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From: Jan Kara <jack@suse.cz>
To: linux-fsdevel@vger.kernel.org
Cc: Jan Kara <jack@suse.cz>,
	linux-nvdimm@lists.01.org, NeilBrown <neilb@suse.com>,
	"Wilcox, Matthew R" <matthew.r.wilcox@intel.com>
Subject: [PATCH 08/12] dax: Fix bogus fault return value on cow faults
Date: Thu, 10 Mar 2016 20:18:51 +0100	[thread overview]
Message-ID: <1457637535-21633-9-git-send-email-jack@suse.cz> (raw)
In-Reply-To: <1457637535-21633-1-git-send-email-jack@suse.cz>

In case of cow fault when there is no page mapped at cow location, we
return VM_FAULT_LOCKED despite we don't return any page from the fault.
The code in do_cow_fault() carefully handled the case when no page was
actually returned so no harm was done but still this is a bug waiting to
happen.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/dax.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/dax.c b/fs/dax.c
index 4aa440f9305b..bf39f16e5390 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -680,7 +680,9 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 		if (error)
 			goto unlock_page;
 		vmf->page = page;
-		return VM_FAULT_LOCKED;
+		if (page)
+			return VM_FAULT_LOCKED;
+		return 0;
 	}
 
 	/* Check we didn't race with a read fault installing a new page */
-- 
2.6.2

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WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack@suse.cz>
To: linux-fsdevel@vger.kernel.org
Cc: "Wilcox, Matthew R" <matthew.r.wilcox@intel.com>,
	Ross Zwisler <ross.zwisler@linux.intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	linux-nvdimm@lists.01.org, NeilBrown <neilb@suse.com>,
	Jan Kara <jack@suse.cz>
Subject: [PATCH 08/12] dax: Fix bogus fault return value on cow faults
Date: Thu, 10 Mar 2016 20:18:51 +0100	[thread overview]
Message-ID: <1457637535-21633-9-git-send-email-jack@suse.cz> (raw)
In-Reply-To: <1457637535-21633-1-git-send-email-jack@suse.cz>

In case of cow fault when there is no page mapped at cow location, we
return VM_FAULT_LOCKED despite we don't return any page from the fault.
The code in do_cow_fault() carefully handled the case when no page was
actually returned so no harm was done but still this is a bug waiting to
happen.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/dax.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/dax.c b/fs/dax.c
index 4aa440f9305b..bf39f16e5390 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -680,7 +680,9 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 		if (error)
 			goto unlock_page;
 		vmf->page = page;
-		return VM_FAULT_LOCKED;
+		if (page)
+			return VM_FAULT_LOCKED;
+		return 0;
 	}
 
 	/* Check we didn't race with a read fault installing a new page */
-- 
2.6.2


  parent reply	other threads:[~2016-03-10 19:18 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-10 19:18 [RFC] [PATCH 0/12] DAX page fault locking Jan Kara
2016-03-10 19:18 ` Jan Kara
2016-03-10 19:18 ` [PATCH 01/12] DAX: move RADIX_DAX_ definitions to dax.c Jan Kara
2016-03-10 19:18   ` Jan Kara
2016-03-11 22:54   ` Ross Zwisler
2016-03-11 22:54     ` Ross Zwisler
2016-03-10 19:18 ` [PATCH 02/12] radix-tree: make 'indirect' bit available to exception entries Jan Kara
2016-03-10 19:18   ` Jan Kara
2016-03-10 19:18 ` [PATCH 03/12] mm: Remove VM_FAULT_MINOR Jan Kara
2016-03-10 19:18   ` Jan Kara
2016-03-10 19:38   ` Wilcox, Matthew R
2016-03-10 19:38     ` Wilcox, Matthew R
2016-03-10 19:48     ` Jan Kara
2016-03-10 19:48       ` Jan Kara
2016-03-10 19:18 ` [PATCH 04/12] ocfs2: Fix return value from ocfs2_page_mkwrite() Jan Kara
2016-03-10 19:18   ` Jan Kara
2016-03-10 19:18 ` [PATCH 05/12] dax: Remove synchronization using i_mmap_lock Jan Kara
2016-03-10 19:55   ` Wilcox, Matthew R
2016-03-10 19:55     ` Wilcox, Matthew R
2016-03-10 20:05     ` Jan Kara
2016-03-10 20:05       ` Jan Kara
2016-03-10 20:10       ` Wilcox, Matthew R
2016-03-10 20:10         ` Wilcox, Matthew R
2016-03-14 10:01         ` Jan Kara
2016-03-14 10:01           ` Jan Kara
2016-03-14 14:51           ` Wilcox, Matthew R
2016-03-14 14:51             ` Wilcox, Matthew R
2016-03-15  9:50             ` Jan Kara
2016-03-15  9:50               ` Jan Kara
2016-03-10 19:18 ` [PATCH 06/12] dax: Remove complete_unwritten argument Jan Kara
2016-03-10 19:18   ` Jan Kara
2016-03-10 19:18 ` [PATCH 07/12] dax: Fix data corruption for written and mmapped files Jan Kara
2016-03-10 19:18   ` Jan Kara
2016-03-10 19:18 ` Jan Kara [this message]
2016-03-10 19:18   ` [PATCH 08/12] dax: Fix bogus fault return value on cow faults Jan Kara
2016-03-10 19:18 ` [PATCH 09/12] dax: Allow DAX code to replace exceptional entries Jan Kara
2016-03-10 19:18   ` Jan Kara
2016-03-10 19:18 ` [PATCH 10/12] dax: Remove redundant inode size checks Jan Kara
2016-03-10 19:18   ` Jan Kara
2016-03-10 19:18 ` [PATCH 11/12] dax: Disable huge page handling Jan Kara
2016-03-10 19:34   ` Dan Williams
2016-03-10 19:34     ` Dan Williams
2016-03-10 19:52     ` Jan Kara
2016-03-10 19:52       ` Jan Kara
2016-03-10 19:18 ` [PATCH 12/12] dax: New fault locking Jan Kara
2016-03-10 19:18   ` Jan Kara
2016-03-10 23:54   ` NeilBrown
2016-03-10 23:54     ` NeilBrown
2016-03-15 21:34     ` NeilBrown
2016-03-15 21:34       ` NeilBrown
2016-03-18 14:16       ` Jan Kara
2016-03-18 14:16         ` Jan Kara
2016-03-18 15:39         ` Jan Kara
2016-03-18 15:39           ` Jan Kara
2016-03-22 21:10           ` NeilBrown
2016-03-22 21:10             ` NeilBrown
2016-03-23 11:00             ` Jan Kara
2016-03-23 11:00               ` Jan Kara
2016-03-31  4:20               ` NeilBrown
2016-03-31  4:20                 ` NeilBrown
2016-03-31  8:54                 ` Jan Kara
2016-03-31  8:54                   ` Jan Kara
2016-04-01  0:34                   ` NeilBrown
2016-04-01  0:34                     ` NeilBrown

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