From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: viro@zeniv.linux.org.uk, jack@suse.cz, hch@lst.de,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Fix queueing work if !bdi_cap_writeback_dirty()
Date: Wed, 12 Sep 2012 17:00:48 +0900 [thread overview]
Message-ID: <87sjan3c27.fsf@devron.myhome.or.jp> (raw)
In-Reply-To: <20120912024249.GB17922@localhost> (Fengguang Wu's message of "Wed, 12 Sep 2012 10:42:49 +0800")
Fengguang Wu <fengguang.wu@intel.com> writes:
> On Wed, Sep 12, 2012 at 03:28:42AM +0900, OGAWA Hirofumi wrote:
>>
>> If bdi has BDI_CAP_NO_WRITEBACK, bdi_forker_thread() doesn't start
>> writeback thread. This means there is no consumer of work item made
>> by bdi_queue_work().
>>
>> This adds to checking of !bdi_cap_writeback_dirty(sb->s_bdi) before
>> calling bdi_queue_work(), otherwise queued work never be consumed.
>
> Thanks for catching this! Does this bug have any side effects other
> than memory leaking?
>
> It may be possible for some caller that actually expect it to do some
> work to make progress, otherwise will eventually block. If so, we'll
> need to fix the caller.
If used custom bdi with BDI_CAP_NO_WRITEBACK, wait_for_completion()
(e.g. sync_inodes_sb()) will be blocked forever.
I tested by custom bdi with BDI_CAP_NO_WRITEBACK - sync(2) blocked
forever by this reason.
Thanks.
--
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
next prev parent reply other threads:[~2012-09-12 8:01 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-11 18:28 [PATCH] Fix queueing work if !bdi_cap_writeback_dirty() OGAWA Hirofumi
2012-09-12 2:42 ` Fengguang Wu
2012-09-12 8:00 ` OGAWA Hirofumi [this message]
2012-09-13 0:33 ` Fengguang Wu
2012-09-13 5:41 ` OGAWA Hirofumi
2012-09-13 6:03 ` Fengguang Wu
2012-09-13 6:31 ` OGAWA Hirofumi
2012-09-13 6:39 ` Fengguang Wu
2012-09-13 7:53 ` OGAWA Hirofumi
2012-09-14 11:13 ` OGAWA Hirofumi
2012-09-14 11:18 ` Fengguang Wu
2012-09-14 11:14 ` Fengguang Wu
2012-09-14 12:12 ` OGAWA Hirofumi
2012-09-14 12:53 ` Fengguang Wu
2012-09-14 13:07 ` OGAWA Hirofumi
2012-09-14 13:33 ` Fengguang Wu
2012-09-14 13:49 ` OGAWA Hirofumi
2012-09-14 13:19 ` Jan Kara
2012-09-14 13:44 ` OGAWA Hirofumi
2012-09-14 14:45 ` Jan Kara
2012-09-14 15:10 ` OGAWA Hirofumi
2012-09-16 21:49 ` Jan Kara
2012-09-16 23:24 ` OGAWA Hirofumi
2012-09-17 8:48 ` Jan Kara
2012-09-17 9:39 ` OGAWA Hirofumi
2012-09-17 9:56 ` Jan Kara
2012-09-17 10:37 ` OGAWA Hirofumi
2012-09-17 15:54 ` Jan Kara
2012-09-17 16:55 ` OGAWA Hirofumi
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