Re: [linux-pm] [RFD] swsusp problem: Drivers allocate much memory during suspend (was: Re: 2.6.21-rc5: swsusp: Not enough free memory)

Rafael J. Wysocki
2007-04-14T22:49:55Z

Hi,

On Saturday, 14 April 2007 00:35, Rafael J. Wysocki wrote:
> On Saturday, 14 April 2007 00:10, Pavel Machek wrote:
[--snip--]
> > > IMO to really fix the problem, we should let the drivers that need much memory
> > > for suspending allocate it _before_ the memory shrinker is called. For this
> > > purpose we can use notifiers that will be called before we start the shrinking
> > > of memory. Namely, if a driver needs to allocate substantial amount
> > > of memory
> >
> > Yes please. Using that notifier without leaking the memory will be
> > "interesting" but if someone needs so much memory during suspend, let
> > them eat their own complexity.
>
> Okay, I'm going to prepare a patch along these lines.

The appended patch shows how I think this might look like.

There are a couple of things I'm not sure about in it:
1) Names (if you have better ideas, please tell me)
2) I don't know if SUSPEND_THAW_PREPARE is necessary, at least for now I don't
see any obvious case in which it may be useful, but I've added it for symmetry
3) Perhaps we can use the second argument of raw_notifier_call_chain() to pass
the information of what kind of suspend is going to happen (eg. STD vs STR), in
which case we'll need a second argument for suspend_notifier_call_chain()

Greetings,
Rafael

---
include/linux/notifier.h | 6 +++++
include/linux/suspend.h | 27 ++++++++++++++++++++++---
kernel/power/Makefile | 2 -
kernel/power/disk.c | 21 ++++++++++++++++++++
kernel/power/main.c | 13 ++++++++++++
kernel/power/notify.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++
kernel/power/power.h | 3 ++
kernel/power/user.c | 19 ++++++++++++++++++
8 files changed, 135 insertions(+), 5 deletions(-)

Index: linux-2.6.21-rc6/kernel/power/notify.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.21-rc6/kernel/power/notify.c 2007-04-14 23:35:35.000000000 +0200
@@ -0,0 +1,49 @@
+/*
+ * linux/kernel/power/notify.c
+ *
+ * This file contains functions used for registering and calling suspend
+ * notifiers that can be used by subsystems for carrying out some special
+ * suspend-related operations.
+ *
+ * Copyright (C) 2007 Rafael J. Wysocki <rjw@sisk.pl>
+ *
+ * This file is released under the GPLv2.
+ *
+ */
+
+#include <linux/smp.h>
+#include <linux/notifier.h>
+#include <linux/module.h>
+#include <linux/suspend.h>
+
+static DEFINE_MUTEX(suspend_notifier_lock);
+
+static RAW_NOTIFIER_HEAD(suspend_chain);
+
+int register_suspend_notifier(struct notifier_block *nb)
+{
+ int ret;
+ mutex_lock(&suspend_notifier_lock);
+ ret = raw_notifier_chain_register(&suspend_chain, nb);
+ mutex_unlock(&suspend_notifier_lock);
+ return ret;
+}
+EXPORT_SYMBOL(register_suspend_notifier);
+
+void unregister_suspend_notifier(struct notifier_block *nb)
+{
+ mutex_lock(&suspend_notifier_lock);
+ raw_notifier_chain_unregister(&suspend_chain, nb);
+ mutex_unlock(&suspend_notifier_lock);
+}
+EXPORT_SYMBOL(unregister_suspend_notifier);
+
+int suspend_notifier_call_chain(unsigned long val)
+{
+ int error;
+
+ mutex_lock(&suspend_notifier_lock);
+ error = raw_notifier_call_chain(&suspend_chain, val, NULL);
+ mutex_unlock(&suspend_notifier_lock);
+ return error;
+}
Index: linux-2.6.21-rc6/include/linux/suspend.h
===================================================================
--- linux-2.6.21-rc6.orig/include/linux/suspend.h 2007-04-14 22:04:58.000000000 +0200
+++ linux-2.6.21-rc6/include/linux/suspend.h 2007-04-14 23:32:18.000000000 +0200
@@ -24,15 +24,16 @@ struct pbe {
extern void drain_local_pages(void);
extern void mark_free_pages(struct zone *zone);

-#if defined(CONFIG_PM) && defined(CONFIG_VT) && defined(CONFIG_VT_CONSOLE)
+#ifdef CONFIG_PM
+#if defined(CONFIG_VT) && defined(CONFIG_VT_CONSOLE)
extern int pm_prepare_console(void);
extern void pm_restore_console(void);
#else
static inline int pm_prepare_console(void) { return 0; }
static inline void pm_restore_console(void) {}
-#endif
+#endif /* defined(CONFIG_VT) && defined(CONFIG_VT_CONSOLE) */

-#if defined(CONFIG_PM) && defined(CONFIG_SOFTWARE_SUSPEND)
+#ifdef CONFIG_SOFTWARE_SUSPEND
/* kernel/power/swsusp.c */
extern int software_suspend(void);
/* kernel/power/snapshot.c */
@@ -52,7 +53,7 @@ static inline void register_nosave_regio
static inline int swsusp_page_is_forbidden(struct page *p) { return 0; }
static inline void swsusp_set_page_free(struct page *p) {}
static inline void swsusp_unset_page_free(struct page *p) {}
-#endif /* defined(CONFIG_PM) && defined(CONFIG_SOFTWARE_SUSPEND) */
+#endif /* CONFIG_SOFTWARE_SUSPEND */

void save_processor_state(void);
void restore_processor_state(void);
@@ -60,4 +61,22 @@ struct saved_context;
void __save_processor_state(struct saved_context *ctxt);
void __restore_processor_state(struct saved_context *ctxt);

+int register_suspend_notifier(struct notifier_block *nb);
+void unregister_suspend_notifier(struct notifier_block *nb);
+
+#define suspend_notifier(fn, pri) { \
+ static struct notifier_block fn##_nb = \
+ { .notifier_call = fn, .priority = pri }; \
+ register_suspend_notifier(&fn##_nb); \
+}
+#else /* CONFIG_PM */
+static inline int register_suspend_notifier(struct notifier_block *nb) {
+ return 0;
+}
+static inline void unregister_suspend_notifier(struct notifier_block *nb) {
+}
+
+#define suspend_notifier(fn, pri) do { (void)(fn); } while (0)
+#endif
+
#endif /* _LINUX_SWSUSP_H */
Index: linux-2.6.21-rc6/kernel/power/Makefile
===================================================================
--- linux-2.6.21-rc6.orig/kernel/power/Makefile 2007-02-04 19:44:54.000000000 +0100
+++ linux-2.6.21-rc6/kernel/power/Makefile 2007-04-14 23:34:30.000000000 +0200
@@ -3,7 +3,7 @@ ifeq ($(CONFIG_PM_DEBUG),y)
EXTRA_CFLAGS += -DDEBUG
endif

-obj-y := main.o process.o console.o
+obj-y := main.o process.o console.o notify.o
obj-$(CONFIG_PM_LEGACY) += pm.o
obj-$(CONFIG_SOFTWARE_SUSPEND) += swsusp.o disk.o snapshot.o swap.o user.o

Index: linux-2.6.21-rc6/kernel/power/power.h
===================================================================
--- linux-2.6.21-rc6.orig/kernel/power/power.h 2007-04-14 23:38:11.000000000 +0200
+++ linux-2.6.21-rc6/kernel/power/power.h 2007-04-14 23:40:07.000000000 +0200
@@ -171,3 +171,6 @@ extern int suspend_enter(suspend_state_t
struct timeval;
extern void swsusp_show_speed(struct timeval *, struct timeval *,
unsigned int, char *);
+
+/* kernel/power/notify.c */
+extern int suspend_notifier_call_chain(unsigned long val);
Index: linux-2.6.21-rc6/include/linux/notifier.h
===================================================================
--- linux-2.6.21-rc6.orig/include/linux/notifier.h 2007-02-04 19:44:54.000000000 +0100
+++ linux-2.6.21-rc6/include/linux/notifier.h 2007-04-15 00:31:04.000000000 +0200
@@ -187,5 +187,11 @@ extern int srcu_notifier_call_chain(stru
#define CPU_DOWN_FAILED 0x0006 /* CPU (unsigned)v NOT going down */
#define CPU_DEAD 0x0007 /* CPU (unsigned)v dead */

+#define SUSPEND_PREPARE 0x0002 /* Going to freeze tasks */
+#define SUSPEND_ENTER_PREPARE 0x0003 /* Tasks are frozen, we are suspending */
+#define SUSPEND_THAW_PREPARE 0x0004 /* Going to thaw frozen tasks */
+#define SUSPEND_FINISHED 0x0005 /* Tasks have been thawed */
+#define SUSPEND_RESTORE_PREPARE 0x0006 /* STD restore is going to happen */
+
#endif /* __KERNEL__ */
#endif /* _LINUX_NOTIFIER_H */
Index: linux-2.6.21-rc6/kernel/power/disk.c
===================================================================
--- linux-2.6.21-rc6.orig/kernel/power/disk.c 2007-04-14 21:49:23.000000000 +0200
+++ linux-2.6.21-rc6/kernel/power/disk.c 2007-04-15 00:31:44.000000000 +0200
@@ -100,6 +100,7 @@ static int prepare_processes(void)
pm_prepare_console();
if (freeze_processes()) {
error = -EBUSY;
+ suspend_notifier_call_chain(SUSPEND_THAW_PREPARE);
unprepare_processes();
}
return error;
@@ -127,6 +128,10 @@ int pm_suspend_disk(void)
if (error)
goto Exit;

+ error = suspend_notifier_call_chain(SUSPEND_PREPARE);
+ if (error)
+ goto Finish;
+
error = prepare_processes();
if (error)
goto Finish;
@@ -137,6 +142,10 @@ int pm_suspend_disk(void)
goto Thaw;
}

+ error = suspend_notifier_call_chain(SUSPEND_ENTER_PREPARE);
+ if (error)
+ goto Thaw;
+
/* Free memory before shutting down devices. */
error = swsusp_shrink_memory();
if (error)
@@ -193,8 +202,10 @@ int pm_suspend_disk(void)
device_resume();
resume_console();
Thaw:
+ suspend_notifier_call_chain(SUSPEND_THAW_PREPARE);
unprepare_processes();
Finish:
+ suspend_notifier_call_chain(SUSPEND_FINISHED);
free_basic_memory_bitmaps();
Exit:
atomic_inc(&snapshot_device_available);
@@ -255,6 +266,10 @@ static int software_resume(void)
if (error)
goto Finish;

+ error = suspend_notifier_call_chain(SUSPEND_PREPARE);
+ if (error)
+ goto Done;
+
pr_debug("PM: Preparing processes for restore.\n");
error = prepare_processes();
if (error) {
@@ -271,6 +286,10 @@ static int software_resume(void)
goto Thaw;
}

+ error = suspend_notifier_call_chain(SUSPEND_RESTORE_PREPARE);
+ if (error)
+ goto Thaw;
+
pr_debug("PM: Preparing devices for restore.\n");

suspend_console();
@@ -289,8 +308,10 @@ static int software_resume(void)
resume_console();
Thaw:
printk(KERN_ERR "PM: Restore failed, recovering.\n");
+ suspend_notifier_call_chain(SUSPEND_THAW_PREPARE);
unprepare_processes();
Done:
+ suspend_notifier_call_chain(SUSPEND_FINISHED);
free_basic_memory_bitmaps();
Finish:
atomic_inc(&snapshot_device_available);
Index: linux-2.6.21-rc6/kernel/power/main.c
===================================================================
--- linux-2.6.21-rc6.orig/kernel/power/main.c 2007-04-07 12:15:28.000000000 +0200
+++ linux-2.6.21-rc6/kernel/power/main.c 2007-04-15 00:27:52.000000000 +0200
@@ -69,11 +69,19 @@ static int suspend_prepare(suspend_state

pm_prepare_console();

+ error = suspend_notifier_call_chain(SUSPEND_PREPARE);
+ if (error)
+ goto Finish;
+
if (freeze_processes()) {
error = -EAGAIN;
goto Thaw;
}

+ error = suspend_notifier_call_chain(SUSPEND_ENTER_PREPARE);
+ if (error)
+ goto Thaw;
+
if ((free_pages = global_page_state(NR_FREE_PAGES))
< FREE_PAGE_NUMBER) {
pr_debug("PM: free some memory\n");
@@ -106,8 +114,11 @@ static int suspend_prepare(suspend_state
device_resume();
resume_console();
Thaw:
+ suspend_notifier_call_chain(SUSPEND_THAW_PREPARE);
thaw_processes();
+ Finish:
pm_restore_console();
+ suspend_notifier_call_chain(SUSPEND_FINISHED);
return error;
}

@@ -145,8 +156,10 @@ static void suspend_finish(suspend_state
pm_finish(state);
device_resume();
resume_console();
+ suspend_notifier_call_chain(SUSPEND_THAW_PREPARE);
thaw_processes();
pm_restore_console();
+ suspend_notifier_call_chain(SUSPEND_FINISHED);
}

Index: linux-2.6.21-rc6/kernel/power/user.c
===================================================================
--- linux-2.6.21-rc6.orig/kernel/power/user.c 2007-04-14 21:49:23.000000000 +0200
+++ linux-2.6.21-rc6/kernel/power/user.c 2007-04-15 00:38:23.000000000 +0200
@@ -148,6 +148,10 @@ static inline int snapshot_suspend(int p
int error;

mutex_lock(&pm_mutex);
+ error = suspend_notifier_call_chain(SUSPEND_ENTER_PREPARE);
+ if (error)
+ goto Finish;
+
/* Free memory before shutting down devices. */
error = swsusp_shrink_memory();
if (error)
@@ -186,6 +190,10 @@ static inline int snapshot_restore(int p

mutex_lock(&pm_mutex);
pm_prepare_console();
+ error = suspend_notifier_call_chain(SUSPEND_RESTORE_PREPARE);
+ if (error)
+ goto Finish;
+
if (platform_suspend) {
error = platform_prepare();
if (error)
@@ -236,7 +244,12 @@ static int snapshot_ioctl(struct inode *
if (data->frozen)
break;
mutex_lock(&pm_mutex);
+ error = suspend_notifier_call_chain(SUSPEND_PREPARE);
+ if (error)
+ break;
+
if (freeze_processes()) {
+ suspend_notifier_call_chain(SUSPEND_THAW_PREPARE);
thaw_processes();
error = -EBUSY;
}
@@ -249,7 +262,9 @@ static int snapshot_ioctl(struct inode *
if (!data->frozen)
break;
mutex_lock(&pm_mutex);
+ suspend_notifier_call_chain(SUSPEND_THAW_PREPARE);
thaw_processes();
+ suspend_notifier_call_chain(SUSPEND_FINISHED);
mutex_unlock(&pm_mutex);
data->frozen = 0;
break;
@@ -350,6 +365,10 @@ static int snapshot_ioctl(struct inode *
break;
}

+ error = suspend_notifier_call_chain(SUSPEND_ENTER_PREPARE);
+ if (error)
+ break;
+
if (pm_ops->prepare) {
error = pm_ops->prepare(PM_SUSPEND_MEM);
if (error)