From: Will Deacon <will@kernel.org>
To: Liu Shixin <liushixin2@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
David Hildenbrand <dhildenb@redhat.com>,
Rafael Aquini <raquini@redhat.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] arm64/mm: fix incorrect file_map_count for invalid pmd
Date: Mon, 21 Nov 2022 18:18:59 +0000 [thread overview]
Message-ID: <20221121181859.GE7645@willie-the-truck> (raw)
In-Reply-To: <20221121073608.4183459-1-liushixin2@huawei.com>
On Mon, Nov 21, 2022 at 03:36:08PM +0800, Liu Shixin wrote:
> The page table check trigger BUG_ON() unexpectedly when split hugepage:
>
> ------------[ cut here ]------------
> kernel BUG at mm/page_table_check.c:119!
> Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
> Dumping ftrace buffer:
> (ftrace buffer empty)
> Modules linked in:
> CPU: 7 PID: 210 Comm: transhuge-stres Not tainted 6.1.0-rc3+ #748
> Hardware name: linux,dummy-virt (DT)
> pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : page_table_check_set.isra.0+0x398/0x468
> lr : page_table_check_set.isra.0+0x1c0/0x468
> [...]
> Call trace:
> page_table_check_set.isra.0+0x398/0x468
> __page_table_check_pte_set+0x160/0x1c0
> __split_huge_pmd_locked+0x900/0x1648
> __split_huge_pmd+0x28c/0x3b8
> unmap_page_range+0x428/0x858
> unmap_single_vma+0xf4/0x1c8
> zap_page_range+0x2b0/0x410
> madvise_vma_behavior+0xc44/0xe78
> do_madvise+0x280/0x698
> __arm64_sys_madvise+0x90/0xe8
> invoke_syscall.constprop.0+0xdc/0x1d8
> do_el0_svc+0xf4/0x3f8
> el0_svc+0x58/0x120
> el0t_64_sync_handler+0xb8/0xc0
> el0t_64_sync+0x19c/0x1a0
> [...]
>
> On arm64, pmd_leaf() will return true even if the pmd is invalid due to
> pmd_present_invalid() check. So in pmdp_invalidate() the file_map_count
> will not only decrease once but also increase once. Then in set_pte_at(),
> the file_map_count increase again, and so trigger BUG_ON() unexpectedly.
>
> Add !pmd_present_invalid() check in pmd_user_accessible_page() to fix the
> problem.
>
> Fixes: 42b2547137f5 ("arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK")
> Reported-by: Denys Vlasenko <dvlasenk@redhat.com>
> Signed-off-by: Liu Shixin <liushixin2@huawei.com>
> Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com>
> Acked-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
> v1->v2: Update comment and optimize the code by moving p?d_valid() at
> first place suggested by Mark.
> v2->v3: Replace pmd_valid() with pmd_present_invalid() suggested by Will.
>
> arch/arm64/include/asm/pgtable.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index edf6625ce965..17afb09f386f 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -863,7 +863,7 @@ static inline bool pte_user_accessible_page(pte_t pte)
>
> static inline bool pmd_user_accessible_page(pmd_t pmd)
> {
> - return pmd_leaf(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
> + return pmd_leaf(pmd) && !pmd_present_invalid(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
> }
Acked-by: Will Deacon <will@kernel.org>
But please see my comment on v2 about pud_user_exec() for the PUD case.
Will
next prev parent reply other threads:[~2022-11-21 18:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-21 7:36 [PATCH v3] arm64/mm: fix incorrect file_map_count for invalid pmd Liu Shixin
2022-11-21 18:18 ` Will Deacon [this message]
2022-11-28 16:26 ` Denys Vlasenko
2022-11-29 14:26 ` Will Deacon
2023-01-05 18:03 ` Will Deacon
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