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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B8B5C433E0 for ; Mon, 1 Feb 2021 19:01:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0501764DDF for ; Mon, 1 Feb 2021 19:01:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231508AbhBATBO (ORCPT ); Mon, 1 Feb 2021 14:01:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59014 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231831AbhBATBK (ORCPT ); Mon, 1 Feb 2021 14:01:10 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 57118C061573 for ; Mon, 1 Feb 2021 11:00:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=fgOq7F84WfyhkfPnzhyCYr96g+FlgtMswaV08yg0yE4=; b=RoXGhrP2Was+Jin2P0O/pP5PU+ UszkgEQPN5Sv5YR3shwf87rddmm73hZHr7s8szxxhQOt0a16FxixuzmiMYv+7Zlhw70dtCVAwuwWx bUb1VprT6QEQNo2UAijR86NThUhJvn42SfobKO8wUd1oIsobCgAiRaBSoxCP1s0LcLOvX6vqKwDvN XIA5PToGWJgxG3pVlU4eYWWbvKZsx19bkjOZ6izzS1JPHM0jnIwItxUQ9LbKcjhdFM9l7+9PY/98R /K7QgL28EBVRdHOKkAOemy0b2g3Taa+8FSqmuK3rdn9ANvXmvsfAxHZlWVVUBxwC8i4xYbZa9rYET TVE9D92w==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1l6eQG-00EBcI-VK; Mon, 01 Feb 2021 18:59:41 +0000 Date: Mon, 1 Feb 2021 18:59:40 +0000 From: Matthew Wilcox To: Joe Perches Cc: Yafang Shao , andriy.shevchenko@linux.intel.com, david@redhat.com, vbabka@suse.cz, linmiaohe@huawei.com, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, pmladek@suse.com, rostedt@goodmis.org, sergey.senozhatsky@gmail.com, linux@rasmusvillemoes.dk, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 3/3] vsprintf: dump full information of page flags in pGp Message-ID: <20210201185940.GS308988@casper.infradead.org> References: <20210201115610.87808-1-laoar.shao@gmail.com> <20210201115610.87808-4-laoar.shao@gmail.com> <20210201141505.GR308988@casper.infradead.org> <9c475803276ea2b32cadc8f72d397c180475d0cc.camel@perches.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9c475803276ea2b32cadc8f72d397c180475d0cc.camel@perches.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 01, 2021 at 10:51:03AM -0800, Joe Perches wrote: > On Mon, 2021-02-01 at 14:15 +0000, Matthew Wilcox wrote: > > On Mon, Feb 01, 2021 at 07:56:10PM +0800, Yafang Shao wrote: > > > - Before the patch, > > > [ 6343.396602] Slab 0x000000004382e02b objects=33 used=3 fp=0x000000009ae06ffc flags=0x17ffffc0010200(slab|head) > > > > > > - After the patch, > > > [ 6871.296131] Slab 0x00000000c0e19a37 objects=33 used=3 fp=0x00000000c4902159 flags=0x17ffffc0010200(Node 0,Zone 2,Lastcpupid 0x1fffff,slab|head) > > > > I would suggest it will be easier to parse as: > > > > flags=0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff) > > > > That should alleviate the concerns about debugfs format change -- we've > > never guaranteed that flag names won't change, and they now look enough > > like flags that parsers shouldn't fall over them. > > Seems sensible and would make the generating code simpler too. > > But is it worth the vsprintf code expansion for the 5 current uses? > > mm/debug.c: pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags, > mm/memory-failure.c: pr_info("soft offline: %#lx: %s migration failed %d, type %lx (%pGp)\n", > mm/memory-failure.c: pr_info("soft offline: %#lx: %s isolation failed, page count %d, type %lx (%pGp)\n", > mm/memory-failure.c: pr_info("%s: %#lx: unknown page type: %lx (%pGp)\n", > mm/page_owner.c: "PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n", > > Wouldn't it be more sensible just to put this code in a new function > call in mm? Does it matter whether the code lives in vsprintf.c or mm/debug.c? It's built into the kernel core either way. I'm not a huge fan of the current way %pFoo is handled, but unless/until it's drastically revised, I don't think this proposed patch makes anything worse.