From: Tianyu Lan <[email protected]>
If size of offline memory region passed to offline_pages() is
not aligned with PAGES_PER_SECTION, memory section will be set
to offline in the offline_mem_sections() with some pages of
memory section online. Fix it, Update memory section status after
marking offline pages as "reserved" in __offline_isolated_pages()
and check all pages in memory are reserved or not before setting
memory section offline.
Signed-off-by: Tianyu Lan <[email protected]>
---
This patch is to prepare for hot remove memory function in Hyper-V
balloon driver. It requests to offline memory with random size.
---
mm/page_alloc.c | 3 ++-
mm/sparse.c | 10 ++++++++++
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index dbd0d5cbbcbb..cc02866924ae 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8540,7 +8540,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
if (pfn == end_pfn)
return offlined_pages;
- offline_mem_sections(pfn, end_pfn);
zone = page_zone(pfn_to_page(pfn));
spin_lock_irqsave(&zone->lock, flags);
pfn = start_pfn;
@@ -8576,6 +8575,8 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
}
spin_unlock_irqrestore(&zone->lock, flags);
+ offline_mem_sections(pfn, end_pfn);
+
return offlined_pages;
}
#endif
diff --git a/mm/sparse.c b/mm/sparse.c
index fd13166949b5..eb5860487b84 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -571,6 +571,7 @@ void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
+ int i;
for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
unsigned long section_nr = pfn_to_section_nr(pfn);
@@ -583,6 +584,15 @@ void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
if (WARN_ON(!valid_section_nr(section_nr)))
continue;
+ /*
+ * Check whether all pages in the section are reserverd before
+ * setting setction offline.
+ */
+ for (i = 0; i < PAGES_PER_SECTION; i++)
+ if (!PageReserved(pfn_to_page(
+ SECTION_ALIGN_DOWN(pfn + i))))
+ continue;
+
ms = __nr_to_section(section_nr);
ms->section_mem_map &= ~SECTION_IS_ONLINE;
}
--
2.14.5
On 08.10.19 16:36, [email protected] wrote:
> From: Tianyu Lan <[email protected]>
>
> If size of offline memory region passed to offline_pages() is
> not aligned with PAGES_PER_SECTION, memory section will be set
> to offline in the offline_mem_sections() with some pages of
> memory section online. Fix it, Update memory section status after
> marking offline pages as "reserved" in __offline_isolated_pages()
> and check all pages in memory are reserved or not before setting
> memory section offline.
>
> Signed-off-by: Tianyu Lan <[email protected]>
> ---
> This patch is to prepare for hot remove memory function in Hyper-V
> balloon driver. It requests to offline memory with random size.
I proposed roughly the same a while ago. See
https://lkml.org/lkml/2018/4/30/207
Memory onlining/offlining works in memory block granularity only.
Sub-sections, you have to emulate it on top, similar to how hyper-v
balloon handles it already. E.g., have a look how virtio-mem handles it
using alloc_contig_range/free_contig_range and PG_offline extensions.
https://lkml.org/lkml/2018/4/30/207
So a clear NACK from my side.
> ---
> mm/page_alloc.c | 3 ++-
> mm/sparse.c | 10 ++++++++++
> 2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index dbd0d5cbbcbb..cc02866924ae 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -8540,7 +8540,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
> if (pfn == end_pfn)
> return offlined_pages;
>
> - offline_mem_sections(pfn, end_pfn);
> zone = page_zone(pfn_to_page(pfn));
> spin_lock_irqsave(&zone->lock, flags);
> pfn = start_pfn;
> @@ -8576,6 +8575,8 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
> }
> spin_unlock_irqrestore(&zone->lock, flags);
>
> + offline_mem_sections(pfn, end_pfn);
> +
> return offlined_pages;
> }
> #endif
> diff --git a/mm/sparse.c b/mm/sparse.c
> index fd13166949b5..eb5860487b84 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -571,6 +571,7 @@ void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
> void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
> {
> unsigned long pfn;
> + int i;
>
> for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
> unsigned long section_nr = pfn_to_section_nr(pfn);
> @@ -583,6 +584,15 @@ void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
> if (WARN_ON(!valid_section_nr(section_nr)))
> continue;
>
> + /*
> + * Check whether all pages in the section are reserverd before
> + * setting setction offline.
> + */
> + for (i = 0; i < PAGES_PER_SECTION; i++)
> + if (!PageReserved(pfn_to_page(
> + SECTION_ALIGN_DOWN(pfn + i))))
> + continue;
> +
> ms = __nr_to_section(section_nr);
> ms->section_mem_map &= ~SECTION_IS_ONLINE;
> }
>
--
Thanks,
David / dhildenb