linux-kernel - Re: [PATCH] mm/slub: Refactor note_cmpxchg

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Message-ID: <c089b941-97c7-4392-828f-923e8da3510a@linux.dev>
Date: Mon, 8 Sep 2025 16:56:40 +0800
From: Ye Liu <ye.liu@...ux.dev>
To: Harry Yoo <harry.yoo@...cle.com>
Cc: Vlastimil Babka <vbabka@...e.cz>,
 Andrew Morton <akpm@...ux-foundation.org>, Ye Liu <liuye@...inos.cn>,
 Christoph Lameter <cl@...two.org>, David Rientjes <rientjes@...gle.com>,
 Roman Gushchin <roman.gushchin@...ux.dev>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/slub: Refactor note_cmpxchg_failure for better
 readability



在 2025/9/8 16:39, Harry Yoo 写道:
> On Mon, Sep 08, 2025 at 03:19:21PM +0800, Ye Liu wrote:
>> From: Ye Liu <liuye@...inos.cn>
>>
>> Use IS_ENABLED() and standard if-else to make the code clearer.
>>
>> Signed-off-by: Ye Liu <liuye@...inos.cn>
>> ---
> 
> Looks good to me,
> Reviewed-by: Harry Yoo <harry.yoo@...cle.com>
> 
> with a nit,
> 
>>  mm/slub.c | 10 ++++------
>>  1 file changed, 4 insertions(+), 6 deletions(-)
>>
>> diff --git a/mm/slub.c b/mm/slub.c
>> index 30003763d224..34853c0441a6 100644
>> --- a/mm/slub.c
>> +++ b/mm/slub.c
>> @@ -3064,18 +3064,16 @@ static inline void note_cmpxchg_failure(const char *n,
>>  
>>  	pr_info("%s %s: cmpxchg redo ", n, s->name);
>>  
>> -#ifdef CONFIG_PREEMPTION
>> -	if (tid_to_cpu(tid) != tid_to_cpu(actual_tid))
>> +	if (IS_ENABLED(CONFIG_PREEMPTION) && tid_to_cpu(tid) != tid_to_cpu(actual_tid)) {
> 
> nit: insert newline after && as it's more than 80 columns?

I noticed this too, but using the script ./scripts/checkpatch.pl , there were no warnings.

$ ./scripts/checkpatch.pl 0001-mm-slub-Refactor-note_cmpxchg_failure-for-better-rea.patch 
total: 0 errors, 0 warnings, 22 lines checked

0001-mm-slub-Refactor-note_cmpxchg_failure-for-better-rea.patch has no obvious style problems and is ready for submission.


> 
>>  		pr_warn("due to cpu change %d -> %d\n",
>>  			tid_to_cpu(tid), tid_to_cpu(actual_tid));
>> -	else
>> -#endif
>> -	if (tid_to_event(tid) != tid_to_event(actual_tid))
>> +	} else if (tid_to_event(tid) != tid_to_event(actual_tid)) {
>>  		pr_warn("due to cpu running other code. Event %ld->%ld\n",
>>  			tid_to_event(tid), tid_to_event(actual_tid));
>> -	else
>> +	} else {
>>  		pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n",
>>  			actual_tid, tid, next_tid(tid));
>> +	}
>>  #endif
>>  	stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
>>  }
>> -- 
>> 2.43.0

-- 
Thanks,
Ye Liu