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x86/xen: dont add memory above max allowed allocation

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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 <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Juergen Gross 2019-02-14 11:42:40 +01:00
parent 357b4da50a
commit 1d988ed465
3 changed files with 28 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
arch/x86/xen/setup.c
View File

@ -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);
#if defined(CONFIG_MEMORY_HOTPLUG) && defined(CONFIG_XEN_BALLOON)
xen_saved_max_mem_size = max_mem_size;
#endif
op = xen_initial_domain() ?
XENMEM_machine_memory_map :
XENMEM_memory_map;

11
drivers/xen/xen-balloon.c
View File

@ -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 */

4
include/xen/xen.h
View File

@ -46,4 +46,8 @@ struct bio_vec;
bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
const struct bio_vec *vec2);
#if defined(CONFIG_MEMORY_HOTPLUG) && defined(CONFIG_XEN_BALLOON)
extern u64 xen_saved_max_mem_size;
#endif
#endif /* _XEN_XEN_H */