linux-kernel - Re: [PATCH 2/4] mm: move per-vma lock into vm_area

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Message-ID: <07a72c38-22f5-4b99-9d74-0877eaf2bee2@suse.cz>
Date: Tue, 12 Nov 2024 16:57:47 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Suren Baghdasaryan <surenb@...gle.com>, akpm@...ux-foundation.org
Cc: willy@...radead.org, liam.howlett@...cle.com, lorenzo.stoakes@...cle.com,
 mhocko@...e.com, hannes@...xchg.org, mjguzik@...il.com,
 oliver.sang@...el.com, mgorman@...hsingularity.net, david@...hat.com,
 peterx@...hat.com, oleg@...hat.com, dave@...olabs.net, paulmck@...nel.org,
 brauner@...nel.org, dhowells@...hat.com, hdanton@...a.com, hughd@...gle.com,
 minchan@...gle.com, jannh@...gle.com, shakeel.butt@...ux.dev,
 souravpanda@...gle.com, pasha.tatashin@...een.com, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, kernel-team@...roid.com
Subject: Re: [PATCH 2/4] mm: move per-vma lock into vm_area_struct

On 11/11/24 21:55, Suren Baghdasaryan wrote:
> @@ -511,7 +476,6 @@ void __vm_area_free(struct vm_area_struct *vma)
>  {
>  	vma_numab_state_free(vma);
>  	free_anon_vma_name(vma);
> -	vma_lock_free(vma);
>  	kmem_cache_free(vm_area_cachep, vma);
>  }

Have you investigated if this allows to perform vma_numab_state_free() and
free_anon_vma_name() immediately, and only kfree_rcu() the vma itself,
instead of performing all this in a call_rcu() callback?

Of course if we succeed converting vma's to SLAB_TYPESAFE_RCU this immediate
freeing of numab state and anon_vma_name would be implied, but maybe it's an
useful intermediate step on its own.