linux-kernel - Re: [PATCH v2 1/3] mm: refactor vm_area_struct::anon_vma

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Message-ID: <YhdDg1oPpI7bkshf@dhcp22.suse.cz>
Date:   Thu, 24 Feb 2022 09:36:19 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     akpm@...ux-foundation.org, ccross@...gle.com,
        sumit.semwal@...aro.org, dave.hansen@...el.com,
        keescook@...omium.org, willy@...radead.org,
        kirill.shutemov@...ux.intel.com, vbabka@...e.cz,
        hannes@...xchg.org, ebiederm@...ssion.com, brauner@...nel.org,
        legion@...nel.org, ran.xiaokai@....com.cn, sashal@...nel.org,
        chris.hyser@...cle.com, dave@...olabs.net, pcc@...gle.com,
        caoxiaofeng@...ong.com, david@...hat.com, gorcunov@...il.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        kernel-team@...roid.com
Subject: Re: [PATCH v2 1/3] mm: refactor vm_area_struct::anon_vma_name usage
 code

On Wed 23-02-22 07:36:11, Suren Baghdasaryan wrote:
> Avoid mixing strings and their anon_vma_name referenced pointers
> by using struct anon_vma_name whenever possible. This simplifies
> the code and allows easier sharing of anon_vma_name structures when
> they represent the same name.
> 
> Suggested-by: Matthew Wilcox <willy@...radead.org>
> Suggested-by: Michal Hocko <mhocko@...e.com>
> Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>

LGTM
Acked-by: Michal Hocko <mhocko@...e.com>

Thanks and one minor nit below

[...]
> +static inline void free_anon_vma_name(struct vm_area_struct *vma)
>  {
> -	const char *vma_name = vma_anon_name(vma);
> +	/*
> +	 * Not using anon_vma_name because it generates a warning if vma->vm_mm
> +	 * is not held, which might be the case here.

s@...->vm_mm@...p_lock@

> +	 */
> +	if (!vma->vm_file)
> +		anon_vma_name_put(vma->anon_name);
> +}
>  
> -	/* either both NULL, or pointers to same string */
> -	if (vma_name == name)

-- 
Michal Hocko
SUSE Labs