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Subject: Re: [PATCH 2/3] mm/memory_hotplug: fix potential permanent lru cache
 disable
To:     Miaohe Lin <linmiaohe@huawei.com>, akpm@linux-foundation.org
Cc:     naoya.horiguchi@nec.com, mhocko@suse.com, minchan@kernel.org,
        cgoldswo@codeaurora.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <20210821094246.10149-1-linmiaohe@huawei.com>
 <20210821094246.10149-3-linmiaohe@huawei.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Message-ID: <985b591a-ef1f-cbbe-c627-a17240dc7bb6@redhat.com>
Date:   Mon, 23 Aug 2021 14:15:07 +0200
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On 21.08.21 11:42, Miaohe Lin wrote:
> If offline_pages failed after lru_cache_disable(), it forgot to do
> lru_cache_enable() in error path. So we would have lru cache disabled
> permanently in this case.
> 
> Fixes: d479960e44f2 ("mm: disable LRU pagevec during the migration temporarily")
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
>   mm/memory_hotplug.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index d986d3791986..9fd0be32a281 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -2033,6 +2033,7 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages,
>   	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
>   	memory_notify(MEM_CANCEL_OFFLINE, &arg);
>   failed_removal_pcplists_disabled:
> +	lru_cache_enable();
>   	zone_pcp_enable(zone);
>   failed_removal:
>   	pr_debug("memory offlining [mem %#010llx-%#010llx] failed due to %s\n",
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

As mentioned, this should be backported to stable.

-- 
Thanks,

David / dhildenb