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From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: axboe@kernel.dk, brauner@kernel.org, mst@redhat.com,
	linux@leemhuis.info, linux-kernel@vger.kernel.org,
	stefanha@redhat.com, nicolas.dichtel@6wind.com,
	virtualization@lists.linux-foundation.org,
	torvalds@linux-foundation.org
Subject: Re: [CFT][PATCH v3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression
Date: Wed, 14 Jun 2023 19:08:04 +0200	[thread overview]
Message-ID: <20230614170803.GA18850@redhat.com> (raw)
In-Reply-To: <87o7llycau.fsf@email.froward.int.ebiederm.org>

On 06/11, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg@redhat.com> writes:
>
> > Could you spell to explain why this can't work (again, in this simple case) ?
> >
> > My current (and I know, very poor) understanding is that .release() should
> > roughly do the following:
> >
> > 	1. Ensure that vhost_work_queue() can't add the new callbacks
> >
> > 	2. Call vhost_dev_flush() to ensure that worker->work_list is empty
> >
> > 	3. Call vhost_task_stop()
>
> At least in the case of exec by the time the final fput happens
> from close_on_exec the task has already changed it's mm.

Of course you are right.

But can't resist, please note that I only meant "this simple case" which
doesn't include exec/etc.

Nevermind. As Mike explains there are more problems even in this particular
"simple" case, and I am not surprised.

Sorry for noise,

Oleg.

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Mike Christie <michael.christie@oracle.com>,
	linux@leemhuis.info, nicolas.dichtel@6wind.com, axboe@kernel.dk,
	torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, mst@redhat.com,
	sgarzare@redhat.com, jasowang@redhat.com, stefanha@redhat.com,
	brauner@kernel.org
Subject: Re: [CFT][PATCH v3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression
Date: Wed, 14 Jun 2023 19:08:04 +0200	[thread overview]
Message-ID: <20230614170803.GA18850@redhat.com> (raw)
In-Reply-To: <87o7llycau.fsf@email.froward.int.ebiederm.org>

On 06/11, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg@redhat.com> writes:
>
> > Could you spell to explain why this can't work (again, in this simple case) ?
> >
> > My current (and I know, very poor) understanding is that .release() should
> > roughly do the following:
> >
> > 	1. Ensure that vhost_work_queue() can't add the new callbacks
> >
> > 	2. Call vhost_dev_flush() to ensure that worker->work_list is empty
> >
> > 	3. Call vhost_task_stop()
>
> At least in the case of exec by the time the final fput happens
> from close_on_exec the task has already changed it's mm.

Of course you are right.

But can't resist, please note that I only meant "this simple case" which
doesn't include exec/etc.

Nevermind. As Mike explains there are more problems even in this particular
"simple" case, and I am not surprised.

Sorry for noise,

Oleg.


  reply	other threads:[~2023-06-14 17:08 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-01 18:32 [PATCH 1/1] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression Mike Christie
2023-06-01 18:32 ` Mike Christie
2023-06-01 19:11 ` Michael S. Tsirkin
2023-06-01 19:11   ` Michael S. Tsirkin
2023-06-02  0:43 ` Eric W. Biederman
2023-06-02  0:43   ` Eric W. Biederman
2023-06-02 14:34 ` Nicolas Dichtel
2023-06-02 19:22 ` Oleg Nesterov
2023-06-02 19:22   ` Oleg Nesterov
2023-06-03  3:44   ` Eric W. Biederman
2023-06-03  3:44     ` Eric W. Biederman
2023-06-05 13:26     ` Oleg Nesterov
2023-06-05 13:26       ` Oleg Nesterov
2023-06-03  4:15   ` [CFT][PATCH v3] " Eric W. Biederman
2023-06-03  4:15     ` Eric W. Biederman
2023-06-04  3:28     ` michael.christie
2023-06-04  3:28       ` michael.christie
2023-06-05 15:10       ` Oleg Nesterov
2023-06-05 15:10         ` Oleg Nesterov
2023-06-05 15:46         ` Mike Christie
2023-06-05 15:46           ` Mike Christie
2023-06-06 12:16           ` Oleg Nesterov
2023-06-06 12:16             ` Oleg Nesterov
2023-06-06 15:57             ` Mike Christie
2023-06-06 15:57               ` Mike Christie
2023-06-06 19:39               ` Oleg Nesterov
2023-06-06 19:39                 ` Oleg Nesterov
2023-06-06 20:38                 ` Mike Christie
2023-06-06 20:38                   ` Mike Christie
2023-06-14  6:02                   ` Can vhost translate to io_uring? Eric W. Biederman
2023-06-14  6:02                     ` Eric W. Biederman
2023-06-14  6:25                     ` michael.christie
2023-06-14  6:25                       ` michael.christie
2023-06-14 14:30                       ` Jens Axboe
2023-06-14 14:30                         ` Jens Axboe
2023-06-14 17:59                       ` Mike Christie
2023-06-14 17:59                         ` Mike Christie
2023-06-14 14:20                     ` Michael S. Tsirkin
2023-06-14 14:20                       ` Michael S. Tsirkin
2023-06-14 15:02                     ` Michael S. Tsirkin
2023-06-14 15:02                       ` Michael S. Tsirkin
2023-06-11 20:27                 ` [CFT][PATCH v3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression Eric W. Biederman
2023-06-11 20:27                   ` Eric W. Biederman
2023-06-14 17:08                   ` Oleg Nesterov [this message]
2023-06-14 17:08                     ` Oleg Nesterov
2023-06-05 12:38     ` Oleg Nesterov
2023-06-05 12:38       ` Oleg Nesterov
2023-06-05 13:48 ` [PATCH 1/1] " Oleg Nesterov
2023-06-05 13:48   ` Oleg Nesterov

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