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From: David Hildenbrand <david@redhat.com>
To: Oscar Salvador <osalvador@suse.de>, akpm@linux-foundation.org
Cc: dan.j.williams@intel.com, pasha.tatashin@soleen.com,
	mhocko@suse.com, aneesh.kumar@linux.ibm.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm,sparse: Fix deactivate_section for early sections
Date: Thu, 18 Jul 2019 14:07:13 +0200
Message-ID: <d2268f86-f20d-22ff-e54f-48a2e609385b@redhat.com> (raw)
In-Reply-To: <20190715081549.32577-2-osalvador@suse.de>

On 15.07.19 10:15, Oscar Salvador wrote:
> deactivate_section checks whether a section is early or not
> in order to either call free_map_bootmem() or depopulate_section_memmap().
> Being the former for sections added at boot time, and the latter for
> sections hotplugged.
> 
> The problem is that we zero section_mem_map, so the last early_section()
> will always report false and the section will not be removed.
> 
> Fix this checking whether a section is early or not at function
> entry.
> 
> Fixes: mmotm ("mm/sparsemem: Support sub-section hotplug")
> Signed-off-by: Oscar Salvador <osalvador@suse.de>
> ---
>  mm/sparse.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 3267c4001c6d..1e224149aab6 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -738,6 +738,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
>  	DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
>  	DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
>  	struct mem_section *ms = __pfn_to_section(pfn);
> +	bool section_is_early = early_section(ms);
>  	struct page *memmap = NULL;
>  	unsigned long *subsection_map = ms->usage
>  		? &ms->usage->subsection_map[0] : NULL;
> @@ -772,7 +773,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
>  	if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION)) {
>  		unsigned long section_nr = pfn_to_section_nr(pfn);
>  
> -		if (!early_section(ms)) {
> +		if (!section_is_early) {
>  			kfree(ms->usage);
>  			ms->usage = NULL;
>  		}
> @@ -780,7 +781,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
>  		ms->section_mem_map = sparse_encode_mem_map(NULL, section_nr);
>  	}
>  
> -	if (early_section(ms) && memmap)
> +	if (section_is_early && memmap)
>  		free_map_bootmem(memmap);
>  	else
>  		depopulate_section_memmap(pfn, nr_pages, altmap);
> 

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

-- 

Thanks,

David / dhildenb


  parent reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-15  8:15 [PATCH 0/2] Fixes for sub-section hotplug Oscar Salvador
2019-07-15  8:15 ` [PATCH 1/2] mm,sparse: Fix deactivate_section for early sections Oscar Salvador
2019-07-15 16:02   ` Aneesh Kumar K.V
2019-07-16  4:33   ` Dan Williams
2019-07-18 12:07   ` David Hildenbrand [this message]
2019-07-15  8:15 ` [PATCH 2/2] mm,memory_hotplug: Fix shrink_{zone,node}_span Oscar Salvador
2019-07-15 16:11   ` Aneesh Kumar K.V
2019-07-15 21:24     ` Oscar Salvador
2019-07-17  2:28       ` Dan Williams
2019-07-17  7:38         ` Oscar Salvador
2019-07-17  8:01           ` David Hildenbrand
2019-07-17  8:08             ` Oscar Salvador
2019-07-17  5:38       ` Aneesh Kumar K.V
2019-07-17  7:42         ` Oscar Salvador
2019-07-18 12:05   ` Oscar Salvador

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