From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 3014A3A6EEC; Thu, 10 Sep 2026 07:44:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789026281; cv=none; b=YyVX3V7VLNhfPO9qbkprgvobdjNy0WQOyMcG5VuSZkogb6Bx9No1Adw8x1TXW6Nr9ud8XHlj1Ag9xyHJ+1Ncc41G8itISgUj/KYoy6hbg3priuDmPpfJocGfuXEpdsoZvoS6TXr6ELJMSO0e+aDh+roABiZ93J91mugx4xgL4qA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789026281; c=relaxed/simple; bh=oXHqWI81ExKc994Budubub91hz5MKneNZl7a2oh+O20=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=th60UXe18vQ0VzgfXfuiZwgJJn6MLSkVFZfuy5eK39NLOXMNc1Y76kDrEemkF2FLrBbD7KlN/OX1L825UP0dorrgF/xeIetEsS7TxClncYVzm1Os2iIONWTcHtUb7J9YU0+KUwe6h1cOFoI6BSiqib31glPnmE/eYZ8NEeKRu9I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=K/1yX6wY; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="K/1yX6wY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 534431F000FF; Thu, 10 Sep 2026 07:44:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789026279; bh=KeY2ecBYXILjnJfvlD+aKbn3Fj7q03e1zhdxzP3owm4=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=K/1yX6wYqGx3DlHOpx6z/zg5BRMRmre61T0TfyWVd7E6qvYnkkqKgkjYP8bl+8p4K Fz/WMtRF+bz6n4RmOcAd4SRb1SS9EBF+Wam8pC4EKJqKfHOiVbxbwC1pQW5e72ATWn BTulP01ah/PWT1SKdtfCFZ835ua++8yjbDQgpnWcCbcMaIF7w9F+GCauHPtwyuWqXJ lijRSdW/evnZOnPtk6oD+LlfebWXweMNXh80ckD2iODwAySofHwKwFOi8WKGtUrLXT g84/ydHeHETnkXPU5XSl13qkllkRGo7e+SjUzrHEza8LSKroR1KzNDTpgmyaJ/K89y XOETAU5f/2JTA== Message-ID: Date: Thu, 10 Sep 2026 09:44:33 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 4/5] proc/task_mmu: read proc/pid/smaps_rollup under per-vma lock To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, liam@infradead.org, ljs@kernel.org, vbabka@kernel.org, willy@infradead.org, jannh@google.com, paulmck@kernel.org, pfalcato@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <20260907063918.3432401-1-surenb@google.com> <20260907063918.3432401-5-surenb@google.com> <19e428e5-d8bc-4abb-b052-e23442464cba@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 9/9/26 19:58, Suren Baghdasaryan wrote: > On Wed, Sep 9, 2026 at 10:23 AM David Hildenbrand (Arm) > wrote: >> >> >>> - vma_start = vma->vm_start; >>> - do { >>> - smap_gather_stats(priv, vma, &mss, vma->vm_start); >>> - last_vma_end = vma->vm_end; >>> + if (!IS_ERR(vma) && vma != get_gate_vma(lock_ctx->mm)) >>> + vma_start = vma->vm_start; >>> + >>> + while (vma) { >>> + if (IS_ERR(vma)) { >>> + ret = PTR_ERR(vma); >>> + goto out_unlock; >>> + } >>> + >> >> Can we add a comment whey we break (and not e.g., continue) whenw e hit the gate >> VMA? >> >> (I seriously don't kmow ... should I know? :) ) > > The way m_next() is implemented, the gate VMA always placed at the end > of the address space, so the next VMA will be NULL and we can break > once we see the gate. But now that I'm looking closer into this code, > reading smaps_rollup file does not invoke m_next(), so we should never > encounter a gate VMA (it's not in the maple tree, so for_each_vma() > should never return it). I think I can remove the special handling for > that case. > > Thanks for the question, David! It made me realize we can simplify this further. good! :) -- Cheers, David