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SubjectRe: [PATCH 1/2] mm, memory_hotplug: cleanup memory offline path
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On 04.04.19 14:59, Oscar Salvador wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> check_pages_isolated_cb currently accounts the whole pfn range as being
> offlined if test_pages_isolated suceeds on the range. This is based on
> the assumption that all pages in the range are freed which is currently
> the case in most cases but it won't be with later changes, as pages
> marked as vmemmap won't be isolated.
>
> Move the offlined pages counting to offline_isolated_pages_cb and
> rely on __offline_isolated_pages to return the correct value.
> check_pages_isolated_cb will still do it's primary job and check the pfn
> range.
>
> While we are at it remove check_pages_isolated and offline_isolated_pages
> and use directly walk_system_ram_range as do in online_pages.
>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> Signed-off-by: Oscar Salvador <osalvador@suse.de>
> ---
> include/linux/memory_hotplug.h | 3 ++-
> mm/memory_hotplug.c | 46 +++++++++++-------------------------------
> mm/page_alloc.c | 11 ++++++++--
> 3 files changed, 23 insertions(+), 37 deletions(-)
>
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index 8ade08c50d26..3c8cf347804c 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -87,7 +87,8 @@ extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
> extern int online_pages(unsigned long, unsigned long, int);
> extern int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
> unsigned long *valid_start, unsigned long *valid_end);
> -extern void __offline_isolated_pages(unsigned long, unsigned long);
> +extern unsigned long __offline_isolated_pages(unsigned long start_pfn,
> + unsigned long end_pfn);
>
> typedef void (*online_page_callback_t)(struct page *page, unsigned int order);
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index f206b8b66af1..d8a3e9554aec 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1451,15 +1451,11 @@ static int
> offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
> void *data)
> {
> - __offline_isolated_pages(start, start + nr_pages);
> - return 0;
> -}
> + unsigned long offlined_pages;
>
> -static void
> -offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
> -{
> - walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
> - offline_isolated_pages_cb);
> + offlined_pages = __offline_isolated_pages(start, start + nr_pages);
> + *(unsigned long *)data += offlined_pages;

unsigned long *offlined_pages = data;

*offlined_pages += __offline_isolated_pages(start, start + nr_pages);

> + return 0;
> }
>
> /*
> @@ -1469,26 +1465,7 @@ static int
> check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
> void *data)
> {
> - int ret;
> - long offlined = *(long *)data;
> - ret = test_pages_isolated(start_pfn, start_pfn + nr_pages, true);
> - offlined = nr_pages;
> - if (!ret)
> - *(long *)data += offlined;
> - return ret;
> -}
> -
> -static long
> -check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
> -{
> - long offlined = 0;
> - int ret;
> -
> - ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
> - check_pages_isolated_cb);
> - if (ret < 0)
> - offlined = (long)ret;
> - return offlined;
> + return test_pages_isolated(start_pfn, start_pfn + nr_pages, true);
> }
>
> static int __init cmdline_parse_movable_node(char *p)
> @@ -1573,7 +1550,7 @@ static int __ref __offline_pages(unsigned long start_pfn,
> unsigned long end_pfn)
> {
> unsigned long pfn, nr_pages;
> - long offlined_pages;
> + unsigned long offlined_pages = 0;
> int ret, node, nr_isolate_pageblock;
> unsigned long flags;
> unsigned long valid_start, valid_end;
> @@ -1649,14 +1626,15 @@ static int __ref __offline_pages(unsigned long start_pfn,
> goto failed_removal_isolated;
> }
> /* check again */
> - offlined_pages = check_pages_isolated(start_pfn, end_pfn);
> - } while (offlined_pages < 0);
> + ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
> + check_pages_isolated_cb);

indentation looks strange, but might be my mail client.

> + } while (ret);
>
> - pr_info("Offlined Pages %ld\n", offlined_pages);
> /* Ok, all of our target is isolated.
> We cannot do rollback at this point. */
> - offline_isolated_pages(start_pfn, end_pfn);
> -
> + walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined_pages,
> + offline_isolated_pages_cb);

dito

> + pr_info("Offlined Pages %ld\n", offlined_pages);
> /*
> * Onlining will reset pagetype flags and makes migrate type
> * MOVABLE, so just need to decrease the number of isolated
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0c53807a2943..d36ca67064c9 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -8375,7 +8375,7 @@ void zone_pcp_reset(struct zone *zone)
> * All pages in the range must be in a single zone and isolated
> * before calling this.
> */
> -void
> +unsigned long
> __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
> {
> struct page *page;
> @@ -8383,12 +8383,15 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
> unsigned int order, i;
> unsigned long pfn;
> unsigned long flags;
> + unsigned long offlined_pages = 0;
> +
> /* find the first valid pfn */
> for (pfn = start_pfn; pfn < end_pfn; pfn++)
> if (pfn_valid(pfn))
> break;
> if (pfn == end_pfn)
> - return;
> + return offlined_pages;
> +
> offline_mem_sections(pfn, end_pfn);
> zone = page_zone(pfn_to_page(pfn));
> spin_lock_irqsave(&zone->lock, flags);
> @@ -8406,12 +8409,14 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
> if (unlikely(!PageBuddy(page) && PageHWPoison(page))) {
> pfn++;
> SetPageReserved(page);
> + offlined_pages++;
> continue;
> }
>
> BUG_ON(page_count(page));
> BUG_ON(!PageBuddy(page));
> order = page_order(page);
> + offlined_pages += 1 << order;
> #ifdef CONFIG_DEBUG_VM
> pr_info("remove from free list %lx %d %lx\n",
> pfn, 1 << order, end_pfn);
> @@ -8422,6 +8427,8 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
> pfn += (1 << order);
> }
> spin_unlock_irqrestore(&zone->lock, flags);
> +
> + return offlined_pages;
> }
> #endif
>
>


Only nits

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

--

Thanks,

David / dhildenb

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