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From: Michael Lyle <mlyle@lyle.org>
To: Coly Li <i@coly.li>
Cc: Coly Li <colyli@suse.de>,
	linux-bcache@vger.kernel.org, linux-block@vger.kernel.org,
	axboe@kernel.dk, Eric Wheeler <bcache@lists.ewheeler.net>,
	Byungchul Park <byungchul.park@lge.com>,
	Kent Overstreet <kent.overstreet@gmail.com>
Subject: Re: [PATCH 04/12] bcache: Don't reinvent the wheel but use existing llist API
Date: Tue, 26 Sep 2017 12:55:54 -0700	[thread overview]
Message-ID: <CAJ+L6qc1KAMrj6bpp2R7A=O1HmT=Gq_Wt6f4LVc6rAxQ=O8kwQ@mail.gmail.com> (raw)
In-Reply-To: <1433ecdd-3394-c65f-9588-4d2a20df25d5@coly.li>

Thanks everyone--

Yes, this looks good to me and works in testing.

Mike

On Tue, Sep 26, 2017 at 12:46 AM, Coly Li <i@coly.li> wrote:
> On 2017/9/26 =E4=B8=8B=E5=8D=8812:38, Michael Lyle wrote:
>> I believe this introduces a critical bug.
>>
>> cl->list is used to link together the llists for both things waiting,
>> and for things that are being woken.
>>
>> If a closure that is woken decides to wait again, it will corrupt the
>> llist that __closure_wake_up is using.
>>
>> The previous iteration structure gets the next element of the list
>> before waking and is therefore safe.
>
>
> Hi Michael and Byungchul,
>
> This is my fault to suggest Byungchul to change his correct patch into
> wrong one. But it's good to learn such an implicit race behind bcache
> code. I just post a patch to explain how this race may happen and
> corrupt the reverse list iteration. Could you please to review the fix ?
>
> And thanks to Michael again to catch this bug.
>
> --
> Coly Li

WARNING: multiple messages have this Message-ID (diff)
From: Michael Lyle <mlyle@lyle.org>
To: Coly Li <i@coly.li>
Cc: Coly Li <colyli@suse.de>,
	linux-bcache@vger.kernel.org, linux-block@vger.kernel.org,
	axboe@kernel.dk, Eric Wheeler <bcache@lists.ewheeler.net>,
	Byungchul Park <byungchul.park@lge.com>,
	Kent Overstreet <kent.overstreet@gmail.com>
Subject: Re: [PATCH 04/12] bcache: Don't reinvent the wheel but use existing llist API
Date: Tue, 26 Sep 2017 12:55:54 -0700	[thread overview]
Message-ID: <CAJ+L6qc1KAMrj6bpp2R7A=O1HmT=Gq_Wt6f4LVc6rAxQ=O8kwQ@mail.gmail.com> (raw)
In-Reply-To: <1433ecdd-3394-c65f-9588-4d2a20df25d5@coly.li>

Thanks everyone--

Yes, this looks good to me and works in testing.

Mike

On Tue, Sep 26, 2017 at 12:46 AM, Coly Li <i@coly.li> wrote:
> On 2017/9/26 下午12:38, Michael Lyle wrote:
>> I believe this introduces a critical bug.
>>
>> cl->list is used to link together the llists for both things waiting,
>> and for things that are being woken.
>>
>> If a closure that is woken decides to wait again, it will corrupt the
>> llist that __closure_wake_up is using.
>>
>> The previous iteration structure gets the next element of the list
>> before waking and is therefore safe.
>
>
> Hi Michael and Byungchul,
>
> This is my fault to suggest Byungchul to change his correct patch into
> wrong one. But it's good to learn such an implicit race behind bcache
> code. I just post a patch to explain how this race may happen and
> corrupt the reverse list iteration. Could you please to review the fix ?
>
> And thanks to Michael again to catch this bug.
>
> --
> Coly Li

  reply	other threads:[~2017-09-26 19:55 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-06  6:25 [PATCH 00/13] bcache: fixes and update for 4.14 Coly Li
2017-09-06  6:25 ` [PATCH 01/12] bcache: Fix leak of bdev reference Coly Li
2017-09-06  6:25 ` [PATCH 02/12] bcache: fix sequential large write IO bypass Coly Li
2017-09-06  6:25 ` [PATCH 03/12] bcache: do not subtract sectors_to_gc for bypassed IO Coly Li
2017-09-06  6:25 ` [PATCH 04/12] bcache: Don't reinvent the wheel but use existing llist API Coly Li
2017-09-26  4:38   ` Michael Lyle
2017-09-26  6:39     ` 박병철/선임연구원/SW Platform(연)AOT팀(byungchul.park@lge.com)
2017-09-26  6:39       ` 박병철/선임연구원/SW Platform(연)AOT팀(byungchul.park@lge.com)
2017-09-26  7:09       ` Coly Li
2017-09-26  7:15         ` 박병철/선임연구원/SW Platform(연)AOT팀(byungchul.park@lge.com)
2017-09-26  7:15           ` 박병철/선임연구원/SW Platform(연)AOT팀(byungchul.park@lge.com)
2017-09-26  7:22           ` Coly Li
2017-09-26  7:08     ` Coly Li
2017-09-26  7:16       ` 박병철/선임연구원/SW Platform(연)AOT팀(byungchul.park@lge.com)
2017-09-26  7:16         ` 박병철/선임연구원/SW Platform(연)AOT팀(byungchul.park@lge.com)
2017-09-26  7:24         ` Coly Li
2017-09-26  7:46     ` Coly Li
2017-09-26 19:55       ` Michael Lyle [this message]
2017-09-26 19:55         ` Michael Lyle
2017-09-06  6:25 ` [PATCH 05/12] bcache: gc does not work when triggering by manual command Coly Li
2017-09-06  6:25 ` [PATCH 06/12] bcache: correct cache_dirty_target in __update_writeback_rate() Coly Li
2017-09-06  6:25 ` [PATCH 07/12] bcache: Correct return value for sysfs attach errors Coly Li
2017-09-06  6:25 ` [PATCH 08/12] bcache: increase the number of open buckets Coly Li
2017-09-06  6:25   ` Coly Li
2017-09-06  6:25 ` [PATCH 09/12] bcache: fix for gc and write-back race Coly Li
2017-09-06  6:26 ` [PATCH 10/12] bcache: silence static checker warning Coly Li
2017-09-06  6:26 ` [PATCH 11/12] bcache: Update continue_at() documentation Coly Li
2017-09-06  6:26 ` [PATCH 12/12] bcache: fix bch_hprint crash and improve output Coly Li
2017-09-06 14:20 ` [PATCH 00/13] bcache: fixes and update for 4.14 Jens Axboe
2017-09-06 15:41   ` Coly Li
2017-09-06 15:46     ` Jens Axboe
2017-09-06 17:38       ` Coly Li
2017-09-07 18:51         ` Eddie Chapman
2017-09-07 19:31           ` Jens Axboe
2017-09-07 19:01         ` Eddie Chapman

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