Features and fixes:
- new version of memory hotplug patch which supports
among others memory allocation policies during errors
(try until success or stop at first error),
- this version of patch was tested with tmem
(selfballooning and frontswap) and works
very well with it,
- some other minor fixes.
Signed-off-by: Daniel Kiper <[email protected]>
---
drivers/xen/Kconfig | 10 ++
drivers/xen/balloon.c | 222 ++++++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 221 insertions(+), 11 deletions(-)
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 60d71e9..ada8ef5 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -9,6 +9,16 @@ config XEN_BALLOON
the system to expand the domain's memory allocation, or alternatively
return unneeded memory to the system.
+config XEN_BALLOON_MEMORY_HOTPLUG
+ bool "Xen memory balloon driver with memory hotplug support"
+ default n
+ depends on XEN_BALLOON && MEMORY_HOTPLUG
+ help
+ Xen memory balloon driver with memory hotplug support allows expanding
+ memory available for the system above limit declared at system startup.
+ It is very useful on critical systems which require long run without
+ rebooting.
+
config XEN_SCRUB_PAGES
bool "Scrub pages before returning them to system"
depends on XEN_BALLOON
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index f105e67..73abacd 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -6,6 +6,7 @@
* Copyright (c) 2003, B Dragovic
* Copyright (c) 2003-2004, M Williamson, K Fraser
* Copyright (c) 2005 Dan M. Smith, IBM Corporation
+ * Copyright (c) 2010 Daniel Kiper
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
@@ -44,6 +45,7 @@
#include <linux/list.h>
#include <linux/sysdev.h>
#include <linux/gfp.h>
+#include <linux/memory.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
@@ -79,6 +81,9 @@ enum bp_state {
BP_HUNGRY
};
+#define MH_POLICY_TRY_UNTIL_SUCCESS 0
+#define MH_POLICY_STOP_AT_FIRST_ERROR 1
+
struct balloon_stats {
/* We aim for 'current allocation' == 'target allocation'. */
unsigned long current_pages;
@@ -88,6 +93,10 @@ struct balloon_stats {
unsigned long balloon_high;
unsigned long schedule_delay;
unsigned long max_schedule_delay;
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+ unsigned long boot_max_pfn;
+ unsigned long mh_policy;
+#endif
};
static DEFINE_MUTEX(balloon_mutex);
@@ -201,18 +210,195 @@ static void update_schedule_delay(enum bp_state state)
balloon_stats.schedule_delay = new_schedule_delay;
}
-static unsigned long current_target(void)
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+static int allocate_memory_resource(struct resource **r, unsigned long nr_pages)
{
- unsigned long target = balloon_stats.target_pages;
+ int rc;
+ resource_size_t r_min, r_size;
+
+ /*
+ * Look for first unused memory region starting at page
+ * boundary. Skip last memory section created at boot time
+ * becuase it may contains unused memory pages with PG_reserved
+ * bit not set (online_pages require PG_reserved bit set).
+ */
+
+ *r = kzalloc(sizeof(struct resource), GFP_KERNEL);
- target = min(target,
- balloon_stats.current_pages +
- balloon_stats.balloon_low +
- balloon_stats.balloon_high);
+ if (!*r)
+ return -ENOMEM;
- return target;
+ (*r)->name = "System RAM";
+ (*r)->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+ r_min = PFN_PHYS(section_nr_to_pfn(pfn_to_section_nr(balloon_stats.boot_max_pfn) + 1));
+ r_size = nr_pages << PAGE_SHIFT;
+
+ rc = allocate_resource(&iomem_resource, *r, r_size, r_min,
+ ULONG_MAX, PAGE_SIZE, NULL, NULL);
+
+ if (rc < 0) {
+ kfree(*r);
+ *r = NULL;
+ }
+
+ return rc;
}
+static void adjust_memory_resource(struct resource **r, unsigned long nr_pages)
+{
+ if ((*r)->end + 1 - (nr_pages << PAGE_SHIFT) == (*r)->start) {
+ BUG_ON(release_resource(*r) < 0);
+ kfree(*r);
+ *r = NULL;
+ return;
+ }
+
+ BUG_ON(adjust_resource(*r, (*r)->start, (*r)->end + 1 - (*r)->start -
+ (nr_pages << PAGE_SHIFT)) < 0);
+}
+
+static int allocate_additional_memory(struct resource *r, unsigned long nr_pages)
+{
+ int rc;
+ struct xen_memory_reservation reservation = {
+ .address_bits = 0,
+ .extent_order = 0,
+ .domid = DOMID_SELF
+ };
+ unsigned long flags, i, pfn, pfn_start;
+
+ if (!nr_pages)
+ return 0;
+
+ pfn_start = PFN_UP(r->end) - nr_pages;
+
+ if (nr_pages > ARRAY_SIZE(frame_list))
+ nr_pages = ARRAY_SIZE(frame_list);
+
+ for (i = 0, pfn = pfn_start; i < nr_pages; ++i, ++pfn)
+ frame_list[i] = pfn;
+
+ set_xen_guest_handle(reservation.extent_start, frame_list);
+ reservation.nr_extents = nr_pages;
+
+ spin_lock_irqsave(&xen_reservation_lock, flags);
+
+ rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
+
+ if (rc <= 0)
+ return (rc < 0) ? rc : -ENOMEM;
+
+ for (i = 0, pfn = pfn_start; i < rc; ++i, ++pfn) {
+ BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
+ phys_to_machine_mapping_valid(pfn));
+ set_phys_to_machine(pfn, frame_list[i]);
+ }
+
+ spin_unlock_irqrestore(&xen_reservation_lock, flags);
+
+ return rc;
+}
+
+static void hotplug_allocated_memory(struct resource **r)
+{
+ int nid, rc;
+ resource_size_t r_size;
+ struct memory_block *mem;
+ unsigned long pfn;
+
+ r_size = (*r)->end + 1 - (*r)->start;
+ nid = memory_add_physaddr_to_nid((*r)->start);
+
+ rc = add_registered_memory(nid, (*r)->start, r_size);
+
+ if (rc) {
+ pr_err("%s: add_registered_memory: Memory hotplug failed: %i\n",
+ __func__, rc);
+ balloon_stats.target_pages = balloon_stats.current_pages;
+ *r = NULL;
+ return;
+ }
+
+ if (xen_pv_domain())
+ for (pfn = PFN_DOWN((*r)->start); pfn < PFN_UP((*r)->end); ++pfn)
+ if (!PageHighMem(pfn_to_page(pfn)))
+ BUG_ON(HYPERVISOR_update_va_mapping(
+ (unsigned long)__va(pfn << PAGE_SHIFT),
+ mfn_pte(pfn_to_mfn(pfn), PAGE_KERNEL), 0));
+
+ rc = online_pages(PFN_DOWN((*r)->start), r_size >> PAGE_SHIFT);
+
+ if (rc) {
+ pr_err("%s: online_pages: Failed: %i\n", __func__, rc);
+ balloon_stats.target_pages = balloon_stats.current_pages;
+ *r = NULL;
+ return;
+ }
+
+ for (pfn = PFN_DOWN((*r)->start); pfn < PFN_UP((*r)->end); pfn += PAGES_PER_SECTION) {
+ mem = find_memory_block(__pfn_to_section(pfn));
+ BUG_ON(!mem);
+ BUG_ON(!present_section_nr(mem->phys_index));
+ mutex_lock(&mem->state_mutex);
+ mem->state = MEM_ONLINE;
+ mutex_unlock(&mem->state_mutex);
+ }
+
+ balloon_stats.current_pages += r_size >> PAGE_SHIFT;
+
+ *r = NULL;
+}
+
+static enum bp_state request_additional_memory(long credit)
+{
+ int rc;
+ static struct resource *r;
+ static unsigned long pages_left;
+
+ if ((credit <= 0 || balloon_stats.balloon_low ||
+ balloon_stats.balloon_high) && !r)
+ return BP_DONE;
+
+ if (!r) {
+ rc = allocate_memory_resource(&r, credit);
+
+ if (rc)
+ return BP_ERROR;
+
+ pages_left = credit;
+ }
+
+ rc = allocate_additional_memory(r, pages_left);
+
+ if (rc < 0) {
+ if (balloon_stats.mh_policy == MH_POLICY_TRY_UNTIL_SUCCESS)
+ return BP_ERROR;
+
+ adjust_memory_resource(&r, pages_left);
+
+ if (!r)
+ return BP_ERROR;
+ } else {
+ pages_left -= rc;
+
+ if (pages_left)
+ return BP_HUNGRY;
+ }
+
+ hotplug_allocated_memory(&r);
+
+ return BP_DONE;
+}
+#else
+static enum bp_state request_additional_memory(long credit)
+{
+ if (balloon_stats.balloon_low && balloon_stats.balloon_high &&
+ balloon_stats.target_pages > balloon_stats.current_pages)
+ balloon_stats.target_pages = balloon_stats.current_pages;
+ return BP_DONE;
+}
+#endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */
+
static enum bp_state increase_reservation(unsigned long nr_pages)
{
enum bp_state state = BP_DONE;
@@ -358,15 +544,17 @@ static enum bp_state decrease_reservation(unsigned long nr_pages)
*/
static void balloon_process(struct work_struct *work)
{
- enum bp_state rc, state = BP_DONE;
+ enum bp_state rc, state;
long credit;
mutex_lock(&balloon_mutex);
do {
- credit = current_target() - balloon_stats.current_pages;
+ credit = balloon_stats.target_pages - balloon_stats.current_pages;
+
+ state = request_additional_memory(credit);
- if (credit > 0) {
+ if (credit > 0 && state == BP_DONE) {
rc = increase_reservation(credit);
state = (rc == BP_ERROR) ? BP_ERROR : state;
}
@@ -458,6 +646,11 @@ static int __init balloon_init(void)
balloon_stats.schedule_delay = 1;
balloon_stats.max_schedule_delay = 32;
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+ balloon_stats.boot_max_pfn = max_pfn;
+ balloon_stats.mh_policy = MH_POLICY_STOP_AT_FIRST_ERROR;
+#endif
+
register_balloon(&balloon_sysdev);
/* Initialise the balloon with excess memory space. */
@@ -501,6 +694,10 @@ BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
static SYSDEV_ULONG_ATTR(schedule_delay, 0644, balloon_stats.schedule_delay);
static SYSDEV_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+static SYSDEV_ULONG_ATTR(memory_hotplug_policy, 0644, balloon_stats.mh_policy);
+#endif
+
static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr,
char *buf)
{
@@ -563,7 +760,10 @@ static struct sysdev_attribute *balloon_attrs[] = {
&attr_target_kb,
&attr_target,
&attr_schedule_delay.attr,
- &attr_max_schedule_delay.attr
+ &attr_max_schedule_delay.attr,
+#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
+ &attr_memory_hotplug_policy.attr
+#endif
};
static struct attribute *balloon_info_attrs[] = {
--
1.4.4.4
On Mon, Jan 03, 2011 at 02:33:22PM -0800, Dave Hansen wrote:
> On Wed, 2010-12-29 at 18:07 +0100, Daniel Kiper wrote:
> > +config XEN_BALLOON_MEMORY_HOTPLUG
> > + bool "Xen memory balloon driver with memory hotplug support"
> > + default n
> > + depends on XEN_BALLOON && MEMORY_HOTPLUG
> > + help
> > + Xen memory balloon driver with memory hotplug support allows expanding
> > + memory available for the system above limit declared at system startup.
> > + It is very useful on critical systems which require long run without
> > + rebooting.
>
> This might be better phrased as "Memory hotplug support for Xen balloon
> driver". It might otherwise confuse people about whether they're seeing
> some kind of choice or an _enhancement_ to the existing driver.
Thx. Done. I will send new patch release today.
> Also, why bother even making this a config option? What are the
> downsides if it was always compiled in? You could even make it a
> non-prompting Kconfig option and just automatically turn it on with
> XEN_BALLOON && MEMORY_HOTPLUG.
At this stage of development I think it is better to leave this
as an option for user. Later when this future will be mature it could
be removed. However, I realized that this solution does not give
possibility for user to disable this future at runtime. Maybe
it shoudl be as boot/sysfs option. I am not sure it is required or not.
Currently it is not implemented.
> > +static int allocate_memory_resource(struct resource **r, unsigned long nr_pages)
> > {
> > - unsigned long target = balloon_stats.target_pages;
> > + int rc;
> > + resource_size_t r_min, r_size;
> > +
> > + /*
> > + * Look for first unused memory region starting at page
> > + * boundary. Skip last memory section created at boot time
> > + * becuase it may contains unused memory pages with PG_reserved
> > + * bit not set (online_pages require PG_reserved bit set).
> > + */
> > +
> > + *r = kzalloc(sizeof(struct resource), GFP_KERNEL);
> >
> > - target = min(target,
> > - balloon_stats.current_pages +
> > - balloon_stats.balloon_low +
> > - balloon_stats.balloon_high);
> > + if (!*r)
> > + return -ENOMEM;
> >
> > - return target;
> > + (*r)->name = "System RAM";
> > + (*r)->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> > + r_min = PFN_PHYS(section_nr_to_pfn(pfn_to_section_nr(balloon_stats.boot_max_pfn) + 1));
> > + r_size = nr_pages << PAGE_SHIFT;
> > +
> > + rc = allocate_resource(&iomem_resource, *r, r_size, r_min,
> > + ULONG_MAX, PAGE_SIZE, NULL, NULL);
> > +
> > + if (rc < 0) {
> > + kfree(*r);
> > + *r = NULL;
> > + }
> > +
> > + return rc;
> > }
>
> The double-pointer stuff here ends up looking a little funky. Is there
> any reason you don't just use ERR_PTRs? That might look a bit more
> sane.
After another review I removed all double-pointer stuff (it was
very simple, however, if I read many times code written by myself
it was very difficult to discover that). Now I think it is much better.
Thanks.
> > +static void adjust_memory_resource(struct resource **r, unsigned long nr_pages)
> > +{
> > + if ((*r)->end + 1 - (nr_pages << PAGE_SHIFT) == (*r)->start) {
> > + BUG_ON(release_resource(*r) < 0);
>
> In some kernels, people do:
>
> #define BUG_ON(...) do{}while(0)
>
> to save space. If anyone ever does that with this code, it'll break
> horribly. It's also hard to read these. So, please break logic actions
> _out_ of the BUG_ON() arguments.
>
> That's repeated in quite a few places in here. Make sure to go get them
> all.
Done.
> It also isn't evident what this patch set is trying to do until you get
> down to this 7/7 patch. You might want to put a more complete
> description in 0/7.
Will be done. :-))) Thank you for your help.
Daniel