From: "Eric W. Biederman" <ebiederm@xmission.com>
To: Mike Christie <michael.christie@oracle.com>
Cc: axboe@kernel.dk, brauner@kernel.org, mst@redhat.com,
linux-kernel@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>,
stefanha@redhat.com, linux@leemhuis.info,
nicolas.dichtel@6wind.com,
virtualization@lists.linux-foundation.org,
torvalds@linux-foundation.org
Subject: Re: [PATCH 3/3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression
Date: Sat, 27 May 2023 20:41:29 -0500 [thread overview]
Message-ID: <87a5xpkzau.fsf@email.froward.int.ebiederm.org> (raw)
In-Reply-To: <c6e9a5db-798f-fa40-5ae2-a41f2d8ebab5@oracle.com> (Mike Christie's message of "Thu, 25 May 2023 11:15:59 -0500")
Mike Christie <michael.christie@oracle.com> writes:
> On 5/23/23 7:15 AM, Oleg Nesterov wrote:
>>
>> Now the main question. Whatever we do, SIGKILL/SIGSTOP/etc can come right
>> before we call work->fn(). Is it "safe" to run this callback with
>> signal_pending() or fatal_signal_pending() ?
>
> The questions before this one I'll leave for the core vhost devs since
> they know best.
Let me ask a clarifying question:
Is it only the call to schedule() in vhost_worker that you are worried
about not sleeping if signal_pending() or fatal_signal_pending()?
Is there concern that the worker functions aka "work->fn()" will also
have killable or interruptible sleeps that also will misbehave.
We can handle schedule() in vhost_worker without problem.
If a worker function has interruptible or killable sleeps that will turn
into busy waits or worse not sleeping long enough that seems like a
problem. There is no way to guarantee that the outer loop of
vhost_worker will protect the worker functions from signal_pending()
or fatal_signal_pending() becoming true.
Eric
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next prev parent reply other threads:[~2023-05-28 1:41 UTC|newest]
Thread overview: 51+ 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 ` [PATCH 1/3] signal: Don't always put SIGKILL in shared_pending Mike Christie
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 ` [PATCH 3/3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression Mike Christie
2023-05-22 12:30 ` Oleg Nesterov
2023-05-22 17:00 ` Mike Christie
2023-05-22 17:47 ` Oleg Nesterov
2023-05-23 12:15 ` Oleg Nesterov
2023-05-23 15:57 ` Eric W. Biederman
2023-05-24 14:10 ` Oleg Nesterov
2023-05-24 14:44 ` Eric W. Biederman
2023-05-25 11:55 ` Oleg Nesterov
2023-05-25 15:30 ` Eric W. Biederman
2023-05-25 16:20 ` Linus Torvalds
2023-05-27 9:49 ` Eric W. Biederman
2023-05-27 16:12 ` Linus Torvalds
2023-05-28 1:17 ` Eric W. Biederman
2023-05-28 1:21 ` Linus Torvalds
2023-05-29 11:19 ` Oleg Nesterov
2023-05-29 16:09 ` michael.christie
2023-05-29 17:46 ` Oleg Nesterov
2023-05-29 17:54 ` Oleg Nesterov
2023-05-29 19:03 ` Mike Christie
2023-05-29 19:35 ` Mike Christie
2023-05-29 19:46 ` michael.christie
2023-05-30 2:48 ` Eric W. Biederman
2023-05-30 2:38 ` Eric W. Biederman
2023-05-30 15:34 ` Mike Christie
2023-05-31 3:30 ` Mike Christie
2023-05-29 16:11 ` michael.christie
[not found] ` <20230530-autor-faxnummer-01e0a31c0fb8@brauner>
2023-05-30 17:55 ` Oleg Nesterov
2023-05-30 15:01 ` Eric W. Biederman
2023-05-31 5:22 ` Jason Wang
2023-05-24 0:02 ` Mike Christie
2023-05-25 16:15 ` Mike Christie
2023-05-28 1:41 ` Eric W. Biederman [this message]
2023-05-28 19:29 ` Mike Christie
2023-05-31 5:22 ` Jason Wang
2023-05-31 7:25 ` Oleg Nesterov
2023-05-31 8:17 ` Jason Wang
2023-05-31 9:14 ` Oleg Nesterov
2023-06-01 2:44 ` Jason Wang
2023-06-01 7:43 ` Oleg Nesterov
2023-06-02 5:03 ` Jason Wang
2023-06-02 17:58 ` Oleg Nesterov
2023-06-02 20:07 ` Linus Torvalds
2023-06-05 14:20 ` Oleg Nesterov
2023-05-22 19:40 ` Michael S. Tsirkin
2023-05-23 15:39 ` Eric W. Biederman
2023-05-23 15:48 ` Mike Christie
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