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