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[79.242.62.87]) by smtp.gmail.com with ESMTPSA id k13sm211285wri.6.2021.12.07.08.40.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Dec 2021 08:40:37 -0800 (PST) Message-ID: <235e8656-a947-b446-c39c-fa0f72b65ac7@redhat.com> Date: Tue, 7 Dec 2021 17:40:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v3] mm: fix panic in __alloc_pages Content-Language: en-US To: Michal Hocko Cc: Alexey Makhalov , Dennis Zhou , Eric Dumazet , "linux-mm@kvack.org" , Andrew Morton , Oscar Salvador , Tejun Heo , Christoph Lameter , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" References: <1043a1a4-b7f2-8730-d192-7cab9f15ee24@redhat.com> <77e785e6-cf34-0cff-26a5-852d3786a9b8@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07.12.21 17:36, Michal Hocko wrote: > On Tue 07-12-21 17:27:29, Michal Hocko wrote: > [...] >> So your proposal is to drop set_node_online from the patch and add it as >> a separate one which handles >> - sysfs part (i.e. do not register a node which doesn't span a >> physical address space) >> - hotplug side of (drop the pgd allocation, register node lazily >> when a first memblocks are registered) > > In other words, the first stage > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index c5952749ad40..f9024ba09c53 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6382,7 +6382,11 @@ static void __build_all_zonelists(void *data) > if (self && !node_online(self->node_id)) { > build_zonelists(self); > } else { > - for_each_online_node(nid) { > + /* > + * All possible nodes have pgdat preallocated > + * free_area_init > + */ > + for_each_node(nid) { > pg_data_t *pgdat = NODE_DATA(nid); > > build_zonelists(pgdat); > @@ -8032,8 +8036,24 @@ void __init free_area_init(unsigned long *max_zone_pfn) > /* Initialise every node */ > mminit_verify_pageflags_layout(); > setup_nr_node_ids(); > - for_each_online_node(nid) { > - pg_data_t *pgdat = NODE_DATA(nid); > + for_each_node(nid) { > + pg_data_t *pgdat; > + > + if (!node_online(nid)) { > + pr_warn("Node %d uninitialized by the platform. Please report with boot dmesg.\n", nid); > + pgdat = arch_alloc_nodedata(nid); Is the buddy fully up an running at that point? I don't think so, so we might have to allocate via memblock instead. But I might be wrong. > + pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat); > + arch_refresh_nodedata(nid, pgdat); > + free_area_init_memoryless_node(nid); > + /* > + * not marking this node online because we do not want to > + * confuse userspace by sysfs files/directories for node > + * without any memory attached to it (see topology_init) > + */ > + continue; > + } > + > + pgdat = NODE_DATA(nid); > free_area_init_node(nid); > > /* Any memory on that node */ > Yes, and maybe in the same go, remove/rework hotadd_new_pgdat(), because there is nothing to hotadd anymore. (we should double-check the initialization performed in there, it might all not be necessary anymore) -- Thanks, David / dhildenb