diff options
authorJens Axboe <>2017-06-28 15:30:13 -0600
committerJens Axboe <>2017-06-28 15:30:13 -0600
commit9ae3b3f52c62ddd5eb12c57f195f4f38121faa01 (patch)
parentebef7368571d88f0f80b817e6898075c62265b4e (diff)
block: provide bio_uninit() free freeing integrity/task associations
Wen reports significant memory leaks with DIF and O_DIRECT: "With nvme devive + T10 enabled, On a system it has 256GB and started logging /proc/meminfo & /proc/slabinfo for every minute and in an hour it increased by 15968128 kB or ~15+GB.. Approximately 256 MB / minute leaking. /proc/meminfo | grep SUnreclaim... SUnreclaim: 6752128 kB SUnreclaim: 6874880 kB SUnreclaim: 7238080 kB .... SUnreclaim: 22307264 kB SUnreclaim: 22485888 kB SUnreclaim: 22720256 kB When testcases with T10 enabled call into __blkdev_direct_IO_simple, code doesn't free memory allocated by bio_integrity_alloc. The patch fixes the issue. HTX has been run with +60 hours without failure." Since __blkdev_direct_IO_simple() allocates the bio on the stack, it doesn't go through the regular bio free. This means that any ancillary data allocated with the bio through the stack is not freed. Hence, we can leak the integrity data associated with the bio, if the device is using DIF/DIX. Fix this by providing a bio_uninit() and export it, so that we can use it to free this data. Note that this is a minimal fix for this issue. Any current user of bio's that are allocated outside of bio_alloc_bioset() suffers from this issue, most notably some drivers. We will fix those in a more comprehensive patch for 4.13. This also means that the commit marked as being fixed by this isn't the real culprit, it's just the most obvious one out there. Fixes: 542ff7bf18c6 ("block: new direct I/O implementation") Reported-by: Wen Xiong <> Reviewed-by: Christoph Hellwig <> Signed-off-by: Jens Axboe <>
3 files changed, 14 insertions, 4 deletions
diff --git a/block/bio.c b/block/bio.c
index 888e7801c638..26b0810fb8ea 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -240,20 +240,21 @@ fallback:
return bvl;
-static void __bio_free(struct bio *bio)
+void bio_uninit(struct bio *bio)
if (bio_integrity(bio))
static void bio_free(struct bio *bio)
struct bio_set *bs = bio->bi_pool;
void *p;
- __bio_free(bio);
+ bio_uninit(bio);
if (bs) {
bvec_free(bs->bvec_pool, bio->bi_io_vec, BVEC_POOL_IDX(bio));
@@ -271,6 +272,11 @@ static void bio_free(struct bio *bio)
+ * Users of this function have their own bio allocation. Subsequently,
+ * they must remember to pair any call to bio_init() with bio_uninit()
+ * when IO has completed, or when the bio is released.
+ */
void bio_init(struct bio *bio, struct bio_vec *table,
unsigned short max_vecs)
@@ -297,7 +303,7 @@ void bio_reset(struct bio *bio)
unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
- __bio_free(bio);
+ bio_uninit(bio);
memset(bio, 0, BIO_RESET_BYTES);
bio->bi_flags = flags;
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 519599dddd36..0a7404ef9335 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -263,7 +263,10 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
if (unlikely(bio.bi_error))
- return bio.bi_error;
+ ret = bio.bi_error;
+ bio_uninit(&bio);
return ret;
diff --git a/include/linux/bio.h b/include/linux/bio.h
index d1b04b0e99cf..a7e29fa0981f 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -426,6 +426,7 @@ extern void bio_advance(struct bio *, unsigned);
extern void bio_init(struct bio *bio, struct bio_vec *table,
unsigned short max_vecs);
+extern void bio_uninit(struct bio *);
extern void bio_reset(struct bio *);
void bio_chain(struct bio *, struct bio *);