* [PATCH v3 1/2] x86: respect memory size limiting via mem= parameter
2019-02-14 10:42 [PATCH v3 0/2] x86: respect memory size limits Juergen Gross
@ 2019-02-14 10:42 ` Juergen Gross
2019-02-14 11:00 ` William Kucharski
2019-02-14 10:42 ` [PATCH v3 2/2] x86/xen: dont add memory above max allowed allocation Juergen Gross
1 sibling, 1 reply; 5+ messages in thread
From: Juergen Gross @ 2019-02-14 10:42 UTC (permalink / raw)
To: linux-kernel, xen-devel, x86, linux-mm
Cc: boris.ostrovsky, sstabellini, hpa, tglx, mingo, bp, Juergen Gross
When limiting memory size via kernel parameter "mem=" this should be
respected even in case of memory made accessible via a PCI card.
Today this kind of memory won't be made usable in initial memory
setup as the memory won't be visible in E820 map, but it might be
added when adding PCI devices due to corresponding ACPI table entries.
Not respecting "mem=" can be corrected by adding a global max_mem_size
variable set by parse_memopt() which will result in rejecting adding
memory areas resulting in a memory size above the allowed limit.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/e820.c | 5 +++++
include/linux/memory_hotplug.h | 2 ++
mm/memory_hotplug.c | 6 ++++++
3 files changed, 13 insertions(+)
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 50895c2f937d..e67513e2cbbb 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -14,6 +14,7 @@
#include <linux/acpi.h>
#include <linux/firmware-map.h>
#include <linux/sort.h>
+#include <linux/memory_hotplug.h>
#include <asm/e820/api.h>
#include <asm/setup.h>
@@ -881,6 +882,10 @@ static int __init parse_memopt(char *p)
e820__range_remove(mem_size, ULLONG_MAX - mem_size, E820_TYPE_RAM, 1);
+#ifdef CONFIG_MEMORY_HOTPLUG
+ max_mem_size = mem_size;
+#endif
+
return 0;
}
early_param("mem", parse_memopt);
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 368267c1b71b..cfd12078172a 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -100,6 +100,8 @@ extern void __online_page_free(struct page *page);
extern int try_online_node(int nid);
+extern u64 max_mem_size;
+
extern bool memhp_auto_online;
/* If movable_node boot option specified */
extern bool movable_node_enabled;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 124e794867c5..519f9db063ff 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -96,10 +96,16 @@ void mem_hotplug_done(void)
cpus_read_unlock();
}
+u64 max_mem_size = U64_MAX;
+
/* add this memory to iomem resource */
static struct resource *register_memory_resource(u64 start, u64 size)
{
struct resource *res, *conflict;
+
+ if (start + size > max_mem_size)
+ return ERR_PTR(-E2BIG);
+
res = kzalloc(sizeof(struct resource), GFP_KERNEL);
if (!res)
return ERR_PTR(-ENOMEM);
--
2.16.4
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH v3 2/2] x86/xen: dont add memory above max allowed allocation
2019-02-14 10:42 [PATCH v3 0/2] x86: respect memory size limits Juergen Gross
2019-02-14 10:42 ` [PATCH v3 1/2] x86: respect memory size limiting via mem= parameter Juergen Gross
@ 2019-02-14 10:42 ` Juergen Gross
2019-02-14 19:41 ` Boris Ostrovsky
1 sibling, 1 reply; 5+ messages in thread
From: Juergen Gross @ 2019-02-14 10:42 UTC (permalink / raw)
To: linux-kernel, xen-devel, x86, linux-mm
Cc: boris.ostrovsky, sstabellini, hpa, tglx, mingo, bp, Juergen Gross
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>
---
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
^ permalink raw reply [flat|nested] 5+ messages in thread