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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 975E9C433DB for ; Wed, 10 Feb 2021 12:51:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 02BE264E32 for ; Wed, 10 Feb 2021 12:51:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 02BE264E32 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3F4C56B0006; Wed, 10 Feb 2021 07:51:26 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 37D366B006C; Wed, 10 Feb 2021 07:51:26 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 26CC56B006E; Wed, 10 Feb 2021 07:51:26 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0174.hostedemail.com [216.40.44.174]) by kanga.kvack.org (Postfix) with ESMTP id 0A3946B0006 for ; Wed, 10 Feb 2021 07:51:26 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id B57E1824556B for ; Wed, 10 Feb 2021 12:51:25 +0000 (UTC) X-FDA: 77802344130.04.snake64_3e0bc4927610 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id 9AF8D801B8E1 for ; Wed, 10 Feb 2021 12:51:25 +0000 (UTC) X-HE-Tag: snake64_3e0bc4927610 X-Filterd-Recvd-Size: 8948 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf28.hostedemail.com (Postfix) with ESMTP for ; Wed, 10 Feb 2021 12:51:24 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1612961484; h=from:from:reply-to: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=9eYi99J7mxFQDOzF/dkA+if59XFW+gFl2AA2TsPnXfA=; b=rqFNp+jkPLtRw66YyBi/vmcTyFZIC0ZMM/T4dwkcg3F7xDYsatvzl7qgin6ZxsZ/oRWjGH UxQZAnHYBy4iGvsuHffoPp7gS7cyOqpZFXogVG2LFuz4HlT6u21728eTgWIgEnyuTkfq06 GCSfZ5E23bGFs8PVqYsKx8NCvQ7AqmA= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id D04A7AEB9; Wed, 10 Feb 2021 12:51:23 +0000 (UTC) Date: Wed, 10 Feb 2021 13:51:22 +0100 From: Petr Mladek To: Yafang Shao Cc: Matthew Wilcox , Andy Shevchenko , David Hildenbrand , Miaohe Lin , Vlastimil Babka , Christoph Lameter , penberg@kernel.org, David Rientjes , iamjoonsoo.kim@lge.com, Andrew Morton , Steven Rostedt , Sergey Senozhatsky , Joe Perches , Linux MM , LKML Subject: Re: [PATCH v4 3/3] vsprintf: dump full information of page flags in pGp Message-ID: References: <20210209105613.42747-1-laoar.shao@gmail.com> <20210209105613.42747-4-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed 2021-02-10 00:21:37, Yafang Shao wrote: > On Tue, Feb 9, 2021 at 9:53 PM Petr Mladek wrote: > > > > On Tue 2021-02-09 18:56:13, Yafang Shao wrote: > > > Currently the pGp only shows the names of page flags, rather than > > > the full information including section, node, zone, last cpupid and > > > kasan tag. While it is not easy to parse these information manually > > > because there're so many flavors. Let's interpret them in pGp as well. > > > > > > To be compitable with the existed format of pGp, the new introduced ones > > > also use '|' as the separator, then the user tools parsing pGp won't > > > need to make change, suggested by Matthew. The new information is > > > tracked onto the end of the existed one. > > > > > > On example of the output in mm/slub.c as follows, > > > - Before the patch, > > > [ 6343.396602] Slab 0x000000004382e02b objects=33 used=3 fp=0x000000009ae06ffc flags=0x17ffffc0010200(slab|head) > > > > > > - After the patch, > > > [ 8838.835456] Slab 0x000000002828b78a objects=33 used=3 fp=0x00000000d04efc88 flags=0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff) > > > > > > The documentation and test cases are also updated. The output of the > > > test cases as follows, > > > [ 501.485081] test_printf: loaded. > > > [ 501.485768] test_printf: all 388 tests passed > > > [ 501.488762] test_printf: unloaded. > > > > > > > > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > > > index 14c9a6af1b23..3f26611adb34 100644 > > > --- a/lib/vsprintf.c > > > +++ b/lib/vsprintf.c > > > @@ -1916,6 +1916,66 @@ char *format_flags(char *buf, char *end, unsigned long flags, > > > return buf; > > > } > > > > > > +struct page_flags_layout { > > > + int width; > > > + int shift; > > > + int mask; > > > + const struct printf_spec *spec; > > > + const char *name; > > > +}; > > > + > > > +static const struct page_flags_layout pfl[] = { > > > + {SECTIONS_WIDTH, SECTIONS_PGSHIFT, SECTIONS_MASK, > > > + &default_dec_spec, "section"}, > > > + {NODES_WIDTH, NODES_PGSHIFT, NODES_MASK, > > > + &default_dec_spec, "node"}, > > > + {ZONES_WIDTH, ZONES_PGSHIFT, ZONES_MASK, > > > + &default_dec_spec, "zone"}, > > > + {LAST_CPUPID_WIDTH, LAST_CPUPID_PGSHIFT, LAST_CPUPID_MASK, > > > + &default_flag_spec, "lastcpupid"}, > > > + {KASAN_TAG_WIDTH, KASAN_TAG_PGSHIFT, KASAN_TAG_MASK, > > > + &default_flag_spec, "kasantag"}, > > > +}; > > > + > > > +static > > > +char *format_page_flags(char *buf, char *end, unsigned long flags) > > > +{ > > > + DECLARE_BITMAP(mask, ARRAY_SIZE(pfl)); > > > + unsigned long last; > > > + int i; > > > + > > > + if (flags & (BIT(NR_PAGEFLAGS) - 1)) { > > > + if (buf < end) > > > + *buf = '|'; > > > + buf++; > > > + } > > > > This is far from obvious. You print '|' here because you printed > > something somewhere else. See below. > > > > > + > > > + for (i = 0; i < ARRAY_SIZE(pfl); i++) > > > + __assign_bit(i, mask, pfl[i].width); > > > > The bitmap looks like an overkill. If I get it correctly, it is a > > tricky way to handle only flags defined by the used build > > configuration. See below. > > > > > + last = find_last_bit(mask, ARRAY_SIZE(pfl)); > > > + > > > + for_each_set_bit(i, mask, ARRAY_SIZE(pfl)) { > > > + /* Format: Flag Name + '=' (equals sign) + Number + '|' (separator) */ > > > + buf = string(buf, end, pfl[i].name, *pfl[i].spec); > > > + > > > + if (buf < end) > > > + *buf = '='; > > > + buf++; > > > + buf = number(buf, end, (flags >> pfl[i].shift) & pfl[i].mask, > > > + *pfl[i].spec); > > > + > > > + /* No separator for the last entry */ > > > + if (i != last) { > > > + if (buf < end) > > > + *buf = '|'; > > > + buf++; > > > + } > > > + } > > > + > > > + return buf; > > > +} > > > + > > > static noinline_for_stack > > > char *flags_string(char *buf, char *end, void *flags_ptr, > > > struct printf_spec spec, const char *fmt) > > > @@ -1929,10 +1989,10 @@ char *flags_string(char *buf, char *end, void *flags_ptr, > > > switch (fmt[1]) { > > > case 'p': > > > flags = *(unsigned long *)flags_ptr; > > > - /* Remove zone id */ > > > - flags &= (1UL << NR_PAGEFLAGS) - 1; > > > names = pageflag_names; > > > > The "names" variable is needed only with "break;" when using the final > > format_flags(buf, end, flags, names); > > > > > - break; > > > + buf = format_flags(buf, end, flags & (BIT(NR_PAGEFLAGS) - 1), names); > > > + buf = format_page_flags(buf, end, flags); > > > > I am sorry for my ignorance. I am not familiar with MM. > > But it is pretty hard to understand what call does what. > > > > I have found the following comment in include/linux/page_flags.h: > > > > * The page flags field is split into two parts, the main flags area > > * which extends from the low bits upwards, and the fields area which > > * extends from the high bits downwards. > > > > Sigh, I know that you already reworked this several times because > > people "nitpicked" about the code style. But it seems that it > > rather diverged instead of converged. > > > > What about the following? > > > > Note: It is inpired by the names "main area" and "fields area" > > mentioned in the above comment from page_flags.h. > > I have later realized that "page_flags_layout" actually made > > sense as well. Feel free to rename page_flags_fileds > > back to page_flags_layout. > > > > Anyway, this is my proposal: > > > > This proposal is similar to v2. > I don't mind changing it back with your additional better naming. Great. > By the way, it will be better to make a little change per Joe's > suggestion on v2 that using a pointer instead of the index, for > example, > > for (p = pff; p < pff + ARRAY_SIZE(pff); p++) { This looks a bit non-standard. IMHO, Joe was not against using index. He proposed: for (i = 0; i < ARRAY_SIZE(pfl) && buf < end; i++) { , see https://lore.kernel.org/lkml/e5ea9e8b1190c2a397a1b84dd55bb9c706dc7058.camel@perches.com/ I am not sure about the (buf < end) check. It might be some optimization or it did fit the the old code. Anyway, I like the currently used: for (i = 0; i < ARRAY_SIZE(pff); i++) { It is standard, easy to understand, and thus more safe. I am sure that compiler will optimize it very well. Best Regards, Petr