kmemleak report after 9082e87bfbf8 ("block: remove struct bio_batch")

From	Catalin Marinas <catalin.marinas@arm.com>
Newsgroups	linux.kernel
Subject	kmemleak report after 9082e87bfbf8 ("block: remove struct bio_batch")
Date	2016-06-06 13:30 +0200
Message-ID	<rH0Tf-4eU-5@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Hi Christoph,

I tried enabling kmemleak on 4.7-rc2 on an x86 host (macbook pro running
Debian sid) and I get some kmemleak reports every few minutes coming
from the block layer. Reverting commit 9082e87bfbf8 ("block: remove
struct bio_batch") makes them go away:

unreferenced object 0xffff880077859c00 (size 256):
  comm "upowerd", pid 1185, jiffies 4295046823 (age 1874.852s)
  hex dump (first 32 bytes):
    80 39 08 00 00 ea ff ff 00 10 00 00 00 00 00 00  .9..............
    00 00 00 00 00 00 00 00 00 e4 21 49 02 88 ff ff  ..........!I....
  backtrace:
    [<ffffffff811d244e>] kmem_cache_alloc+0xfe/0x250
    [<ffffffff812dc8b7>] bvec_alloc+0x57/0xe0
    [<ffffffff812dcaaf>] bio_alloc_bioset+0x16f/0x240
    [<ffffffff812eca7f>] next_bio+0x1f/0x50
    [<ffffffff812ecf1a>] blkdev_issue_zeroout+0xea/0x1d0
    [<ffffffffc025b610>] ext4_issue_zeroout+0x40/0x50 [ext4]
    [<ffffffffc028c58d>] ext4_ext_map_blocks+0x144d/0x1bb0 [ext4]
    [<ffffffff811839f4>] release_pages+0x254/0x310
    [<ffffffff8118437a>] __pagevec_release+0x2a/0x40
    [<ffffffffc025b297>] mpage_prepare_extent_to_map+0x227/0x2c0 [ext4]
    [<ffffffffc025b793>] ext4_map_blocks+0x173/0x5d0 [ext4]
    [<ffffffffc025f1d0>] ext4_writepages+0x700/0xd40 [ext4]
    [<ffffffff8121312e>] legitimize_mnt+0xe/0x50
    [<ffffffff811d244e>] kmem_cache_alloc+0xfe/0x250
    [<ffffffff81173fd5>] __filemap_fdatawrite_range+0xc5/0x100
    [<ffffffff81174113>] filemap_write_and_wait_range+0x33/0x70

It's coming from various processes, not just upowerd. I haven't got the
chance to dig further but you may have a better idea.

Thanks.

-- 
Catalin

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kmemleak report after 9082e87bfbf8 ("block: remove struct bio_batch") Catalin Marinas <catalin.marinas@arm.com> - 2016-06-06 13:30 +0200
  Re: kmemleak report after 9082e87bfbf8 ("block: remove struct  bio_batch") Christoph Hellwig <hch@lst.de> - 2016-06-06 16:20 +0200
    Re: kmemleak report after 9082e87bfbf8 ("block: remove struct  bio_batch") Catalin Marinas <catalin.marinas@arm.com> - 2016-06-06 18:20 +0200
      Re: kmemleak report after 9082e87bfbf8 ("block: remove struct bio_batch") Shaun Tancheff <shaun.tancheff@seagate.com> - 2016-06-06 19:20 +0200
        Re: kmemleak report after 9082e87bfbf8 ("block: remove struct  bio_batch") Christoph Hellwig <hch@lst.de> - 2016-06-06 19:30 +0200
          Re: kmemleak report after 9082e87bfbf8 ("block: remove struct  bio_batch") Catalin Marinas <catalin.marinas@arm.com> - 2016-06-06 19:40 +0200
          Re: kmemleak report after 9082e87bfbf8 ("block: remove struct  bio_batch") Jens Axboe <axboe@kernel.dk> - 2016-06-06 20:20 +0200
        Re: kmemleak report after 9082e87bfbf8 ("block: remove struct  bio_batch") Catalin Marinas <catalin.marinas@arm.com> - 2016-06-07 11:50 +0200
          Re: kmemleak report after 9082e87bfbf8 ("block: remove struct  bio_batch") Larry Finger <Larry.Finger@lwfinger.net> - 2016-06-07 16:20 +0200
            Re: kmemleak report after 9082e87bfbf8 ("block: remove struct bio_batch") David Drysdale <drysdale@google.com> - 2016-06-07 17:50 +0200
      Re: kmemleak report after 9082e87bfbf8 ("block: remove struct  bio_batch") Larry Finger <Larry.Finger@lwfinger.net> - 2016-06-07 06:10 +0200
        Re: kmemleak report after 9082e87bfbf8 ("block: remove struct  bio_batch") Christoph Hellwig <hch@lst.de> - 2016-06-07 08:40 +0200

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