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    Subject[PATCH] GSoC 2010 - Memory hotplug support for Xen guests - patch for review only
    Hello,

    As I promised I am sending first patch which enables
    memory hotplug in Xen guests. It is version for review
    only. It has been tested on Xen Ver 4.0.0 in PV guest x86_64
    with Linux kernel Ver. 2.6.32.16. In general it works,
    however... For details look below...

    This patch enables two modes of operation:
    - enabled by CONFIG_XEN_MEMORY_HOTPLUG config option:
    - set memory limit for chosen domU from dom0:
    xm mem-max <domU> <new_memory_size_limit>
    - add memory in chosen domU: echo <unused_address> > \
    /sys/devices/system/memory/probe
    - online memory in chosen domU: echo online > \
    /sys/devices/system/memory/memory<section_number>/state
    - enabled by CONFIG_XEN_BALLOON_MEMORY_HOTPLUG config option:
    - set memory limit for chosen domU from dom0:
    xm mem-max <domU> <new_memory_size_limit>
    - add memory for chosen domU from dom0:
    xm mem-set <domU> <new_memory_size>

    TODO:
    - there is bug which generate oops when memory
    is added and removed a few times from domU
    (CONFIG_XEN_BALLOON_MEMORY_HOTPLUG); probably
    I missed something,
    - there is no synchronization between CONFIG_XEN_MEMORY_HOTPLUG
    and CONFIG_XEN_BALLOON_MEMORY_HOTPLUG yet; memory
    added from domU is not added to balloon_stats,
    - some additional error checking should be implemented,
    - final patch will be available for Linux kernel
    Ver. 2.6.32.y, latest stable and RC,
    - tests on all planned platforms.

    I am waiting for your comments.

    Daniel

    diff -Nru linux-2.6.32.16.orig/drivers/base/memory.c linux-2.6.32.16/drivers/base/memory.c
    --- linux-2.6.32.16.orig/drivers/base/memory.c 2010-07-05 20:14:00.000000000 +0200
    +++ linux-2.6.32.16/drivers/base/memory.c 2010-07-16 11:48:45.000000000 +0200
    @@ -3,6 +3,7 @@
    *
    * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
    * Dave Hansen <haveblue@us.ibm.com>
    + * Daniel Kiper <dkiper@net-space.pl>
    *
    * This file provides the necessary infrastructure to represent
    * a SPARSEMEM-memory-model system's physical memory in /sysfs.
    @@ -26,6 +27,16 @@
    #include <asm/atomic.h>
    #include <asm/uaccess.h>

    +#ifdef CONFIG_XEN_MEMORY_HOTPLUG
    +#include <linux/vmalloc.h>
    +#include <asm/xen/hypervisor.h>
    +#include <asm/xen/hypercall.h>
    +#include <xen/interface/xen.h>
    +#include <xen/interface/memory.h>
    +#include <xen/features.h>
    +#include <xen/page.h>
    +#endif
    +
    #define MEMORY_CLASS_NAME "memory"

    static struct sysdev_class memory_sysdev_class = {
    @@ -314,13 +325,61 @@
    memory_probe_store(struct class *class, const char *buf, size_t count)
    {
    u64 phys_addr;
    - int nid;
    - int ret;
    + long ret;
    +
    +#ifdef CONFIG_XEN_MEMORY_HOTPLUG
    + struct xen_memory_reservation reservation = {
    + .address_bits = 0,
    + .extent_order = 0,
    + .domid = DOMID_SELF,
    + .nr_extents = PAGES_PER_SECTION
    + };
    + unsigned long *frame_list, i, nr_pages, pfn;
    +#endif

    phys_addr = simple_strtoull(buf, NULL, 0);

    - nid = memory_add_physaddr_to_nid(phys_addr);
    - ret = add_memory(nid, phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);
    +#ifdef CONFIG_XEN_MEMORY_HOTPLUG
    + if (xen_domain()) {
    + if (!(frame_list = vmalloc(PAGES_PER_SECTION * sizeof(unsigned long)))) {
    + printk(KERN_ERR "%s: vmalloc: Out of memory\n", __func__);
    + return -ENOMEM;
    + }
    +
    + set_xen_guest_handle(reservation.extent_start, frame_list);
    + for (i = 0, pfn = phys_addr >> PAGE_SHIFT; i < PAGES_PER_SECTION; ++i, ++pfn)
    + frame_list[i] = pfn;
    +
    + ret = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
    +
    + if (ret < PAGES_PER_SECTION) {
    + if (ret > 0) {
    + printk(KERN_ERR "%s: PHYSMAP is not fully populated: %li/%lu\n",
    + __func__, ret, PAGES_PER_SECTION);
    + reservation.nr_extents = nr_pages = ret;
    + ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
    + BUG_ON(ret != nr_pages);
    + ret = -ENOMEM;
    + } else {
    + ret = (ret < 0) ? ret : -ENOMEM;
    + printk(KERN_ERR "%s: Can't populate PHYSMAP: %li\n", __func__, ret);
    + }
    + vfree(frame_list);
    + return ret;
    + }
    +
    + for (i = 0, pfn = phys_addr >> PAGE_SHIFT; i < PAGES_PER_SECTION; ++i, ++pfn) {
    + BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
    + phys_to_machine_mapping_valid(pfn));
    + set_phys_to_machine(pfn, frame_list[i]);
    + }
    +
    + vfree(frame_list);
    + }
    +#endif
    +
    + ret = add_memory(memory_add_physaddr_to_nid(phys_addr),
    + phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);

    if (ret)
    count = ret;
    diff -Nru linux-2.6.32.16.orig/drivers/xen/Kconfig linux-2.6.32.16/drivers/xen/Kconfig
    --- linux-2.6.32.16.orig/drivers/xen/Kconfig 2010-07-05 20:14:00.000000000 +0200
    +++ linux-2.6.32.16/drivers/xen/Kconfig 2010-07-09 21:04:17.000000000 +0200
    @@ -7,6 +7,16 @@
    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"
    + depends on EXPERIMENTAL && XEN && XEN_BALLOON && MEMORY_HOTPLUG
    + default n
    + 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
    @@ -60,4 +70,4 @@
    Create entries under /sys/hypervisor describing the Xen
    hypervisor environment. When running native or in another
    virtual environment, /sys/hypervisor will still be present,
    - but will have no xen contents.
    \ No newline at end of file
    + but will have no xen contents.
    diff -Nru linux-2.6.32.16.orig/drivers/xen/balloon.c linux-2.6.32.16/drivers/xen/balloon.c
    --- linux-2.6.32.16.orig/drivers/xen/balloon.c 2010-07-05 20:14:00.000000000 +0200
    +++ linux-2.6.32.16/drivers/xen/balloon.c 2010-07-16 15:06:53.000000000 +0200
    @@ -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
    @@ -74,6 +75,10 @@
    /* Number of pages in high- and low-memory balloons. */
    unsigned long balloon_low;
    unsigned long balloon_high;
    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + u64 hotplug_start_addr;
    + u64 hotplug_size;
    +#endif
    };

    static DEFINE_MUTEX(balloon_mutex);
    @@ -183,6 +188,9 @@

    static unsigned long current_target(void)
    {
    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + return balloon_stats.target_pages;
    +#else
    unsigned long target = balloon_stats.target_pages;

    target = min(target,
    @@ -191,6 +199,7 @@
    balloon_stats.balloon_high);

    return target;
    +#endif
    }

    static int increase_reservation(unsigned long nr_pages)
    @@ -204,17 +213,48 @@
    .domid = DOMID_SELF
    };

    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + struct resource *r;
    +#endif
    +
    if (nr_pages > ARRAY_SIZE(frame_list))
    nr_pages = ARRAY_SIZE(frame_list);

    spin_lock_irqsave(&balloon_lock, flags);

    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + if (!balloon_stats.balloon_low && !balloon_stats.balloon_high) {
    + if (!balloon_stats.hotplug_start_addr)
    + for (r = iomem_resource.child; r; r = r->sibling)
    + if (!r->sibling || r->sibling->start >
    + (((r->end >> PAGE_SHIFT) + balloon_stats.target_pages -
    + balloon_stats.current_pages) << PAGE_SHIFT)) {
    + balloon_stats.hotplug_start_addr = (((r->end >> PAGE_SHIFT) + 1) << PAGE_SHIFT);
    + break;
    + }
    +
    + pfn = (balloon_stats.hotplug_start_addr + balloon_stats.hotplug_size) >> PAGE_SHIFT;
    +
    + for (i = 0; i < nr_pages; ++i, ++pfn)
    + frame_list[i] = pfn;
    +
    + pfn -= nr_pages + 1;
    + } else {
    + page = balloon_first_page();
    + for (i = 0; i < nr_pages; i++) {
    + BUG_ON(page == NULL);
    + frame_list[i] = page_to_pfn(page);
    + page = balloon_next_page(page);
    + }
    + }
    +#else
    page = balloon_first_page();
    for (i = 0; i < nr_pages; i++) {
    BUG_ON(page == NULL);
    frame_list[i] = page_to_pfn(page);
    page = balloon_next_page(page);
    }
    +#endif

    set_xen_guest_handle(reservation.extent_start, frame_list);
    reservation.nr_extents = nr_pages;
    @@ -223,15 +263,30 @@
    goto out;

    for (i = 0; i < rc; i++) {
    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + if (balloon_stats.hotplug_start_addr)
    + ++pfn;
    + else {
    + page = balloon_retrieve();
    + BUG_ON(page == NULL);
    + pfn = page_to_pfn(page);
    + }
    +#else
    page = balloon_retrieve();
    BUG_ON(page == NULL);
    -
    pfn = page_to_pfn(page);
    +#endif
    +
    BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
    phys_to_machine_mapping_valid(pfn));

    set_phys_to_machine(pfn, frame_list[i]);

    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + if (balloon_stats.hotplug_start_addr)
    + continue;
    +#endif
    +
    /* Link back into the page tables if not highmem. */
    if (pfn < max_low_pfn) {
    int ret;
    @@ -248,6 +303,11 @@
    __free_page(page);
    }

    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + if (balloon_stats.hotplug_start_addr)
    + balloon_stats.hotplug_size += rc << PAGE_SHIFT;
    +#endif
    +
    balloon_stats.current_pages += rc;

    out:
    @@ -344,8 +404,24 @@
    } while ((credit != 0) && !need_sleep);

    /* Schedule more work if there is some still to be done. */
    +
    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    if (current_target() != balloon_stats.current_pages)
    mod_timer(&balloon_timer, jiffies + HZ);
    + else
    + if (balloon_stats.hotplug_start_addr) {
    + /* TODO: deallocate memory if something goes wrong !!! */
    + add_memory(memory_add_physaddr_to_nid(balloon_stats.hotplug_start_addr),
    + balloon_stats.hotplug_start_addr, balloon_stats.hotplug_size);
    + online_pages(balloon_stats.hotplug_start_addr >> PAGE_SHIFT,
    + balloon_stats.hotplug_size >> PAGE_SHIFT);
    + balloon_stats.hotplug_start_addr = 0;
    + balloon_stats.hotplug_size = 0;
    + }
    +#else
    + if (current_target() != balloon_stats.current_pages)
    + mod_timer(&balloon_timer, jiffies + HZ);
    +#endif

    mutex_unlock(&balloon_mutex);
    }
    @@ -413,6 +489,11 @@
    balloon_stats.balloon_high = 0;
    balloon_stats.driver_pages = 0UL;

    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + balloon_stats.hotplug_start_addr = 0;
    + balloon_stats.hotplug_size = 0;
    +#endif
    +
    init_timer(&balloon_timer);
    balloon_timer.data = 0;
    balloon_timer.function = balloon_alarm;
    diff -Nru linux-2.6.32.16.orig/mm/Kconfig linux-2.6.32.16/mm/Kconfig
    --- linux-2.6.32.16.orig/mm/Kconfig 2010-07-05 20:14:00.000000000 +0200
    +++ linux-2.6.32.16/mm/Kconfig 2010-07-16 11:44:27.000000000 +0200
    @@ -140,6 +140,15 @@
    depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
    depends on MIGRATION

    +config XEN_MEMORY_HOTPLUG
    + bool "Allow for memory hot-add in Xen guests"
    + depends on EXPERIMENTAL && ARCH_MEMORY_PROBE && XEN
    + default n
    + help
    + Memory hot-add 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.
    +
    #
    # If we have space for more page flags then we can enable additional
    # optimizations and functionality.diff -Nru linux-2.6.32.16.orig/drivers/base/memory.c linux-2.6.32.16/drivers/base/memory.c
    --- linux-2.6.32.16.orig/drivers/base/memory.c 2010-07-05 20:14:00.000000000 +0200
    +++ linux-2.6.32.16/drivers/base/memory.c 2010-07-16 11:48:45.000000000 +0200
    @@ -3,6 +3,7 @@
    *
    * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
    * Dave Hansen <haveblue@us.ibm.com>
    + * Daniel Kiper <dkiper@net-space.pl>
    *
    * This file provides the necessary infrastructure to represent
    * a SPARSEMEM-memory-model system's physical memory in /sysfs.
    @@ -26,6 +27,16 @@
    #include <asm/atomic.h>
    #include <asm/uaccess.h>

    +#ifdef CONFIG_XEN_MEMORY_HOTPLUG
    +#include <linux/vmalloc.h>
    +#include <asm/xen/hypervisor.h>
    +#include <asm/xen/hypercall.h>
    +#include <xen/interface/xen.h>
    +#include <xen/interface/memory.h>
    +#include <xen/features.h>
    +#include <xen/page.h>
    +#endif
    +
    #define MEMORY_CLASS_NAME "memory"

    static struct sysdev_class memory_sysdev_class = {
    @@ -314,13 +325,61 @@
    memory_probe_store(struct class *class, const char *buf, size_t count)
    {
    u64 phys_addr;
    - int nid;
    - int ret;
    + long ret;
    +
    +#ifdef CONFIG_XEN_MEMORY_HOTPLUG
    + struct xen_memory_reservation reservation = {
    + .address_bits = 0,
    + .extent_order = 0,
    + .domid = DOMID_SELF,
    + .nr_extents = PAGES_PER_SECTION
    + };
    + unsigned long *frame_list, i, nr_pages, pfn;
    +#endif

    phys_addr = simple_strtoull(buf, NULL, 0);

    - nid = memory_add_physaddr_to_nid(phys_addr);
    - ret = add_memory(nid, phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);
    +#ifdef CONFIG_XEN_MEMORY_HOTPLUG
    + if (xen_domain()) {
    + if (!(frame_list = vmalloc(PAGES_PER_SECTION * sizeof(unsigned long)))) {
    + printk(KERN_ERR "%s: vmalloc: Out of memory\n", __func__);
    + return -ENOMEM;
    + }
    +
    + set_xen_guest_handle(reservation.extent_start, frame_list);
    + for (i = 0, pfn = phys_addr >> PAGE_SHIFT; i < PAGES_PER_SECTION; ++i, ++pfn)
    + frame_list[i] = pfn;
    +
    + ret = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation);
    +
    + if (ret < PAGES_PER_SECTION) {
    + if (ret > 0) {
    + printk(KERN_ERR "%s: PHYSMAP is not fully populated: %li/%lu\n",
    + __func__, ret, PAGES_PER_SECTION);
    + reservation.nr_extents = nr_pages = ret;
    + ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
    + BUG_ON(ret != nr_pages);
    + ret = -ENOMEM;
    + } else {
    + ret = (ret < 0) ? ret : -ENOMEM;
    + printk(KERN_ERR "%s: Can't populate PHYSMAP: %li\n", __func__, ret);
    + }
    + vfree(frame_list);
    + return ret;
    + }
    +
    + for (i = 0, pfn = phys_addr >> PAGE_SHIFT; i < PAGES_PER_SECTION; ++i, ++pfn) {
    + BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
    + phys_to_machine_mapping_valid(pfn));
    + set_phys_to_machine(pfn, frame_list[i]);
    + }
    +
    + vfree(frame_list);
    + }
    +#endif
    +
    + ret = add_memory(memory_add_physaddr_to_nid(phys_addr),
    + phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);

    if (ret)
    count = ret;
    diff -Nru linux-2.6.32.16.orig/drivers/xen/Kconfig linux-2.6.32.16/drivers/xen/Kconfig
    --- linux-2.6.32.16.orig/drivers/xen/Kconfig 2010-07-05 20:14:00.000000000 +0200
    +++ linux-2.6.32.16/drivers/xen/Kconfig 2010-07-09 21:04:17.000000000 +0200
    @@ -7,6 +7,16 @@
    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"
    + depends on EXPERIMENTAL && XEN && XEN_BALLOON && MEMORY_HOTPLUG
    + default n
    + 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
    @@ -60,4 +70,4 @@
    Create entries under /sys/hypervisor describing the Xen
    hypervisor environment. When running native or in another
    virtual environment, /sys/hypervisor will still be present,
    - but will have no xen contents.
    \ No newline at end of file
    + but will have no xen contents.
    diff -Nru linux-2.6.32.16.orig/drivers/xen/balloon.c linux-2.6.32.16/drivers/xen/balloon.c
    --- linux-2.6.32.16.orig/drivers/xen/balloon.c 2010-07-05 20:14:00.000000000 +0200
    +++ linux-2.6.32.16/drivers/xen/balloon.c 2010-07-16 15:06:53.000000000 +0200
    @@ -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
    @@ -74,6 +75,10 @@
    /* Number of pages in high- and low-memory balloons. */
    unsigned long balloon_low;
    unsigned long balloon_high;
    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + u64 hotplug_start_addr;
    + u64 hotplug_size;
    +#endif
    };

    static DEFINE_MUTEX(balloon_mutex);
    @@ -183,6 +188,9 @@

    static unsigned long current_target(void)
    {
    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + return balloon_stats.target_pages;
    +#else
    unsigned long target = balloon_stats.target_pages;

    target = min(target,
    @@ -191,6 +199,7 @@
    balloon_stats.balloon_high);

    return target;
    +#endif
    }

    static int increase_reservation(unsigned long nr_pages)
    @@ -204,17 +213,48 @@
    .domid = DOMID_SELF
    };

    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + struct resource *r;
    +#endif
    +
    if (nr_pages > ARRAY_SIZE(frame_list))
    nr_pages = ARRAY_SIZE(frame_list);

    spin_lock_irqsave(&balloon_lock, flags);

    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + if (!balloon_stats.balloon_low && !balloon_stats.balloon_high) {
    + if (!balloon_stats.hotplug_start_addr)
    + for (r = iomem_resource.child; r; r = r->sibling)
    + if (!r->sibling || r->sibling->start >
    + (((r->end >> PAGE_SHIFT) + balloon_stats.target_pages -
    + balloon_stats.current_pages) << PAGE_SHIFT)) {
    + balloon_stats.hotplug_start_addr = (((r->end >> PAGE_SHIFT) + 1) << PAGE_SHIFT);
    + break;
    + }
    +
    + pfn = (balloon_stats.hotplug_start_addr + balloon_stats.hotplug_size) >> PAGE_SHIFT;
    +
    + for (i = 0; i < nr_pages; ++i, ++pfn)
    + frame_list[i] = pfn;
    +
    + pfn -= nr_pages + 1;
    + } else {
    + page = balloon_first_page();
    + for (i = 0; i < nr_pages; i++) {
    + BUG_ON(page == NULL);
    + frame_list[i] = page_to_pfn(page);
    + page = balloon_next_page(page);
    + }
    + }
    +#else
    page = balloon_first_page();
    for (i = 0; i < nr_pages; i++) {
    BUG_ON(page == NULL);
    frame_list[i] = page_to_pfn(page);
    page = balloon_next_page(page);
    }
    +#endif

    set_xen_guest_handle(reservation.extent_start, frame_list);
    reservation.nr_extents = nr_pages;
    @@ -223,15 +263,30 @@
    goto out;

    for (i = 0; i < rc; i++) {
    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + if (balloon_stats.hotplug_start_addr)
    + ++pfn;
    + else {
    + page = balloon_retrieve();
    + BUG_ON(page == NULL);
    + pfn = page_to_pfn(page);
    + }
    +#else
    page = balloon_retrieve();
    BUG_ON(page == NULL);
    -
    pfn = page_to_pfn(page);
    +#endif
    +
    BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
    phys_to_machine_mapping_valid(pfn));

    set_phys_to_machine(pfn, frame_list[i]);

    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + if (balloon_stats.hotplug_start_addr)
    + continue;
    +#endif
    +
    /* Link back into the page tables if not highmem. */
    if (pfn < max_low_pfn) {
    int ret;
    @@ -248,6 +303,11 @@
    __free_page(page);
    }

    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + if (balloon_stats.hotplug_start_addr)
    + balloon_stats.hotplug_size += rc << PAGE_SHIFT;
    +#endif
    +
    balloon_stats.current_pages += rc;

    out:
    @@ -344,8 +404,24 @@
    } while ((credit != 0) && !need_sleep);

    /* Schedule more work if there is some still to be done. */
    +
    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    if (current_target() != balloon_stats.current_pages)
    mod_timer(&balloon_timer, jiffies + HZ);
    + else
    + if (balloon_stats.hotplug_start_addr) {
    + /* TODO: deallocate memory if something goes wrong !!! */
    + add_memory(memory_add_physaddr_to_nid(balloon_stats.hotplug_start_addr),
    + balloon_stats.hotplug_start_addr, balloon_stats.hotplug_size);
    + online_pages(balloon_stats.hotplug_start_addr >> PAGE_SHIFT,
    + balloon_stats.hotplug_size >> PAGE_SHIFT);
    + balloon_stats.hotplug_start_addr = 0;
    + balloon_stats.hotplug_size = 0;
    + }
    +#else
    + if (current_target() != balloon_stats.current_pages)
    + mod_timer(&balloon_timer, jiffies + HZ);
    +#endif

    mutex_unlock(&balloon_mutex);
    }
    @@ -413,6 +489,11 @@
    balloon_stats.balloon_high = 0;
    balloon_stats.driver_pages = 0UL;

    +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
    + balloon_stats.hotplug_start_addr = 0;
    + balloon_stats.hotplug_size = 0;
    +#endif
    +
    init_timer(&balloon_timer);
    balloon_timer.data = 0;
    balloon_timer.function = balloon_alarm;
    diff -Nru linux-2.6.32.16.orig/mm/Kconfig linux-2.6.32.16/mm/Kconfig
    --- linux-2.6.32.16.orig/mm/Kconfig 2010-07-05 20:14:00.000000000 +0200
    +++ linux-2.6.32.16/mm/Kconfig 2010-07-16 11:44:27.000000000 +0200
    @@ -140,6 +140,15 @@
    depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
    depends on MIGRATION

    +config XEN_MEMORY_HOTPLUG
    + bool "Allow for memory hot-add in Xen guests"
    + depends on EXPERIMENTAL && ARCH_MEMORY_PROBE && XEN
    + default n
    + help
    + Memory hot-add 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.
    +
    #
    # If we have space for more page flags then we can enable additional
    # optimizations and functionality.
    \
     
     \ /
      Last update: 2010-07-16 16:23    [W:0.054 / U:29.452 seconds]
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