linux-kernel - Re: [regression] boot failure on alpha, bisected

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20121007173336.GA14804@redhat.com>
Date:	Sun, 7 Oct 2012 19:33:36 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	dl8bcu@...bcu.de, peterz@...radead.org, mingo@...nel.org,
	linux-kernel@...r.kernel.org, linux-alpha@...r.kernel.org,
	Richard Henderson <rth@...ddle.net>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Matt Turner <mattst88@...il.com>
Subject: Re: [regression] boot failure on alpha, bisected

On 10/07, Al Viro wrote:
>
> On Sun, Oct 07, 2012 at 06:55:34PM +0200, Oleg Nesterov wrote:
>
> > Hmm. I know nothing about arch/alpha and I can't understand its entry.S.
> > But _it seems_ to me that do_notify_resume() is called with irqs disabled.
> > If this is true, then imho arch/alpha should be fixed.
> >
> > Before this commit task_work_run() enabled irqs, but this was the "side
> > effect" of spin_lock_irq/spin_unlock_irq, we should not rely on this.
>
> Um...  There's a bunch of architectures that are in the same situation.
> grep for do_notify_resume() and you'll see...

And every do_notify_resume() should be changed anyway, do_signal() and
tracehook_notify_resume() should be re-ordered.

> It needs to be dealt with sanely, and actually have patches for alpha
> going in that direction, but breaking a bunch of architectures is not a good
> thing, obviously.  So you've bought yourself a major PITA for coming
> weeks...

So perhaps the patch below until they are fixed?


--- x/kernel/task_work.c
+++ x/kernel/task_work.c
@@ -51,6 +51,9 @@ void task_work_run(void)
 	struct task_struct *task = current;
 	struct callback_head *work, *head, *next;
 
+	if (WARN_ONCE(irqs_disabled(), "notify_resume() with irqs_disabled"))
+		local_irq_enable();
+
 	for (;;) {
 		/*
 		 * work->func() can do task_work_add(), do not set

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/