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Fri, 20 Oct 2023 00:36:30 -0700 (PDT) Received: from [10.84.155.153] ([203.208.167.147]) by smtp.gmail.com with ESMTPSA id n9-20020aa79849000000b00682868714fdsm938225pfq.95.2023.10.20.00.36.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 Oct 2023 00:36:29 -0700 (PDT) Message-ID: <4bfa007c-a20f-9e68-4a9f-935dacf43222@bytedance.com> Date: Fri, 20 Oct 2023 15:35:08 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v3 2/2] mm: memory_hotplug: drop memoryless node from fallback lists Content-Language: en-US To: "Huang, Ying" Cc: akpm@linux-foundation.org, rppt@kernel.org, david@redhat.com, vbabka@suse.cz, mhocko@suse.com, willy@infradead.org, mgorman@techsingularity.net, mingo@kernel.org, aneesh.kumar@linux.ibm.com, hannes@cmpxchg.org, osalvador@suse.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <9f1dbe7ee1301c7163b2770e32954ff5e3ecf2c4.1697711415.git.zhengqi.arch@bytedance.com> <87bkctg4f4.fsf@yhuang6-desk2.ccr.corp.intel.com> From: Qi Zheng In-Reply-To: <87bkctg4f4.fsf@yhuang6-desk2.ccr.corp.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: 98gnhwn93xpt77e5myyp3z5ws5jsai43 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 9434320011 X-Rspam-User: X-HE-Tag: 1697787391-774125 X-HE-Meta: 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 8URtTy9h IsDLc3WElN1L5AkloweYHo9bQ+lkFsn3Mw9mqgBV6KWxe4vM4fnuUMYr+1HTIE1/UMdo3vEhle2G7yQe98x6QkxRLtMAaYzS30XCjdZr20c0oVtZmsnl7etm/iWKgSntSeOqdmGTBDwIX5zWQodfp9pJ1+rO6BXhUZdXVGVTxZ1Rr19188LD+KyNkiF/9f6M2QJU79j0d9kaAcQ1SE22dYdHAzaqUngZfMIB1lk8xb005RE4DSWasyDeXPqnwrQxjq4IDQU57MEF6hitAyfnUlLIYDcnwHDlrEwo77tPC/3FWntDPmzRAl1QKwtYmVElYE7ausq2Vg69MudeH47MrgF4M2ZrKAwMlySLOaw/+X5FFmob2xiADFqjXLyrQDz7gp9GpH5C/D9qexIHiib4AFBuR438I0dxcYTNaiaEwXtFuYHur7lL32lf0SAz0FvN7KeerWiCee3VLrqMDwoGcUS0NZ9qIlReCVWrvKvo8a/FMfxPGR/bbFWp+pdilsipFmC+RPs064/CQjOHfanR0ohp5wuKvblmzdX8v0RH+bLzgnso= 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: Hi Ying, On 2023/10/20 15:05, Huang, Ying wrote: > Qi Zheng writes: > >> In offline_pages(), if a node becomes memoryless, we >> will clear its N_MEMORY state by calling node_states_clear_node(). >> But we do this after rebuilding the zonelists by calling >> build_all_zonelists(), which will cause this memoryless node to >> still be in the fallback list of other nodes. > > For fallback list, do you mean pgdat->node_zonelists[]? If so, in > > build_all_zonelists > __build_all_zonelists > build_zonelists > build_zonelists_in_node_order > build_zonerefs_node > > populated_zone() will be checked before adding zone into zonelist. > > So, IIUC, we will not try to allocate from the memory less node. Normally yes, but if it is the weird topology mentioned in [1], it's possible to allocate memory from it, it is a memoryless node, but it also has memory. In addition to the above case, I think it's reasonable to remove memory less node from node_order[] in advance. In this way it will not to be traversed in build_zonelists_in_node_order(). [1]. https://lore.kernel.org/all/20230212110305.93670-1-zhengqi.arch@bytedance.com/ Thanks, Qi > > -- > Best Regards, > Huang, Ying > > >> This will incur >> some runtime overhead. >> >> To drop memoryless node from fallback lists in this case, just >> call node_states_clear_node() before calling build_all_zonelists(). >> >> Signed-off-by: Qi Zheng >> Acked-by: David Hildenbrand > > [snip] > > -- > Best Regards, > Huang, Ying