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Date:   Mon, 23 May 2022 12:00:06 -0700
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From:   Tadeusz Struk <tadeusz.struk@linaro.org>
Subject: Re: [PATCH] cgroup: don't queue css_release_work if one already
 pending
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On 5/20/22 09:42, Michal Koutný wrote:
> On Fri, May 20, 2022 at 09:38:12AM -0700, Tadeusz Struk <tadeusz.struk@linaro.org> wrote:
>> as this is a result of enqueuing the same css->destroy_work onto the same WQ,
>> one on the rcu path and one on the css_release path.
>> I will prototype it today and test with syzbot.
> 
> In my understanding, you'd need two independent work_structs in a css,
> not two separate workqueues to put the single entry on.

Yes, separating the css_killed_ref and css_release paths with two separate work_structs
fixes the two syzbot list corruption issues [1]&[2].
I tested it on mainline v5.18.0 and v5.10.117
In case of [2] the mainline triggers an issue, but it is unrelated to list corruption.

[1] https://syzkaller.appspot.com/bug?id=e26e54d6eac9d9fb50b221ec3e4627b327465dbd
[2] https://syzkaller.appspot.com/bug?id=3c7ff113ccb695e839b859da3fc481c36eb1cfd5

I will send a patch soon.

-- 
Thanks,
Tadeusz