Re: [PATCH] slab: add flags in cache_show

[Kassey Li <kassey.li@oss.qualcomm.com>]

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在 10/24/2025 4:22 PM, Vlastimil Babka 写道:
> On 10/24/25 05:06, Kassey Li wrote:
>> 在 10/17/2025 6:50 PM, Vlastimil Babka 写道:
>>> On 10/17/25 08:48, Kassey Li wrote:
>>>> Flags info is useful to check the slab type.
>>>>
>>>> for example, _SLAB_RECLAIM_ACCOUNT:
>>>>
>>>>       0x50100 _SLAB_PANIC _SLAB_RECLAIM_ACCOUNT _SLAB_CMPXCHG_DOUBLE
>>>>
>>>> Signed-off-by: Kassey Li<kassey.li@oss.qualcomm.com>
>>> Many of the flags are represented by files in /sys/kernel/slab/<cache>/
>>> If you miss some, we could add it there. Changing slabinfo output could
>>> break some users and the raw hex value is not a stable representation of the
>>> flags anyway.
>> may you review this draft change according your suggest  ? if ok, i will
>> share v2 change.
> What I meant is that that are files for some specific flags, e.g. the
> SLAB_RECLAIM_ACCOUNT you mentioned has a file "reclaim_account".
> Other files could be added for other flags when it's useful. Printing a raw
> number dumping the implementation details isn't great.


Thanks for the suggests, this is clear for me.  I will try the 
"reclaim_account" to match my usage firstly.

>
>> diff --git a/mm/slub.c b/mm/slub.c
>> index b1f15598fbfd..619f446d2251 100644
>> --- a/mm/slub.c
>> +++ b/mm/slub.c
>> @@ -9033,6 +9033,12 @@ static ssize_t slab_size_show(struct kmem_cache
>> *s, char *buf)
>>    }
>>    SLAB_ATTR_RO(slab_size);
>>
>> +static ssize_t slab_flags_show(struct kmem_cache *s, char *buf)
>> +{
>> +       return sysfs_emit(buf, "%u\n", s->flags);
>> +}
>> +SLAB_ATTR_RO(slab_flags);
>> +
>>    static ssize_t align_show(struct kmem_cache *s, char *buf)
>>    {
>>           return sysfs_emit(buf, "%u\n", s->align);
>> @@ -9480,6 +9486,7 @@ SLAB_ATTR(skip_kfence);
>>
>>    static struct attribute *slab_attrs[] = {
>>           &slab_size_attr.attr,
>> +       &slab_flags_attr.attr,
>>           &object_size_attr.attr,
>>           &objs_per_slab_attr.attr,
>>           &order_attr.attr,
>>
>>>> ---
>>>>    mm/slab_common.c | 6 +++---
>>>>    1 file changed, 3 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/mm/slab_common.c b/mm/slab_common.c
>>>> index 932d13ada36c..f43239211e69 100644
>>>> --- a/mm/slab_common.c
>>>> +++ b/mm/slab_common.c
>>>> @@ -1083,7 +1083,7 @@ static void print_slabinfo_header(struct seq_file *m)
>>>>    	 * without _too_ many complaints.
>>>>    	 */
>>>>    	seq_puts(m, "slabinfo - version: 2.1\n");
>>>> -	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
>>>> +	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> <flags>");
>>>>    	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
>>>>    	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
>>>>    	seq_putc(m, '\n');
>>>> @@ -1112,9 +1112,9 @@ static void cache_show(struct kmem_cache *s, struct seq_file *m)
>>>>    	memset(&sinfo, 0, sizeof(sinfo));
>>>>    	get_slabinfo(s, &sinfo);
>>>>    
>>>> -	seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
>>>> +	seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d 0x%-8x",
>>>>    		   s->name, sinfo.active_objs, sinfo.num_objs, s->size,
>>>> -		   sinfo.objects_per_slab, (1 << sinfo.cache_order));
>>>> +		   sinfo.objects_per_slab, (1 << sinfo.cache_order), s->flags);
>>>>    
>>>>    	seq_printf(m, " : tunables %4u %4u %4u",
>>>>    		   sinfo.limit, sinfo.batchcount, sinfo.shared);

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