linux-kernel - Re: [PATCH v3 4/7] mm/vmalloc: explicitly identify vm_map

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Date:   Mon, 16 Jan 2023 12:24:00 +0000
From:   Lorenzo Stoakes <lstoakes@...il.com>
To:     Baoquan He <bhe@...hat.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org, urezki@...il.com,
        stephen.s.brennan@...cle.com, willy@...radead.org,
        akpm@...ux-foundation.org, hch@...radead.org
Subject: Re: [PATCH v3 4/7] mm/vmalloc: explicitly identify vm_map_ram area
 when shown in /proc/vmcoreinfo

On Fri, Jan 13, 2023 at 11:19:18AM +0800, Baoquan He wrote:
> Now, by marking VMAP_RAM in vmap_area->flags for vm_map_ram, we can
> clearly differentiate it with other vmalloc areas. So identify
> vm_map_area area by checking VMAP_RAM of vmap_area->flags when shown
> in /proc/vmcoreinfo.
>
> Meanwhile, the code comment above vm_map_ram area checking in s_show()
> is not needed any more, remove it here.
>
> Signed-off-by: Baoquan He <bhe@...hat.com>
> ---
>  mm/vmalloc.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 13875bc41e27..4a10b3b692fa 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -4225,11 +4225,7 @@ static int s_show(struct seq_file *m, void *p)
>
>  	va = list_entry(p, struct vmap_area, list);
>
> -	/*
> -	 * s_show can encounter race with remove_vm_area, !vm on behalf
> -	 * of vmap area is being tear down or vm_map_ram allocation.
> -	 */
> -	if (!va->vm) {
> +	if (!va->vm && (va->flags & VMAP_RAM)) {
>  		seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n",
>  			(void *)va->va_start, (void *)va->va_end,
>  			va->va_end - va->va_start);
> --
> 2.34.1
>

Reviewed-by: Lorenzo Stoakes <lstoakes@...il.com>