Re: [ANNOUNCE] 2.6.33.5-rt23

[Thomas Gleixner <tglx@linutronix.de>]

On Wed, 9 Jun 2010, Will Schmidt wrote:

> On Wed, 2010-06-09 at 18:44 +0200, Thomas Gleixner wrote:
> I'm still on 2.6.33.5-rt22 on powerpc, and have run into a couple
> "sleeping function called from invalid context..." BUGs.   The first was
> during system boot, second during a 'make'.
> 
> relevant code paths don't seem to have changed between -rt22 and -rt23,
> so I think still valid.. :-)  
> 
> This is on a POWER7 system, which may have opened up some timing
> windows, wrt previous runs on POWER6 systems.
> 
> 
> BUG: sleeping function called from invalid context at
> kernel/rtmutex.c:684

> [c000000078cf2cf0] [c000000000131a04] .irq_to_desc_alloc_node+0xdc/0x2b8

Grr. I thought I had the SPARSE_IRQ stuff disabled on -rt, but seems
it came back somehow. Can you disable that, or does you machine depend
on it ?
 
> BUG: sleeping function called from invalid context at kernel/rtmutex.c:684
> pcnt: 0 0 in_atomic(): 0, irqs_disabled(): 1, pid: 4760, name: make
> Call Trace:
> [c0000000792978b0] [c000000000015550] .show_stack+0xd8/0x218 (unreliable)
> [c000000079297990] [c0000000006a99c8] .dump_stack+0x28/0x3c
> [c000000079297a10] [c00000000006cea8] .__might_sleep+0x134/0x15c
> [c000000079297ab0] [c0000000006a2f78] .rt_spin_lock+0x4c/0x9c
> [c000000079297b40] [c0000000000a1ff0] .get_signal_to_deliver+0xcc/0x4ec
> [c000000079297c50] [c000000000018604] .do_signal_pending.clone.0+0x6c/0x2e0
> [c000000079297d90] [c0000000000188b0] .do_signal+0x38/0x74
> [c000000079297e30] [c000000000008b40] user_work+0x24/0x28

Does the patch below fix it ?

Thanks,

	tglx
-----
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index 00b5078..fa580f9 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -120,6 +120,14 @@ static int do_signal_pending(sigset_t *oldset, struct pt_regs *regs)
 	int ret;
 	int is32 = is_32bit_task();
 
+#ifdef CONFIG_PREEMPT_RT
+	/*
+	 * Fully-preemptible kernel does not need interrupts disabled:
+	 */
+	local_irq_enable();
+	preempt_check_resched();
+#endif
+
 	if (current_thread_info()->local_flags & _TLF_RESTORE_SIGMASK)
 		oldset = &current->saved_sigmask;
 	else if (!oldset)