diff mbox series

[v2,1/2] arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud

Message ID 20221117075602.2904324-2-liushixin2@huawei.com
State New
Headers
Series arm64: fix two bug about page table check |

Commit Message

Liu Shixin Nov. 17, 2022, 7:56 a.m. UTC 
  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>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com>
---
 arch/arm64/include/asm/pgtable.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Kefeng Wang Nov. 17, 2022, 7:56 a.m. UTC | #1 
On 2022/11/17 15:56, 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>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Will Deacon Nov. 18, 2022, 2:35 p.m. UTC | #2 
On Thu, Nov 17, 2022 at 03:56:01PM +0800, 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>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com>
> ---
>  arch/arm64/include/asm/pgtable.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 71a1af42f0e8..edf6625ce965 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -863,12 +863,12 @@ static inline bool pte_user_accessible_page(pte_t pte)
>  
>  static inline bool pmd_user_accessible_page(pmd_t pmd)
>  {
> -	return pmd_present(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
> +	return pmd_leaf(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
>  }
>  
>  static inline bool pud_user_accessible_page(pud_t pud)
>  {
> -	return pud_present(pud) && pud_user(pud);
> +	return pud_leaf(pud) && pud_user(pud);

Acked-by: Will Deacon <will@kernel.org>

Will
Anshuman Khandual Nov. 22, 2022, 3:21 a.m. UTC | #3 
On 11/17/22 13:26, 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>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com>
> ---

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

>  arch/arm64/include/asm/pgtable.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 71a1af42f0e8..edf6625ce965 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -863,12 +863,12 @@ static inline bool pte_user_accessible_page(pte_t pte)
>  
>  static inline bool pmd_user_accessible_page(pmd_t pmd)
>  {
> -	return pmd_present(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
> +	return pmd_leaf(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
>  }
>  
>  static inline bool pud_user_accessible_page(pud_t pud)
>  {
> -	return pud_present(pud) && pud_user(pud);
> +	return pud_leaf(pud) && pud_user(pud);
>  }
>  #endif
>
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 71a1af42f0e8..edf6625ce965 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -863,12 +863,12 @@  static inline bool pte_user_accessible_page(pte_t pte)
 
 static inline bool pmd_user_accessible_page(pmd_t pmd)
 {
-	return pmd_present(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
+	return pmd_leaf(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
 }
 
 static inline bool pud_user_accessible_page(pud_t pud)
 {
-	return pud_present(pud) && pud_user(pud);
+	return pud_leaf(pud) && pud_user(pud);
 }
 #endif