linux-kernel - [PATCH] mm/mmap: Properly unaccount memory on mas

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Date:   Fri,  2 Dec 2022 15:53:39 +1100
From:   Alistair Popple <apopple@...dia.com>
To:     akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        liam.howlett@...cle.com, Alistair Popple <apopple@...dia.com>
Subject: [PATCH] mm/mmap: Properly unaccount memory on mas_preallocate() failure

security_vm_enough_memory_mm() accounts memory via a call to
vm_acct_memory(). Therefore any subsequent failures should unaccount
for this memory prior to returning the error.

Signed-off-by: Alistair Popple <apopple@...dia.com>
Fixes: 28c5609fb236 ("mm/mmap: preallocate maple nodes for brk vma expansion")

---

Pretty trivial fixup that I noticed was needed while working on the
code.
---
 mm/mmap.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 74a84eb33b90..3e50a571c3c4 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2954,7 +2954,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
 	    ((vma->vm_flags & ~VM_SOFTDIRTY) == flags)) {
 		mas_set_range(mas, vma->vm_start, addr + len - 1);
 		if (mas_preallocate(mas, vma, GFP_KERNEL))
-			return -ENOMEM;
+			goto unacct_fail;
 
 		vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
 		if (vma->anon_vma) {
@@ -2976,7 +2976,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
 	/* create a vma struct for an anonymous mapping */
 	vma = vm_area_alloc(mm);
 	if (!vma)
-		goto vma_alloc_fail;
+		goto unacct_fail;
 
 	vma_set_anonymous(vma);
 	vma->vm_start = addr;
@@ -3001,7 +3001,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
 
 mas_store_fail:
 	vm_area_free(vma);
-vma_alloc_fail:
+unacct_fail:
 	vm_unacct_memory(len >> PAGE_SHIFT);
 	return -ENOMEM;
 }
-- 
2.35.1