zsmalloc: expand class bit

commit 85d492f28d056c40629fc25d79f54da618a29dc4 upstream.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 9cc3c0b2c2c13fddddc6d5d52aca4f0b45fdc1ce..f9ed0813d64e6346bd4dea1e3c81fcaa3739e28e 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -280,7 +280,7 @@ 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;
        };