diff mbox series

[v3] arm64/mm: fix incorrect file_map_count for invalid pmd

Message ID 20221121073608.4183459-1-liushixin2@huawei.com
State New
Headers
Series [v3] arm64/mm: fix incorrect file_map_count for invalid pmd |

Commit Message

Liu Shixin Nov. 21, 2022, 7:36 a.m. UTC 
  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(-)

Comments

Will Deacon Nov. 21, 2022, 6:18 p.m. UTC | #1 
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
Denys Vlasenko Nov. 28, 2022, 4:26 p.m. UTC | #2 
On 11/21/22 19:18, Will Deacon wrote:
> 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.

Can you be more specific? Do you ask for pud_user_exec() to be defined
and used here? Or something else?

Until this patch lands, amd64 PAGE_TABLE_CHECK + THP remains broken...
Will Deacon Nov. 29, 2022, 2:26 p.m. UTC | #3 
On Mon, Nov 28, 2022 at 05:26:14PM +0100, Denys Vlasenko wrote:
> On 11/21/22 19:18, Will Deacon wrote:
> > 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.
> 
> Can you be more specific? Do you ask for pud_user_exec() to be defined
> and used here? Or something else?

So we now have three patches, all from Liu, that are tripping over each
other:

1. 5b47348fc0b1 ("arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud")

	Merged upstream in -rc6

2. This patch ("arm64/mm: fix incorrect file_map_count for invalid pmd")

	This could land for -rc8 (I acked it), but I'd be more comfortable
	queuing it at -rc1 seeing it as it isn't a recent regression,
	it explodes in the page-table check code and it will conflict with
	(1).

3. https://lore.kernel.org/r/20221122123137.429686-1-liushixin2@huawei.com
   ("arm64/mm: add pud_user_exec() check in pud_user_accessible_page()")

	This was just found by inspection, so it can definitely wait for
	next time (i.e. 6.3).

> Until this patch lands, arm64 PAGE_TABLE_CHECK + THP remains broken...

It's unfortunate, but I don't think it's new breakage and it's failing a
synthetic check so it's hard to justify squeezing it in this late.

Will
Will Deacon Jan. 5, 2023, 6:03 p.m. UTC | #4 
On Mon, 21 Nov 2022 15:36:08 +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
> [...]
> 
> [...]

Applied to arm64 (for-next/fixes), thanks!

[1/1] arm64/mm: fix incorrect file_map_count for invalid pmd
      https://git.kernel.org/arm64/c/74c2f8105451

Cheers,
diff mbox series

Patch

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));
 }
 
 static inline bool pud_user_accessible_page(pud_t pud)