linux-kernel - Re: [PATCH] mm: kmemleak: Ensure that the task stack is not freed during scanning

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Date:   Wed, 12 Oct 2016 18:16:46 +0800
From:   "Hillf Danton" <hillf.zj@...baba-inc.com>
To:     "'Catalin Marinas'" <catalin.marinas@....com>, <linux-mm@...ck.org>
Cc:     <linux-kernel@...r.kernel.org>,
        "'Andrew Morton'" <akpm@...ux-foundation.org>,
        "'Andy Lutomirski'" <luto@...nel.org>,
        "'CAI Qian'" <caiqian@...hat.com>
Subject: Re: [PATCH] mm: kmemleak: Ensure that the task stack is not freed during scanning

> @@ -1453,8 +1453,11 @@ static void kmemleak_scan(void)
> 
>  		read_lock(&tasklist_lock);
>  		do_each_thread(g, p) {

Take a look at this commit please.
	1da4db0cd5 ("oom_kill: change oom_kill.c to use for_each_thread()")

> -			scan_block(task_stack_page(p), task_stack_page(p) +
> -				   THREAD_SIZE, NULL);
> +			void *stack = try_get_task_stack(p);
> +			if (stack) {
> +				scan_block(stack, stack + THREAD_SIZE, NULL);
> +				put_task_stack(p);
> +			}
>  		} while_each_thread(g, p);
>  		read_unlock(&tasklist_lock);
>  	}
>