linux-kernel - Re: [PATCH] mm/slub: use stackdepot to save stack trace in objects

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Message-ID: <f9dd0692-e490-56ce-3cd8-b99aea559e79@suse.cz>
Date:   Wed, 12 May 2021 16:33:50 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Andrew Morton <akpm@...ux-foundation.org>, glittao@...il.com
Cc:     cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        iamjoonsoo.kim@....com, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, "Paul E . McKenney" <paulmck@...nel.org>
Subject: Re: [PATCH] mm/slub: use stackdepot to save stack trace in objects

On 5/10/21 6:46 AM, Andrew Morton wrote:
> On Wed, 14 Apr 2021 18:34:34 +0200 glittao@...il.com wrote:
> 
>> Many stack traces are similar so there are many similar arrays.
>> Stackdepot saves each unique stack only once.
>> 
>> Replace field addrs in struct track with depot_stack_handle_t handle.
>> Use stackdepot to save stack trace.
>> 
>> The benefits are smaller memory overhead and possibility to aggregate
>> per-cache statistics in the future using the stackdepot handle
>> instead of matching stacks manually.
> 
> Which tree was this prepared against?  5.12's kmem_obj_info() is
> significantly different from the version you were working on.

It was based on -next at the time of submission, which contained patch in Paul's
tree that expands kmem_obj_info to print also free call stack [1] so that also
needs to be switched to stackdepot to work.

> Please take a look, redo, retest and resend?  Thanks.

I expected [1] to be in 5.13-rc1, but as Paul explained to me, it's queued for
5.14. So if we (Oliver) rebase on current -next, can you queue it in the section
of mmotm series that goes after -next?

Vlastimil

[1]
https://lore.kernel.org/linux-arm-kernel/1615891032-29160-2-git-send-email-maninder1.s@samsung.com/