[PATCH 1/8] Enhance process freezer interface for usage beyond software suspend

[Gautham R Shenoy <ego@in.ibm.com>]

 This patch provides an interface to extend the use of the process
 freezer beyond Suspend.

The tasks can selectively mark themselves to be exempted from specific
freeze events like SUSPEND /KPROBES/CPU_HOTPLUG.

This patch however, *does not* sort non freezable threads into
different categories based on the freeze events. Thus all 
tasks which were previously marked PF_NOFREEZE are now
exempted from freezer using 
	freezer_exempt(FE_ALL);
which means exempt from all kinds of freezes.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

--
 arch/i386/kernel/apm.c              |    2 -
 drivers/block/loop.c                |    2 -
 drivers/char/apm-emulation.c        |    6 ++--
 drivers/ieee1394/ieee1394_core.c    |    2 -
 drivers/md/md.c                     |    2 -
 drivers/mmc/card/queue.c            |    3 +-
 drivers/mtd/mtd_blkdevs.c           |    3 +-
 drivers/scsi/libsas/sas_scsi_host.c |    2 -
 drivers/scsi/scsi_error.c           |    2 -
 drivers/usb/storage/usb.c           |    2 -
 include/linux/freezer.h             |   52 ++++++++++++++++++++++++++++++++----
 include/linux/sched.h               |   15 +++++++++-
 init/do_mounts_initrd.c             |    2 -
 kernel/fork.c                       |    2 -
 kernel/kprobes.c                    |    4 +-
 kernel/power/disk.c                 |    4 +-
 kernel/power/main.c                 |    6 ++--
 kernel/power/process.c              |   29 +++++++++++---------
 kernel/power/user.c                 |    8 ++---
 kernel/rcutorture.c                 |    4 +-
 kernel/sched.c                      |    2 -
 kernel/softirq.c                    |    2 -
 kernel/softlockup.c                 |    2 -
 kernel/workqueue.c                  |    2 -
 24 files changed, 110 insertions(+), 50 deletions(-)

Index: linux-2.6.21-rc5/include/linux/sched.h
===================================================================
--- linux-2.6.21-rc5.orig/include/linux/sched.h
+++ linux-2.6.21-rc5/include/linux/sched.h
@@ -1186,8 +1186,21 @@ static inline void put_task_struct(struc
 #define PF_MEMALLOC	0x00000800	/* Allocating memory */
 #define PF_FLUSHER	0x00001000	/* responsible for disk writeback */
 #define PF_USED_MATH	0x00002000	/* if unset the fpu must be initialized before use */
-#define PF_NOFREEZE	0x00008000	/* this thread should not be frozen */
+
+/* Per process freezer specific flags */
+#define PF_FE_SUSPEND	0x00008000	/* This thread should not be frozen
+					 * for suspend
+					 */
+
+#define PF_FE_KPROBES	0x00000010	/* This thread should not be frozen
+					 * for Kprobes
+					 */
+
 #define PF_FROZEN	0x00010000	/* frozen for system suspend */
+
+#define PF_FE_ALL	(PF_FE_SUSPEND | PF_FE_KPROBES)
+					/* Exempt from all kinds freeze chills*/
+
 #define PF_FSTRANS	0x00020000	/* inside a filesystem transaction */
 #define PF_KSWAPD	0x00040000	/* I am kswapd */
 #define PF_SWAPOFF	0x00080000	/* I am in swapoff */
Index: linux-2.6.21-rc5/include/linux/freezer.h
===================================================================
--- linux-2.6.21-rc5.orig/include/linux/freezer.h
+++ linux-2.6.21-rc5/include/linux/freezer.h
@@ -2,7 +2,49 @@
 
 #include <linux/sched.h>
 
-#ifdef CONFIG_PM
+#if defined(CONFIG_PM) || defined(CONFIG_HOTPLUG_CPU) || \
+					defined(CONFIG_KPROBES)
+
+/* These are the events which make use of the process freezer */
+#define FE_NONE		0
+#define FE_ALL		PF_FE_ALL
+#define FE_SUSPEND	PF_FE_SUSPEND
+#define FE_KPROBES	PF_FE_KPROBES
+
+/*
+ * Exempt the current process from being frozen for a certain event
+ */
+static inline void freezer_exempt(unsigned long exempt_freeze_event)
+{
+	if (exempt_freeze_event == FE_NONE)
+		current->flags &= ~PF_FE_ALL;
+	else
+		current->flags |= exempt_freeze_event;
+}
+
+/*
+ * Consider the current process to be frozen for a certain event
+ */
+static inline void freezer_consider(unsigned long freeze_event)
+{
+	current->flags &= ~freeze_event;
+}
+
+/*
+ * Check if the process is exempted from freeze for the particular event.
+ */
+static inline int freezer_is_exempted(struct task_struct *p,
+					unsigned long freeze_event)
+{
+	return p->flags & freeze_event;
+}
+
+/* Returns the mask of the events for which this process is freezeable */
+static inline unsigned long freezeable_event_mask(struct task_struct *p)
+{
+	return ~p->flags & PF_FE_ALL;
+}
+
 /*
  * Check if a process has been frozen
  */
@@ -63,8 +105,8 @@ static inline void frozen_process(struct
 }
 
 extern void refrigerator(void);
-extern int freeze_processes(void);
-extern void thaw_processes(void);
+extern int freeze_processes(unsigned long freeze_event);
+extern void thaw_processes(unsigned long freeze_event);
 
 static inline int try_to_freeze(void)
 {
@@ -127,8 +169,8 @@ static inline int thaw_process(struct ta
 static inline void frozen_process(struct task_struct *p) { BUG(); }
 
 static inline void refrigerator(void) {}
-static inline int freeze_processes(void) { BUG(); return 0; }
-static inline void thaw_processes(void) {}
+static inline int freeze_processes(int a) { BUG(); return 1; }
+static inline void thaw_processes(int a) {}
 
 static inline int try_to_freeze(void) { return 0; }
 
Index: linux-2.6.21-rc5/kernel/power/process.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/power/process.c
+++ linux-2.6.21-rc5/kernel/power/process.c
@@ -24,10 +24,10 @@
 #define FREEZER_KERNEL_THREADS 0
 #define FREEZER_USER_SPACE 1
 
-static inline int freezeable(struct task_struct * p)
+static inline int freezeable(struct task_struct * p, unsigned long freeze_event)
 {
 	if ((p == current) ||
-	    (p->flags & PF_NOFREEZE) ||
+	    (freezer_is_exempted(p, freeze_event)) ||
 	    (p->exit_state != 0))
 		return 0;
 	return 1;
@@ -106,7 +106,8 @@ static inline int is_user_space(struct t
 	return ret;
 }
 
-static unsigned int try_to_freeze_tasks(int freeze_user_space)
+static unsigned int try_to_freeze_tasks(int freeze_user_space,
+					unsigned long freeze_event)
 {
 	struct task_struct *g, *p;
 	unsigned long end_time;
@@ -117,7 +118,7 @@ static unsigned int try_to_freeze_tasks(
 		todo = 0;
 		read_lock(&tasklist_lock);
 		do_each_thread(g, p) {
-			if (!freezeable(p))
+			if (!freezeable(p, freeze_event))
 				continue;
 
 			if (frozen(p))
@@ -158,7 +159,7 @@ static unsigned int try_to_freeze_tasks(
 				continue;
 
 			task_lock(p);
-			if (freezeable(p) && !frozen(p) &&
+			if (freezeable(p, freeze_event) && !frozen(p) &&
 			    !freezer_should_skip(p))
 				printk(KERN_ERR " %s\n", p->comm);
 
@@ -173,21 +174,23 @@ static unsigned int try_to_freeze_tasks(
 
 /**
  *	freeze_processes - tell processes to enter the refrigerator
+ *	@freeze_event: The system event for which processes are being
+ *			frozen.
  *
  *	Returns 0 on success, or the number of processes that didn't freeze,
  *	although they were told to.
  */
-int freeze_processes(void)
+int freeze_processes(unsigned long freeze_event)
 {
 	unsigned int nr_unfrozen;
 
 	printk("Stopping tasks ... ");
-	nr_unfrozen = try_to_freeze_tasks(FREEZER_USER_SPACE);
+	nr_unfrozen = try_to_freeze_tasks(FREEZER_USER_SPACE, freeze_event);
 	if (nr_unfrozen)
 		return nr_unfrozen;
 
 	sys_sync();
-	nr_unfrozen = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
+	nr_unfrozen = try_to_freeze_tasks(FREEZER_KERNEL_THREADS, freeze_event);
 	if (nr_unfrozen)
 		return nr_unfrozen;
 
@@ -196,13 +199,13 @@ int freeze_processes(void)
 	return 0;
 }
 
-static void thaw_tasks(int thaw_user_space)
+static void thaw_tasks(int thaw_user_space, unsigned long freeze_event)
 {
 	struct task_struct *g, *p;
 
 	read_lock(&tasklist_lock);
 	do_each_thread(g, p) {
-		if (!freezeable(p))
+		if (!freezeable(p, freeze_event))
 			continue;
 
 		if (is_user_space(p) == !thaw_user_space)
@@ -213,11 +216,11 @@ static void thaw_tasks(int thaw_user_spa
 	read_unlock(&tasklist_lock);
 }
 
-void thaw_processes(void)
+void thaw_processes(unsigned long freeze_event)
 {
 	printk("Restarting tasks ... ");
-	thaw_tasks(FREEZER_KERNEL_THREADS);
-	thaw_tasks(FREEZER_USER_SPACE);
+	thaw_tasks(FREEZER_KERNEL_THREADS, freeze_event);
+	thaw_tasks(FREEZER_USER_SPACE, freeze_event);
 	schedule();
 	printk("done.\n");
 }
Index: linux-2.6.21-rc5/kernel/sched.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/sched.c
+++ linux-2.6.21-rc5/kernel/sched.c
@@ -5057,6 +5057,7 @@ static int migration_thread(void *data)
 	BUG_ON(rq->migration_thread != current);
 
 	set_current_state(TASK_INTERRUPTIBLE);
+	freezer_exempt(FE_ALL);
 	while (!kthread_should_stop()) {
 		struct migration_req *req;
 		struct list_head *head;
@@ -5407,7 +5408,6 @@ migration_call(struct notifier_block *nf
 		p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
 		if (IS_ERR(p))
 			return NOTIFY_BAD;
-		p->flags |= PF_NOFREEZE;
 		kthread_bind(p, cpu);
 		/* Must be high prio: stop_machine expects to yield to it. */
 		rq = task_rq_lock(p, &flags);
Index: linux-2.6.21-rc5/kernel/softlockup.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/softlockup.c
+++ linux-2.6.21-rc5/kernel/softlockup.c
@@ -96,7 +96,7 @@ static int watchdog(void * __bind_cpu)
 	struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
 
 	sched_setscheduler(current, SCHED_FIFO, &param);
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 
 	/*
 	 * Run briefly once per second to reset the softlockup timestamp.
Index: linux-2.6.21-rc5/kernel/workqueue.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/workqueue.c
+++ linux-2.6.21-rc5/kernel/workqueue.c
@@ -292,7 +292,7 @@ static int worker_thread(void *__cwq)
 	struct k_sigaction sa;
 
 	if (!cwq->wq->freezeable)
-		current->flags |= PF_NOFREEZE;
+		freezer_exempt(FE_ALL);
 
 	/*
 	 * We inherited MPOL_INTERLEAVE from the booting kernel.
Index: linux-2.6.21-rc5/kernel/rcutorture.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/rcutorture.c
+++ linux-2.6.21-rc5/kernel/rcutorture.c
@@ -559,7 +559,7 @@ rcu_torture_fakewriter(void *arg)
 
 	VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 	set_user_nice(current, 19);
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 
 	do {
 		schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
@@ -590,7 +590,7 @@ rcu_torture_reader(void *arg)
 
 	VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 	set_user_nice(current, 19);
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 
 	do {
 		idx = cur_ops->readlock();
Index: linux-2.6.21-rc5/arch/i386/kernel/apm.c
===================================================================
--- linux-2.6.21-rc5.orig/arch/i386/kernel/apm.c
+++ linux-2.6.21-rc5/arch/i386/kernel/apm.c
@@ -1395,6 +1395,7 @@ static void apm_mainloop(void)
 
 	add_wait_queue(&apm_waitqueue, &wait);
 	set_current_state(TASK_INTERRUPTIBLE);
+	freezer_exempt(FE_ALL);
 	for (;;) {
 		try_to_freeze();
 		schedule_timeout(APM_CHECK_TIMEOUT);
@@ -2315,7 +2316,6 @@ static int __init apm_init(void)
 		remove_proc_entry("apm", NULL);
 		return err;
 	}
-	kapmd_task->flags |= PF_NOFREEZE;
 	wake_up_process(kapmd_task);
 
 	if (num_online_cpus() > 1 && !smp ) {
Index: linux-2.6.21-rc5/drivers/char/apm-emulation.c
===================================================================
--- linux-2.6.21-rc5.orig/drivers/char/apm-emulation.c
+++ linux-2.6.21-rc5/drivers/char/apm-emulation.c
@@ -336,7 +336,7 @@ apm_ioctl(struct inode * inode, struct f
 			 * threads.
 			 */
 			flags = current->flags;
-			current->flags |= PF_NOFREEZE;
+			freezer_exempt(FE_ALL);
 
 			wait_event(apm_suspend_waitqueue,
 				   as->suspend_state == SUSPEND_DONE);
@@ -372,7 +372,7 @@ apm_ioctl(struct inode * inode, struct f
 			 * threads.
 			 */
 			flags = current->flags;
-			current->flags |= PF_NOFREEZE;
+			freezer_exempt(FE_ALL);
 
 			wait_event_interruptible(apm_suspend_waitqueue,
 					 as->suspend_state == SUSPEND_DONE);
@@ -536,6 +536,7 @@ static int apm_get_info(char *buf, char 
 
 static int kapmd(void *arg)
 {
+	freezer_exempt(FE_ALL);
 	do {
 		apm_event_t event;
 		int ret;
@@ -601,7 +602,6 @@ static int __init apm_init(void)
 		kapmd_tsk = NULL;
 		return ret;
 	}
-	kapmd_tsk->flags |= PF_NOFREEZE;
 	wake_up_process(kapmd_tsk);
 
 #ifdef CONFIG_PROC_FS
Index: linux-2.6.21-rc5/drivers/block/loop.c
===================================================================
--- linux-2.6.21-rc5.orig/drivers/block/loop.c
+++ linux-2.6.21-rc5/drivers/block/loop.c
@@ -587,7 +587,7 @@ static int loop_thread(void *data)
 	 * hence, it mustn't be stopped at all
 	 * because it could be indirectly used during suspension
 	 */
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 
 	set_user_nice(current, -20);
 
Index: linux-2.6.21-rc5/drivers/ieee1394/ieee1394_core.c
===================================================================
--- linux-2.6.21-rc5.orig/drivers/ieee1394/ieee1394_core.c
+++ linux-2.6.21-rc5/drivers/ieee1394/ieee1394_core.c
@@ -1134,7 +1134,7 @@ static int hpsbpkt_thread(void *__hi)
 	struct list_head tmp;
 	int may_schedule;
 
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 
 	while (!kthread_should_stop()) {
 
Index: linux-2.6.21-rc5/drivers/md/md.c
===================================================================
--- linux-2.6.21-rc5.orig/drivers/md/md.c
+++ linux-2.6.21-rc5/drivers/md/md.c
@@ -4527,7 +4527,7 @@ static int md_thread(void * arg)
 	 * many dirty RAID5 blocks.
 	 */
 
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 	allow_signal(SIGKILL);
 	while (!kthread_should_stop()) {
 
Index: linux-2.6.21-rc5/drivers/mtd/mtd_blkdevs.c
===================================================================
--- linux-2.6.21-rc5.orig/drivers/mtd/mtd_blkdevs.c
+++ linux-2.6.21-rc5/drivers/mtd/mtd_blkdevs.c
@@ -82,7 +82,8 @@ static int mtd_blktrans_thread(void *arg
 	struct request_queue *rq = tr->blkcore_priv->rq;
 
 	/* we might get involved when memory gets low, so use PF_MEMALLOC */
-	current->flags |= PF_MEMALLOC | PF_NOFREEZE;
+	current->flags |= PF_MEMALLOC;
+	freezer_exempt(FE_ALL);
 
 	daemonize("%sd", tr->name);
 
Index: linux-2.6.21-rc5/drivers/scsi/libsas/sas_scsi_host.c
===================================================================
--- linux-2.6.21-rc5.orig/drivers/scsi/libsas/sas_scsi_host.c
+++ linux-2.6.21-rc5/drivers/scsi/libsas/sas_scsi_host.c
@@ -871,7 +871,7 @@ static int sas_queue_thread(void *_sas_h
 	struct scsi_core *core = &sas_ha->core;
 
 	daemonize("sas_queue_%d", core->shost->host_no);
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 
 	complete(&queue_th_comp);
 
Index: linux-2.6.21-rc5/drivers/scsi/scsi_error.c
===================================================================
--- linux-2.6.21-rc5.orig/drivers/scsi/scsi_error.c
+++ linux-2.6.21-rc5/drivers/scsi/scsi_error.c
@@ -1536,7 +1536,7 @@ int scsi_error_handler(void *data)
 {
 	struct Scsi_Host *shost = data;
 
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 
 	/*
 	 * We use TASK_INTERRUPTIBLE so that the thread is not
Index: linux-2.6.21-rc5/drivers/usb/storage/usb.c
===================================================================
--- linux-2.6.21-rc5.orig/drivers/usb/storage/usb.c
+++ linux-2.6.21-rc5/drivers/usb/storage/usb.c
@@ -301,7 +301,7 @@ static int usb_stor_control_thread(void 
 	struct us_data *us = (struct us_data *)__us;
 	struct Scsi_Host *host = us_to_host(us);
 
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 
 	for(;;) {
 		try_to_freeze();
Index: linux-2.6.21-rc5/init/do_mounts_initrd.c
===================================================================
--- linux-2.6.21-rc5.orig/init/do_mounts_initrd.c
+++ linux-2.6.21-rc5/init/do_mounts_initrd.c
@@ -55,7 +55,7 @@ static void __init handle_initrd(void)
 	sys_mount(".", "/", NULL, MS_MOVE, NULL);
 	sys_chroot(".");
 
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 	pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
 	if (pid > 0) {
 		while (pid != sys_wait4(-1, NULL, 0, NULL))
Index: linux-2.6.21-rc5/kernel/softirq.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/softirq.c
+++ linux-2.6.21-rc5/kernel/softirq.c
@@ -490,7 +490,7 @@ void __init softirq_init(void)
 static int ksoftirqd(void * __bind_cpu)
 {
 	set_user_nice(current, 19);
-	current->flags |= PF_NOFREEZE;
+	freezer_exempt(FE_ALL);
 
 	set_current_state(TASK_INTERRUPTIBLE);
 
Index: linux-2.6.21-rc5/kernel/kprobes.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/kprobes.c
+++ linux-2.6.21-rc5/kernel/kprobes.c
@@ -104,7 +104,7 @@ static int __kprobes check_safety(void)
 {
 	int ret = 0;
 #if defined(CONFIG_PREEMPT) && defined(CONFIG_PM)
-	ret = freeze_processes();
+	ret = freeze_processes(FE_KPROBES);
 	if (ret == 0) {
 		struct task_struct *p, *q;
 		do_each_thread(p, q) {
@@ -117,7 +117,7 @@ static int __kprobes check_safety(void)
 		} while_each_thread(p, q);
 	}
 loop_end:
-	thaw_processes();
+	thaw_processes(FE_KPROBES);
 #else
 	synchronize_sched();
 #endif
Index: linux-2.6.21-rc5/kernel/power/disk.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/power/disk.c
+++ linux-2.6.21-rc5/kernel/power/disk.c
@@ -104,7 +104,7 @@ static inline void platform_finish(void)
 
 static void unprepare_processes(void)
 {
-	thaw_processes();
+	thaw_processes(FE_SUSPEND);
 	pm_restore_console();
 }
 
@@ -113,7 +113,7 @@ static int prepare_processes(void)
 	int error = 0;
 
 	pm_prepare_console();
-	if (freeze_processes()) {
+	if (freeze_processes(FE_SUSPEND)) {
 		error = -EBUSY;
 		unprepare_processes();
 	}
Index: linux-2.6.21-rc5/kernel/power/main.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/power/main.c
+++ linux-2.6.21-rc5/kernel/power/main.c
@@ -86,7 +86,7 @@ static int suspend_prepare(suspend_state
 
 	pm_prepare_console();
 
-	if (freeze_processes()) {
+	if (freeze_processes(FE_SUSPEND)) {
 		error = -EAGAIN;
 		goto Thaw;
 	}
@@ -123,7 +123,7 @@ static int suspend_prepare(suspend_state
 	device_resume();
 	resume_console();
  Thaw:
-	thaw_processes();
+	thaw_processes(FE_SUSPEND);
 	pm_restore_console();
 	return error;
 }
@@ -162,7 +162,7 @@ static void suspend_finish(suspend_state
 	pm_finish(state);
 	device_resume();
 	resume_console();
-	thaw_processes();
+	thaw_processes(FE_SUSPEND);
 	pm_restore_console();
 }
 
Index: linux-2.6.21-rc5/kernel/power/user.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/power/user.c
+++ linux-2.6.21-rc5/kernel/power/user.c
@@ -88,7 +88,7 @@ static int snapshot_release(struct inode
 	free_bitmap(data->bitmap);
 	if (data->frozen) {
 		mutex_lock(&pm_mutex);
-		thaw_processes();
+		thaw_processes(FE_SUSPEND);
 		enable_nonboot_cpus();
 		mutex_unlock(&pm_mutex);
 	}
@@ -239,8 +239,8 @@ static int snapshot_ioctl(struct inode *
 		if (data->frozen)
 			break;
 		mutex_lock(&pm_mutex);
-		if (freeze_processes()) {
-			thaw_processes();
+		if (freeze_processes(FE_SUSPEND)) {
+			thaw_processes(FE_SUSPEND);
 			error = -EBUSY;
 		}
 		mutex_unlock(&pm_mutex);
@@ -252,7 +252,7 @@ static int snapshot_ioctl(struct inode *
 		if (!data->frozen)
 			break;
 		mutex_lock(&pm_mutex);
-		thaw_processes();
+		thaw_processes(FE_SUSPEND);
 		mutex_unlock(&pm_mutex);
 		data->frozen = 0;
 		break;
Index: linux-2.6.21-rc5/drivers/mmc/card/queue.c
===================================================================
--- linux-2.6.21-rc5.orig/drivers/mmc/card/queue.c
+++ linux-2.6.21-rc5/drivers/mmc/card/queue.c
@@ -66,7 +66,8 @@ static int mmc_queue_thread(void *d)
 	 * Set iothread to ensure that we aren't put to sleep by
 	 * the process freezing.  We handle suspension ourselves.
 	 */
-	current->flags |= PF_MEMALLOC|PF_NOFREEZE;
+	current->flags |= PF_MEMALLOC;
+	freezer_exempt(FE_ALL);
 
 	down(&mq->thread_sem);
 	do {
Index: linux-2.6.21-rc5/kernel/fork.c
===================================================================
--- linux-2.6.21-rc5.orig/kernel/fork.c
+++ linux-2.6.21-rc5/kernel/fork.c
@@ -921,7 +921,7 @@ static inline void copy_flags(unsigned l
 {
 	unsigned long new_flags = p->flags;
 
-	new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE);
+	new_flags &= ~(PF_SUPERPRIV | PF_FE_ALL);
 	new_flags |= PF_FORKNOEXEC;
 	new_flags |= PF_STARTING;
 	p->flags = new_flags;
-- 
Gautham R Shenoy
Linux Technology Center
IBM India.
"Freedom comes with a price tag of responsibility, which is still a bargain,
because Freedom is priceless!"