From: Anshuman Khandual <anshuman.khandual@arm.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
linux-mm@kvack.org, akpm@linux-foundation.org
Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2] mm/debug_vm_pgtable: Fix kernel crash by checking for THP support
Date: Tue, 9 Jun 2020 08:17:04 +0530 [thread overview]
Message-ID: <826398c3-9abe-e173-407e-e7a84c772517@arm.com> (raw)
In-Reply-To: <20200608125252.407659-1-aneesh.kumar@linux.ibm.com>
On 06/08/2020 06:22 PM, Aneesh Kumar K.V wrote:
> Architectures can have CONFIG_TRANSPARENT_HUGEPAGE enabled but
> no THP support enabled based on platforms. For ex: with 4K
> PAGE_SIZE ppc64 supports THP only with radix translation.
>
> This results in below crash when running with hash translation and
> 4K PAGE_SIZE.
>
> kernel BUG at arch/powerpc/include/asm/book3s/64/hash-4k.h:140!
> cpu 0x61: Vector: 700 (Program Check) at [c000000ff948f860]
> pc: c0000000018810f8: debug_vm_pgtable+0x480/0x8b0
> lr: c0000000018810ec: debug_vm_pgtable+0x474/0x8b0
> ...
> [c000000ff948faf0] c000000001880fec debug_vm_pgtable+0x374/0x8b0 (unreliable)
> [c000000ff948fbf0] c000000000011648 do_one_initcall+0x98/0x4f0
> [c000000ff948fcd0] c000000001843928 kernel_init_freeable+0x330/0x3fc
> [c000000ff948fdb0] c0000000000122ac kernel_init+0x24/0x148
> [c000000ff948fe20] c00000000000cc44 ret_from_kernel_thread+0x5c/0x78
>
> Check for THP support correctly
>
> Cc: anshuman.khandual@arm.com
> Fixes: 399145f9eb6c ("mm/debug: add tests validating architecture page table helpers")
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> ---
> mm/debug_vm_pgtable.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 188c18908964..df3a3a08f4f8 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -61,6 +61,9 @@ static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot)
> {
> pmd_t pmd = pfn_pmd(pfn, prot);
>
> + if (!has_transparent_hugepage())
> + return;
> +
> WARN_ON(!pmd_same(pmd, pmd));
> WARN_ON(!pmd_young(pmd_mkyoung(pmd_mkold(pmd))));
> WARN_ON(!pmd_dirty(pmd_mkdirty(pmd_mkclean(pmd))));
> @@ -80,6 +83,9 @@ static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot)
> {
> pud_t pud = pfn_pud(pfn, prot);
>
> + if (!has_transparent_hugepage())
> + return;
> +
> WARN_ON(!pud_same(pud, pud));
> WARN_ON(!pud_young(pud_mkyoung(pud_mkold(pud))));
> WARN_ON(!pud_write(pud_mkwrite(pud_wrprotect(pud))));
>
Builds with THP on arc, s390 and runs with THP on x86 and arm64 platforms.
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
prev parent reply other threads:[~2020-06-09 2:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-08 12:52 [PATCH v2] mm/debug_vm_pgtable: Fix kernel crash by checking for THP support Aneesh Kumar K.V
2020-06-09 2:47 ` Anshuman Khandual [this message]
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