Don't allow memory to be added above the allowed maximum allocation
limit set by Xen.
Trying to do so would result in cases like the following:
[ 584.559652] ------------[ cut here ]------------
[ 584.564897] WARNING: CPU: 2 PID: 1 at ../arch/x86/xen/multicalls.c:129
xen_alloc_pte+0x1c7/0x390()
[ 584.575151] Modules linked in:
[ 584.578643] Supported: Yes
[ 584.581750] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.4.120-92.70-default
#1
[ 584.590000] Hardware name: Cisco Systems Inc UCSC-C460-M4/UCSC-C460-M4, BIOS
C460M4.4.0.1b.0.0629181419 06/29/2018
[ 584.601862] 0000000000000000 ffffffff813175a0 0000000000000000
ffffffff8184777c
[ 584.610200] ffffffff8107f4e1 ffff880487eb7000 ffff8801862b79c0
ffff88048608d290
[ 584.618537] 0000000000487eb7 ffffea0000000201 ffffffff81009de7
ffffffff81068561
[ 584.626876] Call Trace:
[ 584.629699] [<ffffffff81019ad9>] dump_trace+0x59/0x340
[ 584.635645] [<ffffffff81019eaa>] show_stack_log_lvl+0xea/0x170
[ 584.642391] [<ffffffff8101ac51>] show_stack+0x21/0x40
[ 584.648238] [<ffffffff813175a0>] dump_stack+0x5c/0x7c
[ 584.654085] [<ffffffff8107f4e1>] warn_slowpath_common+0x81/0xb0
[ 584.660932] [<ffffffff81009de7>] xen_alloc_pte+0x1c7/0x390
[ 584.667289] [<ffffffff810647f0>] pmd_populate_kernel.constprop.6+0x40/0x80
[ 584.675241] [<ffffffff815ecfe8>] phys_pmd_init+0x210/0x255
[ 584.681587] [<ffffffff815ed207>] phys_pud_init+0x1da/0x247
[ 584.687931] [<ffffffff815edb3b>] kernel_physical_mapping_init+0xf5/0x1d4
[ 584.695682] [<ffffffff815e9bdd>] init_memory_mapping+0x18d/0x380
[ 584.702631] [<ffffffff81064699>] arch_add_memory+0x59/0xf0
Signed-off-by: Juergen Gross <jgr...@suse.com>
---
arch/x86/xen/setup.c | 13 +++++++++++++
drivers/xen/xen-balloon.c | 11 +++++++++++
include/xen/xen.h | 4 ++++
3 files changed, 28 insertions(+)
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index d5f303c0e656..0e770f5e5e8c 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -12,6 +12,7 @@
#include <linux/memblock.h>
#include <linux/cpuidle.h>
#include <linux/cpufreq.h>
+#include <linux/memory_hotplug.h>
#include <asm/elf.h>
#include <asm/vdso.h>
@@ -589,6 +590,14 @@ static void __init
xen_align_and_add_e820_region(phys_addr_t start,
if (type == E820_TYPE_RAM) {
start = PAGE_ALIGN(start);
end &= ~((phys_addr_t)PAGE_SIZE - 1);
+#ifdef CONFIG_MEMORY_HOTPLUG
+ /*
+ * Don't allow adding memory not in E820 map while booting the
+ * system. Once the balloon driver is up it will remove that
+ * restriction again.
+ */
+ max_mem_size = end;
+#endif
}
e820__range_add(start, end - start, type);
@@ -748,6 +757,10 @@ char * __init xen_memory_setup(void)
memmap.nr_entries = ARRAY_SIZE(xen_e820_table.entries);
set_xen_guest_handle(memmap.buffer, xen_e820_table.entries);
+#ifdef CONFIG_MEMORY_HOTPLUG
+ xen_saved_max_mem_size = max_mem_size;
+#endif
+
op = xen_initial_domain() ?
XENMEM_machine_memory_map :
XENMEM_memory_map;
diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c
index 2acbfe104e46..a67236b02452 100644
--- a/drivers/xen/xen-balloon.c
+++ b/drivers/xen/xen-balloon.c
@@ -37,6 +37,7 @@
#include <linux/mm_types.h>
#include <linux/init.h>
#include <linux/capability.h>
+#include <linux/memory_hotplug.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
@@ -50,6 +51,10 @@
#define BALLOON_CLASS_NAME "xen_memory"
+#ifdef CONFIG_MEMORY_HOTPLUG
+u64 xen_saved_max_mem_size = 0;
+#endif
+
static struct device balloon_dev;
static int register_balloon(struct device *dev);
@@ -63,6 +68,12 @@ static void watch_target(struct xenbus_watch *watch,
static bool watch_fired;
static long target_diff;
+#ifdef CONFIG_MEMORY_HOTPLUG
+ /* The balloon driver will take care of adding memory now. */
+ if (xen_saved_max_mem_size)
+ max_mem_size = xen_saved_max_mem_size;
+#endif
+
err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
if (err != 1) {
/* This is ok (for domain0 at least) - so just return */
diff --git a/include/xen/xen.h b/include/xen/xen.h
index 0e2156786ad2..d8f1ab43ab56 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -46,4 +46,8 @@ struct bio_vec;
bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
const struct bio_vec *vec2);
+#ifdef CONFIG_MEMORY_HOTPLUG
+extern u64 xen_saved_max_mem_size;
+#endif
+
#endif /* _XEN_XEN_H */
--
2.16.4
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
