From: Thomas Gleixner <tglx@linutronix.de>
To: "Harris, Robert" <robert.harris@alertlogic.com>
Cc: Ingo Molnar <mingo@kernel.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"dvhart@infradead.org" <dvhart@infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Help requested: futex(..., FUTEX_WAIT_PRIVATE, ...) returns EPERM
Date: Wed, 13 Nov 2019 22:34:50 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.21.1911132220090.2507@nanos.tec.linutronix.de> (raw)
In-Reply-To: <90781C7F-BF54-4913-8548-2FE815CCAC95@alertlogic.com>
On Wed, 13 Nov 2019, Harris, Robert wrote:
> > On 13 Nov 2019, at 09:04, Thomas Gleixner <tglx@linutronix.de> wrote:
> > On Tue, 12 Nov 2019, Harris, Robert wrote:
> >> Understanding the circumstances under which EPERM can be returned for
> >> FUTEX_WAIT_PRIVATE would be useful but it is not a documented failure
> >> mode. I have spent some time looking through futex.c but have not
> >> found anything yet. I would be grateful for a hint from someone more
> >> knowledgeable.
> >
> > sys_futex(FUTEX_WAIT_PRIVATE) does not return -EPERM. Only the PI variants
> > do that.
>
> In that case I would appreciate a second pair of eyes. The error I see
> (intermittently) is
The code looks innocent enough. As I don't know whether the kernel version
you mentioned is a vanilla 4.19.184 from the stable tree or some patched up
frankenkernel which pretends to have this version number, I can't be sure
that this is an issue in that particular kernel.
In the vanilla 4.19.184 I really cant find how that would return EPERM for
regular futexes.
Thanks,
tglx
next prev parent reply other threads:[~2019-11-13 21:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-12 17:40 Harris, Robert
2019-11-13 7:29 ` Harris, Robert
2019-11-13 9:04 ` Thomas Gleixner
2019-11-13 10:15 ` Harris, Robert
2019-11-13 21:34 ` Thomas Gleixner [this message]
2019-11-13 13:29 ` Mikael Pettersson
2019-11-13 17:03 ` Harris, Robert
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