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

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Message-ID: <82c2553f-822e-40c2-9bf8-433689b3669d@linux.dev>
Date: Mon, 26 Feb 2024 12:30:01 +0800
From: Chengming Zhou <chengming.zhou@...ux.dev>
To: Xiubo Li <xiubli@...hat.com>, idryomov@...il.com, jlayton@...nel.org
Cc: ceph-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, vbabka@...e.cz, roman.gushchin@...ux.dev,
 Xiongwei.Song@...driver.com, Chengming Zhou <zhouchengming@...edance.com>
Subject: Re: [PATCH] ceph: remove SLAB_MEM_SPREAD flag usage

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.

Thanks!

> 
> - Xiubo
> 
>> Thanks!
>>
>>> Thanks
>>>
>>> - Xiubo
>>>
>>> On 2/24/24 21:47, chengming.zhou@...ux.dev wrote:
>>>> From: Chengming Zhou <zhouchengming@...edance.com>
>>>>
>>>> The SLAB_MEM_SPREAD flag is already a no-op as of 6.8-rc1, remove
>>>> its usage so we can delete it from slab. No functional change.
>>>>
>>>> Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
>>>> ---
>>>>    fs/ceph/super.c | 18 +++++++++---------
>>>>    1 file changed, 9 insertions(+), 9 deletions(-)
>>>>
>>>> diff --git a/fs/ceph/super.c b/fs/ceph/super.c
>>>> index 5ec102f6b1ac..4dcbbaa297f6 100644
>>>> --- a/fs/ceph/super.c
>>>> +++ b/fs/ceph/super.c
>>>> @@ -928,36 +928,36 @@ static int __init init_caches(void)
>>>>        ceph_inode_cachep = kmem_cache_create("ceph_inode_info",
>>>>                          sizeof(struct ceph_inode_info),
>>>>                          __alignof__(struct ceph_inode_info),
>>>> -                      SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD|
>>>> -                      SLAB_ACCOUNT, ceph_inode_init_once);
>>>> +                      SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
>>>> +                      ceph_inode_init_once);
>>>>        if (!ceph_inode_cachep)
>>>>            return -ENOMEM;
>>>>    -    ceph_cap_cachep = KMEM_CACHE(ceph_cap, SLAB_MEM_SPREAD);
>>>> +    ceph_cap_cachep = KMEM_CACHE(ceph_cap, 0);
>>>>        if (!ceph_cap_cachep)
>>>>            goto bad_cap;
>>>> -    ceph_cap_snap_cachep = KMEM_CACHE(ceph_cap_snap, SLAB_MEM_SPREAD);
>>>> +    ceph_cap_snap_cachep = KMEM_CACHE(ceph_cap_snap, 0);
>>>>        if (!ceph_cap_snap_cachep)
>>>>            goto bad_cap_snap;
>>>>        ceph_cap_flush_cachep = KMEM_CACHE(ceph_cap_flush,
>>>> -                       SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD);
>>>> +                       SLAB_RECLAIM_ACCOUNT);
>>>>        if (!ceph_cap_flush_cachep)
>>>>            goto bad_cap_flush;
>>>>          ceph_dentry_cachep = KMEM_CACHE(ceph_dentry_info,
>>>> -                    SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD);
>>>> +                    SLAB_RECLAIM_ACCOUNT);
>>>>        if (!ceph_dentry_cachep)
>>>>            goto bad_dentry;
>>>>    -    ceph_file_cachep = KMEM_CACHE(ceph_file_info, SLAB_MEM_SPREAD);
>>>> +    ceph_file_cachep = KMEM_CACHE(ceph_file_info, 0);
>>>>        if (!ceph_file_cachep)
>>>>            goto bad_file;
>>>>    -    ceph_dir_file_cachep = KMEM_CACHE(ceph_dir_file_info, SLAB_MEM_SPREAD);
>>>> +    ceph_dir_file_cachep = KMEM_CACHE(ceph_dir_file_info, 0);
>>>>        if (!ceph_dir_file_cachep)
>>>>            goto bad_dir_file;
>>>>    -    ceph_mds_request_cachep = KMEM_CACHE(ceph_mds_request, SLAB_MEM_SPREAD);
>>>> +    ceph_mds_request_cachep = KMEM_CACHE(ceph_mds_request, 0);
>>>>        if (!ceph_mds_request_cachep)
>>>>            goto bad_mds_req;
>>>>    
>