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 autolearn=unavailable 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 239B6C433E0 for ; Tue, 9 Feb 2021 13:55:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CE22D64EEE for ; Tue, 9 Feb 2021 13:55:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232037AbhBINzQ (ORCPT ); Tue, 9 Feb 2021 08:55:16 -0500 Received: from mx2.suse.de ([195.135.220.15]:47740 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232031AbhBINyn (ORCPT ); Tue, 9 Feb 2021 08:54:43 -0500 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=1612878835; 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=u3beVktBJeU3nR/gpabKScPIlmh909dbtHxbNDm9Ea0=; b=T6QnCOdL4g5WMz19dLeQVPa8TZ9tGPXT6pUtzsZ7xJ8jrLz1TxGqQ06g30XJJPU5ccmOx0 78J5lnv6tM53NfuhLWoamDfC8nW+Y7XcnlDncfVjV4ktklgPJM04eDeyHfZkaq02DDJekq dmTD+YLbsUlaA/dY01FiUMBAt+Ij4VE= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C4582AD5C; Tue, 9 Feb 2021 13:53:54 +0000 (UTC) Date: Tue, 9 Feb 2021 14:53:53 +0100 From: Petr Mladek To: Yafang Shao Cc: willy@infradead.org, andriy.shevchenko@linux.intel.com, david@redhat.com, linmiaohe@huawei.com, vbabka@suse.cz, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, rostedt@goodmis.org, sergey.senozhatsky@gmail.com, joe@perches.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org 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: <20210209105613.42747-4-laoar.shao@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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: diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 3b53c73580c5..cf67b39d72ae 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1916,6 +1916,67 @@ char *format_flags(char *buf, char *end, unsigned long flags, return buf; } +/* Meta information for page flags in the fields area */ +struct page_flags_fields { + int width; + int shift; + int mask; + const struct printf_spec *spec; + const char *name; +}; + +static const struct page_flags_fields pff[] = { + {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) +{ + unsigned long main_flags = flags & (BIT(NR_PAGEFLAGS) - 1); + bool append = false; + int i; + + /* Page flags from the main area. */ + if (main_flags) { + buf = format_flags(buf, end, main_flags, pageflag_names); + append = true; + } + + /* Page flags from the fields area */ + for (i = 0; i < ARRAY_SIZE(pff); i++) { + /* Skip undefined fields. */ + if (!pff[i].width) + continue; + + /* Format: Flag Name + '=' (equals sign) + Number + '|' (separator) */ + if (append) { + if (buf < end) + *buf = '|'; + buf++; + } + + buf = string(buf, end, pff[i].name, *pff[i].spec); + if (buf < end) + *buf = '='; + buf++; + buf = number(buf, end, (flags >> pff[i].shift) & pff[i].mask, + *pff[i].spec); + + append = true; + } + + 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 +1990,7 @@ 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; - break; + return format_page_flags(buf, end, flags); case 'v': flags = *(unsigned long *)flags_ptr; names = vmaflag_names; -- 2.26.2