From: Denys Vlasenko <dvlasenk@redhat.com>
To: Liu Shixin <liushixin2@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
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>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud
Date: Mon, 21 Nov 2022 16:57:37 +0100 [thread overview]
Message-ID: <aa2c354f-b7d1-6b97-ddff-762f7fec8431@redhat.com> (raw)
In-Reply-To: <20221116083811.464678-2-liushixin2@huawei.com>
On 11/16/22 09:38, Liu Shixin wrote:
> The page table check trigger BUG_ON() unexpectedly when collapse hugepage:
>
> ------------[ cut here ]------------
> kernel BUG at mm/page_table_check.c:82!
> Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
> Dumping ftrace buffer:
> (ftrace buffer empty)
> Modules linked in:
> CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750
> Hardware name: linux,dummy-virt (DT)
> pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : page_table_check_clear.isra.0+0x258/0x3f0
> lr : page_table_check_clear.isra.0+0x240/0x3f0
> [...]
> Call trace:
> page_table_check_clear.isra.0+0x258/0x3f0
> __page_table_check_pmd_clear+0xbc/0x108
> pmdp_collapse_flush+0xb0/0x160
> collapse_huge_page+0xa08/0x1080
> hpage_collapse_scan_pmd+0xf30/0x1590
> khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8
> khugepaged+0x338/0x518
> kthread+0x278/0x2f8
> ret_from_fork+0x10/0x20
> [...]
>
> Since pmd_user_accessible_page() doesn't check if a pmd is leaf, it
> decrease file_map_count for a non-leaf pmd comes from collapse_huge_page().
> and so trigger BUG_ON() unexpectedly.
>
> Fix this problem by using pmd_leaf() insteal of pmd_present() in
> pmd_user_accessible_page(). Moreover, use pud_leaf() for
> pud_user_accessible_page() too.
>
> 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>
Tested on 6.0.6 kernel, no oopses anymore.
WARNING: multiple messages have this Message-ID (diff)
From: Denys Vlasenko <dvlasenk@redhat.com>
To: Liu Shixin <liushixin2@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
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>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud
Date: Mon, 21 Nov 2022 16:57:37 +0100 [thread overview]
Message-ID: <aa2c354f-b7d1-6b97-ddff-762f7fec8431@redhat.com> (raw)
In-Reply-To: <20221116083811.464678-2-liushixin2@huawei.com>
On 11/16/22 09:38, Liu Shixin wrote:
> The page table check trigger BUG_ON() unexpectedly when collapse hugepage:
>
> ------------[ cut here ]------------
> kernel BUG at mm/page_table_check.c:82!
> Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
> Dumping ftrace buffer:
> (ftrace buffer empty)
> Modules linked in:
> CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750
> Hardware name: linux,dummy-virt (DT)
> pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : page_table_check_clear.isra.0+0x258/0x3f0
> lr : page_table_check_clear.isra.0+0x240/0x3f0
> [...]
> Call trace:
> page_table_check_clear.isra.0+0x258/0x3f0
> __page_table_check_pmd_clear+0xbc/0x108
> pmdp_collapse_flush+0xb0/0x160
> collapse_huge_page+0xa08/0x1080
> hpage_collapse_scan_pmd+0xf30/0x1590
> khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8
> khugepaged+0x338/0x518
> kthread+0x278/0x2f8
> ret_from_fork+0x10/0x20
> [...]
>
> Since pmd_user_accessible_page() doesn't check if a pmd is leaf, it
> decrease file_map_count for a non-leaf pmd comes from collapse_huge_page().
> and so trigger BUG_ON() unexpectedly.
>
> Fix this problem by using pmd_leaf() insteal of pmd_present() in
> pmd_user_accessible_page(). Moreover, use pud_leaf() for
> pud_user_accessible_page() too.
>
> 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>
Tested on 6.0.6 kernel, no oopses anymore.
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next prev parent reply other threads:[~2022-11-21 15:58 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-16 8:38 [PATCH 0/2] arm64: fix two bug about page table check Liu Shixin
2022-11-16 8:38 ` Liu Shixin
2022-11-16 8:38 ` [PATCH 1/2] arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud Liu Shixin
2022-11-16 8:38 ` Liu Shixin
2022-11-16 9:04 ` David Hildenbrand
2022-11-16 9:04 ` David Hildenbrand
2022-11-16 14:59 ` Pasha Tatashin
2022-11-16 14:59 ` Pasha Tatashin
2022-11-17 4:09 ` Anshuman Khandual
2022-11-17 4:09 ` Anshuman Khandual
2022-11-17 6:59 ` Liu Shixin
2022-11-17 6:59 ` Liu Shixin
2022-11-21 15:57 ` Denys Vlasenko [this message]
2022-11-21 15:57 ` Denys Vlasenko
2022-11-16 8:38 ` [PATCH 2/2] arm64/mm: fix incorrect file_map_count for invalid pmd/pud Liu Shixin
2022-11-16 8:38 ` Liu Shixin
2022-11-16 9:08 ` David Hildenbrand
2022-11-16 9:08 ` David Hildenbrand
2022-11-16 15:46 ` Mark Rutland
2022-11-16 15:46 ` Mark Rutland
2022-11-17 4:24 ` Anshuman Khandual
2022-11-17 4:24 ` Anshuman Khandual
2022-11-16 15:18 ` Pasha Tatashin
2022-11-16 15:18 ` Pasha Tatashin
2022-11-16 15:52 ` Mark Rutland
2022-11-16 15:52 ` Mark Rutland
2022-11-17 3:15 ` Liu Shixin
2022-11-17 3:15 ` Liu Shixin
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