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From: Vlastimil Babka <vbabka@suse.cz>
To: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: David Rientjes <rientjes@google.com>,
	Christoph Lameter <cl@linux.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Pekka Enberg <penberg@kernel.org>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, patches@lists.linux.dev,
	linux-kernel@vger.kernel.org, Oliver Glitta <glittao@gmail.com>,
	Faiyaz Mohammed <faiyazm@codeaurora.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Randy Dunlap <rdunlap@infradead.org>,
	linux-doc@vger.kernel.org
Subject: Re: [PATCH 5/5] slab, documentation: add description of debugfs files for SLUB caches
Date: Wed, 2 Mar 2022 17:31:53 +0100	[thread overview]
Message-ID: <1cc1eb98-fe46-4563-16d3-ac00b630ecd3@suse.cz> (raw)
In-Reply-To: <Yhr01naZNIa2SxEd@ip-172-31-19-208.ap-northeast-1.compute.internal>

On 2/27/22 04:49, Hyeonggon Yoo wrote:
> I think it's not traces of "currently free objects"
> because index bit of free objects are set in obj_map bitmap?

Hm right, thanks.

> It's weird but it's traces of allocated objects that have been freed at
> least once (or <not available>)
> 
> I think we can fix the code or doc?

For now I'll fix the doc. Not clear to me myself what's the best usecase for
free_traces file. For alloc_traces it's clearly debugging memory leaks.
Freeing traces are most useful when a bug is detected and they are dumped in
dmesg. The debugfs file might be just for a rough idea where freeing usually
happens.

> Please tell me if I'm missing something :)
> 
>> +    Information in the output:
>> +    Number of objects, freeing function, minimal/average/maximal jiffies since free,
>> +    pid range of the freeing processes, cpu mask of freeing cpus, and stack trace.
>> +
>> +    Example:::
>> +
>> +    51 acpi_ut_update_ref_count+0x6a6/0x782 age=236886/237027/237772 pid=1 cpus=1
>> +	kfree+0x2db/0x420
>> +	acpi_ut_update_ref_count+0x6a6/0x782
>> +	acpi_ut_update_object_reference+0x1ad/0x234
>> +	acpi_ut_remove_reference+0x7d/0x84
>> +	acpi_rs_get_prt_method_data+0x97/0xd6
>> +	acpi_get_irq_routing_table+0x82/0xc4
>> +	acpi_pci_irq_find_prt_entry+0x8e/0x2e0
>> +	acpi_pci_irq_lookup+0x3a/0x1e0
>> +	acpi_pci_irq_enable+0x77/0x240
>> +	pcibios_enable_device+0x39/0x40
>> +	do_pci_enable_device.part.0+0x5d/0xe0
>> +	pci_enable_device_flags+0xfc/0x120
>> +	pci_enable_device+0x13/0x20
>> +	virtio_pci_probe+0x9e/0x170
>> +	local_pci_probe+0x48/0x80
>> +	pci_device_probe+0x105/0x1c0
>> +
> 
> Everything else looks nice!
> 
>>  Christoph Lameter, May 30, 2007
>>  Sergey Senozhatsky, October 23, 2015
>> -- 
>> 2.35.1
>> 
>> 
> 



  reply	other threads:[~2022-03-02 16:31 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-25 18:03 [PATCH 0/5] SLUB debugfs improvements based on stackdepot Vlastimil Babka
2022-02-25 18:03 ` [PATCH 1/5] mm/slub: move struct track init out of set_track() Vlastimil Babka
2022-02-26 10:41   ` Hyeonggon Yoo
2022-02-25 18:03 ` [PATCH 2/5] mm/slub: use stackdepot to save stack trace in objects Vlastimil Babka
2022-02-26 10:24   ` Hyeonggon Yoo
2022-02-28 18:44     ` Vlastimil Babka
2022-02-27  3:08   ` [PATCH] lib/stackdepot: Use page allocator if both slab and memblock is unavailable Hyeonggon Yoo
2022-02-27  5:06     ` kernel test robot
2022-02-27  9:23     ` [PATCH v2] " Hyeonggon Yoo
2022-02-27 10:00     ` [PATCH] " kernel test robot
2022-02-28  7:00     ` Marco Elver
2022-02-28 10:05       ` Hyeonggon Yoo
2022-02-28 10:50         ` Marco Elver
2022-02-28 11:48           ` Hyeonggon Yoo
2022-02-28 15:09           ` [PATCH] mm/slub: initialize stack depot in boot process Hyeonggon Yoo
2022-02-28 16:28             ` Marco Elver
2022-03-01  2:12               ` Hyeonggon Yoo
2022-03-01  0:28             ` Vlastimil Babka
2022-02-27  9:44   ` [PATCH 2/5] mm/slub: use stackdepot to save stack trace in objects Hyeonggon Yoo
2022-03-02 16:51     ` Vlastimil Babka
2022-03-02 17:22       ` Hyeonggon Yoo
2022-02-25 18:03 ` [PATCH 3/5] mm/slub: aggregate and print stack traces in debugfs files Vlastimil Babka
2022-02-27  0:18   ` Hyeonggon Yoo
2022-02-27  0:22   ` Hyeonggon Yoo
2022-02-25 18:03 ` [PATCH 4/5] mm/slub: sort debugfs output by frequency of stack traces Vlastimil Babka
2022-02-26 11:03   ` Hyeonggon Yoo
2022-02-25 18:03 ` [PATCH 5/5] slab, documentation: add description of debugfs files for SLUB caches Vlastimil Babka
2022-02-27  3:49   ` Hyeonggon Yoo
2022-03-02 16:31     ` Vlastimil Babka [this message]
2022-02-26  7:19 ` [PATCH 0/5] SLUB debugfs improvements based on stackdepot Hyeonggon Yoo
2022-02-28 19:10   ` Vlastimil Babka
2022-02-28 20:01     ` Mike Rapoport
2022-02-28 21:20       ` Hyeonggon Yoo
2022-02-28 23:38       ` Vlastimil Babka
2022-03-01  9:21         ` Mike Rapoport
2022-03-01  9:41           ` Vlastimil Babka
2022-03-01 14:52             ` Mike Rapoport
2022-02-28 21:27     ` Hyeonggon Yoo
2022-03-01  9:23       ` Mike Rapoport
2022-03-02  8:37       ` Mike Rapoport
2022-03-02  9:09         ` Vlastimil Babka
2022-03-02 12:30           ` Mike Rapoport
2022-03-02 17:02             ` Hyeonggon Yoo
2022-03-02 17:27               ` Marco Elver
2022-02-26 12:18 ` Hyeonggon Yoo
2022-03-04 17:25   ` Vlastimil Babka

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