From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Matthew Wilcox <willy@linux.intel.com>
Subject: Re: [PATCH 06/11] dax: Fix race between simultaneous faults
Date: Wed, 5 Aug 2015 14:43:09 +0300 [thread overview]
Message-ID: <20150805114309.GA25784@node.dhcp.inet.fi> (raw)
In-Reply-To: <1438718285-21168-7-git-send-email-matthew.r.wilcox@intel.com>
On Tue, Aug 04, 2015 at 03:58:00PM -0400, Matthew Wilcox wrote:
> diff --git a/mm/memory.c b/mm/memory.c
> index b94b587..5f46350 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2426,11 +2426,16 @@ void unmap_mapping_range(struct address_space *mapping,
> details.last_index = ULONG_MAX;
>
>
> - /* DAX uses i_mmap_lock to serialise file truncate vs page fault */
> - i_mmap_lock_write(mapping);
> + /*
> + * DAX already holds i_mmap_lock to serialise file truncate vs
> + * page fault and page fault vs page fault.
> + */
> + if (!IS_DAX(mapping->host))
> + i_mmap_lock_write(mapping);
> if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
> unmap_mapping_range_tree(&mapping->i_mmap, &details);
> - i_mmap_unlock_write(mapping);
> + if (!IS_DAX(mapping->host))
> + i_mmap_unlock_write(mapping);
> }
> EXPORT_SYMBOL(unmap_mapping_range);
Huh? What protects mapping->i_mmap here? I don't see anything up by stack
taking the lock.
--
Kirill A. Shutemov
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WARNING: multiple messages have this Message-ID (diff)
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Matthew Wilcox <willy@linux.intel.com>
Subject: Re: [PATCH 06/11] dax: Fix race between simultaneous faults
Date: Wed, 5 Aug 2015 14:43:09 +0300 [thread overview]
Message-ID: <20150805114309.GA25784@node.dhcp.inet.fi> (raw)
In-Reply-To: <1438718285-21168-7-git-send-email-matthew.r.wilcox@intel.com>
On Tue, Aug 04, 2015 at 03:58:00PM -0400, Matthew Wilcox wrote:
> diff --git a/mm/memory.c b/mm/memory.c
> index b94b587..5f46350 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2426,11 +2426,16 @@ void unmap_mapping_range(struct address_space *mapping,
> details.last_index = ULONG_MAX;
>
>
> - /* DAX uses i_mmap_lock to serialise file truncate vs page fault */
> - i_mmap_lock_write(mapping);
> + /*
> + * DAX already holds i_mmap_lock to serialise file truncate vs
> + * page fault and page fault vs page fault.
> + */
> + if (!IS_DAX(mapping->host))
> + i_mmap_lock_write(mapping);
> if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
> unmap_mapping_range_tree(&mapping->i_mmap, &details);
> - i_mmap_unlock_write(mapping);
> + if (!IS_DAX(mapping->host))
> + i_mmap_unlock_write(mapping);
> }
> EXPORT_SYMBOL(unmap_mapping_range);
Huh? What protects mapping->i_mmap here? I don't see anything up by stack
taking the lock.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2015-08-05 11:43 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-04 19:57 [PATCH 00/11] DAX fixes for 4.3 Matthew Wilcox
2015-08-04 19:57 ` Matthew Wilcox
2015-08-04 19:57 ` [PATCH 01/11] ext4: Use ext4_get_block_write() for DAX Matthew Wilcox
2015-08-04 19:57 ` Matthew Wilcox
2015-08-04 19:57 ` [PATCH 02/11] thp: Change insert_pfn's return type to void Matthew Wilcox
2015-08-04 19:57 ` Matthew Wilcox
2015-08-04 19:57 ` [PATCH 03/11] dax: Improve comment about truncate race Matthew Wilcox
2015-08-04 19:57 ` Matthew Wilcox
2015-08-04 19:57 ` [PATCH 04/11] ext4: Add ext4_get_block_dax() Matthew Wilcox
2015-08-04 19:57 ` Matthew Wilcox
2015-08-05 2:03 ` Dave Chinner
2015-08-05 2:03 ` Dave Chinner
2015-08-05 15:19 ` Matthew Wilcox
2015-08-05 15:19 ` Matthew Wilcox
2015-08-04 19:57 ` [PATCH 05/11] ext4: Start transaction before calling into DAX Matthew Wilcox
2015-08-04 19:57 ` Matthew Wilcox
2015-08-04 19:58 ` [PATCH 06/11] dax: Fix race between simultaneous faults Matthew Wilcox
2015-08-04 19:58 ` Matthew Wilcox
2015-08-05 11:43 ` Kirill A. Shutemov [this message]
2015-08-05 11:43 ` Kirill A. Shutemov
2015-08-04 19:58 ` [PATCH 07/11] thp: Decrement refcount on huge zero page if it is split Matthew Wilcox
2015-08-04 19:58 ` Matthew Wilcox
2015-08-04 19:58 ` [PATCH 08/11] thp: Fix zap_huge_pmd() for DAX Matthew Wilcox
2015-08-04 19:58 ` Matthew Wilcox
2015-08-04 19:58 ` [PATCH 09/11] dax: Don't use set_huge_zero_page() Matthew Wilcox
2015-08-04 19:58 ` Matthew Wilcox
2015-08-04 19:58 ` [PATCH 10/11] dax: Ensure that zero pages are removed from other processes Matthew Wilcox
2015-08-04 19:58 ` Matthew Wilcox
2015-08-04 19:58 ` [PATCH 11/11] dax: Use linear_page_index() Matthew Wilcox
2015-08-04 19:58 ` Matthew Wilcox
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