zsmalloc: expand class bit

Now 64K page system, zsamlloc has 257 classes so 8 class bit is not
enough.  With that, it corrupts the system when zsmalloc stores
65536byte data(ie, index number 256) so that this patch increases class
bit for simple fix for stable backport.  We should clean up this mess
soon.

  index	size
  0	32
  1	288
  ..
  ..
  204	52256
  256	65536

Fixes: 3783689a1 ("zsmalloc: introduce zspage structure")
Link: http://lkml.kernel.org/r/1492042622-12074-3-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index b7ee9c34dbd678fc984db3295a70c117ee2fc2f2..d41edd28298b68ff335e6324df7e4e793a481d93 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -276,7 +276,7 @@ struct zs_pool {
 struct zspage {
        struct {
                unsigned int fullness:FULLNESS_BITS;
-               unsigned int class:CLASS_BITS;
+               unsigned int class:CLASS_BITS + 1;
                unsigned int isolated:ISOLATED_BITS;
                unsigned int magic:MAGIC_VAL_BITS;
        };