After a successful hugetlb page migration by soft offline, the source page
will either be freed into hugepage_freelists or buddy(over-commit page). If page is in
buddy, page_hstate(page) will be NULL. It will hit a NULL pointer
dereference in dequeue_hwpoisoned_huge_page().
[ 890.677918] BUG: unable to handle kernel NULL pointer dereference at
0000000000000058
[ 890.685741] IP: [<ffffffff81163761>]
dequeue_hwpoisoned_huge_page+0x131/0x1d0
[ 890.692861] PGD c23762067 PUD c24be2067 PMD 0
[ 890.697314] Oops: 0000 [#1] SMP
So check PageHuge(page) after call migrate_pages() successfull.
Signed-off-by: Jianguo Wu <wujianguo@xxxxxxxxxx>
---
mm/memory-failure.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b7c1716..e5567f2 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1471,7 +1471,8 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags)
static int soft_offline_huge_page(struct page *page, int flags)
{
- int ret;
+ int ret, i;
+ unsigned long nr_pages;
unsigned long pfn = page_to_pfn(page);
struct page *hpage = compound_head(page);
LIST_HEAD(pagelist);
@@ -1489,6 +1490,8 @@ static int soft_offline_huge_page(struct page *page, int flags)
}
unlock_page(hpage);
+ nr_pages = 1 << compound_order(hpage);
+
/* Keep page count to indicate a given hugepage is isolated. */
list_move(&hpage->lru, &pagelist);
ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL,
@@ -1505,10 +1508,16 @@ static int soft_offline_huge_page(struct page *page, int flags)
if (ret > 0)
ret = -EIO;
} else {
- set_page_hwpoison_huge_page(hpage);
- dequeue_hwpoisoned_huge_page(hpage);
- atomic_long_add(1 << compound_order(hpage),
- &num_poisoned_pages);
+ /* over-commit hugetlb page will be freed into buddy */
+ if (PageHuge(page)) {
+ set_page_hwpoison_huge_page(hpage);
+ dequeue_hwpoisoned_huge_page(hpage);
+ } else {
+ for (i = 0; i < nr_pages; i++)
+ SetPageHWPoison(hpage + i);
+ }
+
+ atomic_long_add(nr_pages, &num_poisoned_pages);
}
return ret;
}
--
1.8.2.2
--
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