From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Jan Kara <jack@suse.cz>
Cc: linux-nvdimm@lists.01.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH 19/20] dax: Protect PTE modification on WP fault by radix tree entry lock
Date: Tue, 18 Oct 2016 13:53:32 -0600 [thread overview]
Message-ID: <20161018195332.GF7796@linux.intel.com> (raw)
In-Reply-To: <1474992504-20133-20-git-send-email-jack@suse.cz>
On Tue, Sep 27, 2016 at 06:08:23PM +0200, Jan Kara wrote:
> Currently PTE gets updated in wp_pfn_shared() after dax_pfn_mkwrite()
> has released corresponding radix tree entry lock. When we want to
> writeprotect PTE on cache flush, we need PTE modification to happen
> under radix tree entry lock to ensure consisten updates of PTE and radix
consistent
> tree (standard faults use page lock to ensure this consistency). So move
> update of PTE bit into dax_pfn_mkwrite().
>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
> fs/dax.c | 22 ++++++++++++++++------
> mm/memory.c | 2 +-
> 2 files changed, 17 insertions(+), 7 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index c6cadf8413a3..a2d3781c9f4e 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1163,17 +1163,27 @@ int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
> {
> struct file *file = vma->vm_file;
> struct address_space *mapping = file->f_mapping;
> - void *entry;
> + void *entry, **slot;
> pgoff_t index = vmf->pgoff;
>
> spin_lock_irq(&mapping->tree_lock);
> - entry = get_unlocked_mapping_entry(mapping, index, NULL);
> - if (!entry || !radix_tree_exceptional_entry(entry))
> - goto out;
> + entry = get_unlocked_mapping_entry(mapping, index, &slot);
> + if (!entry || !radix_tree_exceptional_entry(entry)) {
> + if (entry)
> + put_unlocked_mapping_entry(mapping, index, entry);
I don't think you need this call to put_unlocked_mapping_entry(). If we get
in here we know that 'entry' is a page cache page, in which case
put_unlocked_mapping_entry() will just return without doing any work.
With that nit & the spelling error above:
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
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WARNING: multiple messages have this Message-ID (diff)
From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Jan Kara <jack@suse.cz>
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-nvdimm@lists.01.org,
Dan Williams <dan.j.williams@intel.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH 19/20] dax: Protect PTE modification on WP fault by radix tree entry lock
Date: Tue, 18 Oct 2016 13:53:32 -0600 [thread overview]
Message-ID: <20161018195332.GF7796@linux.intel.com> (raw)
In-Reply-To: <1474992504-20133-20-git-send-email-jack@suse.cz>
On Tue, Sep 27, 2016 at 06:08:23PM +0200, Jan Kara wrote:
> Currently PTE gets updated in wp_pfn_shared() after dax_pfn_mkwrite()
> has released corresponding radix tree entry lock. When we want to
> writeprotect PTE on cache flush, we need PTE modification to happen
> under radix tree entry lock to ensure consisten updates of PTE and radix
consistent
> tree (standard faults use page lock to ensure this consistency). So move
> update of PTE bit into dax_pfn_mkwrite().
>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
> fs/dax.c | 22 ++++++++++++++++------
> mm/memory.c | 2 +-
> 2 files changed, 17 insertions(+), 7 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index c6cadf8413a3..a2d3781c9f4e 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1163,17 +1163,27 @@ int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
> {
> struct file *file = vma->vm_file;
> struct address_space *mapping = file->f_mapping;
> - void *entry;
> + void *entry, **slot;
> pgoff_t index = vmf->pgoff;
>
> spin_lock_irq(&mapping->tree_lock);
> - entry = get_unlocked_mapping_entry(mapping, index, NULL);
> - if (!entry || !radix_tree_exceptional_entry(entry))
> - goto out;
> + entry = get_unlocked_mapping_entry(mapping, index, &slot);
> + if (!entry || !radix_tree_exceptional_entry(entry)) {
> + if (entry)
> + put_unlocked_mapping_entry(mapping, index, entry);
I don't think you need this call to put_unlocked_mapping_entry(). If we get
in here we know that 'entry' is a page cache page, in which case
put_unlocked_mapping_entry() will just return without doing any work.
With that nit & the spelling error above:
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
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next prev parent reply other threads:[~2016-10-18 19:53 UTC|newest]
Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-27 16:08 [PATCH 0/20 v3] dax: Clear dirty bits after flushing caches Jan Kara
2016-09-27 16:08 ` [PATCH 01/20] mm: Change type of vmf->virtual_address Jan Kara
[not found] ` <1474992504-20133-2-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-30 9:07 ` Christoph Hellwig
2016-09-30 9:07 ` Christoph Hellwig
2016-10-14 18:02 ` Ross Zwisler
2016-10-14 18:02 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 02/20] mm: Join struct fault_env and vm_fault Jan Kara
[not found] ` <1474992504-20133-3-git-send-email-jack-AlSwsSmVLrQ@public.gmane.org>
2016-09-30 9:10 ` Christoph Hellwig
2016-09-30 9:10 ` Christoph Hellwig
2016-10-03 7:43 ` Jan Kara
2016-10-03 7:43 ` Jan Kara
2016-09-27 16:08 ` [PATCH 03/20] mm: Use pgoff in struct vm_fault instead of passing it separately Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-14 18:42 ` Ross Zwisler
2016-10-14 18:42 ` Ross Zwisler
2016-10-17 9:01 ` Jan Kara
2016-09-27 16:08 ` [PATCH 04/20] mm: Use passed vm_fault structure in __do_fault() Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-14 19:05 ` Ross Zwisler
2016-10-14 19:05 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 05/20] mm: Trim __do_fault() arguments Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-14 20:31 ` Ross Zwisler
2016-10-17 9:04 ` Jan Kara
2016-10-17 9:04 ` Jan Kara
2016-09-27 16:08 ` [PATCH 06/20] mm: Use pass vm_fault structure for in wp_pfn_shared() Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-14 21:04 ` Ross Zwisler
2016-10-14 21:04 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 07/20] mm: Add orig_pte field into vm_fault Jan Kara
2016-10-17 16:45 ` Ross Zwisler
2016-10-17 16:45 ` Ross Zwisler
2016-10-18 10:13 ` Jan Kara
2016-10-18 10:13 ` Jan Kara
2016-09-27 16:08 ` [PATCH 08/20] mm: Allow full handling of COW faults in ->fault handlers Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-17 16:50 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 09/20] mm: Factor out functionality to finish page faults Jan Kara
2016-10-17 17:38 ` Ross Zwisler
2016-10-17 17:38 ` Ross Zwisler
2016-10-17 17:40 ` Ross Zwisler
2016-10-17 17:40 ` Ross Zwisler
2016-10-18 9:44 ` Jan Kara
2016-09-27 16:08 ` [PATCH 10/20] mm: Move handling of COW faults into DAX code Jan Kara
2016-10-17 19:29 ` Ross Zwisler
2016-10-17 19:29 ` Ross Zwisler
2016-10-18 10:32 ` Jan Kara
2016-10-18 10:32 ` Jan Kara
2016-09-27 16:08 ` [PATCH 11/20] mm: Remove unnecessary vma->vm_ops check Jan Kara
2016-10-17 19:40 ` Ross Zwisler
2016-10-17 19:40 ` Ross Zwisler
2016-10-18 10:37 ` Jan Kara
2016-10-18 10:37 ` Jan Kara
2016-09-27 16:08 ` [PATCH 12/20] mm: Factor out common parts of write fault handling Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-17 22:08 ` Ross Zwisler
2016-10-17 22:08 ` Ross Zwisler
2016-10-18 10:50 ` Jan Kara
2016-10-18 17:32 ` Ross Zwisler
2016-10-18 17:32 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 13/20] mm: Pass vm_fault structure into do_page_mkwrite() Jan Kara
2016-10-17 22:29 ` Ross Zwisler
2016-10-17 22:29 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 14/20] mm: Use vmf->page during WP faults Jan Kara
2016-10-18 17:56 ` Ross Zwisler
2016-10-18 17:56 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 15/20] mm: Move part of wp_page_reuse() into the single call site Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-18 17:59 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 16/20] mm: Provide helper for finishing mkwrite faults Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-18 18:35 ` Ross Zwisler
2016-10-18 18:35 ` Ross Zwisler
2016-10-19 7:16 ` Jan Kara
2016-10-19 7:16 ` Jan Kara
2016-10-19 17:21 ` Ross Zwisler
2016-10-19 17:21 ` Ross Zwisler
2016-10-20 8:48 ` Jan Kara
2016-10-20 8:48 ` Jan Kara
2016-09-27 16:08 ` [PATCH 17/20] mm: Export follow_pte() Jan Kara
2016-10-18 18:37 ` Ross Zwisler
2016-10-18 18:37 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 18/20] dax: Make cache flushing protected by entry lock Jan Kara
2016-10-18 19:20 ` Ross Zwisler
2016-10-19 7:19 ` Jan Kara
2016-10-19 7:19 ` Jan Kara
2016-10-19 18:25 ` Ross Zwisler
2016-10-19 18:25 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 19/20] dax: Protect PTE modification on WP fault by radix tree " Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-18 19:53 ` Ross Zwisler [this message]
2016-10-18 19:53 ` Ross Zwisler
2016-10-19 7:25 ` Jan Kara
2016-10-19 7:25 ` Jan Kara
2016-10-19 17:25 ` Ross Zwisler
2016-10-19 17:25 ` Ross Zwisler
2016-09-27 16:08 ` [PATCH 20/20] dax: Clear dirty entry tags on cache flush Jan Kara
2016-09-27 16:08 ` Jan Kara
2016-10-18 22:12 ` Ross Zwisler
2016-10-18 22:12 ` Ross Zwisler
2016-10-19 7:30 ` Jan Kara
2016-10-19 7:30 ` Jan Kara
2016-10-19 16:38 ` Ross Zwisler
2016-10-19 16:38 ` Ross Zwisler
2016-09-30 9:14 ` [PATCH 0/20 v3] dax: Clear dirty bits after flushing caches Christoph Hellwig
2016-10-03 7:59 ` Jan Kara
2016-10-03 8:03 ` Christoph Hellwig
2016-10-03 8:15 ` Jan Kara
2016-10-03 8:15 ` Jan Kara
2016-10-03 9:32 ` Christoph Hellwig
2016-10-03 9:32 ` Christoph Hellwig
2016-10-03 11:13 ` Jan Kara
[not found] ` <20161003111358.GQ6457-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2016-10-13 20:34 ` Ross Zwisler
2016-10-13 20:34 ` Ross Zwisler
2016-10-17 8:47 ` Jan Kara
2016-10-17 8:47 ` Jan Kara
[not found] ` <20161017084732.GD3359-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2016-10-17 18:59 ` Ross Zwisler
2016-10-17 18:59 ` Ross Zwisler
2016-10-18 9:49 ` Jan Kara
2016-10-18 9:49 ` Jan Kara
2016-11-01 22:36 [PATCH 0/21 v4] " Jan Kara
2016-11-01 22:36 ` [PATCH 19/20] dax: Protect PTE modification on WP fault by radix tree entry lock Jan Kara
2016-11-01 22:36 ` Jan Kara
2016-11-01 22:36 ` Jan Kara
2016-11-18 9:17 [PATCH 0/20 v5] dax: Clear dirty bits after flushing caches Jan Kara
2016-11-18 9:17 ` [PATCH 19/20] dax: Protect PTE modification on WP fault by radix tree entry lock Jan Kara
2016-11-18 9:17 ` Jan Kara
2016-11-18 9:17 ` Jan Kara
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