linux-kernel - Re: [PATCH] slab: add flags in cache

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Message-ID: <b7f44bb8-b12e-43e7-b870-f6499ae13e58@oss.qualcomm.com>
Date: Fri, 24 Oct 2025 11:06:42 +0800
From: Kassey Li <kassey.li@....qualcomm.com>
To: Vlastimil Babka <vbabka@...e.cz>, akpm@...ux-foundation.org, cl@...two.org,
        rientjes@...gle.com, roman.gushchin@...ux.dev, harry.yoo@...cle.com,
        linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] slab: add flags in cache_show


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@....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.

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);