linux-kernel - Re: [PATCH] slub: Clear __GFP_COMP flag when allocating 0 order page

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Date: Fri, 12 Apr 2024 17:34:45 +0800
From: Haifeng Xu <haifeng.xu@...pee.com>
To: "Christoph Lameter (Ampere)" <cl@...ux.com>
Cc: vbabka@...e.cz, penberg@...nel.org, rientjes@...gle.com,
 iamjoonsoo.kim@....com, akpm@...ux-foundation.org, roman.gushchin@...ux.dev,
 42.hyeyoo@...il.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] slub: Clear __GFP_COMP flag when allocating 0 order page



On 2024/4/12 00:51, Christoph Lameter (Ampere) wrote:
> On Thu, 11 Apr 2024, Haifeng Xu wrote:
> 
>> @@ -1875,6 +1875,13 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node,
>>     struct slab *slab;
>>     unsigned int order = oo_order(oo);
>>
>> +    /*
>> +     * If fallback to the minimum order allocation and the order is 0,
>> +     * clear the __GFP_COMP flag.
>> +     */
>> +    if (order == 0)
>> +        flags = flags & ~__GFP_COMP;
> 
> 
> This would be better placed in allocate_slab() when the need for a
> fallback to a lower order is detected after the first call to alloc_slab_page().

Yes. Thanks for your suggestion.