linux-kernel - Re: [PATCH mm,percpu_ref,rcu 3/6] mm: Make mem_dump

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Date:   Fri, 8 Jan 2021 16:30:16 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     paulmck@...nel.org, linux-kernel@...r.kernel.org,
        rcu@...r.kernel.org, linux-mm@...ck.org
Cc:     cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        iamjoonsoo.kim@....com, akpm@...ux-foundation.org,
        ming.lei@...hat.com, axboe@...nel.dk, kernel-team@...com
Subject: Re: [PATCH mm,percpu_ref,rcu 3/6] mm: Make mem_dump_obj() handle
 vmalloc() memory

On 1/6/21 2:17 AM, paulmck@...nel.org wrote:
> From: "Paul E. McKenney" <paulmck@...nel.org>
> 
> This commit adds vmalloc() support to mem_dump_obj().  Note that the
> vmalloc_dump_obj() function combines the checking and dumping, in
> contrast with the split between kmem_valid_obj() and kmem_dump_obj().
> The reason for the difference is that the checking in the vmalloc()
> case involves acquiring a global lock, and redundant acquisitions of
> global locks should be avoided, even on not-so-fast paths.
> 
> Note that this change causes on-stack variables to be reported as
> vmalloc() storage from kernel_clone() or similar, depending on the degree
> of inlining that your compiler does.  This is likely more helpful than
> the earlier "non-paged (local) memory".
> 
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
> Cc: <linux-mm@...ck.org>
> Reported-by: Andrii Nakryiko <andrii@...nel.org>
> Signed-off-by: Paul E. McKenney <paulmck@...nel.org>

Acked-by: Vlastimil Babka <vbabka@...e.cz>