linux-kernel - Re: [PATCH] apic: use GFP_ATOMIC in lapic

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Date:	Tue, 28 Dec 2010 15:22:02 +0800
From:	Zhang Rui <rui.zhang@...el.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Subject: Re: [PATCH] apic: use GFP_ATOMIC in lapic_resume

On Tue, 2010-12-28 at 15:00 +0800, David Rientjes wrote:
> On Tue, 28 Dec 2010, Zhang Rui wrote:
> 
> > Index: linux-2.6/arch/x86/kernel/apic/apic.c
> > ===================================================================
> > --- linux-2.6.orig/arch/x86/kernel/apic/apic.c
> > +++ linux-2.6/arch/x86/kernel/apic/apic.c
> > @@ -1459,7 +1459,7 @@ void __init enable_IR_x2apic(void)
> >  	if (dmar_table_init_ret && !x2apic_supported())
> >  		return;
> >  
> > -	ioapic_entries = alloc_ioapic_entries();
> > +	ioapic_entries = alloc_ioapic_entries(GFP_KERNEL);
> >  	if (!ioapic_entries) {
> >  		pr_err("Allocate ioapic_entries failed\n");
> >  		goto out;
> > @@ -2084,7 +2084,7 @@ static int lapic_resume(struct sys_devic
> >  
> >  	local_irq_save(flags);
> >  	if (intr_remapping_enabled) {
> > -		ioapic_entries = alloc_ioapic_entries();
> > +		ioapic_entries = alloc_ioapic_entries(GFP_ATOMIC);
> >  		if (!ioapic_entries) {
> >  			WARN(1, "Alloc ioapic_entries in lapic resume failed.");
> >  			ret = -ENOMEM;
> 
> You can't do the allocation before disabling irqs when 
> intr_remapping_enabled is set?

yes, we can. The first idea came into my mind is to register a pm
notifier callback to allocate/free the memory. But that one duplicates
the code of alloc_ioapic_entries, which doesn't look nice, neither.
Plus, is there any problem with this one?

thanks,
rui
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