linux-kernel - Re: [PATCH 3/3] mm/percpu.c: print error message too if atomic alloc failed

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Date:   Sat, 22 Jul 2023 09:56:50 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Dennis Zhou <dennis@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, tj@...nel.org, cl@...ux.com,
        mawupeng1@...wei.com
Subject: Re: [PATCH 3/3] mm/percpu.c: print error message too if atomic alloc
 failed

On 07/21/23 at 02:03pm, Dennis Zhou wrote:
> On Fri, Jul 21, 2023 at 09:18:00PM +0800, Baoquan He wrote:
> > The variable 'err' is assgigned to an error message if atomic alloc
> > failed, while it has no chance to be printed if is_atomic is true.
> > 
> > Here change to print error message too if atomic alloc failed, while
> > avoid to call dump_stack() if that case.
> > 
> > Signed-off-by: Baoquan He <bhe@...hat.com>
> > ---
> >  mm/percpu.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/mm/percpu.c b/mm/percpu.c
> > index c25b058a46ad..74f75ef0ad58 100644
> > --- a/mm/percpu.c
> > +++ b/mm/percpu.c
> > @@ -1890,13 +1890,15 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
> >  fail:
> >  	trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align);
> >  
> > -	if (!is_atomic && do_warn && warn_limit) {
> > +	if (do_warn && warn_limit) {
> >  		pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n",
> >  			size, align, is_atomic, err);
> > -		dump_stack();
> > +		if (is_atomic)
> > +			dump_stack();
> 
> This should be (!is_atomic) to preserve the current logic?

You are quite right, I must be dizzy at the moment when making change.
Will fix this. Thanks for reviewing.

> 
> >  		if (!--warn_limit)
> >  			pr_info("limit reached, disable warning\n");
> >  	}
> > +
> >  	if (is_atomic) {
> >  		/* see the flag handling in pcpu_balance_workfn() */
> >  		pcpu_atomic_alloc_failed = true;
> > -- 
> > 2.34.1
> > 
> 
> Thanks,
> Dennis
>