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From: Michal Hocko <mhocko@kernel.org>
To: Jan Kara <jack@suse.cz>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	stable@vger.kernel.org, linux-nvdimm@lists.01.org
Subject: Re: [PATCH] mm: Preserve _PAGE_DEVMAP across mprotect() calls
Date: Tue, 9 Oct 2018 15:07:54 +0200	[thread overview]
Message-ID: <20181009130754.GQ8528@dhcp22.suse.cz> (raw)
In-Reply-To: <20181009101917.32497-1-jack@suse.cz>

On Tue 09-10-18 12:19:17, Jan Kara wrote:
> Currently _PAGE_DEVMAP bit is not preserved in mprotect(2) calls. As a
> result we will see warnings such as:
> 
> BUG: Bad page map in process JobWrk0013  pte:800001803875ea25 pmd:7624381067
> addr:00007f0930720000 vm_flags:280000f9 anon_vma:          (null) mapping:ffff97f2384056f0 index:0
> file:457-000000fe00000030-00000009-000000ca-00000001_2001.fileblock fault:xfs_filemap_fault [xfs] mmap:xfs_file_mmap [xfs] readpage:          (null)
> CPU: 3 PID: 15848 Comm: JobWrk0013 Tainted: G        W          4.12.14-2.g7573215-default #1 SLE12-SP4 (unreleased)
> Hardware name: Intel Corporation S2600WFD/S2600WFD, BIOS SE5C620.86B.01.00.0833.051120182255 05/11/2018
> Call Trace:
>  dump_stack+0x5a/0x75
>  print_bad_pte+0x217/0x2c0
>  ? enqueue_task_fair+0x76/0x9f0
>  _vm_normal_page+0xe5/0x100
>  zap_pte_range+0x148/0x740
>  unmap_page_range+0x39a/0x4b0
>  unmap_vmas+0x42/0x90
>  unmap_region+0x99/0xf0
>  ? vma_gap_callbacks_rotate+0x1a/0x20
>  do_munmap+0x255/0x3a0
>  vm_munmap+0x54/0x80
>  SyS_munmap+0x1d/0x30
>  do_syscall_64+0x74/0x150
>  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
> ...
> 
> when mprotect(2) gets used on DAX mappings. Also there is a wide variety
> of other failures that can result from the missing _PAGE_DEVMAP flag
> when the area gets used by get_user_pages() later.
> 
> Fix the problem by including _PAGE_DEVMAP in a set of flags that get
> preserved by mprotect(2).
> 
> Fixes: 69660fd797c3 ("x86, mm: introduce _PAGE_DEVMAP")
> Fixes: ebd31197931d ("powerpc/mm: Add devmap support for ppc64")
> CC: stable@vger.kernel.org
> Signed-off-by: Jan Kara <jack@suse.cz>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  arch/powerpc/include/asm/book3s/64/pgtable.h | 4 ++--
>  arch/x86/include/asm/pgtable_types.h         | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 2fdc865ca374..2a2486526d1f 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -114,7 +114,7 @@
>   */
>  #define _HPAGE_CHG_MASK (PTE_RPN_MASK | _PAGE_HPTEFLAGS | _PAGE_DIRTY | \
>  			 _PAGE_ACCESSED | H_PAGE_THP_HUGE | _PAGE_PTE | \
> -			 _PAGE_SOFT_DIRTY)
> +			 _PAGE_SOFT_DIRTY | _PAGE_DEVMAP)
>  /*
>   * user access blocked by key
>   */
> @@ -132,7 +132,7 @@
>   */
>  #define _PAGE_CHG_MASK	(PTE_RPN_MASK | _PAGE_HPTEFLAGS | _PAGE_DIRTY | \
>  			 _PAGE_ACCESSED | _PAGE_SPECIAL | _PAGE_PTE |	\
> -			 _PAGE_SOFT_DIRTY)
> +			 _PAGE_SOFT_DIRTY | _PAGE_DEVMAP)
>  
>  #define H_PTE_PKEY  (H_PTE_PKEY_BIT0 | H_PTE_PKEY_BIT1 | H_PTE_PKEY_BIT2 | \
>  		     H_PTE_PKEY_BIT3 | H_PTE_PKEY_BIT4)
> diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
> index b64acb08a62b..106b7d0e2dae 100644
> --- a/arch/x86/include/asm/pgtable_types.h
> +++ b/arch/x86/include/asm/pgtable_types.h
> @@ -124,7 +124,7 @@
>   */
>  #define _PAGE_CHG_MASK	(PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT |		\
>  			 _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY |	\
> -			 _PAGE_SOFT_DIRTY)
> +			 _PAGE_SOFT_DIRTY | _PAGE_DEVMAP)
>  #define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE)
>  
>  /*
> -- 
> 2.16.4

-- 
Michal Hocko
SUSE Labs
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  reply	other threads:[~2018-10-09 13:07 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-09 10:19 Jan Kara
2018-10-09 13:07 ` Michal Hocko [this message]
2018-10-09 17:55 ` Dan Williams
2018-10-10  7:45   ` Jan Kara
2018-10-09 18:38 ` Johannes Thumshirn

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