From: Catalin Marinas <catalin.marinas@arm.com>
To: Punit Agrawal <punit.agrawal@arm.com>
Cc: will.deacon@arm.com, David Woods <dwoods@mellanox.com>,
steve.capper@arm.com, tbaicar@codeaurora.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/3] arm64: hugetlb: Fix huge_pte_offset to return poisoned page table entries
Date: Wed, 3 May 2017 13:49:06 +0100 [thread overview]
Message-ID: <20170503124906.GA5622@e104818-lin.cambridge.arm.com> (raw)
In-Reply-To: <20170412140459.21824-2-punit.agrawal@arm.com>
On Wed, Apr 12, 2017 at 03:04:57PM +0100, Punit Agrawal wrote:
> When memory failure is enabled, a poisoned hugepage pte is marked as a
> swap entry. huge_pte_offset() does not return the poisoned page table
> entries when it encounters PUD/PMD hugepages.
>
> This behaviour of huge_pte_offset() leads to error such as below when
> munmap is called on poisoned hugepages.
>
> [ 344.165544] mm/pgtable-generic.c:33: bad pmd 000000083af00074.
>
> Fix huge_pte_offset() to return the poisoned pte which is then
> appropriately handled by the generic layer code.
>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Steve Capper <steve.capper@arm.com>
> Cc: David Woods <dwoods@mellanox.com>
> ---
> arch/arm64/mm/hugetlbpage.c | 20 +++++++++++++++-----
> 1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 7514a000e361..5f1832165d69 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -143,15 +143,24 @@ pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
> pr_debug("%s: addr:0x%lx pgd:%p\n", __func__, addr, pgd);
> if (!pgd_present(*pgd))
> return NULL;
> - pud = pud_offset(pgd, addr);
> - if (!pud_present(*pud))
> - return NULL;
>
> - if (pud_huge(*pud))
> + pud = pud_offset(pgd, addr);
> + /*
> + * In case of HW Poisoning, a hugepage pud/pmd can contain
> + * poisoned entries. Poisoned entries are marked as swap
> + * entries.
> + *
> + * For puds/pmds that are not present, check to see if it
> + * could be a swap entry (!present and !none).
> + */
> + if ((!pte_present(pud_pte(*pud)) && !pud_none(*pud)) || pud_huge(*pud))
> return (pte_t *)pud;
Since we use puds as huge pages, can we just change pud_present() to
match the pmd_present()? I'd like to see similar checks for pud and pmd,
it would be easier to follow. Something like (unchecked):
if (pud_none(*pud))
return NULL;
/* swap or huge page */
if (!pud_present(*pud) || pud_huge(*pud))
return (pte_t *)pud;
/* table; check the next level */
> +
> pmd = pmd_offset(pud, addr);
> - if (!pmd_present(*pmd))
> + if (pmd_none(*pmd))
> return NULL;
> + if (!pmd_present(*pmd) && !pmd_none(*pmd))
> + return (pte_t *)pmd;
At this point, we already know that pmd_none(*pmd) is false, no ned to
check it again.
--
Catalin
next prev parent reply other threads:[~2017-05-03 12:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-12 14:04 [PATCH 0/3] arm64: Add support for handling memory corruption Punit Agrawal
2017-04-12 14:04 ` [PATCH 1/3] arm64: hugetlb: Fix huge_pte_offset to return poisoned page table entries Punit Agrawal
2017-04-14 19:29 ` Baicar, Tyler
2017-05-03 12:49 ` Catalin Marinas [this message]
2017-05-04 15:55 ` Punit Agrawal
2017-05-17 14:35 ` Timur Tabi
2017-05-17 15:27 ` Punit Agrawal
2017-04-12 14:04 ` [PATCH 2/3] arm64: hwpoison: add VM_FAULT_HWPOISON[_LARGE] handling Punit Agrawal
2017-04-12 14:04 ` [PATCH 3/3] arm64: kconfig: allow support for memory failure handling Punit Agrawal
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