linux-kernel - Re: [PATCH] mm/ioremap: Use WARN_ONCE instead of printk() + WARN_ON

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Date:   Thu, 31 Oct 2019 05:00:13 -0700
From:   Joe Perches <joe@...ches.com>
To:     zhong jiang <zhongjiang@...wei.com>, Borislav Petkov <bp@...en8.de>
Cc:     peterz@...radead.org, tglx@...utronix.de, mingo@...hat.com,
        dave.hansen@...ux.intel.com, hpa@...or.com, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/ioremap: Use WARN_ONCE instead of printk() +
 WARN_ON_ONCE()

On Thu, 2019-10-31 at 19:36 +0800, zhong jiang wrote:
> On 2019/10/31 19:03, Borislav Petkov wrote:
> > On Wed, Oct 30, 2019 at 04:57:18PM +0800, zhong jiang wrote:
> > > WARN_ONCE is more clear and simpler. Just replace it.
[]
> > > diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
[]
> > > @@ -172,9 +172,8 @@ static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
> > >  		return NULL;
> > >  
> > >  	if (!phys_addr_valid(phys_addr)) {
> > > -		printk(KERN_WARNING "ioremap: invalid physical address %llx\n",
> > > -		       (unsigned long long)phys_addr);
> > > -		WARN_ON_ONCE(1);
> > > +		WARN_ONCE(1, "ioremap: invalid physical address %llx\n",
> > > +			  (unsigned long long)phys_addr);
> > Does
> > 	WARN_ONCE(!phys_addr_valid(phys_addr),
> > 		  "ioremap: invalid physical address %llx\n",
> > 		  (unsigned long long)phys_addr);
> > 
> > work too?
> > 
> Thanks, That is better. Will repost.

Perhaps this is not good patch concept as now each
invalid physical address will not be emitted.

Before:
	each invalid physical address printed
	one stack dump

After:
	one stck dump with first invalid physical address.