On 9/20/19 9:21 PM, Qiujun Huang wrote:
__get_user_pages_fast try to walk the page table but the
hugepage pte is replace by hwpoison swap entry by mca path.
...
Can you describe this in more details. I guess you are facing the issue
with respect PUD level PTE entry that got updated by hwpoison as a swap
entry. Since we don't specifically check for pud_present(), we walk the
page table with wrong values and that results in corruption?
[15798.177437] mce: Uncorrected hardware memory error in
user-access at 224f1761c0
[15798.180171] MCE 0x224f176: Killing pal_main:6784 due to
hardware memory corruption
[15798.180176] MCE 0x224f176: Killing qemu-system-x86:167336
due to hardware memory corruption
...
[15798.180206] BUG: unable to handle kernel
[15798.180226] paging request at ffff891200003000
[15798.180236] IP: [<ffffffff8106edae>] gup_pud_range+
0x13e/0x1e0
...
We need to skip the hwpoison entry in gup_pud_range.
Signed-off-by: Qiujun Huang <hqjag...@gmail.com>
---
mm/gup.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/mm/gup.c b/mm/gup.c
index 98f13ab..6157ed9 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2230,6 +2230,8 @@ static int gup_pud_range(p4d_t p4d, unsigned long addr,
unsigned long end,
next = pud_addr_end(addr, end);
if (pud_none(pud))
return 0;
+ if (unlikely(!pud_present(pud)))
+ return 0;
You should be able to remove that if (pud_none(pud)) check and just keep
the pud_present() check?
if (unlikely(pud_huge(pud))) {
if (!gup_huge_pud(pud, pudp, addr, next, flags,
pages, nr))
