From: Suren Baghdasaryan <surenb@google.com>
Date: Tue, 8 Nov 2022 19:15:56 +0000 (+0000)
Subject: mm: introduce mod_vm_flags_nolock
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=c249758008406f1715fc9a0c8774f513aacbb456;p=users%2Fjedix%2Flinux-maple.git

mm: introduce mod_vm_flags_nolock

In cases when VMA flags are modified after VMA was isolated and mmap_lock
was downgraded, flags modifications do not require per-VMA locking and
an attempt to lock the VMA would result in an assertion because mmap
write lock is not held.
Introduce mod_vm_flags_nolock to be used in such situation.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 31abff298fe0..cb2d7f8ae532 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -742,6 +742,14 @@ void clear_vm_flags(struct vm_area_struct *vma, unsigned long flags)
 	vma->vm_flags &= ~flags;
 }
 
+static inline
+void mod_vm_flags_nolock(struct vm_area_struct *vma,
+		  unsigned long set, unsigned long clear)
+{
+	vma->vm_flags |= set;
+	vma->vm_flags &= ~clear;
+}
+
 static inline
 void mod_vm_flags(struct vm_area_struct *vma,
 		  unsigned long set, unsigned long clear)