From: Liam R. Howlett <Liam.Howlett@oracle.com>
Date: Tue, 8 Mar 2022 18:25:02 +0000 (-0500)
Subject: mm/mmap: Fix unmapped_area_topdown() and expand_downwards()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7e3cf3583d89baecd2e3cdf54997be2fe741f523;p=users%2Fjedix%2Flinux-maple.git

mm/mmap: Fix unmapped_area_topdown() and expand_downwards()

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

diff --git a/mm/mmap.c b/mm/mmap.c
index 74a4608ac64f..0b470caa74df 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1638,8 +1638,8 @@ static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 				length))
 		return -ENOMEM;
 
-	gap = (mas.index + info->align_mask) & ~info->align_mask;
-	gap -= info->align_offset & info->align_mask;
+	gap = mas.last + 1 - info->length;
+	gap -= (gap - info->align_offset) & info->align_mask;
 	return gap;
 }
 
@@ -2003,6 +2003,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 				vm_stat_account(mm, vma->vm_flags, grow);
 				anon_vma_interval_tree_pre_update_vma(vma);
 				vma->vm_end = address;
+				/* Overwrite old entry in mtree. */
 				vma_store(mm, vma);
 				anon_vma_interval_tree_post_update_vma(vma);
 				spin_unlock(&mm->page_table_lock);
@@ -2023,6 +2024,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 int expand_downwards(struct vm_area_struct *vma, unsigned long address)
 {
 	struct mm_struct *mm = vma->vm_mm;
+	MA_STATE(mas, &mm->mm_mt, vma->vm_start, vma->vm_start);
 	struct vm_area_struct *prev;
 	int error = 0;
 
@@ -2031,7 +2033,7 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address)
 		return -EPERM;
 
 	/* Enforce stack_guard_gap */
-	find_vma_prev(mm, vma->vm_start, &prev);
+	prev = mas_prev(&mas, 0);
 	/* Check that both stack segments have the same anon_vma? */
 	if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
 			vma_is_accessible(prev)) {