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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>,
	Mike Christie <michael.christie@oracle.com>,
	linux@leemhuis.info, nicolas.dichtel@6wind.com, axboe@kernel.dk,
	ebiederm@xmission.com, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, mst@redhat.com,
	sgarzare@redhat.com, stefanha@redhat.com, brauner@kernel.org
Subject: Re: [PATCH 3/3] fork, vhost: Use CLONE_THREAD to fix freezer/ps regression
Date: Fri, 2 Jun 2023 16:07:10 -0400	[thread overview]
Message-ID: <CAHk-=whKyWvzg=7_m1o_KLC3zb9FjTBHftc36-5M9X78AxwRXg@mail.gmail.com> (raw)
In-Reply-To: <20230602175846.GC555@redhat.com>

On Fri, Jun 2, 2023 at 1:59 PM Oleg Nesterov <oleg@redhat.com> wrote:
>
> As I said from the very beginning, this code is fine on x86 because
> atomic ops are fully serialised on x86.

Yes. Other architectures require __smp_mb__{before,after}_atomic for
the bit setting ops to actually be memory barriers.

We *should* probably have acquire/release versions of the bit test/set
helpers, but we don't, so they end up being full memory barriers with
those things. Which isn't optimal, but I doubt it matters on most
architectures.

So maybe we'll some day have a "test_bit_acquire()" and a
"set_bit_release()" etc.

            Linus

  reply	other threads:[~2023-06-02 20:07 UTC|newest]

Thread overview: 52+ 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
2023-05-30 14:15                               ` Christian 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
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 [this message]
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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