kernel26-xen/patches-2.6.25-r1/1041-2.6.25-xen-x86-dcr-fallback.patch

Subject: Add fallback when XENMEM_exchange fails to replace contiguous region
From: jbeulich@novell.com
Patch-mainline: obsolete
References: 181869

This avoids losing precious special memory in places where any memory can be
used.

Index: head-2008-04-15/arch/x86/mm/hypervisor.c
===================================================================
--- head-2008-04-15.orig/arch/x86/mm/hypervisor.c	2008-04-15 10:34:43.000000000 +0200
+++ head-2008-04-15/arch/x86/mm/hypervisor.c	2008-04-15 10:48:04.000000000 +0200
@@ -41,6 +41,7 @@
 #include <xen/interface/memory.h>
 #include <linux/module.h>
 #include <linux/percpu.h>
+#include <linux/highmem.h>
 #include <asm/tlbflush.h>
 #include <linux/highmem.h>
 
@@ -426,6 +427,83 @@ void xen_destroy_contiguous_region(unsig
 		BUG();
 
 	balloon_unlock(flags);
+
+	if (unlikely(!success)) {
+		/* Try hard to get the special memory back to Xen. */
+		exchange.in.extent_order = 0;
+		set_xen_guest_handle(exchange.in.extent_start, &in_frame);
+
+		for (i = 0; i < (1U<<order); i++) {
+			struct page *page = alloc_page(__GFP_HIGHMEM|__GFP_COLD);
+			unsigned long pfn;
+			mmu_update_t mmu;
+			unsigned int j = 0;
+
+			if (!page) {
+				printk(KERN_WARNING "Xen and kernel out of memory "
+				       "while trying to release an order %u "
+				       "contiguous region\n", order);
+				break;
+			}
+			pfn = page_to_pfn(page);
+
+			balloon_lock(flags);
+
+			if (!PageHighMem(page)) {
+				void *v = __va(pfn << PAGE_SHIFT);
+
+				scrub_pages(v, 1);
+				MULTI_update_va_mapping(cr_mcl + j, (unsigned long)v,
+							__pte_ma(0), UVMF_INVLPG|UVMF_ALL);
+				++j;
+			}
+#ifdef CONFIG_XEN_SCRUB_PAGES
+			else {
+				scrub_pages(kmap(page), 1);
+				kunmap(page);
+				kmap_flush_unused();
+			}
+#endif
+
+			frame = pfn_to_mfn(pfn);
+			set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
+
+			MULTI_update_va_mapping(cr_mcl + j, vstart,
+						pfn_pte_ma(frame, PAGE_KERNEL),
+						UVMF_INVLPG|UVMF_ALL);
+			++j;
+
+			pfn = __pa(vstart) >> PAGE_SHIFT;
+			set_phys_to_machine(pfn, frame);
+			if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+				mmu.ptr = ((uint64_t)frame << PAGE_SHIFT) | MMU_MACHPHYS_UPDATE;
+				mmu.val = pfn;
+				cr_mcl[j].op = __HYPERVISOR_mmu_update;
+				cr_mcl[j].args[0] = (unsigned long)&mmu;
+				cr_mcl[j].args[1] = 1;
+				cr_mcl[j].args[2] = 0;
+				cr_mcl[j].args[3] = DOMID_SELF;
+				++j;
+			}
+
+			cr_mcl[j].op = __HYPERVISOR_memory_op;
+			cr_mcl[j].args[0] = XENMEM_decrease_reservation;
+			cr_mcl[j].args[1] = (unsigned long)&exchange.in;
+
+			if (HYPERVISOR_multicall(cr_mcl, j + 1))
+				BUG();
+			BUG_ON(cr_mcl[j].result != 1);
+			while (j--)
+				BUG_ON(cr_mcl[j].result != 0);
+
+			balloon_unlock(flags);
+
+			free_empty_pages(&page, 1);
+
+			in_frame++;
+			vstart += PAGE_SIZE;
+		}
+	}
 }
 EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
 
Index: head-2008-04-15/drivers/xen/balloon/balloon.c
===================================================================
--- head-2008-04-15.orig/drivers/xen/balloon/balloon.c	2008-04-15 10:48:02.000000000 +0200
+++ head-2008-04-15/drivers/xen/balloon/balloon.c	2008-04-15 10:48:04.000000000 +0200
@@ -686,7 +686,7 @@ struct page **alloc_empty_pages_and_page
 	goto out;
 }
 
-void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
+static void _free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages, int free_vec)
 {
 	unsigned long flags;
 	int i;
@@ -701,11 +701,24 @@ void free_empty_pages_and_pagevec(struct
 	}
 	balloon_unlock(flags);
 
-	kfree(pagevec);
+	if (free_vec)
+		kfree(pagevec);
+	else
+		totalram_pages = bs.current_pages -= nr_pages;
 
 	schedule_work(&balloon_worker);
 }
 
+void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
+{
+	_free_empty_pages_and_pagevec(pagevec, nr_pages, 1);
+}
+
+void free_empty_pages(struct page **pagevec, int nr_pages)
+{
+	_free_empty_pages_and_pagevec(pagevec, nr_pages, 0);
+}
+
 void balloon_release_driver_page(struct page *page)
 {
 	unsigned long flags;
Index: head-2008-04-15/include/xen/balloon.h
===================================================================
--- head-2008-04-15.orig/include/xen/balloon.h	2007-06-12 13:14:19.000000000 +0200
+++ head-2008-04-15/include/xen/balloon.h	2008-04-15 10:48:04.000000000 +0200
@@ -44,6 +44,10 @@ void balloon_update_driver_allowance(lon
 struct page **alloc_empty_pages_and_pagevec(int nr_pages);
 void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages);
 
+/* Free an empty page range (not allocated through
+   alloc_empty_pages_and_pagevec), adding to the balloon. */
+void free_empty_pages(struct page **pagevec, int nr_pages);
+
 void balloon_release_driver_page(struct page *page);
 
 /*
1	niro	609	Subject: Add fallback when XENMEM_exchange fails to replace contiguous region
2			From: jbeulich@novell.com
3			Patch-mainline: obsolete
4			References: 181869
5
6			This avoids losing precious special memory in places where any memory can be
7			used.
8
9			Index: head-2008-04-15/arch/x86/mm/hypervisor.c
10			===================================================================
11			--- head-2008-04-15.orig/arch/x86/mm/hypervisor.c 2008-04-15 10:34:43.000000000 +0200
12			+++ head-2008-04-15/arch/x86/mm/hypervisor.c 2008-04-15 10:48:04.000000000 +0200
13			@@ -41,6 +41,7 @@
14			#include <xen/interface/memory.h>
15			#include <linux/module.h>
16			#include <linux/percpu.h>
17			+#include <linux/highmem.h>
18			#include <asm/tlbflush.h>
19			#include <linux/highmem.h>
20
21			@@ -426,6 +427,83 @@ void xen_destroy_contiguous_region(unsig
22			BUG();
23
24			balloon_unlock(flags);
25			+
26			+ if (unlikely(!success)) {
27			+ /* Try hard to get the special memory back to Xen. */
28			+ exchange.in.extent_order = 0;
29			+ set_xen_guest_handle(exchange.in.extent_start, &in_frame);
30			+
31			+ for (i = 0; i < (1U<<order); i++) {
32			+ struct page *page = alloc_page(__GFP_HIGHMEM\|__GFP_COLD);
33			+ unsigned long pfn;
34			+ mmu_update_t mmu;
35			+ unsigned int j = 0;
36			+
37			+ if (!page) {
38			+ printk(KERN_WARNING "Xen and kernel out of memory "
39			+ "while trying to release an order %u "
40			+ "contiguous region\n", order);
41			+ break;
42			+ }
43			+ pfn = page_to_pfn(page);
44			+
45			+ balloon_lock(flags);
46			+
47			+ if (!PageHighMem(page)) {
48			+ void *v = __va(pfn << PAGE_SHIFT);
49			+
50			+ scrub_pages(v, 1);
51			+ MULTI_update_va_mapping(cr_mcl + j, (unsigned long)v,
52			+ __pte_ma(0), UVMF_INVLPG\|UVMF_ALL);
53			+ ++j;
54			+ }
55			+#ifdef CONFIG_XEN_SCRUB_PAGES
56			+ else {
57			+ scrub_pages(kmap(page), 1);
58			+ kunmap(page);
59			+ kmap_flush_unused();
60			+ }
61			+#endif
62			+
63			+ frame = pfn_to_mfn(pfn);
64			+ set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
65			+
66			+ MULTI_update_va_mapping(cr_mcl + j, vstart,
67			+ pfn_pte_ma(frame, PAGE_KERNEL),
68			+ UVMF_INVLPG\|UVMF_ALL);
69			+ ++j;
70			+
71			+ pfn = __pa(vstart) >> PAGE_SHIFT;
72			+ set_phys_to_machine(pfn, frame);
73			+ if (!xen_feature(XENFEAT_auto_translated_physmap)) {
74			+ mmu.ptr = ((uint64_t)frame << PAGE_SHIFT) \| MMU_MACHPHYS_UPDATE;
75			+ mmu.val = pfn;
76			+ cr_mcl[j].op = __HYPERVISOR_mmu_update;
77			+ cr_mcl[j].args[0] = (unsigned long)&mmu;
78			+ cr_mcl[j].args[1] = 1;
79			+ cr_mcl[j].args[2] = 0;
80			+ cr_mcl[j].args[3] = DOMID_SELF;
81			+ ++j;
82			+ }
83			+
84			+ cr_mcl[j].op = __HYPERVISOR_memory_op;
85			+ cr_mcl[j].args[0] = XENMEM_decrease_reservation;
86			+ cr_mcl[j].args[1] = (unsigned long)&exchange.in;
87			+
88			+ if (HYPERVISOR_multicall(cr_mcl, j + 1))
89			+ BUG();
90			+ BUG_ON(cr_mcl[j].result != 1);
91			+ while (j--)
92			+ BUG_ON(cr_mcl[j].result != 0);
93			+
94			+ balloon_unlock(flags);
95			+
96			+ free_empty_pages(&page, 1);
97			+
98			+ in_frame++;
99			+ vstart += PAGE_SIZE;
100			+ }
101			+ }
102			}
103			EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
104
105			Index: head-2008-04-15/drivers/xen/balloon/balloon.c
106			===================================================================
107			--- head-2008-04-15.orig/drivers/xen/balloon/balloon.c 2008-04-15 10:48:02.000000000 +0200
108			+++ head-2008-04-15/drivers/xen/balloon/balloon.c 2008-04-15 10:48:04.000000000 +0200
109			@@ -686,7 +686,7 @@ struct page **alloc_empty_pages_and_page
110			goto out;
111			}
112
113			-void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
114			+static void _free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages, int free_vec)
115			{
116			unsigned long flags;
117			int i;
118			@@ -701,11 +701,24 @@ void free_empty_pages_and_pagevec(struct
119			}
120			balloon_unlock(flags);
121
122			- kfree(pagevec);
123			+ if (free_vec)
124			+ kfree(pagevec);
125			+ else
126			+ totalram_pages = bs.current_pages -= nr_pages;
127
128			schedule_work(&balloon_worker);
129			}
130
131			+void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
132			+{
133			+ _free_empty_pages_and_pagevec(pagevec, nr_pages, 1);
134			+}
135			+
136			+void free_empty_pages(struct page **pagevec, int nr_pages)
137			+{
138			+ _free_empty_pages_and_pagevec(pagevec, nr_pages, 0);
139			+}
140			+
141			void balloon_release_driver_page(struct page *page)
142			{
143			unsigned long flags;
144			Index: head-2008-04-15/include/xen/balloon.h
145			===================================================================
146			--- head-2008-04-15.orig/include/xen/balloon.h 2007-06-12 13:14:19.000000000 +0200
147			+++ head-2008-04-15/include/xen/balloon.h 2008-04-15 10:48:04.000000000 +0200
148			@@ -44,6 +44,10 @@ void balloon_update_driver_allowance(lon
149			struct page **alloc_empty_pages_and_pagevec(int nr_pages);
150			void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages);
151
152			+/* Free an empty page range (not allocated through
153			+ alloc_empty_pages_and_pagevec), adding to the balloon. */
154			+void free_empty_pages(struct page **pagevec, int nr_pages);
155			+
156			void balloon_release_driver_page(struct page *page);
157
158			/*