From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, willy@linux.intel.com
Subject: Re: [PATCH v8 01/22] Fix XIP fault vs truncate race
Date: Wed, 23 Jul 2014 14:21:56 +0300 [thread overview]
Message-ID: <20140723112156.GA10317@node.dhcp.inet.fi> (raw)
In-Reply-To: <78c38d32aa62db1bb86315cf3e287b24be900c5e.1406058387.git.matthew.r.wilcox@intel.com>
On Tue, Jul 22, 2014 at 03:47:49PM -0400, Matthew Wilcox wrote:
> Pagecache faults recheck i_size after taking the page lock to ensure that
> the fault didn't race against a truncate. We don't have a page to lock
> in the XIP case, so use the i_mmap_mutex instead. It is locked in the
> truncate path in unmap_mapping_range() after updating i_size. So while
> we hold it in the fault path, we are guaranteed that either i_size has
> already been updated in the truncate path, or that the truncate will
> subsequently call zap_page_range_single() and so remove the mapping we
> have just inserted.
>
> There is a window of time in which i_size has been reduced and the
> thread has a mapping to a page which will be removed from the file,
> but this is harmless as the page will not be allocated to a different
> purpose before the thread's access to it is revoked.
>
> Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
> Reviewed-by: Jan Kara <jack@suse.cz>
> ---
> mm/filemap_xip.c | 24 ++++++++++++++++++++++--
> 1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
> index d8d9fe3..c8d23e9 100644
> --- a/mm/filemap_xip.c
> +++ b/mm/filemap_xip.c
> @@ -260,8 +260,17 @@ again:
> __xip_unmap(mapping, vmf->pgoff);
>
> found:
> + /* We must recheck i_size under i_mmap_mutex */
> + mutex_lock(&mapping->i_mmap_mutex);
> + size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
> + PAGE_CACHE_SHIFT;
round_up() ?
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
--
Kirill A. Shutemov
next prev parent reply other threads:[~2014-07-23 11:22 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-22 19:47 [PATCH v8 00/22] Support ext4 on NV-DIMMs Matthew Wilcox
2014-07-22 19:47 ` [PATCH v8 01/22] Fix XIP fault vs truncate race Matthew Wilcox
2014-07-23 11:21 ` Kirill A. Shutemov [this message]
2014-07-22 19:47 ` [PATCH v8 02/22] Allow page fault handlers to perform the COW Matthew Wilcox
2014-07-23 11:23 ` Kirill A. Shutemov
2014-07-22 19:47 ` [PATCH v8 03/22] axonram: Fix bug in direct_access Matthew Wilcox
2014-07-23 11:24 ` Kirill A. Shutemov
2014-07-22 19:47 ` [PATCH v8 04/22] Change direct_access calling convention Matthew Wilcox
2014-07-30 16:03 ` Boaz Harrosh
2014-07-30 16:12 ` Boaz Harrosh
2014-07-30 20:34 ` Matthew Wilcox
2014-07-31 10:16 ` Boaz Harrosh
2014-07-30 19:45 ` Matthew Wilcox
2014-07-31 10:11 ` Boaz Harrosh
2014-07-31 14:13 ` Matthew Wilcox
2014-07-31 15:28 ` Boaz Harrosh
2014-07-31 17:19 ` Matthew Wilcox
2014-07-31 18:04 ` Boaz Harrosh
2014-07-31 20:30 ` Zwisler, Ross
2014-08-01 18:45 ` Zwisler, Ross
2014-07-22 19:47 ` [PATCH v8 05/22] Add vm_replace_mixed() Matthew Wilcox
2014-07-23 9:10 ` Jan Kara
2014-07-23 11:45 ` Kirill A. Shutemov
2014-07-23 13:52 ` Matthew Wilcox
2014-07-23 14:20 ` Kirill A. Shutemov
2014-07-23 14:27 ` Matthew Wilcox
2014-07-23 15:55 ` Kirill A. Shutemov
2014-07-24 1:36 ` Zhang, Tianfei
2014-07-25 19:44 ` Matthew Wilcox
2014-07-28 13:25 ` Kirill A. Shutemov
2014-07-29 1:55 ` Zhang, Tianfei
2014-07-22 19:47 ` [PATCH v8 06/22] Introduce IS_DAX(inode) Matthew Wilcox
2014-07-22 19:47 ` [PATCH v8 07/22] Add copy_to_iter(), copy_from_iter() and iov_iter_zero() Matthew Wilcox
2014-07-22 19:47 ` [PATCH v8 08/22] Replace XIP read and write with DAX I/O Matthew Wilcox
2014-07-22 19:47 ` [PATCH v8 09/22] Replace ext2_clear_xip_target with dax_clear_blocks Matthew Wilcox
2014-07-22 19:47 ` [PATCH v8 10/22] Replace the XIP page fault handler with the DAX page fault handler Matthew Wilcox
2014-07-23 12:10 ` Kirill A. Shutemov
2014-07-23 13:55 ` Matthew Wilcox
2014-07-23 14:10 ` [PATCH v8 00/22] Support ext4 on NV-DIMMs Howard Chu
2014-07-23 14:34 ` Matthew Wilcox
2014-07-23 15:28 ` Howard Chu
2014-07-23 20:55 ` Theodore Ts'o
2014-07-23 16:57 ` [PATCH v8 10/22] Replace the XIP page fault handler with the DAX page fault handler Boaz Harrosh
2014-07-23 19:57 ` Matthew Wilcox
2014-07-22 19:47 ` [PATCH v8 11/22] Replace xip_truncate_page with dax_truncate_page Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 12/22] Replace XIP documentation with DAX documentation Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 13/22] Remove get_xip_mem Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 14/22] ext2: Remove ext2_xip_verify_sb() Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 15/22] ext2: Remove ext2_use_xip Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 16/22] ext2: Remove xip.c and xip.h Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 17/22] Remove CONFIG_EXT2_FS_XIP and rename CONFIG_FS_XIP to CONFIG_FS_DAX Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 18/22] ext2: Remove ext2_aops_xip Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 19/22] Get rid of most mentions of XIP in ext2 Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 20/22] xip: Add xip_zero_page_range Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 21/22] ext4: Add DAX functionality Matthew Wilcox
2014-07-22 19:48 ` [PATCH v8 22/22] brd: Rename XIP to DAX Matthew Wilcox
2014-07-23 12:30 ` [PATCH v8 00/22] Support ext4 on NV-DIMMs Kirill A. Shutemov
2014-07-23 13:59 ` Matthew Wilcox
2014-07-23 15:58 ` Boaz Harrosh
2014-07-23 19:50 ` Matthew Wilcox
2014-07-24 18:51 ` Ross Zwisler
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