Message-ID: <388b9a93-423f-33f8-0495-2a4a290fd1aa@redhat.com>
Date:   Wed, 15 Feb 2023 14:16:05 +0100
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Subject: Re: [PATCH] mm/memory_hotplug: return zero from do_migrate_range()
 for only success
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To:     SeongJae Park <sj@kernel.org>, 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 <david@redhat.com>
Organization: Red Hat
In-Reply-To: <20230214223236.58430-1-sj@kernel.org>
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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