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=-14.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 D5895C43381 for ; Thu, 11 Mar 2021 18:18:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A139F64FB8 for ; Thu, 11 Mar 2021 18:18:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229562AbhCKSR2 (ORCPT ); Thu, 11 Mar 2021 13:17:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229675AbhCKSRM (ORCPT ); Thu, 11 Mar 2021 13:17:12 -0500 Received: from mail-pg1-x532.google.com (mail-pg1-x532.google.com [IPv6:2607:f8b0:4864:20::532]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DDB77C061574 for ; Thu, 11 Mar 2021 10:17:11 -0800 (PST) Received: by mail-pg1-x532.google.com with SMTP id g4so14195594pgj.0 for ; Thu, 11 Mar 2021 10:17:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=xyO0tjr3czQHJ74CSGp1W7NkaFObkKH/BgzSQUWd/4c=; b=utUfhSKTSxUX+crWVXtGaBcG79X85FXBhVwJ5yuQdFJ5wCr7Lk6k37+c42JJiOnxL9 t7AN8RNmlfngNlMidifSaDj/JI9nJKrVuNEHAaULd1oFfoxQLBmwZxP4iiaEla7MvWGA ZlmklBOUFRPyprWW1L5bzSgOw1j3HJmlRGqH92n4Zboy1+cNASHG1wH42RGimyBIj4z0 vq2fFA7Wk9KMxdD6pcxIPsGGK1zJR28KSxwSBIkwvNIKQ96HhwtpLFoQcM9FGWSOIouf S7SW3ioP8ca1drCWtw+wwwvblUjMr1Et2LCGF+4NzolNcLuvJpWfCo4CPX27VtsB0s7B Nbjw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=xyO0tjr3czQHJ74CSGp1W7NkaFObkKH/BgzSQUWd/4c=; b=E50fftWRG+xQglkiVuWdzdM5MPetLsdcHS+B4l4RtpfzCyT8k0pmW4vIuVK9hZnSOw 2VfUBy232ESwmLpanpqxyYRqfv1mhwi8Csd9lXZGr45HHVPO18fR7kl/QdWyN7G1pWLf NrjwSaObs3PAagDCo2NYEbjWe3TT7TpkqHWwDQ18mYGnIWH4gydkGYw4wOzW8UzWmvLh YhxBlHpVzVUPMBHQ6fG6UCJGk1IqNgmZl/XOllppCDf30eq6sjZ1q9XrLMOl803kni60 pgiJg2Ykp679z9ylS2a4gG+YnyB1+gW7PadfmiGCgrXdAvFJD6eap+brZSFtv5ffmKOd 0Z9g== X-Gm-Message-State: AOAM533l3nHwS8j8gsPzKNMtw7YMajKBHW8AC96C1BrpFsbOp57taBzz hZk5Ie7kMA7gPuARnyKYTBk= X-Google-Smtp-Source: ABdhPJxg3tlHCUnP70z/OrKBd9ofGsVE7mOejG/hVLppuM8JS7gYdcCDtgRfasTcT7BIyApfqKuDDw== X-Received: by 2002:a63:c90f:: with SMTP id o15mr4851390pgg.400.1615486630790; Thu, 11 Mar 2021 10:17:10 -0800 (PST) Received: from google.com ([2620:15c:211:201:64cb:74c7:f2c:e5e0]) by smtp.gmail.com with ESMTPSA id s26sm3063519pfd.5.2021.03.11.10.17.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Mar 2021 10:17:09 -0800 (PST) Sender: Minchan Kim Date: Thu, 11 Mar 2021 10:17:07 -0800 From: Minchan Kim To: David Hildenbrand Cc: Andrew Morton , linux-mm , LKML , John Dias , Michal Hocko , Jason Baron Subject: Re: [PATCH v3] mm: page_alloc: dump migrate-failed pages Message-ID: References: <20210310180104.517886-1-minchan@kernel.org> 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-kernel@vger.kernel.org On Thu, Mar 11, 2021 at 05:40:35PM +0100, David Hildenbrand wrote: > On 10.03.21 19:01, Minchan Kim wrote: > > Currently, debugging CMA allocation failures is quite limited. > > The most commong source of these failures seems to be page > > migration which doesn't provide any useful information on the > > reason of the failure by itself. alloc_contig_range can report > > those failures as it holds a list of migrate-failed pages. > > > > page refcount, mapcount with page flags on dump_page are > > helpful information to deduce the culprit. Furthermore, > > dump_page_owner was super helpful to find long term pinner > > who initiated the page allocation. > > > > The reason it approach with dynamic debug is the debug message > > could emit lots of noises as alloc_contig_range calls more > > frequently since it's a best effort allocator. > > > > There are two ifdefery conditions to support common dyndbg options: > > > > - CONFIG_DYNAMIC_DEBUG_CORE && DYNAMIC_DEBUG_MODULE > > It aims for supporting the feature with only specific file > > with adding ccflags. > > > > - CONFIG_DYNAMIC_DEBUG > > It aims for supporting the feature with system wide globally. > > > > A simple example to enable the feature: > > > > Admin could enable the dump like this(by default, disabled) > > > > echo "func dump_migrate_failure_pages +p" > control > > > > Admin could disable it. > > > > echo "func dump_migrate_failure_pages =_" > control > > > > Detail goes Documentation/admin-guide/dynamic-debug-howto.rst > > > > A concern is utility functions in dump_page uses inconsistent > > loglevels. > > > > __dump_page: KERN_WARNING > > __dump_page_owner: KERN_ALERT > > stack_trace_print: KERN_DEFAULT > > > > There are bunch of places to use the inconsistent loglevel > > utility functions(e.g., just grep dump_page/strace_trace_print). > > It's unfortunate but here we are. It could be addressed > > different patchset. > > > > Signed-off-by: Minchan Kim > > --- > > * from v2 - https://lore.kernel.org/linux-mm/20210308202047.1903802-1-minchan@kernel.org/ > > * remove ratelimit - mhocko > > > > * from v1 - https://lore.kernel.org/linux-mm/20210217163603.429062-1-minchan@kernel.org/ > > * use dynamic debugging with system wide instead of per-call site - mhocko > > > > mm/page_alloc.c | 22 ++++++++++++++++++++++ > > 1 file changed, 22 insertions(+) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 3e4b29ee2b1e..f42f3e208794 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -8453,6 +8453,27 @@ static unsigned long pfn_max_align_up(unsigned long pfn) > > pageblock_nr_pages)); > > } > > +#if defined(CONFIG_DYNAMIC_DEBUG) || \ > > + (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE)) > > +static void alloc_contig_dump_pages(struct list_head *page_list) > > +{ > > + DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, > > + "migrate failure"); > > + > > + if (DYNAMIC_DEBUG_BRANCH(descriptor)) { > > + struct page *page; > > + > > + WARN(1, "failed callstack"); > > Not sure if we want that here. You can deterministically crash a kernel with > panic_on_warn set - which is what some distros already do. Good point. > > Some other way to dump the current call stack would be handy ... Yub, let's go with dump_stack. > > > + list_for_each_entry(page, page_list, lru) > > + dump_page(page, "migration failure"); > > + } > > +} > > +#else > > +static inline void alloc_contig_dump_pages(struct list_head *page_list) > > +{ > > +} > > +#endif > > + > > /* [start, end) must belong to a single zone. */ > > static int __alloc_contig_migrate_range(struct compact_control *cc, > > unsigned long start, unsigned long end) > > @@ -8496,6 +8517,7 @@ static int __alloc_contig_migrate_range(struct compact_control *cc, > > NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE); > > } > > if (ret < 0) { > > + alloc_contig_dump_pages(&cc->migratepages); > > putback_movable_pages(&cc->migratepages); > > return ret; > > } > > > > For me, this is good enough for now. Thanks. Let me send next revision with addressing your point and Andrew's one.