From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm/memory-failure.c: catch unexpected -EFAULT from vma_address()
It's unexpected to walk the page table when vma_address() return -EFAULT.
But dev_pagemap_mapping_shift() is called only when vma associated to the
error page is found already in collect_procs_{file,anon}, so vma_address()
should not return -EFAULT except with some bug, as Naoya pointed out. We
can use VM_BUG_ON_VMA() to catch this bug here.
Link: https://lkml.kernel.org/r/20220218090118.1105-3-linmiaohe@xxxxxxxxxx
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Acked-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 1 +
1 file changed, 1 insertion(+)
--- a/mm/memory-failure.c~mm-memory-failurec-catch-unexpected-efault-from-vma_address
+++ a/mm/memory-failure.c
@@ -315,6 +315,7 @@ static unsigned long dev_pagemap_mapping
pmd_t *pmd;
pte_t *pte;
+ VM_BUG_ON_VMA(address == -EFAULT, vma);
pgd = pgd_offset(vma->vm_mm, address);
if (!pgd_present(*pgd))
return 0;
_
