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    SubjectRe: [RFC][PATCH] PM: disable nonboot cpus before suspending devices
    Date
    On Monday 01 February 2010, Andrew Morton wrote:
    > On Mon, 1 Feb 2010 16:30:04 +0100 "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
    >
    > > On Monday 01 February 2010, Sebastian Ott wrote:
    > > > Hi Rafael,
    > > >
    > > > since you didn't like the idea of calling the driver callbacks with just
    > > > one cpu enabled, we gave your patch: "MM / PM: Force GFP_NOIO during
    > > > suspend/hibernation and resume" a try and i can confirm that this
    > > > fixes the issue on s390.
    > >
    > > Great, thanks for testing!
    > >
    > > > Will this go in 2.6.33/stable?
    > >
    > > That depends on Andrew, actually.
    > >
    > > Andrew, what do you think of the patch at:
    > > http://patchwork.kernel.org/patch/74740/mbox/ ?
    > >
    > > It helps people and I don't see any major drawbacks of it.
    > >
    >
    > Seems sane. A couple of minor things:
    >
    > - the names mm_force_noio_allocations() and mm_allow_io_allocations()
    > are a bit sucky. Asymmetrical.

    Yeah. The lack of imagination. Sigh.

    > - the functions don't nest: if someone calls
    > mm_force_noio_allocations() twice in succession then the kernel is
    > all mucked up. Why not:
    >
    > gfp_t mm_set_gfp_mask(gfp_t mask)
    > {
    > gfp_t ret = gfp_allowed_mask;
    >
    > gfp_allowed_mask = mask;
    > return ret;
    > }
    >
    > which is of course racy :) Could add a local spinlock if really worried.

    I'm not sure how that helps. I'd need to read gfp_allowed_mask to obtain the
    new value anyway.

    > All your current callers can easily save the old value in a local.

    Indeed.

    Well, does the appended one look better?

    Rafael

    ---
    From: Rafael J. Wysocki <rjw@sisk.pl>
    Subject: MM / PM: Force GFP_NOIO during suspend/hibernation and resume (rev. 2)

    There are quite a few GFP_KERNEL memory allocations made during
    suspend/hibernation and resume that may cause the system to hang,
    because the I/O operations they depend on cannot be completed due to
    the underlying devices being suspended.

    Avoid this problem by clearing the __GFP_IO and __GFP_FS bits in
    gfp_allowed_mask before suspend/hibernation and restoring the
    original values of these bits in gfp_allowed_mask durig the
    subsequent resume.

    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
    Reported-by: Maxim Levitsky <maximlevitsky@gmail.com>
    ---
    include/linux/gfp.h | 8 ++++++++
    kernel/power/hibernate.c | 9 +++++++++
    kernel/power/suspend.c | 3 +++
    3 files changed, 20 insertions(+)

    Index: linux-2.6/kernel/power/hibernate.c
    ===================================================================
    --- linux-2.6.orig/kernel/power/hibernate.c
    +++ linux-2.6/kernel/power/hibernate.c
    @@ -323,6 +323,7 @@ static int create_image(int platform_mod
    int hibernation_snapshot(int platform_mode)
    {
    int error;
    + gfp_t saved_mask;

    error = platform_begin(platform_mode);
    if (error)
    @@ -334,6 +335,7 @@ int hibernation_snapshot(int platform_mo
    goto Close;

    suspend_console();
    + saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
    error = dpm_suspend_start(PMSG_FREEZE);
    if (error)
    goto Recover_platform;
    @@ -351,6 +353,7 @@ int hibernation_snapshot(int platform_mo

    dpm_resume_end(in_suspend ?
    (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
    + set_gfp_allowed_mask(saved_mask);
    resume_console();
    Close:
    platform_end(platform_mode);
    @@ -445,14 +448,17 @@ static int resume_target_kernel(bool pla
    int hibernation_restore(int platform_mode)
    {
    int error;
    + gfp_t saved_mask;

    pm_prepare_console();
    suspend_console();
    + saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
    error = dpm_suspend_start(PMSG_QUIESCE);
    if (!error) {
    error = resume_target_kernel(platform_mode);
    dpm_resume_end(PMSG_RECOVER);
    }
    + set_gfp_allowed_mask(saved_mask);
    resume_console();
    pm_restore_console();
    return error;
    @@ -466,6 +472,7 @@ int hibernation_restore(int platform_mod
    int hibernation_platform_enter(void)
    {
    int error;
    + gfp_t saved_mask;

    if (!hibernation_ops)
    return -ENOSYS;
    @@ -481,6 +488,7 @@ int hibernation_platform_enter(void)

    entering_platform_hibernation = true;
    suspend_console();
    + saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
    error = dpm_suspend_start(PMSG_HIBERNATE);
    if (error) {
    if (hibernation_ops->recover)
    @@ -518,6 +526,7 @@ int hibernation_platform_enter(void)
    Resume_devices:
    entering_platform_hibernation = false;
    dpm_resume_end(PMSG_RESTORE);
    + set_gfp_allowed_mask(saved_mask);
    resume_console();

    Close:
    Index: linux-2.6/kernel/power/suspend.c
    ===================================================================
    --- linux-2.6.orig/kernel/power/suspend.c
    +++ linux-2.6/kernel/power/suspend.c
    @@ -198,6 +198,7 @@ static int suspend_enter(suspend_state_t
    int suspend_devices_and_enter(suspend_state_t state)
    {
    int error;
    + gfp_t saved_mask;

    if (!suspend_ops)
    return -ENOSYS;
    @@ -208,6 +209,7 @@ int suspend_devices_and_enter(suspend_st
    goto Close;
    }
    suspend_console();
    + saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
    suspend_test_start();
    error = dpm_suspend_start(PMSG_SUSPEND);
    if (error) {
    @@ -224,6 +226,7 @@ int suspend_devices_and_enter(suspend_st
    suspend_test_start();
    dpm_resume_end(PMSG_RESUME);
    suspend_test_finish("resume devices");
    + set_gfp_allowed_mask(saved_mask);
    resume_console();
    Close:
    if (suspend_ops->end)
    Index: linux-2.6/include/linux/gfp.h
    ===================================================================
    --- linux-2.6.orig/include/linux/gfp.h
    +++ linux-2.6/include/linux/gfp.h
    @@ -83,6 +83,7 @@ struct vm_area_struct;
    #define GFP_HIGHUSER_MOVABLE (__GFP_WAIT | __GFP_IO | __GFP_FS | \
    __GFP_HARDWALL | __GFP_HIGHMEM | \
    __GFP_MOVABLE)
    +#define GFP_IOFS (__GFP_IO | __GFP_FS)

    #ifdef CONFIG_NUMA
    #define GFP_THISNODE (__GFP_THISNODE | __GFP_NOWARN | __GFP_NORETRY)
    @@ -342,4 +343,11 @@ static inline void set_gfp_allowed_mask(
    gfp_allowed_mask = mask;
    }

    +static inline gfp_t clear_gfp_allowed_mask(gfp_t mask)
    +{
    + gfp_t ret = gfp_allowed_mask;
    + gfp_allowed_mask &= ~mask;
    + return ret;
    +}
    +
    #endif /* __LINUX_GFP_H */

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