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Date: Wed, 1 Dec 2010 21:57:43 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Hugh Dickins <hughd@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: Ondrej Zary <linux@...nbow-software.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Kernel development list <linux-kernel@...r.kernel.org>,
Balbir Singh <balbir@...ibm.com>
Subject: Re: 2.6.35.5: hibernation broken... AGAIN
On Wednesday, December 01, 2010, Hugh Dickins wrote:
> On Wed, 1 Dec 2010, Rafael J. Wysocki wrote:
> > Below is an updated patch in which I tried to address your comments.
> >
> > I didn't find it very useful to couple pm_restore_gfp_mask() with the thawing
> > of tasks, but nevertheless I think all of the spots where it's needed are
> > covered now.
>
> So far as I can see, yes, they are: I'm still a bit worried about
> future changes leaving the wrong gfp mask behind by mistake;
> but I trust you more than I trust me on that, so you can add my
> Acked-by: Hugh Dickins <hughd@...gle.com> when it comes to
> sending in the patch.
Thanks a lot!
Andrew, are the changes in page_alloc.c fine from your standpoint?
Rafael
> > The patch has only been compile-tested for now, so caveat emptor.
> >
> > Thanks,
> > Rafael
> >
> > ---
> > include/linux/gfp.h | 4 ++--
> > kernel/power/hibernate.c | 22 ++++++++++++----------
> > kernel/power/suspend.c | 5 ++---
> > kernel/power/user.c | 2 ++
> > mm/page_alloc.c | 18 +++++++++++-------
> > 5 files changed, 29 insertions(+), 22 deletions(-)
> >
> > Index: linux-2.6/kernel/power/hibernate.c
> > ===================================================================
> > --- linux-2.6.orig/kernel/power/hibernate.c
> > +++ linux-2.6/kernel/power/hibernate.c
> > @@ -327,7 +327,6 @@ 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)
> > @@ -339,7 +338,7 @@ int hibernation_snapshot(int platform_mo
> > goto Close;
> >
> > suspend_console();
> > - saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
> > + pm_restrict_gfp_mask();
> > error = dpm_suspend_start(PMSG_FREEZE);
> > if (error)
> > goto Recover_platform;
> > @@ -348,7 +347,10 @@ int hibernation_snapshot(int platform_mo
> > goto Recover_platform;
> >
> > error = create_image(platform_mode);
> > - /* Control returns here after successful restore */
> > + /*
> > + * Control returns here (1) after the image has been created or the
> > + * image creation has failed and (2) after a successful restore.
> > + */
> >
> > Resume_devices:
> > /* We may need to release the preallocated image pages here. */
> > @@ -357,7 +359,10 @@ int hibernation_snapshot(int platform_mo
> >
> > dpm_resume_end(in_suspend ?
> > (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
> > - set_gfp_allowed_mask(saved_mask);
> > +
> > + if (error || !in_suspend)
> > + pm_restore_gfp_mask();
> > +
> > resume_console();
> > Close:
> > platform_end(platform_mode);
> > @@ -452,17 +457,16 @@ 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);
> > + pm_restrict_gfp_mask();
> > 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);
> > + pm_restore_gfp_mask();
> > resume_console();
> > pm_restore_console();
> > return error;
> > @@ -476,7 +480,6 @@ int hibernation_restore(int platform_mod
> > int hibernation_platform_enter(void)
> > {
> > int error;
> > - gfp_t saved_mask;
> >
> > if (!hibernation_ops)
> > return -ENOSYS;
> > @@ -492,7 +495,6 @@ 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)
> > @@ -536,7 +538,6 @@ 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:
> > @@ -647,6 +648,7 @@ int hibernate(void)
> > if (!error)
> > power_down();
> > in_suspend = 0;
> > + pm_restore_gfp_mask();
> > } else {
> > pr_debug("PM: Image restored successfully.\n");
> > }
> > Index: linux-2.6/kernel/power/user.c
> > ===================================================================
> > --- linux-2.6.orig/kernel/power/user.c
> > +++ linux-2.6/kernel/power/user.c
> > @@ -263,6 +263,7 @@ static long snapshot_ioctl(struct file *
> > case SNAPSHOT_UNFREEZE:
> > if (!data->frozen || data->ready)
> > break;
> > + pm_restore_gfp_mask();
> > thaw_processes();
> > usermodehelper_enable();
> > data->frozen = 0;
> > @@ -275,6 +276,7 @@ static long snapshot_ioctl(struct file *
> > error = -EPERM;
> > break;
> > }
> > + pm_restore_gfp_mask();
> > error = hibernation_snapshot(data->platform_support);
> > if (!error)
> > error = put_user(in_suspend, (int __user *)arg);
> > Index: linux-2.6/mm/page_alloc.c
> > ===================================================================
> > --- linux-2.6.orig/mm/page_alloc.c
> > +++ linux-2.6/mm/page_alloc.c
> > @@ -104,19 +104,23 @@ gfp_t gfp_allowed_mask __read_mostly = G
> > * only be modified with pm_mutex held, unless the suspend/hibernate code is
> > * guaranteed not to run in parallel with that modification).
> > */
> > -void set_gfp_allowed_mask(gfp_t mask)
> > +
> > +static gfp_t saved_gfp_mask;
> > +
> > +void pm_restore_gfp_mask(void)
> > {
> > WARN_ON(!mutex_is_locked(&pm_mutex));
> > - gfp_allowed_mask = mask;
> > + if (saved_gfp_mask) {
> > + gfp_allowed_mask = saved_gfp_mask;
> > + saved_gfp_mask = 0;
> > + }
> > }
> >
> > -gfp_t clear_gfp_allowed_mask(gfp_t mask)
> > +void pm_restrict_gfp_mask(void)
> > {
> > - gfp_t ret = gfp_allowed_mask;
> > -
> > WARN_ON(!mutex_is_locked(&pm_mutex));
> > - gfp_allowed_mask &= ~mask;
> > - return ret;
> > + saved_gfp_mask = gfp_allowed_mask;
> > + gfp_allowed_mask &= ~GFP_IOFS;
> > }
> > #endif /* CONFIG_PM_SLEEP */
> >
> > Index: linux-2.6/include/linux/gfp.h
> > ===================================================================
> > --- linux-2.6.orig/include/linux/gfp.h
> > +++ linux-2.6/include/linux/gfp.h
> > @@ -360,7 +360,7 @@ void drain_local_pages(void *dummy);
> >
> > extern gfp_t gfp_allowed_mask;
> >
> > -extern void set_gfp_allowed_mask(gfp_t mask);
> > -extern gfp_t clear_gfp_allowed_mask(gfp_t mask);
> > +extern void pm_restrict_gfp_mask(void);
> > +extern void pm_restore_gfp_mask(void);
> >
> > #endif /* __LINUX_GFP_H */
> > Index: linux-2.6/kernel/power/suspend.c
> > ===================================================================
> > --- linux-2.6.orig/kernel/power/suspend.c
> > +++ linux-2.6/kernel/power/suspend.c
> > @@ -197,7 +197,6 @@ 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;
> > @@ -208,7 +207,7 @@ int suspend_devices_and_enter(suspend_st
> > goto Close;
> > }
> > suspend_console();
> > - saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
> > + pm_restrict_gfp_mask();
> > suspend_test_start();
> > error = dpm_suspend_start(PMSG_SUSPEND);
> > if (error) {
> > @@ -225,7 +224,7 @@ 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);
> > + pm_restore_gfp_mask();
> > resume_console();
> > Close:
> > if (suspend_ops->end)
> >
> --
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