Message-ID: <3fcad89a-77ad-3369-cd8c-88a223758173@kernel.dk>
Date:   Tue, 21 Mar 2023 13:32:16 -0600
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Subject: Re: [GIT PULL] keys: Miscellaneous fixes/changes
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To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     David Howells <dhowells@redhat.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Bharath SM <bharathsm@microsoft.com>,
        Shyam Prasad N <nspmangalore@gmail.com>,
        Steve French <smfrench@gmail.com>,
        Robbie Harwood <rharwood@redhat.com>,
        Eric Biederman <ebiederm@xmission.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        keyrings@vger.kernel.org, linux-cifs@vger.kernel.org,
        linux-crypto@vger.kernel.org, kexec@lists.infradead.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
References: <2851036.1679417029@warthog.procyon.org.uk>
 <CAHk-=wh1b0r+5SnwWedx=J4aZhRif1HLN_moxEG9Jzy23S6QUA@mail.gmail.com>
 <8d532de2-bf3a-dee4-1cad-e11714e914d0@kernel.dk>
 <CAHk-=wi2yeuwCxvB18=AWG+YKnMgd28WGkHFMqTyMA=59cw3rg@mail.gmail.com>
From:   Jens Axboe <axboe@kernel.dk>
In-Reply-To: <CAHk-=wi2yeuwCxvB18=AWG+YKnMgd28WGkHFMqTyMA=59cw3rg@mail.gmail.com>
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On 3/21/23 1:21?PM, Linus Torvalds wrote:
> On Tue, Mar 21, 2023 at 12:16?PM Jens Axboe <axboe@kernel.dk> wrote:
>>
>> I haven't seen the patch yet as it hasn't been pushed,
> 
> Well, it went out a couple of minutes before your email, so it's out now.

Yep I see it now, looks as expected.

>> It may make sense to add some debug check for
>> PF_KTHREAD having TIF_NOTIFY_RESUME set, or task_work pending for that
>> matter, as that is generally not workable without doing something to
>> handle it explicitly.
> 
> Yeah, I guess we could have some generic check for that. I'm not sure
> where it would be. Scheduler?

Off the top of my head, two options, both in kernel/sched/core.c:

1) Add it to schedule_debug()

2) Add it to sched_submit_work(), adding PF_KTHREAD to the flags checked
   for PF_IO_WORKER | PF_WQ_WORKER to avoid adding any extra fast-path
   overhead.

Alternatively, I guess it could go in kthread_exit() as well. But for
workloads with a persistent kthread that doesn't really go away, that
won't catch it.

-- 
Jens Axboe