linux-kernel - Re: [PATCH] mm/slab: Add slabreclaim flag to slabinfo

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Message-ID: <2f43774a-16cf-412e-b4b7-840889bb796b@suse.cz>
Date: Mon, 5 Feb 2024 09:50:13 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Greg KH <gregkh@...uxfoundation.org>,
 Fangzheng Zhang <fangzheng.zhang@...soc.com>
Cc: Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>,
 David Rientjes <rientjes@...gle.com>, Joonsoo Kim <iamjoonsoo.kim@....com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Roman Gushchin <roman.gushchin@...ux.dev>,
 Hyeonggon Yoo <42.hyeyoo@...il.com>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Fangzheng Zhang
 <fangzheng.zhang1003@...il.com>, Yuming Han <yuming.han@...soc.com>,
 Chunyan Zhang <zhang.lyra@...il.com>
Subject: Re: [PATCH] mm/slab: Add slabreclaim flag to slabinfo

On 2/4/24 14:09, Greg KH wrote:
> On Wed, Jan 31, 2024 at 05:44:42PM +0800, Fangzheng Zhang wrote:
>> In order to enhance slab debugging, we add slabreclaim flag to
>> slabinfo. Slab type is also an important analysis point in slabinfo
>> for per slab, when various problems such as memory leaks or memory
>> statistics occur.
>> 
>> Signed-off-by: Fangzheng Zhang <fangzheng.zhang@...soc.com>
>> ---
>>  mm/slab_common.c | 7 ++++---
>>  1 file changed, 4 insertions(+), 3 deletions(-)
>> 
>> diff --git a/mm/slab_common.c b/mm/slab_common.c
>> index 238293b1dbe1..aeeb2bfe6dda 100644
>> --- a/mm/slab_common.c
>> +++ b/mm/slab_common.c
>> @@ -1038,7 +1038,7 @@ static void print_slabinfo_header(struct seq_file *m)
>>  	seq_puts(m, "slabinfo - version: 2.1\n");
>>  	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
>>  	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
>> -	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
>> +	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail> <slabreclaim>");
> 
> Doesn't this change the slabinfo version number above?  Where is this
> change documented so that userspace knows about it?

Yeah I was vary about this. Do the other longer-time-than-me slab
maintainers recall how we handled this in the past?
Also the information is already available, even if harder to gather, in the
file /sys/kernel/slab/$cache/reclaim_account

> thanks,
> 
> greg k-h