Regular oops on shutdown of KVM/ARM64 machines with VGA device
christoffer.dall at linaro.org
Tue Jun 30 11:50:31 PDT 2015
On Tue, Jun 30, 2015 at 05:20:11PM +0100, Marc Zyngier wrote:
> On 30/06/15 17:16, Dirk Müller wrote:
> > Hi Marc,
> >> Can try the following patch?
> > [..]
> > Thanks a lot for the quick patch, from a brief testing this seems to
> > fix the issue (on a 4k kernel). I'll retest this in our original
> > configuration (which was 64k) but so far I don't see a reason why it
> > shouldn't fix the issue.
> Awesome. Mind if I put your Tested-by on the patch?
Looks to me like the definition of pmd_huge() on arm64 is broken; pretty
sure when I reviewed this original patch I followed the path of both
pmd_huge() and pmd_trans_huge() and checked that they don't return true
if the entry is clear. This happens to be the case on both arm and x86,
and I probably only looked at the arm code and not the arm64 code.
I'm fine with this patch, but I think we should also merge the
following, since by definition, a clear pmd cannot also be a huge pmd:
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 2de9d2e..779520b 100644
@@ -40,7 +40,7 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
int pmd_huge(pmd_t pmd)
- return !(pmd_val(pmd) & PMD_TABLE_BIT);
+ return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
int pud_huge(pud_t pud)
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