linux-kernel - [PATCH 37/41] mm: introduce mod_vm_flags

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Date:   Mon,  9 Jan 2023 12:53:32 -0800
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     akpm@...ux-foundation.org
Cc:     michel@...pinasse.org, jglisse@...gle.com, mhocko@...e.com,
        vbabka@...e.cz, hannes@...xchg.org, mgorman@...hsingularity.net,
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        surenb@...gle.com
Subject: [PATCH 37/41] 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@...gle.com>
---
 include/linux/mm.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2e3be1d45371..7d436a5027cc 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -743,6 +743,14 @@ 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)
-- 
2.39.0