From: Paolo Bonzini <pbonzini@redhat.com>
To: Hillf Danton <hdanton@sina.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
"Michael S. Tsirkin" <mst@redhat.com>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: 5.13-rt1 + KVM = WARNING: at fs/eventfd.c:74 eventfd_signal()
Date: Mon, 26 Jul 2021 13:03:15 +0200 [thread overview]
Message-ID: <d76f08d4-a653-1eb6-bf4f-050f6068753d@redhat.com> (raw)
In-Reply-To: <20210724043320.1654-1-hdanton@sina.com>
On 24/07/21 06:33, Hillf Danton wrote:
> lock WQ
> count += n
> no waiter
> unlock WQ
Ok, this is a write.
>
> lock WQ
> add waiter for EPOLLIN
> unlock WQ
This is eventfd_poll(). It hasn't yet returned EPOLLIN.
> lock WQ
> count = 0
> wakeup EPOLLOUT
> unlock WQ
This is a read().
> lock WQ
> count += n
> no waiter
> unlock WQ
This is wrong; after "unlock WQ" in CPU3 there *is* a waiter, no one has
waked it up yet.
Paolo
> ------------------------------- c1 = count
next prev parent reply other threads:[~2021-07-26 11:03 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-14 8:01 5.13-rt1 + KVM = WARNING: at fs/eventfd.c:74 eventfd_signal() Daniel Bristot de Oliveira
2021-07-14 8:10 ` Paolo Bonzini
2021-07-14 9:23 ` Jason Wang
2021-07-14 10:35 ` Paolo Bonzini
2021-07-14 10:41 ` Michael S. Tsirkin
2021-07-14 10:44 ` Paolo Bonzini
2021-07-14 12:20 ` Daniel Bristot de Oliveira
2021-07-15 4:14 ` Jason Wang
2021-07-15 5:58 ` Paolo Bonzini
2021-07-15 6:45 ` Jason Wang
2021-07-15 8:22 ` Daniel Bristot de Oliveira
2021-07-15 8:44 ` He Zhe
2021-07-15 9:51 ` Paolo Bonzini
2021-07-15 10:10 ` He Zhe
2021-07-15 11:05 ` Paolo Bonzini
2021-07-16 2:26 ` Jason Wang
2021-07-16 2:43 ` He Zhe
2021-07-16 2:46 ` Jason Wang
2021-07-15 9:46 ` Paolo Bonzini
2021-07-15 12:34 ` Daniel Bristot de Oliveira
[not found] ` <20210715102249.2205-1-hdanton@sina.com>
2021-07-15 12:31 ` Daniel Bristot de Oliveira
[not found] ` <20210716020611.2288-1-hdanton@sina.com>
2021-07-16 6:54 ` Paolo Bonzini
[not found] ` <20210716075539.2376-1-hdanton@sina.com>
2021-07-16 7:59 ` Paolo Bonzini
[not found] ` <20210716093725.2438-1-hdanton@sina.com>
2021-07-16 11:55 ` Paolo Bonzini
[not found] ` <20210718124219.1521-1-hdanton@sina.com>
2021-07-19 15:38 ` Paolo Bonzini
[not found] ` <20210721070452.1008-1-hdanton@sina.com>
2021-07-21 7:25 ` Thomas Gleixner
[not found] ` <20210721101119.1103-1-hdanton@sina.com>
2021-07-21 10:59 ` Paolo Bonzini
[not found] ` <20210723022356.1301-1-hdanton@sina.com>
2021-07-23 7:59 ` Paolo Bonzini
[not found] ` <20210723094830.1375-1-hdanton@sina.com>
2021-07-23 10:56 ` Paolo Bonzini
[not found] ` <20210724043320.1654-1-hdanton@sina.com>
2021-07-26 11:03 ` Paolo Bonzini [this message]
2021-07-28 8:06 ` Thomas Gleixner
2021-07-28 10:21 ` Paolo Bonzini
2021-07-28 19:07 ` Thomas Gleixner
2021-07-29 11:01 ` [PATCH] eventfd: Make signal recursion protection a task bit Thomas Gleixner
2021-07-29 14:32 ` Daniel Bristot de Oliveira
2021-07-29 19:23 ` Daniel Bristot de Oliveira
2021-08-26 7:03 ` Jason Wang
2021-08-27 23:41 ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
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