In-use hugetlb pages can be migrated as any other page (LRU
and Movable), so let alloc_contig_range handle them.
All we need is to succesfully isolate such page.
Signed-off-by: Oscar Salvador <[email protected]>
---
include/linux/hugetlb.h | 5 +++--
mm/compaction.c | 11 ++++++++++-
mm/hugetlb.c | 6 ++++--
mm/vmscan.c | 5 +++--
4 files changed, 20 insertions(+), 7 deletions(-)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 72352d718829..8c17d0dbc87c 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -505,7 +505,7 @@ struct huge_bootmem_page {
struct hstate *hstate;
};
-bool isolate_or_dissolve_huge_page(struct page *page);
+bool isolate_or_dissolve_huge_page(struct page *page, struct list_head *list);
struct page *alloc_huge_page(struct vm_area_struct *vma,
unsigned long addr, int avoid_reserve);
struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
@@ -776,7 +776,8 @@ void set_page_huge_active(struct page *page);
#else /* CONFIG_HUGETLB_PAGE */
struct hstate {};
-static inline bool isolate_or_dissolve_huge_page(struct page *page)
+static inline bool isolate_or_dissolve_huge_page(struct page *page,
+ struct list_head *list)
{
return false;
}
diff --git a/mm/compaction.c b/mm/compaction.c
index d52506ed9db7..55a41a9228a9 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -906,9 +906,17 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
}
if (PageHuge(page) && cc->alloc_contig) {
- if (!isolate_or_dissolve_huge_page(page))
+ if (!isolate_or_dissolve_huge_page(page, &cc->migratepages))
goto isolate_fail;
+ if (PageHuge(page)) {
+ /*
+ * Hugepage was succesfully isolated.
+ */
+ low_pfn += compound_nr(page) - 1;
+ goto isolate_success_no_list;
+ }
+
/*
* Ok, the hugepage was dissolved. Now these pages are
* Buddy and cannot be re-allocated because they are
@@ -1053,6 +1061,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
isolate_success:
list_add(&page->lru, &cc->migratepages);
+isolate_success_no_list:
cc->nr_migratepages += compound_nr(page);
nr_isolated += compound_nr(page);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index b78926bca60a..9fa678d13c68 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2351,7 +2351,7 @@ static bool alloc_and_dissolve_huge_page(struct hstate *h, struct page *page)
return ret;
}
-bool isolate_or_dissolve_huge_page(struct page *page)
+bool isolate_or_dissolve_huge_page(struct page *page, struct list_head *list)
{
struct hstate *h = NULL;
struct page *head;
@@ -2379,7 +2379,9 @@ bool isolate_or_dissolve_huge_page(struct page *page)
*/
return ret;
- if(!page_count(head) && alloc_and_dissolve_huge_page(h, head))
+ if (page_count(head) && isolate_huge_page(head, list))
+ ret = true;
+ else if(!page_count(head) && alloc_and_dissolve_huge_page(h, head))
ret = true;
return ret;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b1b574ad199d..0803adca4469 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1506,8 +1506,9 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
LIST_HEAD(clean_pages);
list_for_each_entry_safe(page, next, page_list, lru) {
- if (page_is_file_lru(page) && !PageDirty(page) &&
- !__PageMovable(page) && !PageUnevictable(page)) {
+ if (!PageHuge(page) && page_is_file_lru(page) &&
+ !PageDirty(page) && !__PageMovable(page) &&
+ !PageUnevictable(page)) {
ClearPageActive(page);
list_move(&page->lru, &clean_pages);
}
--
2.16.3
On Wed 17-02-21 14:46:49, Oscar Salvador wrote:
> On Wed, Feb 17, 2021 at 02:36:31PM +0100, Michal Hocko wrote:
> > On Wed 17-02-21 11:08:16, Oscar Salvador wrote:
> > > In-use hugetlb pages can be migrated as any other page (LRU
> > > and Movable), so let alloc_contig_range handle them.
> > >
> > > All we need is to succesfully isolate such page.
> >
> > Again, this is missing a problem statement and a justification why we
> > want/need this.
>
> Heh, I was poor in words.
>
> "alloc_contig_range() will fail miserably if it finds a HugeTLB page within
> the range without a chance to handle them. Since HugeTLB pages can be migrated
> as any other page (LRU and Movable), it does not make sense to bail out.
> Enable the interface to recognize in-use HugeTLB pages and have a chance
> to migrate them"
>
> What about something along those lines?
Is this a real life problem? I know we _can_ but I do not see any
reasoning _why_ should we care all that much.
--
Michal Hocko
SUSE Labs
On Wed 17-02-21 11:08:16, Oscar Salvador wrote:
> In-use hugetlb pages can be migrated as any other page (LRU
> and Movable), so let alloc_contig_range handle them.
>
> All we need is to succesfully isolate such page.
>
> Signed-off-by: Oscar Salvador <[email protected]>
> ---
> include/linux/hugetlb.h | 5 +++--
> mm/compaction.c | 11 ++++++++++-
> mm/hugetlb.c | 6 ++++--
> mm/vmscan.c | 5 +++--
> 4 files changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 72352d718829..8c17d0dbc87c 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -505,7 +505,7 @@ struct huge_bootmem_page {
> struct hstate *hstate;
> };
>
> -bool isolate_or_dissolve_huge_page(struct page *page);
> +bool isolate_or_dissolve_huge_page(struct page *page, struct list_head *list);
> struct page *alloc_huge_page(struct vm_area_struct *vma,
> unsigned long addr, int avoid_reserve);
> struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
> @@ -776,7 +776,8 @@ void set_page_huge_active(struct page *page);
> #else /* CONFIG_HUGETLB_PAGE */
> struct hstate {};
>
> -static inline bool isolate_or_dissolve_huge_page(struct page *page)
> +static inline bool isolate_or_dissolve_huge_page(struct page *page,
> + struct list_head *list)
> {
> return false;
> }
> diff --git a/mm/compaction.c b/mm/compaction.c
> index d52506ed9db7..55a41a9228a9 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -906,9 +906,17 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
> }
>
> if (PageHuge(page) && cc->alloc_contig) {
> - if (!isolate_or_dissolve_huge_page(page))
> + if (!isolate_or_dissolve_huge_page(page, &cc->migratepages))
> goto isolate_fail;
>
> + if (PageHuge(page)) {
> + /*
> + * Hugepage was succesfully isolated.
> + */
> + low_pfn += compound_nr(page) - 1;
> + goto isolate_success_no_list;
> + }
> +
> /*
> * Ok, the hugepage was dissolved. Now these pages are
> * Buddy and cannot be re-allocated because they are
> @@ -1053,6 +1061,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
>
> isolate_success:
> list_add(&page->lru, &cc->migratepages);
> +isolate_success_no_list:
> cc->nr_migratepages += compound_nr(page);
I do not follow. You have successfully isolated huge pages so why don't
you add that page to the migratepages list to be migrated?
--
Michal Hocko
SUSE Labs
On 2021-02-17 16:06, Michal Hocko wrote:
> I do not follow. You have successfully isolated huge pages so why don't
> you add that page to the migratepages list to be migrated?
It is added. Note that I pass de list (cc->migratepages) to
isolate_or_dissolve_huge_page().
It is done this way because we have to pass the list to
isolate_huge_page() directly.
That is why I jump to isolate_success_no_list instead of isolate_sucess.
I know it is subtle, but I could not come up with a better name at that
time.
--
Oscar Salvador
SUSE L3
On Wed 17-02-21 16:27:27, Oscar Salvador wrote:
> On 2021-02-17 16:06, Michal Hocko wrote:
> > I do not follow. You have successfully isolated huge pages so why don't
> > you add that page to the migratepages list to be migrated?
>
> It is added. Note that I pass de list (cc->migratepages) to
> isolate_or_dissolve_huge_page().
> It is done this way because we have to pass the list to isolate_huge_page()
> directly.
> That is why I jump to isolate_success_no_list instead of isolate_sucess.
>
> I know it is subtle, but I could not come up with a better name at that
> time.
OK, I have missed that. Maybe just extend the comment.
/*
* Hugepage was succesfully isolated and on the tmigratepages
* list
*/
--
Michal Hocko
SUSE Labs
On Wed 17-02-21 11:08:16, Oscar Salvador wrote:
> In-use hugetlb pages can be migrated as any other page (LRU
> and Movable), so let alloc_contig_range handle them.
>
> All we need is to succesfully isolate such page.
Again, this is missing a problem statement and a justification why we
want/need this.
--
Michal Hocko
SUSE Labs
On Wed, Feb 17, 2021 at 02:36:31PM +0100, Michal Hocko wrote:
> On Wed 17-02-21 11:08:16, Oscar Salvador wrote:
> > In-use hugetlb pages can be migrated as any other page (LRU
> > and Movable), so let alloc_contig_range handle them.
> >
> > All we need is to succesfully isolate such page.
>
> Again, this is missing a problem statement and a justification why we
> want/need this.
Heh, I was poor in words.
"alloc_contig_range() will fail miserably if it finds a HugeTLB page within
the range without a chance to handle them. Since HugeTLB pages can be migrated
as any other page (LRU and Movable), it does not make sense to bail out.
Enable the interface to recognize in-use HugeTLB pages and have a chance
to migrate them"
What about something along those lines?
--
Oscar Salvador
SUSE L3
On Wed, Feb 17, 2021 at 04:33:18PM +0100, Michal Hocko wrote:
> OK, I have missed that. Maybe just extend the comment.
>
> /*
> * Hugepage was succesfully isolated and on the tmigratepages
> * list
> */
Sure, I will improve it.
Thanks
--
Oscar Salvador
SUSE L3