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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 25425C33CA1 for ; Mon, 20 Jan 2020 06:11:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C023E2073A for ; Mon, 20 Jan 2020 06:11:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C023E2073A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F12826B05A8; Mon, 20 Jan 2020 01:11:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EC2D66B05A9; Mon, 20 Jan 2020 01:11:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DD8D86B05AA; Mon, 20 Jan 2020 01:11:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0042.hostedemail.com [216.40.44.42]) by kanga.kvack.org (Postfix) with ESMTP id C62126B05A8 for ; Mon, 20 Jan 2020 01:11:11 -0500 (EST) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 708683AB7 for ; Mon, 20 Jan 2020 06:11:11 +0000 (UTC) X-FDA: 76396989942.26.stone03_6198579a19451 X-HE-Tag: stone03_6198579a19451 X-Filterd-Recvd-Size: 4921 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf18.hostedemail.com (Postfix) with ESMTP for ; Mon, 20 Jan 2020 06:11:10 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id ABE5C31B; Sun, 19 Jan 2020 22:11:09 -0800 (PST) Received: from [10.162.16.78] (p8cg001049571a15.blr.arm.com [10.162.16.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 234B83F52E; Sun, 19 Jan 2020 22:14:40 -0800 (PST) Subject: Re: [Patch v2 1/4] mm: enable dump several reasons for __dump_page() To: Wei Yang , akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, rientjes@google.com References: <20200120030415.15925-1-richardw.yang@linux.intel.com> <20200120030415.15925-2-richardw.yang@linux.intel.com> From: Anshuman Khandual Message-ID: <8426f31b-606e-deca-acbe-dd59b193e113@arm.com> Date: Mon, 20 Jan 2020 11:42:30 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200120030415.15925-2-richardw.yang@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 01/20/2020 08:34 AM, Wei Yang wrote: > This is a preparation to dump all reasons during check page. This really makes sense rather then just picking the reason from the last "if" statement. > > Signed-off-by: Wei Yang > --- > include/linux/mmdebug.h | 2 +- > mm/debug.c | 11 ++++++----- > mm/page_alloc.c | 2 +- > 3 files changed, 8 insertions(+), 7 deletions(-) > > diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h > index 2ad72d2c8cc5..f0a612db8bae 100644 > --- a/include/linux/mmdebug.h > +++ b/include/linux/mmdebug.h > @@ -10,7 +10,7 @@ struct vm_area_struct; > struct mm_struct; > > extern void dump_page(struct page *page, const char *reason); > -extern void __dump_page(struct page *page, const char *reason); > +extern void __dump_page(struct page *page, int num, const char **reason); > void dump_vma(const struct vm_area_struct *vma); > void dump_mm(const struct mm_struct *mm); > > diff --git a/mm/debug.c b/mm/debug.c > index 0461df1207cb..a8ac6f951f9f 100644 > --- a/mm/debug.c > +++ b/mm/debug.c > @@ -42,11 +42,11 @@ const struct trace_print_flags vmaflag_names[] = { > {0, NULL} > }; > > -void __dump_page(struct page *page, const char *reason) > +void __dump_page(struct page *page, int num, const char **reason) > { > struct address_space *mapping; > bool page_poisoned = PagePoisoned(page); > - int mapcount; > + int mapcount, i; > > /* > * If struct page is poisoned don't access Page*() functions as that > @@ -97,8 +97,9 @@ void __dump_page(struct page *page, const char *reason) > sizeof(unsigned long), page, > sizeof(struct page), false); > > - if (reason) > - pr_warn("page dumped because: %s\n", reason); > + pr_warn("page dumped because:\n"); > + for (i = 0; i < num; i++) > + pr_warn("\t%s\n", reason[i]); We should have a NR_BAD_PAGE_REASONS or something to cap this iteration and also check reason[i] for non-NULL before trying to print the array. There might be call sites like the following which will be problematic otherwise. split_huge_page_to_list() -> dump_page(head, NULL) > > #ifdef CONFIG_MEMCG > if (!page_poisoned && page->mem_cgroup) While here, will it be better to move the above debug print block after mem_cgroup block instead ? > @@ -108,7 +109,7 @@ void __dump_page(struct page *page, const char *reason) > > void dump_page(struct page *page, const char *reason) > { > - __dump_page(page, reason); > + __dump_page(page, 1, &reason); > dump_page_owner(page); > } > EXPORT_SYMBOL(dump_page); > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d047bf7d8fd4..0cf6218aaba7 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -638,7 +638,7 @@ static void bad_page(struct page *page, const char *reason, > > pr_alert("BUG: Bad page state in process %s pfn:%05lx\n", > current->comm, page_to_pfn(page)); > - __dump_page(page, reason); > + __dump_page(page, 1, &reason); > bad_flags &= page->flags; > if (bad_flags) > pr_alert("bad because of flags: %#lx(%pGp)\n", > Do we still need to have bad_flags ? After consolidating all reasons making a page bad should not we just print page->flags unconditionally each time and let the user decipher it instead. __dump_page() will print page->flags for each case (atleast after the new patch from Vlastimil). AFAICS, the only place currently consuming bad_flags is bad_page() which seems redundant after first calling __dump_page().