Merge 6.9-rc5 into char-misc-next

We need the char/misc fixes in here as well to work off of.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 15 insertions, 3 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 9349948f1abf..9e62a00b46dd 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -154,11 +154,23 @@ static int __page_handle_poison(struct page *page)
 {
 	int ret;
 
-	zone_pcp_disable(page_zone(page));
+	/*
+	 * zone_pcp_disable() can't be used here. It will
+	 * hold pcp_batch_high_lock and dissolve_free_huge_page() might hold
+	 * cpu_hotplug_lock via static_key_slow_dec() when hugetlb vmemmap
+	 * optimization is enabled. This will break current lock dependency
+	 * chain and leads to deadlock.
+	 * Disabling pcp before dissolving the page was a deterministic
+	 * approach because we made sure that those pages cannot end up in any
+	 * PCP list. Draining PCP lists expels those pages to the buddy system,
+	 * but nothing guarantees that those pages do not get back to a PCP
+	 * queue if we need to refill those.
+	 */
 	ret = dissolve_free_huge_page(page);
-	if (!ret)
+	if (!ret) {
+		drain_all_pages(page_zone(page));
 		ret = take_page_off_buddy(page);
-	zone_pcp_enable(page_zone(page));
+	}
 
 	return ret;
 }