[113/227] mm/memory-failure.c: catch unexpected -EFAULT from vma_address()

Commit Message

Andrew Morton March 22, 2022, 9:44 p.m. UTC

From: Miaohe Lin <[e-mail]>
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/[e-mail]
Signed-off-by: Miaohe Lin <[e-mail]>
Acked-by: Naoya Horiguchi <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memory-failure.c |    1 +
 1 file changed, 1 insertion(+)

Patch

--- 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;