diff mbox

[2/2] UBIFS: Implement ->migratepage()

Message ID 1459461513-31765-3-git-send-email-richard@nod.at (mailing list archive)
State New, archived
Headers show

Commit Message

Richard Weinberger March 31, 2016, 9:58 p.m. UTC
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

During page migrations UBIFS might get confused
and the following assert triggers:
UBIFS assert failed in ubifs_set_page_dirty at 1451 (pid 436)

UBIFS is using PagePrivate() which can have different meanings across
filesystems. Therefore the generic page migration code cannot handle this
case correctly.
We have to implement our own migration function which basically does a
plain copy but also duplicates the page private flag.
UBIFS is not a block device filesystem and cannot use buffer_migrate_page().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
[rw: Massaged changelog]
Signed-off-by: Richard Weinberger <richard@nod.at>

Signed-off-by: Richard Weinberger <richard@nod.at>
---
 fs/ubifs/file.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

Comments

Vlastimil Babka April 1, 2016, 10:14 a.m. UTC | #1
On 03/31/2016 11:58 PM, Richard Weinberger wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>
> During page migrations UBIFS might get confused
> and the following assert triggers:
> UBIFS assert failed in ubifs_set_page_dirty at 1451 (pid 436)

It would be useful to have the full trace in changelog.

> UBIFS is using PagePrivate() which can have different meanings across
> filesystems. Therefore the generic page migration code cannot handle this
> case correctly.
> We have to implement our own migration function which basically does a
> plain copy but also duplicates the page private flag.
> UBIFS is not a block device filesystem and cannot use buffer_migrate_page().
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> [rw: Massaged changelog]
> Signed-off-by: Richard Weinberger <richard@nod.at>

Stable?

> Signed-off-by: Richard Weinberger <richard@nod.at>
> ---
>   fs/ubifs/file.c | 20 ++++++++++++++++++++
>   1 file changed, 20 insertions(+)
>
> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
> index 065c88f..5eea5f5 100644
> --- a/fs/ubifs/file.c
> +++ b/fs/ubifs/file.c
> @@ -52,6 +52,7 @@
>   #include "ubifs.h"
>   #include <linux/mount.h>
>   #include <linux/slab.h>
> +#include <linux/migrate.h>
>
>   static int read_block(struct inode *inode, void *addr, unsigned int block,
>   		      struct ubifs_data_node *dn)
> @@ -1452,6 +1453,24 @@ static int ubifs_set_page_dirty(struct page *page)
>   	return ret;
>   }
>
> +static int ubifs_migrate_page(struct address_space *mapping,
> +		struct page *newpage, struct page *page, enum migrate_mode mode)
> +{
> +	int rc;
> +
> +	rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
> +	if (rc != MIGRATEPAGE_SUCCESS)
> +		return rc;
> +
> +	if (PagePrivate(page)) {
> +		ClearPagePrivate(page);
> +		SetPagePrivate(newpage);
> +	}
> +
> +	migrate_page_copy(newpage, page);
> +	return MIGRATEPAGE_SUCCESS;
> +}
> +
>   static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags)
>   {
>   	/*
> @@ -1591,6 +1610,7 @@ const struct address_space_operations ubifs_file_address_operations = {
>   	.write_end      = ubifs_write_end,
>   	.invalidatepage = ubifs_invalidatepage,
>   	.set_page_dirty = ubifs_set_page_dirty,
> +	.migratepage	= ubifs_migrate_page,
>   	.releasepage    = ubifs_releasepage,
>   };
>
>

--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Richard Weinberger April 1, 2016, 11:21 a.m. UTC | #2
Am 01.04.2016 um 12:14 schrieb Vlastimil Babka:
> On 03/31/2016 11:58 PM, Richard Weinberger wrote:
>> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>>
>> During page migrations UBIFS might get confused
>> and the following assert triggers:
>> UBIFS assert failed in ubifs_set_page_dirty at 1451 (pid 436)
> 
> It would be useful to have the full trace in changelog.

Oh. Yes.

>> UBIFS is using PagePrivate() which can have different meanings across
>> filesystems. Therefore the generic page migration code cannot handle this
>> case correctly.
>> We have to implement our own migration function which basically does a
>> plain copy but also duplicates the page private flag.
>> UBIFS is not a block device filesystem and cannot use buffer_migrate_page().
>>
>> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>> [rw: Massaged changelog]
>> Signed-off-by: Richard Weinberger <richard@nod.at>
> 
> Stable?

Yep. But first I'd like to clarify if this approach is really the way to go.
It is also not clear to me whether this issue was always the case or if
a recently introduced change in MM uncovered it...
Blindly applying to all stable versions is risky.

Thanks,
//richard
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
kernel test robot April 3, 2016, 12:13 a.m. UTC | #3
Hi Kirill,

[auto build test ERROR on v4.6-rc1]
[also build test ERROR on next-20160401]
[if your patch is applied to the wrong git tree, please drop us a note to help improving the system]

url:    https://github.com/0day-ci/linux/commits/Richard-Weinberger/mm-Export-migrate_page_move_mapping-and-migrate_page_copy/20160401-060041
config: xtensa-audio_kc705_defconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=xtensa 

All errors (new ones prefixed by >>):

   fs/ubifs/file.c: In function 'ubifs_migrate_page':
>> fs/ubifs/file.c:1461:2: error: implicit declaration of function 'migrate_page_move_mapping' [-Werror=implicit-function-declaration]
     rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
     ^
   cc1: some warnings being treated as errors

vim +/migrate_page_move_mapping +1461 fs/ubifs/file.c

  1455	
  1456	static int ubifs_migrate_page(struct address_space *mapping,
  1457			struct page *newpage, struct page *page, enum migrate_mode mode)
  1458	{
  1459		int rc;
  1460	
> 1461		rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
  1462		if (rc != MIGRATEPAGE_SUCCESS)
  1463			return rc;
  1464	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
diff mbox

Patch

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 065c88f..5eea5f5 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -52,6 +52,7 @@ 
 #include "ubifs.h"
 #include <linux/mount.h>
 #include <linux/slab.h>
+#include <linux/migrate.h>
 
 static int read_block(struct inode *inode, void *addr, unsigned int block,
 		      struct ubifs_data_node *dn)
@@ -1452,6 +1453,24 @@  static int ubifs_set_page_dirty(struct page *page)
 	return ret;
 }
 
+static int ubifs_migrate_page(struct address_space *mapping,
+		struct page *newpage, struct page *page, enum migrate_mode mode)
+{
+	int rc;
+
+	rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
+	if (rc != MIGRATEPAGE_SUCCESS)
+		return rc;
+
+	if (PagePrivate(page)) {
+		ClearPagePrivate(page);
+		SetPagePrivate(newpage);
+	}
+
+	migrate_page_copy(newpage, page);
+	return MIGRATEPAGE_SUCCESS;
+}
+
 static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags)
 {
 	/*
@@ -1591,6 +1610,7 @@  const struct address_space_operations ubifs_file_address_operations = {
 	.write_end      = ubifs_write_end,
 	.invalidatepage = ubifs_invalidatepage,
 	.set_page_dirty = ubifs_set_page_dirty,
+	.migratepage	= ubifs_migrate_page,
 	.releasepage    = ubifs_releasepage,
 };