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From: Catalin Marinas <catalin.marinas@arm.com>
Newsgroups: linux.kernel
Subject: Re: kmemleak report after 9082e87bfbf8 ("block: remove struct  bio_batch")
Date: Tue, 07 Jun 2016 11:50:02 +0200
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On Mon, Jun 06, 2016 at 12:09:49PM -0500, Shaun Tancheff wrote:
> I'm pretty sure it is missing a bio_put() after submit_bio_wait().
> 
> Please excuse the hack-y patch but I think you need to do something
> like this ...
> (Note tabs eaten by gmail).
> 
> diff --git a/block/blk-lib.c b/block/blk-lib.c
> index 23d7f30..9e29dc3 100644
> --- a/block/blk-lib.c
> +++ b/block/blk-lib.c
> @@ -113,6 +113,7 @@ int blkdev_issue_discard(struct block_device
> *bdev, sector_t sector,
>                 ret = submit_bio_wait(type, bio);
>                 if (ret == -EOPNOTSUPP)
>                         ret = 0;
> +               bio_put(bio);
>         }
>         blk_finish_plug(&plug);
> 
> @@ -165,8 +166,10 @@ int blkdev_issue_write_same(struct block_device
> *bdev, sector_t sector,
>                 }
>         }
> 
> -       if (bio)
> +       if (bio) {
>                 ret = submit_bio_wait(REQ_WRITE | REQ_WRITE_SAME, bio);
> +               bio_put(bio);
> +       }
>         return ret != -EOPNOTSUPP ? ret : 0;
>  }
>  EXPORT_SYMBOL(blkdev_issue_write_same);
> @@ -206,8 +209,11 @@ static int __blkdev_issue_zeroout(struct
> block_device *bdev, sector_t sector,
>                 }
>         }
> 
> -       if (bio)
> -               return submit_bio_wait(WRITE, bio);
> +       if (bio) {
> +               ret = submit_bio_wait(WRITE, bio);
> +               bio_put(bio);
> +               return ret;
> +       }
>         return 0;
>  }

This patch appears to fix the memory leak on my machine.

Tested-by: Catalin Marinas <catalin.marinas@arm.com>