mm/z3fold.c: avoid modifying HEADLESS page and minor cleanup

Fix erroneous z3fold header access in a HEADLESS page in reclaim
function, and change one remaining direct handle-to-buddy conversion to
use the appropriate helper.

Link: http://lkml.kernel.org/r/5748706F.9020208@gmail.com
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Reviewed-by: Dan Streetman <ddstreet@ieee.org>
Cc: Seth Jennings <sjenning@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 10 deletions

diff --git a/mm/z3fold.c b/mm/z3fold.c
index 34917d55d311..8f9e89ca1d31 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -412,7 +412,7 @@ static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
                 /* HEADLESS page stored */
                 bud = HEADLESS;
         } else {
-                bud = (handle - zhdr->first_num) & BUDDY_MASK;
+                bud = handle_to_buddy(handle);
 
                 switch (bud) {
                 case FIRST:
@@ -572,15 +572,19 @@ next:
                         pool->pages_nr--;
                         spin_unlock(&pool->lock);
                         return 0;
-                } else if (zhdr->first_chunks != 0 &&
-                           zhdr->last_chunks != 0 && zhdr->middle_chunks != 0) {
-                        /* Full, add to buddied list */
-                        list_add(&zhdr->buddy, &pool->buddied);
-                } else if (!test_bit(PAGE_HEADLESS, &page->private)) {
-                        z3fold_compact_page(zhdr);
-                        /* add to unbuddied list */
-                        freechunks = num_free_chunks(zhdr);
-                        list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
+                }  else if (!test_bit(PAGE_HEADLESS, &page->private)) {
+                        if (zhdr->first_chunks != 0 &&
+                            zhdr->last_chunks != 0 &&
+                            zhdr->middle_chunks != 0) {
+                                /* Full, add to buddied list */
+                                list_add(&zhdr->buddy, &pool->buddied);
+                        } else {
+                                z3fold_compact_page(zhdr);
+                                /* add to unbuddied list */
+                                freechunks = num_free_chunks(zhdr);
+                                list_add(&zhdr->buddy,
+                                         &pool->unbuddied[freechunks]);
+                        }
                 }
 
                 /* add to beginning of LRU */