[merged mm-stable] mm-introduce-vma-detached-flag.patch removed from -mm tree

[merged mm-stable] mm-introduce-vma-detached-flag.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm: introduce vma detached flag
has been removed from the -mm tree.  Its filename was
     mm-introduce-vma-detached-flag.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: introduce vma detached flag
Date: Mon, 27 Feb 2023 09:36:21 -0800

Per-vma locking mechanism will search for VMA under RCU protection and
then after locking it, has to ensure it was not removed from the VMA tree
after we found it.  To make this check efficient, introduce a
vma->detached flag to mark VMAs which were removed from the VMA tree.

Link: https://lkml.kernel.org/r/20230227173632.3292573-23-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mm.h       |   11 +++++++++++
 include/linux/mm_types.h |    3 +++
 mm/mmap.c                |    2 ++
 3 files changed, 16 insertions(+)

--- a/include/linux/mm.h~mm-introduce-vma-detached-flag
+++ a/include/linux/mm.h
@@ -711,6 +711,14 @@ static inline void vma_assert_write_lock
 	VM_BUG_ON_VMA(!__is_vma_write_locked(vma, &mm_lock_seq), vma);
 }
 
+static inline void vma_mark_detached(struct vm_area_struct *vma, bool detached)
+{
+	/* When detaching vma should be write-locked */
+	if (detached)
+		vma_assert_write_locked(vma);
+	vma->detached = detached;
+}
+
 #else /* CONFIG_PER_VMA_LOCK */
 
 static inline void vma_init_lock(struct vm_area_struct *vma) {}
@@ -721,6 +729,8 @@ static inline void vma_start_write(struc
 static inline bool vma_try_start_write(struct vm_area_struct *vma)
 		{ return true; }
 static inline void vma_assert_write_locked(struct vm_area_struct *vma) {}
+static inline void vma_mark_detached(struct vm_area_struct *vma,
+				     bool detached) {}
 
 #endif /* CONFIG_PER_VMA_LOCK */
 
@@ -732,6 +742,7 @@ static inline void vma_init(struct vm_ar
 	vma->vm_mm = mm;
 	vma->vm_ops = &dummy_vm_ops;
 	INIT_LIST_HEAD(&vma->anon_vma_chain);
+	vma_mark_detached(vma, false);
 	vma_init_lock(vma);
 }
 
--- a/include/linux/mm_types.h~mm-introduce-vma-detached-flag
+++ a/include/linux/mm_types.h
@@ -506,6 +506,9 @@ struct vm_area_struct {
 #ifdef CONFIG_PER_VMA_LOCK
 	int vm_lock_seq;
 	struct rw_semaphore lock;
+
+	/* Flag to indicate areas detached from the mm->mm_mt tree */
+	bool detached;
 #endif
 
 	/*
--- a/mm/mmap.c~mm-introduce-vma-detached-flag
+++ a/mm/mmap.c
@@ -599,6 +599,7 @@ static inline void vma_complete(struct v
 
 	if (vp->remove) {
 again:
+		vma_mark_detached(vp->remove, true);
 		if (vp->file) {
 			uprobe_munmap(vp->remove, vp->remove->vm_start,
 				      vp->remove->vm_end);
@@ -2276,6 +2277,7 @@ static inline int munmap_sidetree(struct
 	if (mas_store_gfp(mas_detach, vma, GFP_KERNEL))
 		return -ENOMEM;
 
+	vma_mark_detached(vma, true);
 	if (vma->vm_flags & VM_LOCKED)
 		vma->vm_mm->locked_vm -= vma_pages(vma);
 
_

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