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From:   "Eric W. Biederman" <ebiederm@xmission.com>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     linux-arch@vger.kernel.org, Tejun Heo <tj@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Al Viro <viro@ZenIV.linux.org.uk>,
        Jens Axboe <axboe@kernel.dk>,
        Linus Torvalds <torvalds@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        =?utf-8?B?0JzQsNC60YHQuNC8INCa0YPRgtGP0LLQuNC9?= 
        <maximkabox13@gmail.com>
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        <20220506141512.516114-1-ebiederm@xmission.com> <87fslhpi58.ffs@tglx>
        <87v8udwhc6.fsf@email.froward.int.ebiederm.org>
Date:   Wed, 11 May 2022 12:41:44 -0500
In-Reply-To: <87v8udwhc6.fsf@email.froward.int.ebiederm.org> (Eric
        W. Biederman's message of "Tue, 10 May 2022 10:14:01 -0500")
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Subject: Re: [PATCH 1/7] kthread: Don't allocate kthread_struct for init and
 umh
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"Eric W. Biederman" <ebiederm@xmission.com> writes:

> Thomas Gleixner <tglx@linutronix.de> writes:
>
>> I'm worried that there are more of these issues lurking. Haven't looked
>> yet.
>
> I looked earlier and I missed this one.  I am going to look again today,
> along with applying the obvious fix to task_tick_numa.

So I have just looked again and I don't see anything.  There are a
couple of subtle issues on x86.  Especially with saving floating
point but as I read the code copy_thread initializes things
properly so that code that doesn't touch floating point registers
doesn't need to do anything.

The important thing for lurking issues is that even if I missed
something practically all of the uses of PF_KTHREAD are on x86
or generic code so they should be flushed out quickly.

Eric