Possible memory leak in block/ll_rw_blk.c

["Catalin Marinas" <catalin.marinas@gmail.com>]

Hi,

After 2.6.19, kmemleak reports several (few tens) orphan blocks
allocated in bio_alloc_bioset() via __blk_rq_map_user() in
block/ll_rq_blk.c. I think these came with commit
0e75f9063f5c55fb0b0b546a7c356f8ec186825e (support larger block pc
requests). The allocation backtrace for the "bio" structure is:

unreferenced object 0xdd9162b0 (size 64):
 [<c018d46f>] kmem_cache_alloc
 [<c0170b2e>] mempool_alloc_slab
 [<c01709cb>] mempool_alloc
 [<c01b7baa>] bio_alloc_bioset
 [<c01b7d0e>] bio_alloc
 [<c01b83f8>] bio_copy_user
 [<c021a380>] __blk_rq_map_user
 [<c021a4ff>] blk_rq_map_user
 [<c021e687>] sg_io
 [<c021ed3e>] scsi_cmd_ioctl
 [<c02bcc13>] sd_ioctl
 [<c021ca65>] blkdev_driver_ioctl
 [<c021cc27>] blkdev_ioctl
 [<c01ba72b>] block_ioctl
 [<c019ea36>] do_ioctl

Because the above objects cannot be tracked, kmemleak also reports the
bio_map_data structures allocated in bio_alloc_map_data (called from
bio_copy_user via the above backtrace).

Thanks.

--
Catalin
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