Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 30 Nov 2010 14:16:25 -0800 (PST) | From | Hugh Dickins <> | Subject | Re: 2.6.35.5: hibernation broken... AGAIN |
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On Sat, 27 Nov 2010, Rafael J. Wysocki wrote: > On Saturday, November 27, 2010, Ondrej Zary wrote: > > > > > > > > > > Not signing it off yet, > > > > > Hugh > > > > > > > > Could you please do that? The patch fixes the problem.
Sorry for going quiet for so long.
Thanks for testing, Ondrej. I completely agree with Rafael that my patch was inadequate: it turned out to be good enough for your useful feedback on the main path through hibernation, but missed a number of details. We do need something like Rafael's patch - thanks.
(And I realize that it's tiresome and frustrating for you to be trying first that and then this etc; but we had bugs here precisely because this is a confusing area, so I think it is worth some effort to get right now.)
> > > > > > Can you check if the problem is also fixed by the patch below, please? > > > > The patch does not apply to 2.6.35.4, 2.6.35.5 and also 2.6.36. What version > > should I test? > > The patch was against the current mainline. > > The one below was rebased on top of 2.6.36, so please test it with this kernel.
I'll comment on this version, since it has one more line than your original.
> > Thanks, > Rafael > > --- > kernel/power/hibernate.c | 36 ++++++++++++++++++++++++++---------- > kernel/power/power.h | 1 + > kernel/power/user.c | 2 ++ > 3 files changed, 29 insertions(+), 10 deletions(-) > > Index: suspend-2.6/kernel/power/hibernate.c > =================================================================== > --- suspend-2.6.orig/kernel/power/hibernate.c > +++ suspend-2.6/kernel/power/hibernate.c > @@ -29,6 +29,21 @@ > #include "power.h" > > > +static gfp_t saved_gfp_mask; > + > +static void hibernate_restrict_gfp_mask(void) > +{ > + saved_gfp_mask = clear_gfp_allowed_mask(GFP_IOFS); > +} > + > +void hibernate_restore_gfp_mask(void) > +{ > + if (saved_gfp_mask) { > + set_gfp_allowed_mask(saved_gfp_mask); > + saved_gfp_mask = 0; > + } > +} > +
Trivial point, I suppose, but it bothers me that PM is accumulating wrappers around wrappers around gfp_allowed_mask. Looks like clear_gfp_allowed_mask and set_gfp_allowed_mask (oddly asymmetrical) were not really what we need. How about scrapping them, and putting pm_restrict_gfp_mask() and pm_restore_gfp_mask() into page_alloc.c?
> static int noresume = 0; > static char resume_file[256] = CONFIG_PM_STD_PARTITION; > dev_t swsusp_resume_device; > @@ -326,7 +341,6 @@ 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) > @@ -338,7 +352,7 @@ int hibernation_snapshot(int platform_mo > goto Close; > > suspend_console(); > - saved_mask = clear_gfp_allowed_mask(GFP_IOFS); > + hibernate_restrict_gfp_mask();
Yes.
> error = dpm_suspend_start(PMSG_FREEZE); > if (error) > goto Recover_platform; > @@ -347,7 +361,10 @@ 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. */ > @@ -356,7 +373,10 @@ 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) > + hibernate_restore_gfp_mask(); > +
I'm worried that it's hard to find and maintain the places that need this restoration - and if we miss one, we won't find out about it for ages. It would help a lot if the gfp restoration always accompanies some other essential stage - thaw_processes() looks to be right, so could we skip conditionally restoring here if we do it then?
I suggest that in part because I cannot find where you restore in the case that hibernate()'s swsusp_write() fails - that was the case that made me realize my little patch was too simplistic.
> resume_console(); > Close: > platform_end(platform_mode); > @@ -451,17 +471,16 @@ 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); > + hibernate_restrict_gfp_mask();
Yes.
> 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); > + hibernate_restore_gfp_mask();
But this could be left until software_resume()'s thaw_processes()? Ah, that won't cover the SNAPSHOT_ATOMIC_RESTORE case, hmmm.
> resume_console(); > pm_restore_console(); > return error; > @@ -475,7 +494,6 @@ int hibernation_restore(int platform_mod > int hibernation_platform_enter(void) > { > int error; > - gfp_t saved_mask; > > if (!hibernation_ops) > return -ENOSYS; > @@ -491,7 +509,6 @@ int hibernation_platform_enter(void) > > entering_platform_hibernation = true; > suspend_console(); > - saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
Right.
> error = dpm_suspend_start(PMSG_HIBERNATE); > if (error) { > if (hibernation_ops->recover) > @@ -535,7 +552,6 @@ int hibernation_platform_enter(void) > Resume_devices: > entering_platform_hibernation = false; > dpm_resume_end(PMSG_RESTORE); > - set_gfp_allowed_mask(saved_mask);
Right.
> resume_console(); > > Close: > Index: suspend-2.6/kernel/power/power.h > =================================================================== > --- suspend-2.6.orig/kernel/power/power.h > +++ suspend-2.6/kernel/power/power.h > @@ -49,6 +49,7 @@ static inline char *check_image_kernel(s > extern int hibernation_snapshot(int platform_mode); > extern int hibernation_restore(int platform_mode); > extern int hibernation_platform_enter(void); > +extern void hibernate_restore_gfp_mask(void); > #endif > > extern int pfn_is_nosave(unsigned long); > Index: suspend-2.6/kernel/power/user.c > =================================================================== > --- suspend-2.6.orig/kernel/power/user.c > +++ suspend-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; > + hibernate_restore_gfp_mask();
Right, here you have one next to thaw_processes(). But the SNAPSHOT ioctls are a nightmarish maze to me, I cannot comment much on what's right here.
> thaw_processes(); > usermodehelper_enable(); > data->frozen = 0; > @@ -275,6 +276,7 @@ static long snapshot_ioctl(struct file * > error = -EPERM; > break; > } > + hibernate_restore_gfp_mask(); > error = hibernation_snapshot(data->platform_support);
That might be good safety, but it does strongly suggest that you needed to put it somewhere else, and couldn't work out where?
> if (!error) > error = put_user(in_suspend, (int __user *)arg); >
Hugh
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