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bh=U0LgVqQCYtX33qCxw4lWn6glWxSkvnLkN2wB2NOA4GA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=W8P+gEsrGigSC22hdhSFnkZSWjdZBt1gTksC1sU6uwkC2r5cEyvcZHy5gssr7/JGF 0zlcNopIONb+R8RdW3/j22DcAswYke5i7l4L8aWhlVF61J9hZdIDdfJlu8/6LVIMAW akmtaoyT625q8e+zD0hRVdplWJk63pwb+KPChv90WrpG6YnDaDLRqYyd2u/oANAEqL bZwgRjWr5ItMyjnb2wuLyUHptD+v/z4YVxABvOb/RsNMOk8EeWX9BtoIA2fBk9lo+x jtvwfSQPyu/IO/Q9uqNayocoJRGPM4qglv4YvMdKiamKK1PUyZy74bAA2/B9A2eoXR 3c2iWylgFj+ng== From: SeongJae Park To: David Hildenbrand Cc: SeongJae Park , akpm@linux-foundation.org, osalvador@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/memory_hotplug: return zero from do_migrate_range() for only success Date: Wed, 15 Feb 2023 18:03:16 +0000 Message-Id: <20230215180316.75431-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <388b9a93-423f-33f8-0495-2a4a290fd1aa@redhat.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 69FBE100002 X-Stat-Signature: 4q9dhzyhpaii4ha7pf8objqgnbfbg4hu X-Rspam-User: X-HE-Tag: 1676484200-324387 X-HE-Meta: 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 C6fSdPc5 k5lP2xMaPRWAxjsLaUIfjPhVRbL67PR16VJQx0HA6ck/ZA8Ed3t04QONnNAK3eh+Xf6rBKjJ9skal8hJnd1hUTFINC15bm8ToCRxwV2QfyStRfXrHpFOWZ4XQQxj0WWrQG1v+z2kfE6A1GtbVxFmHJDtpxToacy7i3diyo/4e4o+cVeCdR+Pg94Y1RSvEl9CDlPANCESZQpQfFcPEEmu+0EeSlgDxvEZCtSFPp1g5siJNWa0YW9s9e3/1g4TreITJwkfQ2rQzMMDBrmx14/YZQrKJ6MzFwjFbH95o6FjlRdM3kJ0+0Xj/Fv5pCFZnjV5pyCmVHREto+t+BLNJpRMyATcmFunj4sC5YlPi6TYJilZ16Ko= 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 Wed, 15 Feb 2023 14:16:05 +0100 David Hildenbrand wrote: > 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. Makes sense, I will send next spin soon. > > It's still unclear which kind of fatal migration issues we actually care > about and how to really detect them. What do you think about treating the isolation/migration rate limit (migrate_rs) hit in do_migrate_range() as fatal? It warns for the event already, so definitely a bad sign. If that's not that bad enough to be treated as fatal, I think we could have yet another rate limit to be considered fatal. Thanks, SJ > > -- > Thanks, > > David / dhildenb