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Groups > linux.kernel > #1662274
| From | Wei Wang <wei.w.wang@intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v11 4/6] mm: function to offer a page block on the free list |
| Date | 2017-06-09 12:50 +0200 |
| Message-ID | <tQpEl-qv-7@gated-at.bofh.it> (permalink) |
| References | <tQpEl-qv-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Add a function to find a page block on the free list specified by the
caller. Pages from the page block may be used immediately after the
function returns. The caller is responsible for detecting or preventing
the use of such pages.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Liang Li <liang.z.li@intel.com>
---
include/linux/mm.h | 5 +++
mm/page_alloc.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 96 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5d22e69..82361a6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1841,6 +1841,11 @@ extern void free_area_init_node(int nid, unsigned long * zones_size,
unsigned long zone_start_pfn, unsigned long *zholes_size);
extern void free_initmem(void);
+#if IS_ENABLED(CONFIG_VIRTIO_BALLOON)
+extern int report_unused_page_block(struct zone *zone, unsigned int order,
+ unsigned int migratetype,
+ struct page **page);
+#endif
/*
* Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
* into the buddy system. The freed pages will be poisoned with pattern
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2c25de4..0aefe02 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4615,6 +4615,97 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
show_swap_cache_info();
}
+#if IS_ENABLED(CONFIG_VIRTIO_BALLOON)
+
+/*
+ * Heuristically get a page block in the system that is unused.
+ * It is possible that pages from the page block are used immediately after
+ * report_unused_page_block() returns. It is the caller's responsibility
+ * to either detect or prevent the use of such pages.
+ *
+ * The free list to check: zone->free_area[order].free_list[migratetype].
+ *
+ * If the caller supplied page block (i.e. **page) is on the free list, offer
+ * the next page block on the list to the caller. Otherwise, offer the first
+ * page block on the list.
+ *
+ * Return 0 when a page block is found on the caller specified free list.
+ */
+int report_unused_page_block(struct zone *zone, unsigned int order,
+ unsigned int migratetype, struct page **page)
+{
+ struct zone *this_zone;
+ struct list_head *this_list;
+ int ret = 0;
+ unsigned long flags;
+
+ /* Sanity check */
+ if (zone == NULL || page == NULL || order >= MAX_ORDER ||
+ migratetype >= MIGRATE_TYPES)
+ return -EINVAL;
+
+ /* Zone validity check */
+ for_each_populated_zone(this_zone) {
+ if (zone == this_zone)
+ break;
+ }
+
+ /* Got a non-existent zone from the caller? */
+ if (zone != this_zone)
+ return -EINVAL;
+
+ spin_lock_irqsave(&this_zone->lock, flags);
+
+ this_list = &zone->free_area[order].free_list[migratetype];
+ if (list_empty(this_list)) {
+ *page = NULL;
+ ret = 1;
+ goto out;
+ }
+
+ /* The caller is asking for the first free page block on the list */
+ if ((*page) == NULL) {
+ *page = list_first_entry(this_list, struct page, lru);
+ ret = 0;
+ goto out;
+ }
+
+ /*
+ * The page block passed from the caller is not on this free list
+ * anymore (e.g. a 1MB free page block has been split). In this case,
+ * offer the first page block on the free list that the caller is
+ * asking for.
+ */
+ if (PageBuddy(*page) && order != page_order(*page)) {
+ *page = list_first_entry(this_list, struct page, lru);
+ ret = 0;
+ goto out;
+ }
+
+ /*
+ * The page block passed from the caller has been the last page block
+ * on the list.
+ */
+ if ((*page)->lru.next == this_list) {
+ *page = NULL;
+ ret = 1;
+ goto out;
+ }
+
+ /*
+ * Finally, fall into the regular case: the page block passed from the
+ * caller is still on the free list. Offer the next one.
+ */
+ *page = list_next_entry((*page), lru);
+ ret = 0;
+out:
+ spin_unlock_irqrestore(&this_zone->lock, flags);
+ return ret;
+}
+EXPORT_SYMBOL(report_unused_page_block);
+
+#endif
+
static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
{
zoneref->zone = zone;
--
2.7.4
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH v11 0/6] Virtio-balloon Enhancement Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
[PATCH v11 5/6] mm: export symbol of next_zone and first_online_pgdat Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
[PATCH v11 4/6] mm: function to offer a page block on the free list Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
Re: [PATCH v11 4/6] mm: function to offer a page block on the free list Dave Hansen <dave.hansen@intel.com> - 2017-06-12 16:20 +0200
Re: [PATCH v11 4/6] mm: function to offer a page block on the free list "Michael S. Tsirkin" <mst@redhat.com> - 2017-06-12 18:30 +0200
Re: [PATCH v11 4/6] mm: function to offer a page block on the free list Dave Hansen <dave.hansen@intel.com> - 2017-06-12 18:50 +0200
Re: [PATCH v11 4/6] mm: function to offer a page block on the free list "Michael S. Tsirkin" <mst@redhat.com> - 2017-06-12 22:40 +0200
Re: [PATCH v11 4/6] mm: function to offer a page block on the free list Dave Hansen <dave.hansen@intel.com> - 2017-06-12 23:00 +0200
Re: [PATCH v11 4/6] mm: function to offer a page block on the free list Wei Wang <wei.w.wang@intel.com> - 2017-06-13 05:00 +0200
[PATCH v11 1/6] virtio-balloon: deflate via a page list Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
[PATCH v11 2/6] virtio-balloon: coding format cleanup Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
[PATCH v11 6/6] virtio-balloon: VIRTIO_BALLOON_F_CMD_VQ Wei Wang <wei.w.wang@intel.com> - 2017-06-09 12:50 +0200
Re: [PATCH v11 6/6] virtio-balloon: VIRTIO_BALLOON_F_CMD_VQ Dave Hansen <dave.hansen@intel.com> - 2017-06-12 16:10 +0200
Re: [PATCH v11 6/6] virtio-balloon: VIRTIO_BALLOON_F_CMD_VQ Wei Wang <wei.w.wang@intel.com> - 2017-06-13 12:20 +0200
[PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS Wei Wang <wei.w.wang@intel.com> - 2017-06-09 13:00 +0200
Re: [PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS "Michael S. Tsirkin" <mst@redhat.com> - 2017-06-13 20:00 +0200
Re: [PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS Dave Hansen <dave.hansen@intel.com> - 2017-06-13 20:00 +0200
Re: [PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS "Michael S. Tsirkin" <mst@redhat.com> - 2017-06-13 21:00 +0200
Re: [virtio-dev] Re: [PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS Wei Wang <wei.w.wang@intel.com> - 2017-06-15 10:10 +0200
Re: [virtio-dev] Re: [PATCH v11 3/6] virtio-balloon: VIRTIO_BALLOON_F_PAGE_CHUNKS "Michael S. Tsirkin" <mst@redhat.com> - 2017-06-16 05:20 +0200
RE: [PATCH v11 0/6] Virtio-balloon Enhancement "Wang, Wei W" <wei.w.wang@intel.com> - 2017-06-09 13:20 +0200
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