linux-kernel - Re: [PATCH] ceph: remove SLAB_MEM

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Date: Mon, 26 Feb 2024 09:32:12 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Xiubo Li <xiubli@...hat.com>, Chengming Zhou <chengming.zhou@...ux.dev>,
 idryomov@...il.com, jlayton@...nel.org
Cc: ceph-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, roman.gushchin@...ux.dev, Xiongwei.Song@...driver.com,
 Chengming Zhou <zhouchengming@...edance.com>
Subject: Re: [PATCH] ceph: remove SLAB_MEM_SPREAD flag usage

On 2/26/24 05:54, Xiubo Li wrote:
> 
> On 2/26/24 12:30, Chengming Zhou wrote:
>> On 2024/2/26 12:23, Xiubo Li wrote:
>>> On 2/26/24 10:42, Chengming Zhou wrote:
>>>> On 2024/2/26 09:43, Xiubo Li wrote:
>>>>> Hi Chengming,
>>>>>
>>>>> Thanks for your patch.
>>>>>
>>>>> BTW, could you share the link of the relevant patches to mark this a no-op ?
>>>> Update changelog to make it clearer:
>>>>
>>>> The SLAB_MEM_SPREAD flag used to be implemented in SLAB, which was
>>>> removed as of v6.8-rc1, so it became a dead flag. And the series[1]
>>>> went on to mark it obsolete to avoid confusion for users. Here we
>>>> can just remove all its users, which has no functional change.
>>>>
>>>> [1] https://lore.kernel.org/all/20240223-slab-cleanup-flags-v2-1-02f1753e8303@suse.cz/
>>> Thanks for your quick feedback.
>>>
>>> BTW, I couldn't find this change in Linus' tree in the master and even the v6.8-rc1 tag, please see https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/include/linux/slab.h?h=master.
>>>
>>> Did I miss something ? Or has this patch been merged ?
>> You're right, this patch hasn't been merged. But it's already a dead flag as of v6.8-rc1.
>>
>> Update changelog to make it clearer:
>>
>> The SLAB_MEM_SPREAD flag used to be implemented in SLAB, which was
>> removed as of v6.8-rc1, so it became a dead flag since the commit
>> 16a1d968358a ("mm/slab: remove mm/slab.c and slab_def.h"). And the
>> series[1] went on to mark it obsolete to avoid confusion for users.
>> Here we can just remove all its users, which has no functional change.
>>
>> [1] https://lore.kernel.org/all/20240223-slab-cleanup-flags-v2-1-02f1753e8303@suse.cz/
>>
>> Does this look clearer to you? I can improve it if there is still confusion.
> 
> Yeah, much clearer, thanks!
> 
> Maybe we should just wait for the [1] to get merged first ?

It's really not necessary to wait, [1] just makes it explicit but the flag
is really effectively dead since v6.8-rc1 because nothing acts on it.