Merge tag 'irqchip-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/core

Pull irqchip updates from Marc Zyngier

- The huge (and terrifying) TI INTR/INTA set of drivers
- Rewrite of the stm32mp1-exti driver as a platform driver
- Update the IOMMU MSI mapping API to be RT friendly
- A number of cleanups and other low impact fixes

1 files changed, 14 insertions, 1 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 76769749b5a5..6b10c21630f5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -966,6 +966,10 @@ static inline bool is_pci_p2pdma_page(const struct page *page)
 }
 #endif /* CONFIG_DEV_PAGEMAP_OPS */
 
+/* 127: arbitrary random number, small enough to assemble well */
+#define page_ref_zero_or_close_to_overflow(page) \
+	((unsigned int) page_ref_count(page) + 127u <= 127u)
+
 static inline void get_page(struct page *page)
 {
 	page = compound_head(page);
@@ -973,8 +977,17 @@ static inline void get_page(struct page *page)
 	 * Getting a normal page or the head of a compound page
 	 * requires to already have an elevated page->_refcount.
 	 */
-	VM_BUG_ON_PAGE(page_ref_count(page) <= 0, page);
+	VM_BUG_ON_PAGE(page_ref_zero_or_close_to_overflow(page), page);
+	page_ref_inc(page);
+}
+
+static inline __must_check bool try_get_page(struct page *page)
+{
+	page = compound_head(page);
+	if (WARN_ON_ONCE(page_ref_count(page) <= 0))
+		return false;
 	page_ref_inc(page);
+	return true;
 }
 
 static inline void put_page(struct page *page)