linux-stable.git/drivers/staging/zram, branch linux-3.7.y

zram: Fix deadlock bug in partial read/write

2013-02-27T17:21:08+00:00

commit 7e5a5104c6af709a8d97d5f4711e7c917761d464 upstream.

Now zram allocates new page with GFP_KERNEL in zram I/O path
if IO is partial. Unfortunately, It may cause deadlock with
reclaim path like below.

write_page from fs
fs_lock
allocation(GFP_KERNEL)
reclaim
pageout
				write_page from fs
				fs_lock <-- deadlock

This patch fixes it by using GFP_NOIO.  In read path, we
reorganize code flow so that kmap_atomic is called after the
GFP_NOIO allocation.

Acked-by: Jerome Marchand 
Acked-by: Nitin Gupta 
[ penberg@kernel.org: don't use GFP_ATOMIC ]
Signed-off-by: Pekka Enberg 
Signed-off-by: Minchan Kim 
Signed-off-by: Greg Kroah-Hartman

staging: zram: fix invalid memory references during disk write

2013-01-17T16:46:36+00:00

commit 397c60668aa5ae7130b5ad4e73870d7b8a787085 upstream.

Fixes a bug introduced by commit c8f2f0db1 ("zram: Fix handling
of incompressible pages") which caused invalid memory references
during disk write. Invalid references could occur in two cases:
 - Incoming data expands on compression: In this case, reference was
made to kunmap()'ed bio page.
 - Partial (non PAGE_SIZE) write with incompressible data: In this
case, reference was made to a kfree()'ed buffer.

Fixes bug 50081:
https://bugzilla.kernel.org/show_bug.cgi?id=50081

Signed-off-by: Nitin Gupta 
Reported-by: Mihail Kasadjikov 
Reported-by: Tomas M 
Reviewed-by: Minchan Kim 
Signed-off-by: Greg Kroah-Hartman

staging: zram: factor-out zram_decompress_page() function

2013-01-17T16:46:36+00:00

commit 37b51fdddf64e7ba0971d070428655f8d6f36578 upstream.

zram_bvec_read() shared decompress functionality with zram_read_before_write() function.
Factor-out and make commonly used zram_decompress_page() function, which also simplified
error handling in zram_bvec_read().

Signed-off-by: Sergey Senozhatsky 
Reviewed-by: Nitin Gupta 
Signed-off-by: Greg Kroah-Hartman

staging: zram: Fix handling of incompressible pages

2012-10-22T20:45:19+00:00

Change 130f315a (staging: zram: remove special handle of uncompressed page)
introduced a bug in the handling of incompressible pages which resulted in
memory allocation failure for such pages.

When a page expands on compression, say from 4K to 4K+30, we were trying to
do zsmalloc(pool, 4K+30). However, the maximum size which zsmalloc can
allocate is PAGE_SIZE (for obvious reasons), so such allocation requests
always return failure (0).

For a page that has compressed size larger than the original size (this may
happen with already compressed or random data), there is no point storing
the compressed version as that would take more space and would also require
time for decompression when needed again. So, the fix is to store any page,
whose compressed size exceeds a threshold (max_zpage_size), as-it-is i.e.
without compression.  Memory required for storing this uncompressed page can
then be requested from zsmalloc which supports PAGE_SIZE sized allocations.

Lastly, the fix checks that we do not attempt to "decompress" the page which
we stored in the uncompressed form -- we just memcpy() out such pages.

Signed-off-by: Nitin Gupta 
Reported-by: viechweg@gmail.com
Reported-by: paerley@gmail.com
Reported-by: wu.tommy@gmail.com
Acked-by: Minchan Kim 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

staging: zsmalloc: add mapping modes

2012-07-09T18:35:00+00:00

This patch improves mapping performance in zsmalloc by getting
usage information from the user in the form of a "mapping mode"
and using it to avoid unnecessary copying for objects that span
pages.

Signed-off-by: Seth Jennings 
Signed-off-by: Greg Kroah-Hartman

staging: zram/zcache: swtich Kconfig dependency from X86 to ZSMALLOC

2012-06-25T17:00:53+00:00

This patch switches zcache and zram dependency to ZSMALLOC
rather than X86.  There is no net change since ZSMALLOC
depends on X86, however, this prevent further changes to
these files as zsmalloc dependencies change.

Signed-off-by: Seth Jennings 
Signed-off-by: Greg Kroah-Hartman

staging: zram: conventions, __aligned() attribute

2012-06-11T16:04:15+00:00

Using the __aligned() attribute in favor of __attribute__((aligned(size)))

Signed-off-by: Sam Hansen 
Signed-off-by: Greg Kroah-Hartman

staging: zram: conventions pr_warning -> pr_warn()

2012-06-11T16:04:14+00:00

Porting zram to use the pr_warn() function instead of the deprecated
pr_warning().

Signed-off-by: Sam Hansen 
Signed-off-by: Greg Kroah-Hartman

staging: zram: remove special handle of uncompressed page

2012-06-11T16:00:01+00:00

xvmalloc can't handle PAGE_SIZE page so that zram have to
handle it specially but zsmalloc can do it so let's remove
unnecessary special handling code.

Quote from Nitin
"I think page vs handle distinction was added since xvmalloc could not
handle full page allocation. Now that zsmalloc allows full page
allocation, we can just use it for both cases. This would also allow
removing the ZRAM_UNCOMPRESSED flag. The only downside will be slightly
slower code path for full page allocation but this event is anyways
supposed to be rare, so should be fine."

1. This patch reduces code very much.

 drivers/staging/zram/zram_drv.c   |  104 +++++--------------------------------
 drivers/staging/zram/zram_drv.h   |   17 +-----
 drivers/staging/zram/zram_sysfs.c |    6 +--
 3 files changed, 15 insertions(+), 112 deletions(-)

2. change pages_expand with bad_compress so it can count
   bad compression(above 75%) ratio.

3. remove zobj_header which is for back-reference for defragmentation
   because firstly, it's not used at the moment and zsmalloc can't handle
   bigger size than PAGE_SIZE so zram can't do it any more without redesign.

Cc: Seth Jennings 
Signed-off-by: Minchan Kim 
Acked-by: Nitin Gupta 
Signed-off-by: Greg Kroah-Hartman

staging: zram: fix random data read

2012-06-11T15:59:47+00:00

fd1a30de makes a bug that it uses (struct page *) as zsmalloc's handle
although it's a uncompressed page so that it can access random page,
return random data or even crashed by get_first_page in zs_map_object.

Cc: Seth Jennings 
Cc: Jerome Marchand 
Signed-off-by: Minchan Kim 
Acked-by: Nitin Gupta 
Signed-off-by: Greg Kroah-Hartman