z3fold: fix memory leak in kmem cache

Currently there is a leak in init_z3fold_page() -- it allocates handles
from kmem cache even for headless pages, but then they are never used and
never freed, so eventually kmem cache may get exhausted.  This patch
provides a fix for that.

Link: http://lkml.kernel.org/r/20190917185352.44cf285d3ebd9e64548de5de@gmail.com
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Reported-by: Markus Linnala <markus.linnala@gmail.com>
Tested-by: Markus Linnala <markus.linnala@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Henry Burns <henrywolfeburns@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
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/z3fold.c b/mm/z3fold.c
index d637d9e..05bdf90 100644 (file)
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -295,14 +295,11 @@ static void z3fold_unregister_migration(struct z3fold_pool *pool)
  }
 
 /* Initializes the z3fold header of a newly allocated z3fold page */
-static struct z3fold_header *init_z3fold_page(struct page *page,
+static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
                                        struct z3fold_pool *pool, gfp_t gfp)
 {
        struct z3fold_header *zhdr = page_address(page);
-       struct z3fold_buddy_slots *slots = alloc_slots(pool, gfp);
-
-       if (!slots)
-               return NULL;
+       struct z3fold_buddy_slots *slots;
 
        INIT_LIST_HEAD(&page->lru);
        clear_bit(PAGE_HEADLESS, &page->private);
@@ -310,6 +307,12 @@ static struct z3fold_header *init_z3fold_page(struct page *page,
        clear_bit(NEEDS_COMPACTING, &page->private);
        clear_bit(PAGE_STALE, &page->private);
        clear_bit(PAGE_CLAIMED, &page->private);
+       if (headless)
+               return zhdr;
+
+       slots = alloc_slots(pool, gfp);
+       if (!slots)
+               return NULL;
 
        spin_lock_init(&zhdr->page_lock);
        kref_init(&zhdr->refcount);
@@ -930,7 +933,7 @@ retry:
        if (!page)
                return -ENOMEM;
 
-       zhdr = init_z3fold_page(page, pool, gfp);
+       zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
        if (!zhdr) {
                __free_page(page);
                return -ENOMEM;