From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Wed, 28 Oct 2020 00:25:17 +0000 (-0400)
Subject: mm/mmap: Fix vma locking on brk
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=3a4a55e6898103fc17c7efad4a226e25f6b580b9;p=users%2Fjedix%2Flinux-maple.git

mm/mmap: Fix vma locking on brk

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---

diff --git a/mm/mmap.c b/mm/mmap.c
index 728c62da9f91..66ecfc8f3a31 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2904,33 +2904,16 @@ static int do_brk_munmap(struct vm_area_struct *vma, unsigned long newbrk,
 
 	// Change the oldbrk of vma to the newbrk of the munmap area
 	vma_adjust_trans_huge(vma, vma->vm_start, newbrk, 0);
-	if (vma->anon_vma) {
-		anon_vma_lock_write(vma->anon_vma);
-		anon_vma_interval_tree_pre_update_vma(vma);
-	}
 	vma_mt_szero(vma->vm_mm, newbrk, vma->vm_end);
 	vma->vm_end = newbrk;
 	vmacache_invalidate(vma->vm_mm);
-	if (vma->anon_vma) {
-		anon_vma_interval_tree_post_update_vma(vma);
-		anon_vma_unlock_write(vma->anon_vma);
-	}
-
 	unmap_pages = vma_pages(&unmap);
 	if (unmap.vm_flags & VM_LOCKED) {
 		mm->locked_vm -= unmap_pages;
 		munlock_vma_pages_range(&unmap, newbrk, oldbrk);
 	}
 
-	// prev of unmap_pages is just vma.
-	if (vma->vm_flags & VM_GROWSUP)
-		ret = 0;
-	else if (vma->vm_next && (vma->vm_next->vm_flags & VM_GROWSDOWN))
-		ret = 0;
-
-	if (ret)
-		mmap_write_downgrade(mm);
-
+	mmap_write_downgrade(mm);
 	unmap_region(mm, &unmap, vma, newbrk, oldbrk);
 	/* Statistics */
 	vm_stat_account(mm, unmap.vm_flags, -unmap_pages);
@@ -2939,7 +2922,7 @@ static int do_brk_munmap(struct vm_area_struct *vma, unsigned long newbrk,
 
 munmap_full_vma:
 	validate_mm_mt(mm);
-	return ret;
+	return 1;
 }
 
 /*