Merge back earlier material related to system sleep for 6.19

Documentation/ABI/testing/sysfs-power

···
 		disables it.  Reads from the file return the current value.
 		The default is "1" if the build-time "SUSPEND_SKIP_SYNC" config
 		flag is unset, or "0" otherwise.
+
+What:           /sys/power/hibernate_compression_threads
+Date:           October 2025
+Contact:        <[e-mail]>
+Description:
+                Controls the number of threads used for compression
+                and decompression of hibernation images.
+
+                The value can be adjusted at runtime to balance
+                performance and CPU utilization.
+
+                The change takes effect on the next hibernation or
+                resume operation.
+
+                Minimum value: 1
+                Default value: 3

Documentation/admin-guide/kernel-parameters.txt

···
 			/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
 			is set. Default value is 5.
 
+	hibernate_compression_threads=
+			[HIBERNATION]
+			Set the number of threads used for compressing or decompressing
+			hibernation images.
+
+			Format: <integer>
+			Default: 3
+			Minimum: 1
+			Example: hibernate_compression_threads=4
+
 	highmem=nn[KMG]	[KNL,BOOT,EARLY] forces the highmem zone to have an exact
 			size of <nn>. This works even on boxes that have no
 			highmem otherwise. This also works to reduce highmem

Documentation/power/index.rst

···
     power_supply_class
     runtime_pm
     s2ram
+    shutdown-debugging
     suspend-and-cpuhotplug
     suspend-and-interrupts
     swsusp-and-swap-files

Documentation/power/shutdown-debugging.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+Debugging Kernel Shutdown Hangs with pstore
++++++++++++++++++++++++++++++++++++++++++++
+
+Overview
+========
+If the system hangs while shutting down, the kernel logs may need to be
+retrieved to debug the issue.
+
+On systems that have a UART available, it is best to configure the kernel to use
+this UART for kernel console output.
+
+If a UART isn't available, the ``pstore`` subsystem provides a mechanism to
+persist this data across a system reset, allowing it to be retrieved on the next
+boot.
+
+Kernel Configuration
+====================
+To enable ``pstore`` and enable saving kernel ring buffer logs, set the
+following kernel configuration options:
+
+* ``CONFIG_PSTORE=y``
+* ``CONFIG_PSTORE_CONSOLE=y``
+
+Additionally, enable a backend to store the data. Depending upon your platform
+some potential options include:
+
+* ``CONFIG_EFI_VARS_PSTORE=y``
+* ``CONFIG_PSTORE_RAM=y``
+* ``CONFIG_CHROMEOS_PSTORE=y``
+* ``CONFIG_PSTORE_BLK=y``
+
+Kernel Command-line Parameters
+==============================
+Add these parameters to your kernel command line:
+
+* ``printk.always_kmsg_dump=Y``
+	* Forces the kernel to dump the entire message buffer to pstore during
+		shutdown
+* ``efi_pstore.pstore_disable=N``
+	* For EFI-based systems, ensures the EFI backend is active
+
+Userspace Interaction and Log Retrieval
+=======================================
+On the next boot after a hang, pstore logs will be available in the pstore
+filesystem (``/sys/fs/pstore``) and can be retrieved by userspace.
+
+On systemd systems, the ``systemd-pstore`` service will help do the following:
+
+#. Locate pstore data in ``/sys/fs/pstore``
+#. Read and save it to ``/var/lib/systemd/pstore``
+#. Clear pstore data for the next event

drivers/base/power/generic_ops.c

···
 #include <linux/pm_runtime.h>
 #include <linux/export.h>
 
+#define CALL_PM_OP(dev, op) \
+({ \
+	struct device *_dev = (dev); \
+	const struct dev_pm_ops *pm = _dev->driver ? _dev->driver->pm : NULL; \
+	pm && pm->op ? pm->op(_dev) : 0; \
+})
+
 #ifdef CONFIG_PM
 /**
  * pm_generic_runtime_suspend - Generic runtime suspend callback for subsystems.
···
  */
 int pm_generic_runtime_suspend(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-	int ret;
-
-	ret = pm && pm->runtime_suspend ? pm->runtime_suspend(dev) : 0;
-
-	return ret;
+	return CALL_PM_OP(dev, runtime_suspend);
 }
 EXPORT_SYMBOL_GPL(pm_generic_runtime_suspend);
 
···
  */
 int pm_generic_runtime_resume(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-	int ret;
-
-	ret = pm && pm->runtime_resume ? pm->runtime_resume(dev) : 0;
-
-	return ret;
+	return CALL_PM_OP(dev, runtime_resume);
 }
 EXPORT_SYMBOL_GPL(pm_generic_runtime_resume);
 #endif /* CONFIG_PM */
···
  */
 int pm_generic_suspend_noirq(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->suspend_noirq ? pm->suspend_noirq(dev) : 0;
+	return CALL_PM_OP(dev, suspend_noirq);
 }
 EXPORT_SYMBOL_GPL(pm_generic_suspend_noirq);
 
···
  */
 int pm_generic_suspend_late(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->suspend_late ? pm->suspend_late(dev) : 0;
+	return CALL_PM_OP(dev, suspend_late);
 }
 EXPORT_SYMBOL_GPL(pm_generic_suspend_late);
 
···
  */
 int pm_generic_suspend(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->suspend ? pm->suspend(dev) : 0;
+	return CALL_PM_OP(dev, suspend);
 }
 EXPORT_SYMBOL_GPL(pm_generic_suspend);
 
···
  */
 int pm_generic_freeze_noirq(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->freeze_noirq ? pm->freeze_noirq(dev) : 0;
+	return CALL_PM_OP(dev, freeze_noirq);
 }
 EXPORT_SYMBOL_GPL(pm_generic_freeze_noirq);
 
···
  */
 int pm_generic_freeze(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->freeze ? pm->freeze(dev) : 0;
+	return CALL_PM_OP(dev, freeze);
 }
 EXPORT_SYMBOL_GPL(pm_generic_freeze);
 
···
  */
 int pm_generic_poweroff_noirq(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->poweroff_noirq ? pm->poweroff_noirq(dev) : 0;
+	return CALL_PM_OP(dev, poweroff_noirq);
 }
 EXPORT_SYMBOL_GPL(pm_generic_poweroff_noirq);
 
···
  */
 int pm_generic_poweroff_late(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->poweroff_late ? pm->poweroff_late(dev) : 0;
+	return CALL_PM_OP(dev, poweroff_late);
 }
 EXPORT_SYMBOL_GPL(pm_generic_poweroff_late);
 
···
  */
 int pm_generic_poweroff(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->poweroff ? pm->poweroff(dev) : 0;
+	return CALL_PM_OP(dev, poweroff);
 }
 EXPORT_SYMBOL_GPL(pm_generic_poweroff);
 
···
  */
 int pm_generic_thaw_noirq(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->thaw_noirq ? pm->thaw_noirq(dev) : 0;
+	return CALL_PM_OP(dev, thaw_noirq);
 }
 EXPORT_SYMBOL_GPL(pm_generic_thaw_noirq);
 
···
  */
 int pm_generic_thaw(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->thaw ? pm->thaw(dev) : 0;
+	return CALL_PM_OP(dev, thaw);
 }
 EXPORT_SYMBOL_GPL(pm_generic_thaw);
 
···
  */
 int pm_generic_resume_noirq(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->resume_noirq ? pm->resume_noirq(dev) : 0;
+	return CALL_PM_OP(dev, resume_noirq);
 }
 EXPORT_SYMBOL_GPL(pm_generic_resume_noirq);
 
···
  */
 int pm_generic_resume_early(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->resume_early ? pm->resume_early(dev) : 0;
+	return CALL_PM_OP(dev, resume_early);
 }
 EXPORT_SYMBOL_GPL(pm_generic_resume_early);
 
···
  */
 int pm_generic_resume(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->resume ? pm->resume(dev) : 0;
+	return CALL_PM_OP(dev, resume);
 }
 EXPORT_SYMBOL_GPL(pm_generic_resume);
 
···
  */
 int pm_generic_restore_noirq(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->restore_noirq ? pm->restore_noirq(dev) : 0;
+	return CALL_PM_OP(dev, restore_noirq);
 }
 EXPORT_SYMBOL_GPL(pm_generic_restore_noirq);
 
···
  */
 int pm_generic_restore_early(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->restore_early ? pm->restore_early(dev) : 0;
+	return CALL_PM_OP(dev, restore_early);
 }
 EXPORT_SYMBOL_GPL(pm_generic_restore_early);
 
···
  */
 int pm_generic_restore(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-
-	return pm && pm->restore ? pm->restore(dev) : 0;
+	return CALL_PM_OP(dev, restore);
 }
 EXPORT_SYMBOL_GPL(pm_generic_restore);
 

drivers/base/power/main.c

···
 #include <linux/cpufreq.h>
 #include <linux/devfreq.h>
 #include <linux/timer.h>
+#include <linux/nmi.h>
 
 #include "../base.h"
 #include "power.h"
···
 		return "restore";
 	case PM_EVENT_RECOVER:
 		return "recover";
+	case PM_EVENT_POWEROFF:
+		return "poweroff";
 	default:
 		return "(unknown PM event)";
 	}
···
 	case PM_EVENT_FREEZE:
 	case PM_EVENT_QUIESCE:
 		return ops->freeze;
+	case PM_EVENT_POWEROFF:
 	case PM_EVENT_HIBERNATE:
 		return ops->poweroff;
 	case PM_EVENT_THAW:
···
 	case PM_EVENT_FREEZE:
 	case PM_EVENT_QUIESCE:
 		return ops->freeze_late;
+	case PM_EVENT_POWEROFF:
 	case PM_EVENT_HIBERNATE:
 		return ops->poweroff_late;
 	case PM_EVENT_THAW:
···
 	case PM_EVENT_FREEZE:
 	case PM_EVENT_QUIESCE:
 		return ops->freeze_noirq;
+	case PM_EVENT_POWEROFF:
 	case PM_EVENT_HIBERNATE:
 		return ops->poweroff_noirq;
 	case PM_EVENT_THAW:
···
 #define DECLARE_DPM_WATCHDOG_ON_STACK(wd) \
 	struct dpm_watchdog wd
 
+static bool __read_mostly dpm_watchdog_all_cpu_backtrace;
+module_param(dpm_watchdog_all_cpu_backtrace, bool, 0644);
+MODULE_PARM_DESC(dpm_watchdog_all_cpu_backtrace,
+		 "Backtrace all CPUs on DPM watchdog timeout");
+
 /**
  * dpm_watchdog_handler - Driver suspend / resume watchdog handler.
  * @t: The timer that PM watchdog depends on.
···
 	unsigned int time_left;
 
 	if (wd->fatal) {
+		unsigned int this_cpu = smp_processor_id();
+
 		dev_emerg(wd->dev, "**** DPM device timeout ****\n");
 		show_stack(wd->tsk, NULL, KERN_EMERG);
+		if (dpm_watchdog_all_cpu_backtrace)
+			trigger_allbutcpu_cpu_backtrace(this_cpu);
 		panic("%s %s: unrecoverable failure\n",
 			dev_driver_string(wd->dev), dev_name(wd->dev));
 	}

drivers/base/power/trace.c

···
 		unsigned int hash = hash_string(DEVSEED, dev_name(dev),
 						DEVHASH);
 		if (hash == value) {
-			int len = snprintf(buf, size, "%s\n",
+			int len = scnprintf(buf, size, "%s\n",
 					    dev_driver_string(dev));
-			if (len > size)
-				len = size;
 			buf += len;
 			ret += len;
 			size -= len;

drivers/base/power/wakeup.c

···
 	if (WARN_ON(!ws))
 		return;
 
+	/*
+	 * After shutting down the timer, wakeup_source_activate() will warn if
+	 * the given wakeup source is passed to it.
+	 */
+	timer_shutdown_sync(&ws->timer);
+
 	raw_spin_lock_irqsave(&events_lock, flags);
 	list_del_rcu(&ws->entry);
 	raw_spin_unlock_irqrestore(&events_lock, flags);
 	synchronize_srcu(&wakeup_srcu);
-
-	timer_delete_sync(&ws->timer);
-	/*
-	 * Clear timer.function to make wakeup_source_not_registered() treat
-	 * this wakeup source as not registered.
-	 */
-	ws->timer.function = NULL;
 }
 
 /**
···
 EXPORT_SYMBOL_GPL(device_set_wakeup_enable);
 
 /**
- * wakeup_source_not_registered - validate the given wakeup source.
+ * wakeup_source_not_usable - validate the given wakeup source.
  * @ws: Wakeup source to be validated.
  */
-static bool wakeup_source_not_registered(struct wakeup_source *ws)
+static bool wakeup_source_not_usable(struct wakeup_source *ws)
 {
 	/*
-	 * Use timer struct to check if the given source is initialized
-	 * by wakeup_source_add.
+	 * Use the timer struct to check if the given wakeup source has been
+	 * initialized by wakeup_source_add() and it is not going away.
 	 */
 	return ws->timer.function != pm_wakeup_timer_fn;
 }
···
 {
 	unsigned int cec;
 
-	if (WARN_ONCE(wakeup_source_not_registered(ws),
-			"unregistered wakeup source\n"))
+	if (WARN_ONCE(wakeup_source_not_usable(ws), "unusable wakeup source\n"))
 		return;
 
 	ws->active = true;

drivers/scsi/mesh.c

···
 	case PM_EVENT_SUSPEND:
 	case PM_EVENT_HIBERNATE:
 	case PM_EVENT_FREEZE:
+	case PM_EVENT_POWEROFF:
 		break;
 	default:
 		return 0;

drivers/scsi/stex.c

···
 	case PM_EVENT_SUSPEND:
 		return ST_S3;
 	case PM_EVENT_HIBERNATE:
+	case PM_EVENT_POWEROFF:
 		hba->msi_lock = 0;
 		return ST_S4;
 	default:

drivers/usb/host/sl811-hcd.c

···
 		break;
 	case PM_EVENT_SUSPEND:
 	case PM_EVENT_HIBERNATE:
+	case PM_EVENT_POWEROFF:
 	case PM_EVENT_PRETHAW:		/* explicitly discard hw state */
 		port_power(sl811, 0);
 		break;

include/linux/freezer.h

···
 extern unsigned int freeze_timeout_msecs;
 
 /*
- * Check if a process has been frozen
+ * Check if a process has been frozen for PM or cgroup1 freezer. Note that
+ * cgroup2 freezer uses the job control mechanism and does not interact with
+ * the PM freezer.
  */
 extern bool frozen(struct task_struct *p);
 
 extern bool freezing_slow_path(struct task_struct *p);
 
 /*
- * Check if there is a request to freeze a process
+ * Check if there is a request to freeze a task from PM or cgroup1 freezer.
+ * Note that cgroup2 freezer uses the job control mechanism and does not
+ * interact with the PM freezer.
  */
 static inline bool freezing(struct task_struct *p)
 {
···
 extern bool set_freezable(void);
 
 #ifdef CONFIG_CGROUP_FREEZER
-extern bool cgroup_freezing(struct task_struct *task);
+extern bool cgroup1_freezing(struct task_struct *task);
 #else /* !CONFIG_CGROUP_FREEZER */
-static inline bool cgroup_freezing(struct task_struct *task)
+static inline bool cgroup1_freezing(struct task_struct *task)
 {
 	return false;
 }

include/linux/pm.h

···
 
 struct device; /* we have a circular dep with device.h */
 #ifdef CONFIG_VT_CONSOLE_SLEEP
-extern void pm_vt_switch_required(struct device *dev, bool required);
+extern int pm_vt_switch_required(struct device *dev, bool required);
 extern void pm_vt_switch_unregister(struct device *dev);
 #else
-static inline void pm_vt_switch_required(struct device *dev, bool required)
+static inline int pm_vt_switch_required(struct device *dev, bool required)
 {
+	return 0;
 }
 static inline void pm_vt_switch_unregister(struct device *dev)
 {
···
  * RECOVER	Creation of a hibernation image or restoration of the main
  *		memory contents from a hibernation image has failed, call
  *		->thaw() and ->complete() for all devices.
+ * POWEROFF	System will poweroff, call ->poweroff() for all devices.
  *
  * The following PM_EVENT_ messages are defined for internal use by
  * kernel subsystems.  They are never issued by the PM core.
···
 #define PM_EVENT_USER		0x0100
 #define PM_EVENT_REMOTE		0x0200
 #define PM_EVENT_AUTO		0x0400
+#define PM_EVENT_POWEROFF	0x0800
 
 #define PM_EVENT_SLEEP		(PM_EVENT_SUSPEND | PM_EVENT_HIBERNATE)
 #define PM_EVENT_USER_SUSPEND	(PM_EVENT_USER | PM_EVENT_SUSPEND)
···
 #define PMSG_QUIESCE	((struct pm_message){ .event = PM_EVENT_QUIESCE, })
 #define PMSG_SUSPEND	((struct pm_message){ .event = PM_EVENT_SUSPEND, })
 #define PMSG_HIBERNATE	((struct pm_message){ .event = PM_EVENT_HIBERNATE, })
+#define PMSG_POWEROFF	((struct pm_message){ .event = PM_EVENT_POWEROFF, })
 #define PMSG_RESUME	((struct pm_message){ .event = PM_EVENT_RESUME, })
 #define PMSG_THAW	((struct pm_message){ .event = PM_EVENT_THAW, })
 #define PMSG_RESTORE	((struct pm_message){ .event = PM_EVENT_RESTORE, })

include/trace/events/power.h

···
 		{ PM_EVENT_HIBERNATE, "hibernate" }, \
 		{ PM_EVENT_THAW, "thaw" }, \
 		{ PM_EVENT_RESTORE, "restore" }, \
-		{ PM_EVENT_RECOVER, "recover" })
+		{ PM_EVENT_RECOVER, "recover" }, \
+		{ PM_EVENT_POWEROFF, "poweroff" })
 
 DEFINE_EVENT(cpu, cpu_frequency,
 

kernel/cgroup/legacy_freezer.c

···
 	return css_freezer(freezer->css.parent);
 }
 
-bool cgroup_freezing(struct task_struct *task)
+bool cgroup1_freezing(struct task_struct *task)
 {
 	bool ret;
 

kernel/freezer.c

···
 	if (tsk_is_oom_victim(p))
 		return false;
 
-	if (pm_nosig_freezing || cgroup_freezing(p))
+	if (pm_nosig_freezing || cgroup1_freezing(p))
 		return true;
 
 	if (pm_freezing && !(p->flags & PF_KTHREAD))

kernel/power/console.c

···
  * no_console_suspend argument has been passed on the command line, VT
  * switches will occur.
  */
-void pm_vt_switch_required(struct device *dev, bool required)
+int pm_vt_switch_required(struct device *dev, bool required)
 {
 	struct pm_vt_switch *entry, *tmp;
+	int ret = 0;
 
 	mutex_lock(&vt_switch_mutex);
 	list_for_each_entry(tmp, &pm_vt_switch_list, head) {
···
 	}
 
 	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
-	if (!entry)
+	if (!entry) {
+		ret = -ENOMEM;
 		goto out;
+		}
 
 	entry->required = required;
 	entry->dev = dev;
···
 	list_add(&entry->head, &pm_vt_switch_list);
 out:
 	mutex_unlock(&vt_switch_mutex);
+	return ret;
 }
 EXPORT_SYMBOL(pm_vt_switch_required);
 

kernel/power/snapshot.c

···
 {
 	unsigned int nr_pages, nr_highmem;
 
-	pr_info("Creating image:\n");
+	pm_deferred_pr_dbg("Creating image\n");
 
 	drain_local_pages(NULL);
 	nr_pages = count_data_pages();
 	nr_highmem = count_highmem_pages();
-	pr_info("Need to copy %u pages\n", nr_pages + nr_highmem);
+	pm_deferred_pr_dbg("Need to copy %u pages\n", nr_pages + nr_highmem);
 
 	if (!enough_free_mem(nr_pages, nr_highmem)) {
-		pr_err("Not enough free memory\n");
+		pm_deferred_pr_dbg("Not enough free memory for image creation\n");
 		return -ENOMEM;
 	}
 
-	if (swsusp_alloc(&copy_bm, nr_pages, nr_highmem)) {
-		pr_err("Memory allocation failed\n");
+	if (swsusp_alloc(&copy_bm, nr_pages, nr_highmem))
 		return -ENOMEM;
-	}
 
 	/*
 	 * During allocating of suspend pagedir, new cold pages may appear.
···
 	nr_zero_pages = nr_pages - nr_copy_pages;
 	nr_meta_pages = DIV_ROUND_UP(nr_pages * sizeof(long), PAGE_SIZE);
 
-	pr_info("Image created (%d pages copied, %d zero pages)\n", nr_copy_pages, nr_zero_pages);
+	pm_deferred_pr_dbg("Image created (%d pages copied, %d zero pages)\n",
+			   nr_copy_pages, nr_zero_pages);
 
 	return 0;
 }

kernel/power/suspend.c

···
 static int suspend_test(int level)
 {
 #ifdef CONFIG_PM_DEBUG
+	int i;
+
 	if (pm_test_level == level) {
 		pr_info("suspend debug: Waiting for %d second(s).\n",
 				pm_test_delay);
-		mdelay(pm_test_delay * 1000);
+		for (i = 0; i < pm_test_delay && !pm_wakeup_pending(); i++)
+			msleep(1000);
+
 		return 1;
 	}
 #endif /* !CONFIG_PM_DEBUG */

kernel/power/swap.c

···
 				CMP_HEADER, PAGE_SIZE)
 #define CMP_SIZE	(CMP_PAGES * PAGE_SIZE)
 
-/* Maximum number of threads for compression/decompression. */
-#define CMP_THREADS	3
+/* Default number of threads for compression/decompression. */
+#define CMP_THREADS    3
+static unsigned int hibernate_compression_threads = CMP_THREADS;
 
 /* Minimum/maximum number of pages for read buffering. */
 #define CMP_MIN_RD_PAGES	1024
···
 	wait_queue_head_t go;                     /* start crc update */
 	wait_queue_head_t done;                   /* crc update done */
 	u32 *crc32;                               /* points to handle's crc32 */
-	size_t *unc_len[CMP_THREADS];             /* uncompressed lengths */
-	unsigned char *unc[CMP_THREADS];          /* uncompressed data */
+	size_t **unc_len;			  /* uncompressed lengths */
+	unsigned char **unc;			  /* uncompressed data */
 };
+
+static struct crc_data *alloc_crc_data(int nr_threads)
+{
+	struct crc_data *crc;
+
+	crc = kzalloc(sizeof(*crc), GFP_KERNEL);
+	if (!crc)
+		return NULL;
+
+	crc->unc = kcalloc(nr_threads, sizeof(*crc->unc), GFP_KERNEL);
+	if (!crc->unc)
+		goto err_free_crc;
+
+	crc->unc_len = kcalloc(nr_threads, sizeof(*crc->unc_len), GFP_KERNEL);
+	if (!crc->unc_len)
+		goto err_free_unc;
+
+	return crc;
+
+err_free_unc:
+	kfree(crc->unc);
+err_free_crc:
+	kfree(crc);
+	return NULL;
+}
+
+static void free_crc_data(struct crc_data *crc)
+{
+	if (!crc)
+		return;
+
+	if (crc->thr)
+		kthread_stop(crc->thr);
+
+	kfree(crc->unc_len);
+	kfree(crc->unc);
+	kfree(crc);
+}
 
 /*
  * CRC32 update function that runs in its own thread.
···
 	 * footprint.
 	 */
 	nr_threads = num_online_cpus() - 1;
-	nr_threads = clamp_val(nr_threads, 1, CMP_THREADS);
+	nr_threads = clamp_val(nr_threads, 1, hibernate_compression_threads);
 
 	page = (void *)__get_free_page(GFP_NOIO | __GFP_HIGH);
 	if (!page) {
···
 		goto out_clean;
 	}
 
-	crc = kzalloc(sizeof(*crc), GFP_KERNEL);
+	crc = alloc_crc_data(nr_threads);
 	if (!crc) {
 		pr_err("Failed to allocate crc\n");
 		ret = -ENOMEM;
···
 
 out_clean:
 	hib_finish_batch(&hb);
-	if (crc) {
-		if (crc->thr)
-			kthread_stop(crc->thr);
-		kfree(crc);
-	}
+	free_crc_data(crc);
 	if (data) {
 		for (thr = 0; thr < nr_threads; thr++) {
 			if (data[thr].thr)
···
 	 * footprint.
 	 */
 	nr_threads = num_online_cpus() - 1;
-	nr_threads = clamp_val(nr_threads, 1, CMP_THREADS);
+	nr_threads = clamp_val(nr_threads, 1, hibernate_compression_threads);
 
 	page = vmalloc_array(CMP_MAX_RD_PAGES, sizeof(*page));
 	if (!page) {
···
 		goto out_clean;
 	}
 
-	crc = kzalloc(sizeof(*crc), GFP_KERNEL);
+	crc = alloc_crc_data(nr_threads);
 	if (!crc) {
 		pr_err("Failed to allocate crc\n");
 		ret = -ENOMEM;
···
 	hib_finish_batch(&hb);
 	for (i = 0; i < ring_size; i++)
 		free_page((unsigned long)page[i]);
-	if (crc) {
-		if (crc->thr)
-			kthread_stop(crc->thr);
-		kfree(crc);
-	}
+	free_crc_data(crc);
 	if (data) {
 		for (thr = 0; thr < nr_threads; thr++) {
 			if (data[thr].thr)
···
 }
 #endif
 
+static ssize_t hibernate_compression_threads_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", hibernate_compression_threads);
+}
+
+static ssize_t hibernate_compression_threads_store(struct kobject *kobj,
+				struct kobj_attribute *attr,
+				const char *buf, size_t n)
+{
+	unsigned long val;
+
+	if (kstrtoul(buf, 0, &val))
+		return -EINVAL;
+
+	if (val < 1)
+		return -EINVAL;
+
+	hibernate_compression_threads = val;
+	return n;
+}
+power_attr(hibernate_compression_threads);
+
+static struct attribute *g[] = {
+	&hibernate_compression_threads_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group attr_group = {
+	.attrs = g,
+};
+
 static int __init swsusp_header_init(void)
 {
+	int error;
+
+	error = sysfs_create_group(power_kobj, &attr_group);
+	if (error)
+		return -ENOMEM;
+
 	swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
 	if (!swsusp_header)
 		panic("Could not allocate memory for swsusp_header\n");
···
 }
 
 core_initcall(swsusp_header_init);
+
+static int __init hibernate_compression_threads_setup(char *str)
+{
+	int rc = kstrtouint(str, 0, &hibernate_compression_threads);
+
+	if (rc)
+		return rc;
+
+	if (hibernate_compression_threads < 1)
+		hibernate_compression_threads = CMP_THREADS;
+
+	return 1;
+
+}
+
+__setup("hibernate_compression_threads=", hibernate_compression_threads_setup);