From ea3f8272876f2958463992f6736ab690fde7fa9c Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 29 Jun 2023 23:04:57 -0700
Subject: [PATCH] parisc: fix expand_stack() conversion
In commit 8d7071af8907 ("mm: always expand the stack with the mmap write
lock held") I tried to deal with the remaining odd page fault handling
cases. The oddest one is ia64, which has stacks that grow both up and
down. And because ia64 was _so_ odd, I asked people to verify the end
result.
But a close second oddity is parisc, which is the only one that has a
main stack growing up (our "CONFIG_STACK_GROWSUP" config option). But
it looked obvious enough that I didn't worry about it.
I should have worried a bit more. Not because it was particularly
complex, but because I just used the wrong variable name.
The previous vma isn't called "prev", it's called "prev_vma". Blush.
Fixes: 8d7071af8907 ("mm: always expand the stack with the mmap write lock held")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/parisc/mm/fault.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index 6e894afa42499..a4c7c7630f48b 100644
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -289,7 +289,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
mmap_read_lock(mm);
vma = find_vma_prev(mm, address, &prev_vma);
if (!vma || address < vma->vm_start) {
- if (!prev || !(prev->vm_flags & VM_GROWSUP))
+ if (!prev_vma || !(prev_vma->vm_flags & VM_GROWSUP))
goto bad_area;
vma = expand_stack(mm, address);
if (!vma)
--
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