linux-kernel - Re: [PATCH v2] kmemleak: skip scanning holes in the .bss section

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Date:   Tue, 19 Mar 2019 11:57:47 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Qian Cai <cai@....pw>
Cc:     akpm@...ux-foundation.org, paulus@...abs.org,
        benh@...nel.crashing.org, mpe@...erman.id.au, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, kvm-ppc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v2] kmemleak: skip scanning holes in the .bss section

Hi Qian,

On Wed, Mar 13, 2019 at 10:57:17AM -0400, Qian Cai wrote:
> @@ -1531,7 +1547,14 @@ static void kmemleak_scan(void)
>  
>  	/* data/bss scanning */
>  	scan_large_block(_sdata, _edata);
> -	scan_large_block(__bss_start, __bss_stop);
> +
> +	if (bss_hole_start) {
> +		scan_large_block(__bss_start, bss_hole_start);
> +		scan_large_block(bss_hole_stop, __bss_stop);
> +	} else {
> +		scan_large_block(__bss_start, __bss_stop);
> +	}
> +
>  	scan_large_block(__start_ro_after_init, __end_ro_after_init);

I'm not a fan of this approach but I couldn't come up with anything
better. I was hoping we could check for PageReserved() in scan_block()
but on arm64 it ends up not scanning the .bss at all.

Until another user appears, I'm ok with this patch.

Acked-by: Catalin Marinas <catalin.marinas@....com>