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authorGerald Schaefer <gerald.schaefer@de.ibm.com>2016-10-07 17:01:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-07 18:46:29 -0700
commit082d5b6b60e9f25e1511557fcfcb21eedd267446 (patch)
tree96193389b0c0ec724e7cb8ae8c34270642fbd15b /mm
parent2247bb335ab9c40058484cac36ea74ee652f3b7b (diff)
mm/hugetlb: check for reserved hugepages during memory offline
In dissolve_free_huge_pages(), free hugepages will be dissolved without making sure that there are enough of them left to satisfy hugepage reservations. Fix this by adding a return value to dissolve_free_huge_pages() and checking h->free_huge_pages vs. h->resv_huge_pages. Note that this may lead to the situation where dissolve_free_huge_page() returns an error and all free hugepages that were dissolved before that error are lost, while the memory block still cannot be set offline. Fixes: c8721bbb ("mm: memory-hotplug: enable memory hotplug to handle hugepage") Link: http://lkml.kernel.org/r/20160926172811.94033-3-gerald.schaefer@de.ibm.com Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Rui Teng <rui.teng@linux.vnet.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/hugetlb.c26
-rw-r--r--mm/memory_hotplug.c4
2 files changed, 24 insertions, 6 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 603bdd01ec2c..91ae1f567997 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1437,22 +1437,32 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
/*
* Dissolve a given free hugepage into free buddy pages. This function does
- * nothing for in-use (including surplus) hugepages.
+ * nothing for in-use (including surplus) hugepages. Returns -EBUSY if the
+ * number of free hugepages would be reduced below the number of reserved
+ * hugepages.
*/
-static void dissolve_free_huge_page(struct page *page)
+static int dissolve_free_huge_page(struct page *page)
{
+ int rc = 0;
+
spin_lock(&hugetlb_lock);
if (PageHuge(page) && !page_count(page)) {
struct page *head = compound_head(page);
struct hstate *h = page_hstate(head);
int nid = page_to_nid(head);
+ if (h->free_huge_pages - h->resv_huge_pages == 0) {
+ rc = -EBUSY;
+ goto out;
+ }
list_del(&head->lru);
h->free_huge_pages--;
h->free_huge_pages_node[nid]--;
h->max_huge_pages--;
update_and_free_page(h, head);
}
+out:
spin_unlock(&hugetlb_lock);
+ return rc;
}
/*
@@ -1460,16 +1470,22 @@ static void dissolve_free_huge_page(struct page *page)
* make specified memory blocks removable from the system.
* Note that this will dissolve a free gigantic hugepage completely, if any
* part of it lies within the given range.
+ * Also note that if dissolve_free_huge_page() returns with an error, all
+ * free hugepages that were dissolved before that error are lost.
*/
-void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
+int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
+ int rc = 0;
if (!hugepages_supported())
- return;
+ return rc;
for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order)
- dissolve_free_huge_page(pfn_to_page(pfn));
+ if (rc = dissolve_free_huge_page(pfn_to_page(pfn)))
+ break;
+
+ return rc;
}
/*
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9d29ba0f7192..962927309b6e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1945,7 +1945,9 @@ repeat:
* dissolve free hugepages in the memory block before doing offlining
* actually in order to make hugetlbfs's object counting consistent.
*/
- dissolve_free_huge_pages(start_pfn, end_pfn);
+ ret = dissolve_free_huge_pages(start_pfn, end_pfn);
+ if (ret)
+ goto failed_removal;
/* check again */
offlined_pages = check_pages_isolated(start_pfn, end_pfn);
if (offlined_pages < 0) {