[PATCH 3/6] lib/scatterlist: Do not leak pages when high-order allocation fails

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursu...@intel.com>

If a higher-order allocation fails, the existing abort and cleanup path
would consider all segments allocated so far as 0-order page allocations
and would therefore leak memory.

Fix this by cleaning up using sgl_free_n_order which allows the correct
page order to be passed in.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Cc: Bart Van Assche <bart.vanass...@wdc.com>
Cc: Hannes Reinecke <h...@suse.com>
Cc: Johannes Thumshirn <jthumsh...@suse.de>
Cc: Jens Axboe <ax...@kernel.dk>
---
 lib/scatterlist.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 9884be50a2c0..e13a759c5c49 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -493,7 +493,7 @@ struct scatterlist *sgl_alloc_order(unsigned long length, 
unsigned int order,
 {
        unsigned int chunk_len = PAGE_SIZE << order;
        struct scatterlist *sgl, *sg;
-       unsigned int nent;
+       unsigned int nent, i;
 
        nent = round_up(length, chunk_len) >> (PAGE_SHIFT + order);
 
@@ -517,11 +517,12 @@ struct scatterlist *sgl_alloc_order(unsigned long length, 
unsigned int order,
 
        sg_init_table(sgl, nent);
        sg = sgl;
+       i = 0;
        while (length) {
                struct page *page = alloc_pages(gfp, order);
 
                if (!page) {
-                       sgl_free(sgl);
+                       sgl_free_n_order(sgl, i, order);
                        return NULL;
                }
 
@@ -529,6 +530,7 @@ struct scatterlist *sgl_alloc_order(unsigned long length, 
unsigned int order,
                sg_set_page(sg, page, chunk_len, 0);
                length -= chunk_len;
                sg = sg_next(sg);
+               i++;
        }
        WARN_ONCE(length, "length = %ld\n", length);
        return sgl;
-- 
2.14.1