From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C001C3ECBEE for ; Mon, 15 Jun 2026 12:30:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781526605; cv=none; b=Tv/zNneBTgL4U+Iwi5hVNVzqUxlLb8rWkGl84KI3AjsUs0KtYaPj/mLXjGgonMnWdlsoK0tqZuQxmc1BxKs2HzGWlraO/uLOKONFhyPLEOR4uCPjjeR1tkVng340TuLA3Yak66DqTC/P1q1axIwVwhMVB+vs8AxY6Tcjf8nNEDE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781526605; c=relaxed/simple; bh=iTwPS/H/VVfDYH1eZmJBl+2KCDvMmgD693ZNAikgS7U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Z9jawVdiaGybQVDshUHovTcXfccsC4r/a6TBSA4M87FV64uyvSbl5/0uo2irt8q/ousJ13EKuLr4G9Jey1X+8/Xqqc/XzlJOT/Ie1dhjHGtzNDL4eW6fG3qrbXruQ5P0USdaocLzbR4ooq/Ys0MHPDqw+JjBYy8QXddP8KQHsEA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=ea+MjRp1; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ea+MjRp1" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1781526599; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=6MxYKjqmEg82jtzqXvEH2JnVszujlKcbr71SIAlxpqU=; b=ea+MjRp17i74YESkApFroCUKMbHqpaChjtfE/+XMrKzPtWkb6TbgiVP8F+XtpvwLVK7M// 7UQL8mzFGg7hody+tybo1j8n23R5+vMky06cO45KBRY3HPp08TTBbiMHdPQ8ZNXUxR7coI crNmCElI3sabehBrlCi3aCo1kUK9hzM= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-568-lvM1OmnNO4exSOp_USewIg-1; Mon, 15 Jun 2026 08:29:56 -0400 X-MC-Unique: lvM1OmnNO4exSOp_USewIg-1 X-Mimecast-MFC-AGG-ID: lvM1OmnNO4exSOp_USewIg_1781526594 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EC540195E928; Mon, 15 Jun 2026 12:29:50 +0000 (UTC) Received: from fedora (unknown [10.44.32.13]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id E639918001D2; Mon, 15 Jun 2026 12:29:46 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 15 Jun 2026 14:29:50 +0200 (CEST) Date: Mon, 15 Jun 2026 14:29:45 +0200 From: Oleg Nesterov To: Catalin Marinas Cc: Breno Leitao , Andrew Morton , lance.yang@linux.dev, Davidlohr Bueso , Qian Cai , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, stable@vger.kernel.org Subject: Re: [PATCH v2] mm/kmemleak: avoid soft lockup when scanning task stacks Message-ID: References: <20260612-kmemleak-stack-resched-v2-1-53240de79e88@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 On 06/12, Catalin Marinas wrote: > > Yet anther variant below, untested. Basically, it follows the > next_tgid() or task_seq_get_next() approach (we might as well move this > to a separate function to avoid excessive indentation): > > if (kmemleak_stack_scan) { > struct pid *pid; > int nr = 1; > > do { > struct task_struct *p = NULL; > > rcu_read_lock(); > pid = find_ge_pid(nr, &init_pid_ns); > if (pid) { > nr = pid_nr(pid) + 1; > p = pid_task(pid, PIDTYPE_PID); > if (p) > get_task_struct(p); > } > rcu_read_unlock(); I don't think we need get_task_struct(p), the code above can just do if (p) stack = try_get_task_stack(p); Oleg.