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[2003:cb:c707:1400:b7d:4122:28d:f4c3]) by smtp.gmail.com with ESMTPSA id a17-20020a056000101100b002c57475c375sm178787wrx.110.2023.02.15.05.16.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Feb 2023 05:16:06 -0800 (PST) Message-ID: <388b9a93-423f-33f8-0495-2a4a290fd1aa@redhat.com> Date: Wed, 15 Feb 2023 14:16:05 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH] mm/memory_hotplug: return zero from do_migrate_range() for only success To: SeongJae Park , akpm@linux-foundation.org Cc: osalvador@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230214223236.58430-1-sj@kernel.org> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230214223236.58430-1-sj@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: oh9omrpu1o41cizo7jowxtkxrq4zgdpw X-Rspam-User: X-Rspamd-Queue-Id: C985D8001B X-Rspamd-Server: rspam06 X-HE-Tag: 1676466969-352179 X-HE-Meta: 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 Q7JAikPj M8sLVhQJ0J35weXMz/Xf4vFVSykgn5C3Y7NOffJ91FUSYE2E+ZPbRGjAdbxdROdn30+6wBcKVt0gVA9Pw1WKss5wefu7U8ZVUBsBwlXQiy0eKjn6tlj2MqnAuukBE1m7yXR1NPDbPdzx9kN4b8P5QsWsZyT1tbJsMn+nahHG1faFzsR6Du36rOLRlotn/KUaZbgDYPOWVhUA6kLdZxwo7zpa01l7oLBhGDwwPC7eVtYXAbeHqLuxjmZO3tNf53qHGypYGclxnzh2QoIX8X+QIAz/Rdl98s9edKHnSR+DVF9wB2Fu7uV051Cth42/RKwmC7WW1lYINxTCjEatpBfJ7SGETuPFdt4L5bz2jSK7MEc7eIRa4IyOLcA8NwnKsepJsIavdY/c9QgMzDvYZ5RYQJvTp6of3RVwnsSNRtkYadgpM+wMlTkVpen+tbw+kVpyLbrnA 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 14.02.23 23:32, SeongJae Park wrote: > do_migrate_range() returns migrate_pages() return value, which zero > means perfect success, in usual cases. If all pages are failed to be > isolated, however, it returns isolate_{lru,movalbe}_page() return > values, or zero if all pfn were invalid, were hugetlb or hwpoisoned. So > do_migrate_range() returning zero means either perfect success, or > special cases of isolation total failure. > > Actually, the return value is not checked by any caller, so it might be > better to simply make it a void function. However, there is a TODO for > checking the return value. I'd prefer to not add more dead code ;) Let's not return an error instead. It's still unclear which kind of fatal migration issues we actually care about and how to really detect them. -- Thanks, David / dhildenb