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authorChristoph Hellwig <hch@lst.de>2019-06-17 11:14:12 +0200
committerJens Axboe <axboe@kernel.dk>2019-06-17 09:33:04 -0600
commit4569180495600ac59f5cd27f67242a6cb51254f3 (patch)
tree5fc8de0946ff131ad03282d9bad310f29814a9b0 /block
parentff896738be381efa6e50ba9a3b6cdc94f69ada42 (diff)
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block: fix page leak when merging to same page
When multiple iovecs reference the same page, each get_user_page call will add a reference to the page. But once we've created the bio that information gets lost and only a single reference will be dropped after I/O completion. Use the same_page information returned from __bio_try_merge_page to drop additional references to pages that were already present in the bio. Based on a patch from Ming Lei. Link: https://lkml.org/lkml/2019/4/23/64 Fixes: 576ed913 ("block: use bio_add_page in bio_iov_iter_get_pages") Reported-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/bio.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/block/bio.c b/block/bio.c
index daa1c1ae72cd..ce797d73bb43 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -896,6 +896,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
struct page **pages = (struct page **)bv;
+ bool same_page = false;
ssize_t size, left;
unsigned len, i;
size_t offset;
@@ -916,8 +917,15 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
struct page *page = pages[i];
len = min_t(size_t, PAGE_SIZE - offset, left);
- if (WARN_ON_ONCE(bio_add_page(bio, page, len, offset) != len))
- return -EINVAL;
+
+ if (__bio_try_merge_page(bio, page, len, offset, &same_page)) {
+ if (same_page)
+ put_page(page);
+ } else {
+ if (WARN_ON_ONCE(bio_full(bio)))
+ return -EINVAL;
+ __bio_add_page(bio, page, len, offset);
+ }
offset = 0;
}