[PATCH] swsusp: freeze user space processes first

Allow swsusp to freeze processes successfully under heavy load by freezing
userspace processes before kernel threads.

[Thanks to Nigel Cunningham <nigel@suspend2.net> for suggesting the
way to go.]

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index 4bd68f4..81d4d98 100644 (file)
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -72,7 +72,6 @@ static int prepare_processes(void)
        int error;
 
        pm_prepare_console();
-       sys_sync();
        disable_nonboot_cpus();
 
        if (freeze_processes()) {

diff --git a/kernel/power/process.c b/kernel/power/process.c
index 02a1b3a..8ac7c35 100644 (file)
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -12,11 +12,12 @@
 #include <linux/interrupt.h>
 #include <linux/suspend.h>
 #include <linux/module.h>
+#include <linux/syscalls.h>
 
 /* 
  * Timeout for stopping processes
  */
-#define TIMEOUT        (6 * HZ)
+#define TIMEOUT        (20 * HZ)
 
 
 static inline int freezeable(struct task_struct * p)
@@ -54,38 +55,62 @@ void refrigerator(void)
        current->state = save;
 }
 
+static inline void freeze_process(struct task_struct *p)
+{
+       unsigned long flags;
+
+       if (!freezing(p)) {
+               freeze(p);
+               spin_lock_irqsave(&p->sighand->siglock, flags);
+               signal_wake_up(p, 0);
+               spin_unlock_irqrestore(&p->sighand->siglock, flags);
+       }
+}
+
 /* 0 = success, else # of processes that we failed to stop */
 int freeze_processes(void)
 {
-       int todo;
+       int todo, nr_user, user_frozen;
        unsigned long start_time;
        struct task_struct *g, *p;
        unsigned long flags;
 
        printk( "Stopping tasks: " );
        start_time = jiffies;
+       user_frozen = 0;
        do {
-               todo = 0;
+               nr_user = todo = 0;
                read_lock(&tasklist_lock);
                do_each_thread(g, p) {
                        if (!freezeable(p))
                                continue;
                        if (frozen(p))
                                continue;
-
-                       freeze(p);
-                       spin_lock_irqsave(&p->sighand->siglock, flags);
-                       signal_wake_up(p, 0);
-                       spin_unlock_irqrestore(&p->sighand->siglock, flags);
-                       todo++;
+                       if (p->mm && !(p->flags & PF_BORROWED_MM)) {
+                               /* The task is a user-space one.
+                                * Freeze it unless there's a vfork completion
+                                * pending
+                                */
+                               if (!p->vfork_done)
+                                       freeze_process(p);
+                               nr_user++;
+                       } else {
+                               /* Freeze only if the user space is frozen */
+                               if (user_frozen)
+                                       freeze_process(p);
+                               todo++;
+                       }
                } while_each_thread(g, p);
                read_unlock(&tasklist_lock);
+               todo += nr_user;
+               if (!user_frozen && !nr_user) {
+                       sys_sync();
+                       start_time = jiffies;
+               }
+               user_frozen = !nr_user;
                yield();                        /* Yield is okay here */
-               if (todo && time_after(jiffies, start_time + TIMEOUT)) {
-                       printk( "\n" );
-                       printk(KERN_ERR " stopping tasks timed out (%d tasks remaining)\n", todo );
+               if (todo && time_after(jiffies, start_time + TIMEOUT))
                        break;
-               }
        } while(todo);
 
        /* This does not unfreeze processes that are already frozen
@@ -94,8 +119,14 @@ int freeze_processes(void)
         * but it cleans up leftover PF_FREEZE requests.
         */
        if (todo) {
+               printk( "\n" );
+               printk(KERN_ERR " stopping tasks timed out "
+                       "after %d seconds (%d tasks remaining):\n",
+                       TIMEOUT / HZ, todo);
                read_lock(&tasklist_lock);
-               do_each_thread(g, p)
+               do_each_thread(g, p) {
+                       if (freezeable(p) && !frozen(p))
+                               printk(KERN_ERR "  %s\n", p->comm);
                        if (freezing(p)) {
                                pr_debug("  clean up: %s\n", p->comm);
                                p->flags &= ~PF_FREEZE;
@@ -103,7 +134,7 @@ int freeze_processes(void)
                                recalc_sigpending_tsk(p);
                                spin_unlock_irqrestore(&p->sighand->siglock, flags);
                        }
-               while_each_thread(g, p);
+               } while_each_thread(g, p);
                read_unlock(&tasklist_lock);
                return todo;
        }

diff --git a/kernel/power/user.c b/kernel/power/user.c
index 8cabc40..a97406b 100644 (file)
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -138,7 +138,6 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
        case SNAPSHOT_FREEZE:
                if (data->frozen)
                        break;
-               sys_sync();
                down(&pm_sem);
                pm_prepare_console();
                disable_nonboot_cpus();