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,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 3/3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression
Date: Mon, 29 May 2023 13:19:39 +0200 [thread overview]
Message-ID: <20230529111859.GA15193@redhat.com> (raw)
In-Reply-To: <87mt1pmezu.fsf@email.froward.int.ebiederm.org>
On 05/27, Eric W. Biederman wrote:
>
> Looking forward I don't see not asking the worker threads to stop
> for the coredump right now causing any problems in the future.
> So I think we can use this to resolve the coredump issue I spotted.
But we have almost the same problem with exec.
Execing thread will wait for vhost_worker() while vhost_worker will wait for
.release -> vhost_task_stop().
And even O_CLOEXEC won't help, do_close_on_exec() is called after de_thread().
Or suppose that vhost_worker's sub-thread forks a child with CLONE_FILES...
If we want CLONE_THREAD, I think vhost_worker() should exit after get_signal()
returns SIGKILL. Perhaps it should "disable" vhost_work_queue() somehow and
flush the pending works on ->work_list before exit, I dunno. But imo it should
not wait for the final fput().
Oleg.
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WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Mike Christie <michael.christie@oracle.com>,
linux@leemhuis.info, nicolas.dichtel@6wind.com, axboe@kernel.dk,
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: [PATCH 3/3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression
Date: Mon, 29 May 2023 13:19:39 +0200 [thread overview]
Message-ID: <20230529111859.GA15193@redhat.com> (raw)
In-Reply-To: <87mt1pmezu.fsf@email.froward.int.ebiederm.org>
On 05/27, Eric W. Biederman wrote:
>
> Looking forward I don't see not asking the worker threads to stop
> for the coredump right now causing any problems in the future.
> So I think we can use this to resolve the coredump issue I spotted.
But we have almost the same problem with exec.
Execing thread will wait for vhost_worker() while vhost_worker will wait for
.release -> vhost_task_stop().
And even O_CLOEXEC won't help, do_close_on_exec() is called after de_thread().
Or suppose that vhost_worker's sub-thread forks a child with CLONE_FILES...
If we want CLONE_THREAD, I think vhost_worker() should exit after get_signal()
returns SIGKILL. Perhaps it should "disable" vhost_work_queue() somehow and
flush the pending works on ->work_list before exit, I dunno. But imo it should
not wait for the final fput().
Oleg.
next prev parent reply other threads:[~2023-05-29 11:20 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-22 2:51 [PATCH 0/3] vhost: Fix freezer/ps regressions Mike Christie
2023-05-22 2:51 ` Mike Christie
2023-05-22 2:51 ` [PATCH 1/3] signal: Don't always put SIGKILL in shared_pending Mike Christie
2023-05-22 2:51 ` Mike Christie
2023-05-23 15:30 ` Eric W. Biederman
2023-05-23 15:30 ` Eric W. Biederman
2023-05-22 2:51 ` [PATCH 2/3] signal: Don't exit for PF_USER_WORKER tasks Mike Christie
2023-05-22 2:51 ` Mike Christie
2023-05-22 2:51 ` [PATCH 3/3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression Mike Christie
2023-05-22 2:51 ` Mike Christie
2023-05-22 12:30 ` Oleg Nesterov
2023-05-22 12:30 ` Oleg Nesterov
2023-05-22 17:00 ` Mike Christie
2023-05-22 17:00 ` Mike Christie
2023-05-22 17:47 ` Oleg Nesterov
2023-05-22 17:47 ` Oleg Nesterov
2023-05-23 12:15 ` Oleg Nesterov
2023-05-23 12:15 ` Oleg Nesterov
2023-05-23 15:57 ` Eric W. Biederman
2023-05-23 15:57 ` Eric W. Biederman
2023-05-24 14:10 ` Oleg Nesterov
2023-05-24 14:10 ` Oleg Nesterov
2023-05-24 14:44 ` Eric W. Biederman
2023-05-24 14:44 ` Eric W. Biederman
2023-05-25 11:55 ` Oleg Nesterov
2023-05-25 11:55 ` Oleg Nesterov
2023-05-25 15:30 ` Eric W. Biederman
2023-05-25 15:30 ` Eric W. Biederman
2023-05-25 16:20 ` Linus Torvalds
2023-05-25 16:20 ` Linus Torvalds
2023-05-27 9:49 ` Eric W. Biederman
2023-05-27 9:49 ` Eric W. Biederman
2023-05-27 16:12 ` Linus Torvalds
2023-05-27 16:12 ` Linus Torvalds
2023-05-28 1:17 ` Eric W. Biederman
2023-05-28 1:17 ` Eric W. Biederman
2023-05-28 1:21 ` Linus Torvalds
2023-05-28 1:21 ` Linus Torvalds
2023-05-29 11:19 ` Oleg Nesterov [this message]
2023-05-29 11:19 ` Oleg Nesterov
2023-05-29 16:09 ` michael.christie
2023-05-29 16:09 ` michael.christie
2023-05-29 17:46 ` Oleg Nesterov
2023-05-29 17:46 ` Oleg Nesterov
2023-05-29 17:54 ` Oleg Nesterov
2023-05-29 17:54 ` Oleg Nesterov
2023-05-29 19:03 ` Mike Christie
2023-05-29 19:03 ` Mike Christie
2023-05-29 19:35 ` Mike Christie
2023-05-29 19:35 ` Mike Christie
2023-05-29 19:46 ` michael.christie
2023-05-29 19:46 ` michael.christie
2023-05-30 2:48 ` Eric W. Biederman
2023-05-30 2:48 ` Eric W. Biederman
2023-05-30 2:38 ` Eric W. Biederman
2023-05-30 2:38 ` Eric W. Biederman
2023-05-30 15:34 ` Mike Christie
2023-05-30 15:34 ` Mike Christie
2023-05-31 3:30 ` Mike Christie
2023-05-31 3:30 ` Mike Christie
2023-05-29 16:11 ` michael.christie
2023-05-29 16:11 ` michael.christie
2023-05-30 14:15 ` Christian Brauner
2023-05-30 17:55 ` Oleg Nesterov
2023-05-30 17:55 ` Oleg Nesterov
2023-05-30 15:01 ` Eric W. Biederman
2023-05-30 15:01 ` Eric W. Biederman
2023-05-31 5:22 ` Jason Wang
2023-05-31 5:22 ` Jason Wang
2023-05-24 0:02 ` Mike Christie
2023-05-24 0:02 ` Mike Christie
2023-05-25 16:15 ` Mike Christie
2023-05-25 16:15 ` Mike Christie
2023-05-28 1:41 ` Eric W. Biederman
2023-05-28 1:41 ` Eric W. Biederman
2023-05-28 19:29 ` Mike Christie
2023-05-28 19:29 ` Mike Christie
2023-05-31 5:22 ` Jason Wang
2023-05-31 5:22 ` Jason Wang
2023-05-31 7:25 ` Oleg Nesterov
2023-05-31 7:25 ` Oleg Nesterov
2023-05-31 8:17 ` Jason Wang
2023-05-31 8:17 ` Jason Wang
2023-05-31 9:14 ` Oleg Nesterov
2023-05-31 9:14 ` Oleg Nesterov
2023-06-01 2:44 ` Jason Wang
2023-06-01 2:44 ` Jason Wang
2023-06-01 7:43 ` Oleg Nesterov
2023-06-01 7:43 ` Oleg Nesterov
2023-06-02 5:03 ` Jason Wang
2023-06-02 5:03 ` Jason Wang
2023-06-02 17:58 ` Oleg Nesterov
2023-06-02 17:58 ` Oleg Nesterov
2023-06-02 20:07 ` Linus Torvalds
2023-06-02 20:07 ` Linus Torvalds
2023-06-05 14:20 ` Oleg Nesterov
2023-06-05 14:20 ` Oleg Nesterov
2023-05-22 19:40 ` Michael S. Tsirkin
2023-05-22 19:40 ` Michael S. Tsirkin
2023-05-23 15:39 ` Eric W. Biederman
2023-05-23 15:39 ` Eric W. Biederman
2023-05-23 15:48 ` Mike Christie
2023-05-23 15:48 ` Mike Christie
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