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Subject: Re: [PATCH v6] mm: slub: move sysfs slab alloc/free interfaces to
 debugfs
To:     Vlastimil Babka <vbabka@suse.cz>, cl@linux.com, penberg@kernel.org,
        rientjes@google.com, iamjoonsoo.kim@lge.com,
        akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, glittao@gmail.com, greg@kroah.com
Cc:     vinmenon@codeaurora.org
References: <1621341949-26762-1-git-send-email-faiyazm@codeaurora.org>
 <a8247d42-01d3-6d9c-678f-382ea1e02945@suse.cz>
From:   Faiyaz Mohammed <faiyazm@codeaurora.org>
Message-ID: <a86f72b3-76ff-b767-71bd-044d70fab064@codeaurora.org>
Date:   Fri, 21 May 2021 17:09:32 +0530
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On 5/21/2021 4:43 PM, Vlastimil Babka wrote:
> On 5/18/21 2:45 PM, Faiyaz Mohammed wrote:
>> alloc_calls and free_calls implementation in sysfs have two issues,
>> one is PAGE_SIZE limitiation of sysfs and other is it does not adhere
>> to "one value per file" rule.
>>
>> To overcome this issues, move the alloc_calls and free_calls implemeation
>> to debugfs.
>>
>> Rename the alloc_calls/free_calls to alloc_traces/free_traces,
>> to be inline with what it does.
>>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
>> Signed-off-by: Faiyaz Mohammed <faiyazm@codeaurora.org>
> 
> 
>> @@ -5817,6 +5769,249 @@ static int __init slab_sysfs_init(void)
>>  __initcall(slab_sysfs_init);
>>  #endif /* CONFIG_SYSFS */
>>  
>> +#if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_DEBUG_FS)
>> +static int debugfs_slab_alias(struct kmem_cache *s, const char *name)
>> +{
>> +	struct saved_alias *al;
>> +	struct dentry *slab_cache_dir;
>> +
>> +	if (slab_state == FULL) {
>> +		/*
>> +		 * If we have a leftover link then remove it.
>> +		 */
>> +		slab_cache_dir = debugfs_lookup(s->name, slab_debugfs_root);
>> +		debugfs_remove(slab_cache_dir);
>> +		debugfs_create_symlink(name, slab_debugfs_root, NULL);
> 
> v6 got stuck on boot for me, unlike v5, seems like here you should return 0?
> That helped
> 
oh, it worked me without return, but I think yes, have to return from
here once the symlink is created like sysfs_slab_alias do. I will update
in next patch version.

>> +	}
>> +
>> +	al = kmalloc(sizeof(struct saved_alias), GFP_KERNEL);
>> +	if (!al)
>> +		return -ENOMEM;
>> +
>> +	al->s = s;
>> +	al->name = name;
>> +	al->next = alias_list;
>> +	alias_list = al;
>> +	return 0;
>> +}
>> +

Thanks and regards,
Mohammed Faiyaz