From 1ef5e651fd34ac0fa66393a6eedc16eced2aac22 Mon Sep 17 00:00:00 2001
From: Mark Johnston <markj@FreeBSD.org>
Date: Thu, 6 Jun 2019 16:09:19 +0000
Subject: [PATCH] Make the linuxkpi's alloc_pages() consistently return wired
 pages.

Previously it did this only on platforms without a direct map.  This
also more closely matches Linux's semantics.

Since some DRM v5.0 code assumes the old behaviour, use a
LINUXKPI_VERSION guard to preserve that until the out-of-tree module
is updated.

Reviewed by:	hselasky, kib (earlier versions), johalun
MFC after:	1 week
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D20502
---
 sys/compat/linuxkpi/common/include/linux/gfp.h | 16 ++++++++++++++--
 sys/compat/linuxkpi/common/src/linux_page.c    | 12 +++++++++---
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/sys/compat/linuxkpi/common/include/linux/gfp.h b/sys/compat/linuxkpi/common/include/linux/gfp.h
index a20e3606ca0..49fefb4df61 100644
--- a/sys/compat/linuxkpi/common/include/linux/gfp.h
+++ b/sys/compat/linuxkpi/common/include/linux/gfp.h
@@ -52,12 +52,15 @@
 #define	__GFP_RETRY_MAYFAIL 0
 #define	__GFP_MOVABLE	0
 #define	__GFP_COMP	0
-#define        __GFP_KSWAPD_RECLAIM 0
+#define	__GFP_KSWAPD_RECLAIM 0
 
 #define	__GFP_IO	0
 #define	__GFP_NO_KSWAPD	0
 #define	__GFP_WAIT	M_WAITOK
 #define	__GFP_DMA32	(1U << 24) /* LinuxKPI only */
+#if defined(LINUXKPI_VERSION) && LINUXKPI_VERSION == 50000
+#define	__GFP_NOTWIRED	(1U << 25)
+#endif
 #define	__GFP_BITS_SHIFT 25
 #define	__GFP_BITS_MASK	((1 << __GFP_BITS_SHIFT) - 1)
 #define	__GFP_NOFAIL	M_WAITOK
@@ -74,7 +77,7 @@
 #define	GFP_TEMPORARY	M_NOWAIT
 #define	GFP_NATIVE_MASK	(M_NOWAIT | M_WAITOK | M_USE_RESERVE | M_ZERO)
 #define	GFP_TRANSHUGE	0
-#define        GFP_TRANSHUGE_LIGHT 0
+#define	GFP_TRANSHUGE_LIGHT	0
 
 CTASSERT((__GFP_DMA32 & GFP_NATIVE_MASK) == 0);
 CTASSERT((__GFP_BITS_MASK & GFP_NATIVE_MASK) == GFP_NATIVE_MASK);
@@ -98,6 +101,9 @@ static inline struct page *
 alloc_page(gfp_t flags)
 {
 
+#ifdef __GFP_NOTWIRED
+	flags |= __GFP_NOTWIRED;
+#endif
 	return (linux_alloc_pages(flags, 0));
 }
 
@@ -105,6 +111,9 @@ static inline struct page *
 alloc_pages(gfp_t flags, unsigned int order)
 {
 
+#ifdef __GFP_NOTWIRED
+	flags |= __GFP_NOTWIRED;
+#endif
 	return (linux_alloc_pages(flags, order));
 }
 
@@ -112,6 +121,9 @@ static inline struct page *
 alloc_pages_node(int node_id, gfp_t flags, unsigned int order)
 {
 
+#ifdef __GFP_NOTWIRED
+	flags |= __GFP_NOTWIRED;
+#endif
 	return (linux_alloc_pages(flags, order));
 }
 
diff --git a/sys/compat/linuxkpi/common/src/linux_page.c b/sys/compat/linuxkpi/common/src/linux_page.c
index 59ed47c175b..2ff15a68b98 100644
--- a/sys/compat/linuxkpi/common/src/linux_page.c
+++ b/sys/compat/linuxkpi/common/src/linux_page.c
@@ -91,9 +91,14 @@ linux_alloc_pages(gfp_t flags, unsigned int order)
 
 	if (PMAP_HAS_DMAP) {
 		unsigned long npages = 1UL << order;
-		int req = (flags & M_ZERO) ? (VM_ALLOC_ZERO | VM_ALLOC_NOOBJ |
-		    VM_ALLOC_NORMAL) : (VM_ALLOC_NOOBJ | VM_ALLOC_NORMAL);
+		int req = VM_ALLOC_NOOBJ | VM_ALLOC_WIRED | VM_ALLOC_NORMAL;
 
+#ifdef __GFP_NOTWIRED
+		if ((flags & __GFP_NOTWIRED) != 0)
+			req &= ~VM_ALLOC_WIRED;
+#endif
+		if ((flags & M_ZERO) != 0)
+			req |= VM_ALLOC_ZERO;
 		if (order == 0 && (flags & GFP_DMA32) == 0) {
 			page = vm_page_alloc(NULL, 0, req);
 			if (page == NULL)
@@ -154,7 +159,8 @@ linux_free_pages(vm_page_t page, unsigned int order)
 			vm_page_t pgo = page + x;
 
 			vm_page_lock(pgo);
-			vm_page_free(pgo);
+			if (vm_page_unwire_noq(pgo))
+				vm_page_free(pgo);
 			vm_page_unlock(pgo);
 		}
 	} else {