#include <linux/rwsem.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
+#include <linux/mount.h>
+#include <linux/pseudo_fs.h>
+#include <linux/balloon_compaction.h>
#include <linux/vmw_vmci_defs.h>
#include <linux/vmw_vmci_api.h>
#include <asm/hypervisor.h>
MODULE_ALIAS("vmware_vmmemctl");
MODULE_LICENSE("GPL");
-/*
- * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We don't allow wait
- * (__GFP_RECLAIM) for huge page allocations. Use __GFP_NOWARN, to suppress page
- * allocation failure warnings. Disallow access to emergency low-memory pools.
- */
-#define VMW_HUGE_PAGE_ALLOC_FLAGS (__GFP_HIGHMEM|__GFP_NOWARN| \
- __GFP_NOMEMALLOC)
+static bool __read_mostly vmwballoon_shrinker_enable;
+module_param(vmwballoon_shrinker_enable, bool, 0444);
+MODULE_PARM_DESC(vmwballoon_shrinker_enable,
+ "Enable non-cooperative out-of-memory protection. Disabled by default as it may degrade performance.");
-/*
- * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We allow lightweight
- * reclamation (__GFP_NORETRY). Use __GFP_NOWARN, to suppress page allocation
- * failure warnings. Disallow access to emergency low-memory pools.
- */
-#define VMW_PAGE_ALLOC_FLAGS (__GFP_HIGHMEM|__GFP_NOWARN| \
- __GFP_NOMEMALLOC|__GFP_NORETRY)
+/* Delay in seconds after shrink before inflation. */
+#define VMBALLOON_SHRINK_DELAY (5)
/* Maximum number of refused pages we accumulate during inflation cycle */
#define VMW_BALLOON_MAX_REFUSED 16
+/* Magic number for the balloon mount-point */
+#define BALLOON_VMW_MAGIC 0x0ba11007
+
/*
* Hypervisor communication port definitions.
*/
VMW_BALLOON_STAT_TIMER,
VMW_BALLOON_STAT_DOORBELL,
VMW_BALLOON_STAT_RESET,
- VMW_BALLOON_STAT_LAST = VMW_BALLOON_STAT_RESET
+ VMW_BALLOON_STAT_SHRINK,
+ VMW_BALLOON_STAT_SHRINK_FREE,
+ VMW_BALLOON_STAT_LAST = VMW_BALLOON_STAT_SHRINK_FREE
};
#define VMW_BALLOON_STAT_NUM (VMW_BALLOON_STAT_LAST + 1)
-
static DEFINE_STATIC_KEY_TRUE(vmw_balloon_batching);
static DEFINE_STATIC_KEY_FALSE(balloon_stat_enabled);
struct vmballoon_ctl {
struct list_head pages;
struct list_head refused_pages;
+ struct list_head prealloc_pages;
unsigned int n_refused_pages;
unsigned int n_pages;
enum vmballoon_page_size_type page_size;
enum vmballoon_op op;
};
-struct vmballoon_page_size {
- /* list of reserved physical pages */
- struct list_head pages;
-};
-
/**
* struct vmballoon_batch_entry - a batch entry for lock or unlock.
*
} __packed;
struct vmballoon {
- struct vmballoon_page_size page_sizes[VMW_BALLOON_NUM_PAGE_SIZES];
-
/**
* @max_page_size: maximum supported page size for ballooning.
*
*/
struct page *page;
+ /**
+ * @shrink_timeout: timeout until the next inflation.
+ *
+ * After an shrink event, indicates the time in jiffies after which
+ * inflation is allowed again. Can be written concurrently with reads,
+ * so must use READ_ONCE/WRITE_ONCE when accessing.
+ */
+ unsigned long shrink_timeout;
+
/* statistics */
struct vmballoon_stats *stats;
struct dentry *dbg_entry;
#endif
+ /**
+ * @b_dev_info: balloon device information descriptor.
+ */
+ struct balloon_dev_info b_dev_info;
+
struct delayed_work dwork;
+ /**
+ * @huge_pages - list of the inflated 2MB pages.
+ *
+ * Protected by @b_dev_info.pages_lock .
+ */
+ struct list_head huge_pages;
+
/**
* @vmci_doorbell.
*
* Lock ordering: @conf_sem -> @comm_lock .
*/
spinlock_t comm_lock;
+
+ /**
+ * @shrinker: shrinker interface that is used to avoid over-inflation.
+ */
+ struct shrinker shrinker;
+
+ /**
+ * @shrinker_registered: whether the shrinker was registered.
+ *
+ * The shrinker interface does not handle gracefully the removal of
+ * shrinker that was not registered before. This indication allows to
+ * simplify the unregistration process.
+ */
+ bool shrinker_registered;
};
static struct vmballoon balloon;
unsigned int i;
for (i = 0; i < req_n_pages; i++) {
- if (ctl->page_size == VMW_BALLOON_2M_PAGE)
- page = alloc_pages(VMW_HUGE_PAGE_ALLOC_FLAGS,
- VMW_BALLOON_2M_ORDER);
- else
- page = alloc_page(VMW_PAGE_ALLOC_FLAGS);
-
- /* Update statistics */
- vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC,
- ctl->page_size);
+ /*
+ * First check if we happen to have pages that were allocated
+ * before. This happens when 2MB page rejected during inflation
+ * by the hypervisor, and then split into 4KB pages.
+ */
+ if (!list_empty(&ctl->prealloc_pages)) {
+ page = list_first_entry(&ctl->prealloc_pages,
+ struct page, lru);
+ list_del(&page->lru);
+ } else {
+ if (ctl->page_size == VMW_BALLOON_2M_PAGE)
+ page = alloc_pages(__GFP_HIGHMEM|__GFP_NOWARN|
+ __GFP_NOMEMALLOC, VMW_BALLOON_2M_ORDER);
+ else
+ page = balloon_page_alloc();
+
+ vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC,
+ ctl->page_size);
+ }
if (page) {
vmballoon_mark_page_offline(page, ctl->page_size);
__free_pages(page, vmballoon_page_order(page_size));
}
- *n_pages = 0;
+ if (n_pages)
+ *n_pages = 0;
}
size - target < vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE))
return 0;
+ /* If an out-of-memory recently occurred, inflation is disallowed. */
+ if (target > size && time_before(jiffies, READ_ONCE(b->shrink_timeout)))
+ return 0;
+
return target - size;
}
unsigned int *n_pages,
enum vmballoon_page_size_type page_size)
{
- struct vmballoon_page_size *page_size_info = &b->page_sizes[page_size];
+ unsigned long flags;
+
+ if (page_size == VMW_BALLOON_4K_PAGE) {
+ balloon_page_list_enqueue(&b->b_dev_info, pages);
+ } else {
+ /*
+ * Keep the huge pages in a local list which is not available
+ * for the balloon compaction mechanism.
+ */
+ spin_lock_irqsave(&b->b_dev_info.pages_lock, flags);
+ list_splice_init(pages, &b->huge_pages);
+ __count_vm_events(BALLOON_INFLATE, *n_pages *
+ vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE));
+ spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags);
+ }
- list_splice_init(pages, &page_size_info->pages);
*n_pages = 0;
}
enum vmballoon_page_size_type page_size,
unsigned int n_req_pages)
{
- struct vmballoon_page_size *page_size_info = &b->page_sizes[page_size];
struct page *page, *tmp;
unsigned int i = 0;
+ unsigned long flags;
- list_for_each_entry_safe(page, tmp, &page_size_info->pages, lru) {
+ /* In the case of 4k pages, use the compaction infrastructure */
+ if (page_size == VMW_BALLOON_4K_PAGE) {
+ *n_pages = balloon_page_list_dequeue(&b->b_dev_info, pages,
+ n_req_pages);
+ return;
+ }
+
+ /* 2MB pages */
+ spin_lock_irqsave(&b->b_dev_info.pages_lock, flags);
+ list_for_each_entry_safe(page, tmp, &b->huge_pages, lru) {
list_move(&page->lru, pages);
if (++i == n_req_pages)
break;
}
+
+ __count_vm_events(BALLOON_DEFLATE,
+ i * vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE));
+ spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags);
*n_pages = i;
}
+/**
+ * vmballoon_split_refused_pages() - Split the 2MB refused pages to 4k.
+ *
+ * If inflation of 2MB pages was denied by the hypervisor, it is likely to be
+ * due to one or few 4KB pages. These 2MB pages may keep being allocated and
+ * then being refused. To prevent this case, this function splits the refused
+ * pages into 4KB pages and adds them into @prealloc_pages list.
+ *
+ * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation.
+ */
+static void vmballoon_split_refused_pages(struct vmballoon_ctl *ctl)
+{
+ struct page *page, *tmp;
+ unsigned int i, order;
+
+ order = vmballoon_page_order(ctl->page_size);
+
+ list_for_each_entry_safe(page, tmp, &ctl->refused_pages, lru) {
+ list_del(&page->lru);
+ split_page(page, order);
+ for (i = 0; i < (1 << order); i++)
+ list_add(&page[i].lru, &ctl->prealloc_pages);
+ }
+ ctl->n_refused_pages = 0;
+}
+
/**
* vmballoon_inflate() - Inflate the balloon towards its target size.
*
struct vmballoon_ctl ctl = {
.pages = LIST_HEAD_INIT(ctl.pages),
.refused_pages = LIST_HEAD_INIT(ctl.refused_pages),
+ .prealloc_pages = LIST_HEAD_INIT(ctl.prealloc_pages),
.page_size = b->max_page_size,
.op = VMW_BALLOON_INFLATE
};
break;
/*
- * Ignore errors from locking as we now switch to 4k
- * pages and we might get different errors.
+ * Split the refused pages to 4k. This will also empty
+ * the refused pages list.
*/
- vmballoon_release_refused_pages(b, &ctl);
+ vmballoon_split_refused_pages(&ctl);
ctl.page_size--;
}
*/
if (ctl.n_refused_pages != 0)
vmballoon_release_refused_pages(b, &ctl);
+
+ vmballoon_release_page_list(&ctl.prealloc_pages, NULL, ctl.page_size);
}
/**
}
+/**
+ * vmballoon_shrinker_scan() - deflate the balloon due to memory pressure.
+ * @shrinker: pointer to the balloon shrinker.
+ * @sc: page reclaim information.
+ *
+ * Returns: number of pages that were freed during deflation.
+ */
+static unsigned long vmballoon_shrinker_scan(struct shrinker *shrinker,
+ struct shrink_control *sc)
+{
+ struct vmballoon *b = &balloon;
+ unsigned long deflated_frames;
+
+ pr_debug("%s - size: %llu", __func__, atomic64_read(&b->size));
+
+ vmballoon_stats_gen_inc(b, VMW_BALLOON_STAT_SHRINK);
+
+ /*
+ * If the lock is also contended for read, we cannot easily reclaim and
+ * we bail out.
+ */
+ if (!down_read_trylock(&b->conf_sem))
+ return 0;
+
+ deflated_frames = vmballoon_deflate(b, sc->nr_to_scan, true);
+
+ vmballoon_stats_gen_add(b, VMW_BALLOON_STAT_SHRINK_FREE,
+ deflated_frames);
+
+ /*
+ * Delay future inflation for some time to mitigate the situations in
+ * which balloon continuously grows and shrinks. Use WRITE_ONCE() since
+ * the access is asynchronous.
+ */
+ WRITE_ONCE(b->shrink_timeout, jiffies + HZ * VMBALLOON_SHRINK_DELAY);
+
+ up_read(&b->conf_sem);
+
+ return deflated_frames;
+}
+
+/**
+ * vmballoon_shrinker_count() - return the number of ballooned pages.
+ * @shrinker: pointer to the balloon shrinker.
+ * @sc: page reclaim information.
+ *
+ * Returns: number of 4k pages that are allocated for the balloon and can
+ * therefore be reclaimed under pressure.
+ */
+static unsigned long vmballoon_shrinker_count(struct shrinker *shrinker,
+ struct shrink_control *sc)
+{
+ struct vmballoon *b = &balloon;
+
+ return atomic64_read(&b->size);
+}
+
+static void vmballoon_unregister_shrinker(struct vmballoon *b)
+{
+ if (b->shrinker_registered)
+ unregister_shrinker(&b->shrinker);
+ b->shrinker_registered = false;
+}
+
+static int vmballoon_register_shrinker(struct vmballoon *b)
+{
+ int r;
+
+ /* Do nothing if the shrinker is not enabled */
+ if (!vmwballoon_shrinker_enable)
+ return 0;
+
+ b->shrinker.scan_objects = vmballoon_shrinker_scan;
+ b->shrinker.count_objects = vmballoon_shrinker_count;
+ b->shrinker.seeks = DEFAULT_SEEKS;
+
+ r = register_shrinker(&b->shrinker);
+
+ if (r == 0)
+ b->shrinker_registered = true;
+
+ return r;
+}
+
/*
* DEBUGFS Interface
*/
[VMW_BALLOON_STAT_TIMER] = "timer",
[VMW_BALLOON_STAT_DOORBELL] = "doorbell",
[VMW_BALLOON_STAT_RESET] = "reset",
+ [VMW_BALLOON_STAT_SHRINK] = "shrink",
+ [VMW_BALLOON_STAT_SHRINK_FREE] = "shrinkFree"
};
static int vmballoon_enable_stats(struct vmballoon *b)
DEFINE_SHOW_ATTRIBUTE(vmballoon_debug);
-static int __init vmballoon_debugfs_init(struct vmballoon *b)
+static void __init vmballoon_debugfs_init(struct vmballoon *b)
{
- int error;
-
b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
&vmballoon_debug_fops);
- if (IS_ERR(b->dbg_entry)) {
- error = PTR_ERR(b->dbg_entry);
- pr_err("failed to create debugfs entry, error: %d\n", error);
- return error;
- }
-
- return 0;
}
static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
#else
-static inline int vmballoon_debugfs_init(struct vmballoon *b)
+static inline void vmballoon_debugfs_init(struct vmballoon *b)
{
- return 0;
}
static inline void vmballoon_debugfs_exit(struct vmballoon *b)
#endif /* CONFIG_DEBUG_FS */
+
+#ifdef CONFIG_BALLOON_COMPACTION
+
+static int vmballoon_init_fs_context(struct fs_context *fc)
+{
+ return init_pseudo(fc, BALLOON_VMW_MAGIC) ? 0 : -ENOMEM;
+}
+
+static struct file_system_type vmballoon_fs = {
+ .name = "balloon-vmware",
+ .init_fs_context = vmballoon_init_fs_context,
+ .kill_sb = kill_anon_super,
+};
+
+static struct vfsmount *vmballoon_mnt;
+
+/**
+ * vmballoon_migratepage() - migrates a balloon page.
+ * @b_dev_info: balloon device information descriptor.
+ * @newpage: the page to which @page should be migrated.
+ * @page: a ballooned page that should be migrated.
+ * @mode: migration mode, ignored.
+ *
+ * This function is really open-coded, but that is according to the interface
+ * that balloon_compaction provides.
+ *
+ * Return: zero on success, -EAGAIN when migration cannot be performed
+ * momentarily, and -EBUSY if migration failed and should be retried
+ * with that specific page.
+ */
+static int vmballoon_migratepage(struct balloon_dev_info *b_dev_info,
+ struct page *newpage, struct page *page,
+ enum migrate_mode mode)
+{
+ unsigned long status, flags;
+ struct vmballoon *b;
+ int ret;
+
+ b = container_of(b_dev_info, struct vmballoon, b_dev_info);
+
+ /*
+ * If the semaphore is taken, there is ongoing configuration change
+ * (i.e., balloon reset), so try again.
+ */
+ if (!down_read_trylock(&b->conf_sem))
+ return -EAGAIN;
+
+ spin_lock(&b->comm_lock);
+ /*
+ * We must start by deflating and not inflating, as otherwise the
+ * hypervisor may tell us that it has enough memory and the new page is
+ * not needed. Since the old page is isolated, we cannot use the list
+ * interface to unlock it, as the LRU field is used for isolation.
+ * Instead, we use the native interface directly.
+ */
+ vmballoon_add_page(b, 0, page);
+ status = vmballoon_lock_op(b, 1, VMW_BALLOON_4K_PAGE,
+ VMW_BALLOON_DEFLATE);
+
+ if (status == VMW_BALLOON_SUCCESS)
+ status = vmballoon_status_page(b, 0, &page);
+
+ /*
+ * If a failure happened, let the migration mechanism know that it
+ * should not retry.
+ */
+ if (status != VMW_BALLOON_SUCCESS) {
+ spin_unlock(&b->comm_lock);
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ /*
+ * The page is isolated, so it is safe to delete it without holding
+ * @pages_lock . We keep holding @comm_lock since we will need it in a
+ * second.
+ */
+ balloon_page_delete(page);
+
+ put_page(page);
+
+ /* Inflate */
+ vmballoon_add_page(b, 0, newpage);
+ status = vmballoon_lock_op(b, 1, VMW_BALLOON_4K_PAGE,
+ VMW_BALLOON_INFLATE);
+
+ if (status == VMW_BALLOON_SUCCESS)
+ status = vmballoon_status_page(b, 0, &newpage);
+
+ spin_unlock(&b->comm_lock);
+
+ if (status != VMW_BALLOON_SUCCESS) {
+ /*
+ * A failure happened. While we can deflate the page we just
+ * inflated, this deflation can also encounter an error. Instead
+ * we will decrease the size of the balloon to reflect the
+ * change and report failure.
+ */
+ atomic64_dec(&b->size);
+ ret = -EBUSY;
+ } else {
+ /*
+ * Success. Take a reference for the page, and we will add it to
+ * the list after acquiring the lock.
+ */
+ get_page(newpage);
+ ret = MIGRATEPAGE_SUCCESS;
+ }
+
+ /* Update the balloon list under the @pages_lock */
+ spin_lock_irqsave(&b->b_dev_info.pages_lock, flags);
+
+ /*
+ * On inflation success, we already took a reference for the @newpage.
+ * If we succeed just insert it to the list and update the statistics
+ * under the lock.
+ */
+ if (ret == MIGRATEPAGE_SUCCESS) {
+ balloon_page_insert(&b->b_dev_info, newpage);
+ __count_vm_event(BALLOON_MIGRATE);
+ }
+
+ /*
+ * We deflated successfully, so regardless to the inflation success, we
+ * need to reduce the number of isolated_pages.
+ */
+ b->b_dev_info.isolated_pages--;
+ spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags);
+
+out_unlock:
+ up_read(&b->conf_sem);
+ return ret;
+}
+
+/**
+ * vmballoon_compaction_deinit() - removes compaction related data.
+ *
+ * @b: pointer to the balloon.
+ */
+static void vmballoon_compaction_deinit(struct vmballoon *b)
+{
+ if (!IS_ERR(b->b_dev_info.inode))
+ iput(b->b_dev_info.inode);
+
+ b->b_dev_info.inode = NULL;
+ kern_unmount(vmballoon_mnt);
+ vmballoon_mnt = NULL;
+}
+
+/**
+ * vmballoon_compaction_init() - initialized compaction for the balloon.
+ *
+ * @b: pointer to the balloon.
+ *
+ * If during the initialization a failure occurred, this function does not
+ * perform cleanup. The caller must call vmballoon_compaction_deinit() in this
+ * case.
+ *
+ * Return: zero on success or error code on failure.
+ */
+static __init int vmballoon_compaction_init(struct vmballoon *b)
+{
+ vmballoon_mnt = kern_mount(&vmballoon_fs);
+ if (IS_ERR(vmballoon_mnt))
+ return PTR_ERR(vmballoon_mnt);
+
+ b->b_dev_info.migratepage = vmballoon_migratepage;
+ b->b_dev_info.inode = alloc_anon_inode(vmballoon_mnt->mnt_sb);
+
+ if (IS_ERR(b->b_dev_info.inode))
+ return PTR_ERR(b->b_dev_info.inode);
+
+ b->b_dev_info.inode->i_mapping->a_ops = &balloon_aops;
+ return 0;
+}
+
+#else /* CONFIG_BALLOON_COMPACTION */
+
+static void vmballoon_compaction_deinit(struct vmballoon *b)
+{
+}
+
+static int vmballoon_compaction_init(struct vmballoon *b)
+{
+ return 0;
+}
+
+#endif /* CONFIG_BALLOON_COMPACTION */
+
static int __init vmballoon_init(void)
{
- enum vmballoon_page_size_type page_size;
int error;
/*
if (x86_hyper_type != X86_HYPER_VMWARE)
return -ENODEV;
- for (page_size = VMW_BALLOON_4K_PAGE;
- page_size <= VMW_BALLOON_LAST_SIZE; page_size++)
- INIT_LIST_HEAD(&balloon.page_sizes[page_size].pages);
-
-
INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
- error = vmballoon_debugfs_init(&balloon);
+ error = vmballoon_register_shrinker(&balloon);
+ if (error)
+ goto fail;
+
+ /*
+ * Initialization of compaction must be done after the call to
+ * balloon_devinfo_init() .
+ */
+ balloon_devinfo_init(&balloon.b_dev_info);
+ error = vmballoon_compaction_init(&balloon);
if (error)
- return error;
+ goto fail;
+ INIT_LIST_HEAD(&balloon.huge_pages);
spin_lock_init(&balloon.comm_lock);
init_rwsem(&balloon.conf_sem);
balloon.vmci_doorbell = VMCI_INVALID_HANDLE;
queue_delayed_work(system_freezable_wq, &balloon.dwork, 0);
+ vmballoon_debugfs_init(&balloon);
+
return 0;
+fail:
+ vmballoon_unregister_shrinker(&balloon);
+ vmballoon_compaction_deinit(&balloon);
+ return error;
}
/*
static void __exit vmballoon_exit(void)
{
+ vmballoon_unregister_shrinker(&balloon);
vmballoon_vmci_cleanup(&balloon);
cancel_delayed_work_sync(&balloon.dwork);
*/
vmballoon_send_start(&balloon, 0);
vmballoon_pop(&balloon);
+
+ /* Only once we popped the balloon, compaction can be deinit */
+ vmballoon_compaction_deinit(&balloon);
}
module_exit(vmballoon_exit);
projects / linux-2.6-block.git / blobdiff