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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DD0EC433FE for ; Wed, 9 Nov 2022 06:04:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229516AbiKIGEg (ORCPT ); Wed, 9 Nov 2022 01:04:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229452AbiKIGEe (ORCPT ); Wed, 9 Nov 2022 01:04:34 -0500 Received: from mail-pj1-x1035.google.com (mail-pj1-x1035.google.com [IPv6:2607:f8b0:4864:20::1035]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C84EC13D63; Tue, 8 Nov 2022 22:04:32 -0800 (PST) Received: by mail-pj1-x1035.google.com with SMTP id l6so15823323pjj.0; Tue, 08 Nov 2022 22:04:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=NrHD8wLzW2vOh67ueVVQM6HR2KgSCKRKBNGUVxIg0Xw=; b=KkK14nw7ANwd2Yzpl+m5rI4utFgMgZs7bo5F3vx1zQK7ozGIVQcz4WVswUtpEnXbMy hNd+nkUnqk5qo92hDJAxeq7tdYnE3fb7sbeM7N1lrc6fRc2NYhCMMDJvuz7KxUJpEkML b6j3pBgJBB2daq7mu7/8xVkieNrmUkfxunK1s6LZRce5UM0ksefwEt0MukxqSMS2MPVR r3yYla3JIy/X8U4RIkGI22e+j9zF6neB4c++651AI1Xn1FvZNfkprrwt7uKbUEgsUZer ov4JptMbBS2dBD6loiZhngvap1EzjUCJVY8vOw92RJBhhbSN7dp6O9jthuIWCPu+Rjt4 aGxg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=NrHD8wLzW2vOh67ueVVQM6HR2KgSCKRKBNGUVxIg0Xw=; b=ZoG1gOk7mitaX592tHcltyV4c8YyGzhrpZeFbxCf1ShldjDLwe7yl1ZwTlH6bii8Lp 3JYY4kHZ5zscQrvxoKY1YnEeFFm6avU7Zi3ky0+A779813iXa/hHWaS2TenSwxzogRYv wUyIHl5/LwwlBdbXj+3QAAaajJGw0wgVyDni8XnwslGQKg4g0lSAMCXDwU2PYwj3Zrem pH+WNg96SPMsIFN+zKPgvFryzihSq9xr6lgMabRrj2xqZYZjiEHGKm4ypfWmLX3aR/mA yyiXvjYP4IbQga/9vRmbR3r26VJMwRu/wO7x8gUYNpR0XGA1y6XwpzTTbm0iIMzfStdG t7qw== X-Gm-Message-State: ACrzQf07oGUd4cRlP5sfZ1EKLJ4PDgTScWZKSBzANOBfloHsPFCtCHzK nUwpQsfnngat3hYzBbifYpo= X-Google-Smtp-Source: AMsMyM7v2kLUmw8TIrBi4FO6Texz6tMiK5p4/wsREpvhZgUjwNBJ7ijTl3LcD+Ry/CZ9EYsNL1jlbQ== X-Received: by 2002:a17:90b:388f:b0:215:f01f:7975 with SMTP id mu15-20020a17090b388f00b00215f01f7975mr32961783pjb.53.1667973872294; Tue, 08 Nov 2022 22:04:32 -0800 (PST) Received: from hyeyoo ([114.29.91.56]) by smtp.gmail.com with ESMTPSA id v19-20020a17090a899300b0020063e7d63asm331124pjn.30.2022.11.08.22.04.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Nov 2022 22:04:31 -0800 (PST) Date: Wed, 9 Nov 2022 15:04:23 +0900 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Petr Mladek Cc: Andy Shevchenko , linux-mm@kvack.org, Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Vlastimil Babka , Naoya Horiguchi , Miaohe Lin , Matthew Wilcox , Minchan Kim , Mel Gorman , Andrea Arcangeli , Dan Williams , Hugh Dickins , Muchun Song , David Hildenbrand , Steven Rostedt , Sergey Senozhatsky , Rasmus Villemoes , Jonathan Corbet , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC v2 3/3] mm, printk: introduce new format %pGt for page_type Message-ID: References: <20221106140355.294845-1-42.hyeyoo@gmail.com> <20221106140355.294845-4-42.hyeyoo@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Mon, Nov 07, 2022 at 03:20:34PM +0100, Petr Mladek wrote: > On Mon 2022-11-07 13:18:52, Andy Shevchenko wrote: > > On Sun, Nov 06, 2022 at 11:03:55PM +0900, Hyeonggon Yoo wrote: > > > dump_page() uses %pGp format to print 'flags' field of struct page. > > > As some page flags (e.g. PG_buddy, see page-flags.h for more details) > > > are set in page_type field, introduce %pGt format which provides > > > human readable output of page_type. And use it in dump_page(). > > > > > > Note that the sense of bits are different in page_type. if page_type is > > > 0xffffffff, no flags are set. if PG_slab (0x00100000) flag is set, > > > page_type is 0xffefffff. Clearing a bit means we set the bit. Bits in > > > page_type are inverted when printing type names. > > > > > > Below is examples of dump_page(). One is just after alloc_pages() and > > > the other is after __SetPageSlab(). > > > > > > [ 1.814728] page:ffffea000415e200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x105788 > > > [ 1.815961] flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff) > > > > > [ 1.816443] page_type: 0xffffffff() > > Thank you both for looking at this! :-) > > Why do we have empty parentheses? I would expect either something there, or no > > parentheses at all. > > This looks fine. format_page_flags() does the same for %pGp. > > > ... > > > > > + %pGt 0xffefffff(slab) > > > > No space before ( ? > > Also looks fine. %pGp does the same. > > > ... > > > > > +static > > > +char *format_page_type(char *buf, char *end, unsigned int page_type) > > > +{ > > > + if (!(page_type & PAGE_TYPE_BASE)) > > > + return string(buf, end, "no type for user-mapped page", default_str_spec); > > > > It's too long, can we make it shorten? > > I wonder if it would help to write the value. Something like: > > page_type: 0x0ace5768(no type) > > That said. I am not familiar with the page types and am not sure > about the semantic of this value. MM people should decide what they > want to see in this case. Hmm, then for consistency let's try: - 0xffefffff(slab) - 0xffffffff() - 0x0ace5768() this way. > > ... > > > > > pr_warn("%sflags: %pGp%s\n", type, &head->flags, > > > page_cma ? " CMA" : ""); > > > + pr_warn("page_type: %pGt\n", &head->page_type); > > > + > > > print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32, > > > sizeof(unsigned long), page, > > > sizeof(struct page), false); > > > diff --git a/mm/internal.h b/mm/internal.h > > > index cb4c663a714e..956eaa9f12c0 100644 > > > --- a/mm/internal.h > > > +++ b/mm/internal.h > > > @@ -773,6 +773,7 @@ static inline void flush_tlb_batched_pending(struct mm_struct *mm) > > > #endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */ > > > > > > extern const struct trace_print_flags pageflag_names[]; > > > +extern const struct trace_print_flags pagetype_names[]; > > > extern const struct trace_print_flags vmaflag_names[]; > > > extern const struct trace_print_flags gfpflag_names[]; > > > > I would split this to a separate change, but it's up to PRINTK maintainers. > > I guess that you are talking about the line: > > + pr_warn("page_type: %pGt\n", &head->page_type); > > > Yes, it would be better to have implementation of %pGt modifier > in one patch and add the user in another one. Sounds reasonable. Will split its caller into another patch next to this one. -- Thanks, Hyeonggon