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[195.135.220.15]) by mx.google.com with ESMTPS id d48si2255493eda.214.2019.06.27.08.35.40 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Jun 2019 08:35:40 -0700 (PDT) Received-SPF: pass (google.com: domain of jgross@suse.com designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jgross@suse.com designates 195.135.220.15 as permitted sender) smtp.mailfrom=jgross@suse.com X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 50103ABC4; Thu, 27 Jun 2019 15:35:40 +0000 (UTC) Subject: Re: [Xen-devel] [PATCH] mm: fix regression with deferred struct page init To: xen-devel@lists.xenproject.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Alexander Duyck , Andrew Morton , Michal Hocko , pasha.tatashin@soleen.com, rppt@linux.ibm.com References: <20190620160821.4210-1-jgross@suse.com> <79797c17-58d6-b09c-3aad-73e375a7f208@suse.com> From: Juergen Gross Message-ID: Date: Thu, 27 Jun 2019 17:35:39 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <79797c17-58d6-b09c-3aad-73e375a7f208@suse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: de-DE Content-Transfer-Encoding: 8bit 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 25.06.19 10:25, Juergen Gross wrote: > Gentle ping. > > I'd really like to have that in 5.2 in order to avoid the regression > introduced with 5.2-rc1. Adding some maintainers directly... Juergen > > > Juergen > > On 20.06.19 18:08, Juergen Gross wrote: >> Commit 0e56acae4b4dd4a9 ("mm: initialize MAX_ORDER_NR_PAGES at a time >> instead of doing larger sections") is causing a regression on some >> systems when the kernel is booted as Xen dom0. >> >> The system will just hang in early boot. >> >> Reason is an endless loop in get_page_from_freelist() in case the first >> zone looked at has no free memory. deferred_grow_zone() is always >> returning true due to the following code snipplet: >> >>    /* If the zone is empty somebody else may have cleared out the zone */ >>    if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, >>                                             first_deferred_pfn)) { >>            pgdat->first_deferred_pfn = ULONG_MAX; >>            pgdat_resize_unlock(pgdat, &flags); >>            return true; >>    } >> >> This in turn results in the loop as get_page_from_freelist() is >> assuming forward progress can be made by doing some more struct page >> initialization. >> >> Cc: Alexander Duyck >> Fixes: 0e56acae4b4dd4a9 ("mm: initialize MAX_ORDER_NR_PAGES at a time >> instead of doing larger sections") >> Suggested-by: Alexander Duyck >> Signed-off-by: Juergen Gross >> --- >>   mm/page_alloc.c | 3 ++- >>   1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index d66bc8abe0af..8e3bc949ebcc 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -1826,7 +1826,8 @@ deferred_grow_zone(struct zone *zone, unsigned >> int order) >>                            first_deferred_pfn)) { >>           pgdat->first_deferred_pfn = ULONG_MAX; >>           pgdat_resize_unlock(pgdat, &flags); >> -        return true; >> +        /* Retry only once. */ >> +        return first_deferred_pfn != ULONG_MAX; >>       } >>       /* >> > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xenproject.org > https://lists.xenproject.org/mailman/listinfo/xen-devel