From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
Oleg Nesterov <oleg@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Ben Segall <bsegall@google.com>, Borislav Petkov <bp@alien8.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>, Mel Gorman <mgorman@suse.de>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Vincent Guittot <vincent.guittot@linaro.org>
Subject: Re: [PATCH] signal/x86: Delay calling signals in atomic
Date: Fri, 1 Apr 2022 13:45:03 +0200 [thread overview]
Message-ID: <Ykblv2aKh3ekqpi4@linutronix.de> (raw)
In-Reply-To: <87o81nl3b6.fsf@email.froward.int.ebiederm.org>
On 2022-03-30 13:10:05 [-0500], Eric W. Biederman wrote:
> But it looks like if we are coming from userspace then we use the same
> stack as any other time we would come from userspace. AKA a stack
> that allows the kernel to sleep.
>
> So I don't see what the problem is that is trying to be fixed.
It is not only the stack. In atomic context / disabled interrupts it is
not possible to acquire a spinlock_t (sighand_struct::siglock) which is
done later.
> I know that code has been changed over the years, perhaps this is
> something that was fixed upstream and the real time tree didn't realize
> there was no longer a need to fix anything?
>
> Or am I missing something subtle when reading the idtentry assembly?
It certainly is true that the code changed over the years. The per-CPU
stack is one problem, the siglock in atomic context is the other one.
Thank you for the input. Let me digest the informations I have here and
get back.
> Eric
Sebastian
next prev parent reply other threads:[~2022-04-01 11:45 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-14 20:19 [PATCH] signal/x86: Delay calling signals in atomic Sebastian Andrzej Siewior
2022-03-28 14:25 ` Eric W. Biederman
2022-03-28 14:41 ` Eric W. Biederman
2022-03-28 16:32 ` Sebastian Andrzej Siewior
2022-03-28 14:48 ` Eric W. Biederman
2022-03-28 16:17 ` Sebastian Andrzej Siewior
2022-03-28 22:07 ` Eric W. Biederman
2022-03-29 9:31 ` Sebastian Andrzej Siewior
2022-03-30 18:10 ` Eric W. Biederman
2022-04-01 11:45 ` Sebastian Andrzej Siewior [this message]
2022-04-04 14:29 ` Eric W. Biederman
2022-03-28 16:28 ` Thomas Gleixner
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