prevent-pagefault-handler-from-racing-with-mmu_notifier-registration
+++ a/mm/mmap.c
@@ -3494,6 +3494,7 @@ static void vm_lock_mapping(struct mm_st
  * of mm/rmap.c:
  *   - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
  *     hugetlb mapping);
+ *   - all vmas marked locked
  *   - all i_mmap_rwsem locks;
  *   - all anon_vma->rwseml
  *
@@ -3519,6 +3520,13 @@ int mm_take_all_locks(struct mm_struct *
 	mas_for_each(&mas, vma, ULONG_MAX) {
 		if (signal_pending(current))
 			goto out_unlock;
+		vma_start_write(vma);
+	}
+
+	mas_set(&mas, 0);
+	mas_for_each(&mas, vma, ULONG_MAX) {
+		if (signal_pending(current))
+			goto out_unlock;
 		if (vma->vm_file && vma->vm_file->f_mapping &&
 				is_vm_hugetlb_page(vma))
 			vm_lock_mapping(mm, vma->vm_file->f_mapping);
@@ -3605,6 +3613,7 @@ void mm_drop_all_locks(struct mm_struct
 		if (vma->vm_file && vma->vm_file->f_mapping)
 			vm_unlock_mapping(vma->vm_file->f_mapping);
 	}
+	vma_end_write_all(mm);
 
 	mutex_unlock(&mm_all_locks_mutex);
 }
_

Patches currently in -mm which might be from surenb@google.com are