linux-kernel - Re: [PATCH v11 8/8] vhost: use vhost

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Message-ID: <CAHk-=wgTpRDwS+F0Gd6+bM+TEh+x4Aiz8EBDTnTm3Q4TFdWOww@mail.gmail.com>
Date:   Mon, 15 May 2023 15:54:49 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Mike Christie <michael.christie@...cle.com>,
        Oleg Nesterov <oleg@...hat.com>
Cc:     Christian Brauner <brauner@...nel.org>,
        Thorsten Leemhuis <linux@...mhuis.info>,
        nicolas.dichtel@...nd.com,
        Linux kernel regressions list <regressions@...ts.linux.dev>,
        hch@...radead.org, stefanha@...hat.com, jasowang@...hat.com,
        mst@...hat.com, sgarzare@...hat.com,
        virtualization@...ts.linux-foundation.org, ebiederm@...ssion.com,
        konrad.wilk@...cle.com, linux-kernel@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH v11 8/8] vhost: use vhost_tasks for worker threads

On Mon, May 15, 2023 at 3:23 PM Mike Christie
<michael.christie@...cle.com> wrote:
>
> The vhost layer really doesn't want any signals and wants to work like kthreads
> for that case. To make it really simple can we do something like this where it
> separates user and io worker behavior where the major diff is how they handle
> signals and exit. I also included a fix for the freeze case:

I don't love the SIGKILL special case, but I also don't find this
deeply offensive. So if this is what it takes, I'm ok with it.

I wonder if we could make that special case simply check for "is
SIGKILL blocked" instead? No normal case will cause that, and it means
that a PF_USER_WORKER thread could decide per-thread what it wants to
do wrt SIGKILL.

Christian? And I guess we should Cc: Oleg too, since the signal parts
are an area he's familiar with and has worked on.. Eric Biederman has
already been on the list and has also been involved

Oleg: see

  https://lore.kernel.org/lkml/122b597e-a5fa-daf7-27bb-6f04fa98d496@oracle.com/

for the context here.

              Linus