Date:   Wed, 25 Jan 2023 14:47:21 +0000
From:   Catalin Marinas <catalin.marinas@arm.com>
To:     George Prekas <george@enfabrica.net>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        "Liam R. Howlett" <Liam.Howlett@oracle.com>,
        Fenghua Yu <fenghua.yu@intel.com>,
        Andrei Vagin <avagin@gmail.com>
Subject: Re: [PATCH 1/9] mm: kmemleak: properly disable task stack scanning
Message-ID: <Y9FA+fFBytksYZi9@arm.com>
References: <20230123170419.7292-1-george@enfabrica.net>
 <20230123170419.7292-2-george@enfabrica.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230123170419.7292-2-george@enfabrica.net>
Precedence: bulk

On Mon, Jan 23, 2023 at 11:04:11AM -0600, George Prekas wrote:
> @@ -1586,23 +1608,6 @@ static void kmemleak_scan(void)
>  	}
>  	put_online_mems();
>  
> -	/*
> -	 * Scanning the task stacks (may introduce false negatives).
> -	 */
> -	if (kmemleak_stack_scan) {
> -		struct task_struct *p, *g;
> -
> -		rcu_read_lock();
> -		for_each_process_thread(g, p) {
> -			void *stack = try_get_task_stack(p);
> -			if (stack) {
> -				scan_block(stack, stack + THREAD_SIZE, NULL);
> -				put_task_stack(p);
> -			}
> -		}
> -		rcu_read_unlock();
> -	}

On architectures without VMAP_STACK, we still need the above otherwise
it could lead to some false positives.

-- 
Catalin