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Subject[PATCH 3/6] lib/scatterlist: Do not leak pages when high-order allocation fails
Date
From: Tvrtko Ursulin <tvrtko.ursulin@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.ursulin@intel.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Jens Axboe <axboe@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
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