From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65A48C433F5 for ; Fri, 5 Nov 2021 10:08:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47A0661265 for ; Fri, 5 Nov 2021 10:08:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233024AbhKEKKu (ORCPT ); Fri, 5 Nov 2021 06:10:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:52922 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230110AbhKEKKt (ORCPT ); Fri, 5 Nov 2021 06:10:49 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 902CC611EE; Fri, 5 Nov 2021 10:08:08 +0000 (UTC) Date: Fri, 5 Nov 2021 10:08:05 +0000 From: Catalin Marinas To: Qian Cai Cc: Mike Rapoport , Will Deacon , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64: Track no early_pgtable_alloc() for kmemleak Message-ID: References: <20211104155623.11158-1-quic_qiancai@quicinc.com> <9bb6fe11-c10a-a373-9288-d44a5ba976fa@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9bb6fe11-c10a-a373-9288-d44a5ba976fa@quicinc.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 04, 2021 at 01:57:03PM -0400, Qian Cai wrote: > On 11/4/21 1:06 PM, Mike Rapoport wrote: > > I think I'll be better to rename MEMBLOCK_ALLOC_KASAN to, say, > > MEMBLOCK_ALLOC_NOKMEMLEAK and use that for both KASAN and page table cases. > > Okay, that would look a bit nicer. Or MEMBLOCK_ALLOC_ACCESSIBLE_NOLEAKTRACE to match SLAB_NOLEAKTRACE and also hint that it's accessible memory. > > But more generally, we are going to hit this again and again. > > Couldn't we add a memblock allocation as a mean to get more memory to > > kmemleak::mem_pool_alloc()? > > For the last 5 years, this is the second time I am ware of this kind of > issue just because of the 64KB->4KB switch on those servers, although I > agree it could happen again in the future due to some new debugging > features etc. I don't feel a strong need to rewrite it now though. Not > sure if Catalin saw things differently. Anyway, Mike, do you agree that > we could rewrite that separately in the future? I was talking to Mike on IRC last night and I think you still need a flag, otherwise you could get a recursive memblock -> kmemleak -> memblock call (that's why we have SLAB_NOLEAKTRACE). So for the time being, a new MEMBLOCK_* definition would do. I wonder whether we could actually use the bottom bits in the end/limit as actual flags so one can do (MEMBLOCK_ALLOC_ACCESSIBLE | MEMBLOCK_NOLEAKTRACE). But that could be for a separate clean-up. -- Catalin