From: Suren Baghdasaryan <surenb@google.com>
Date: Sun, 30 Oct 2022 17:35:38 +0000 (+0000)
Subject: mm/mmap: write-lock VMAs affected by VMA expansion
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=4f181a975e6ab8994f27c3694da3c2fb66da7329;p=users%2Fjedix%2Flinux-maple.git

mm/mmap: write-lock VMAs affected by VMA expansion

vma_expand changes VMA boundaries and might result in freeing an adjacent
VMA. Write-lock affected VMAs to prevent concurrent page faults.

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

diff --git a/mm/mmap.c b/mm/mmap.c
index c25a39a4a617..ae585a6287ea 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -542,6 +542,7 @@ inline int vma_expand(struct ma_state *mas, struct vm_area_struct *vma,
 	if (mas_preallocate(mas, vma, GFP_KERNEL))
 		goto nomem;
 
+	vma_write_lock(vma);
 	vma_adjust_trans_huge(vma, start, end, 0);
 
 	if (file) {
@@ -588,6 +589,7 @@ inline int vma_expand(struct ma_state *mas, struct vm_area_struct *vma,
 	}
 
 	if (remove_next) {
+		vma_write_lock(next);
 		if (file) {
 			uprobe_munmap(next, next->vm_start, next->vm_end);
 			fput(file);