Re: 2.6.35.5: hibernation broken... AGAIN

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Saturday, November 27, 2010, Ondrej Zary wrote:
> On Saturday 27 November 2010 00:10:04 Rafael J. Wysocki wrote:
> > On Friday, November 26, 2010, Ondrej Zary wrote:
> > > On Thursday 18 November 2010, Hugh Dickins wrote:
> > > > On Wed, 17 Nov 2010, Ondrej Zary wrote:
> > > > > On Wednesday 17 November 2010 22:12:01 Rafael J. Wysocki wrote:
> > > > > > On Wednesday, November 17, 2010, Andrew Morton wrote:
> > > > > > > On Wed, 17 Nov 2010 21:53:52 +0100
> > > > > > >
> > > > > > > "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
> > > > > > > > On Wednesday, November 17, 2010, Ondrej Zary wrote:
> > > > > > > > > Hello,
> > > > > > > > > the nasty memory-corrupting hibernation bug
> > > > > > > > > https://bugzilla.kernel.org/show_bug.cgi?id=15753 is back
> > > > > > > > > since 2.6.35.5. 2.6.35.4 works fine, 2.6.35.5 crashes after
> > > > > > > > > two days.
> > > >
> > > > That's distressing, for both and all of us: I'm sorry.
> > > >
> > > > > > > > > It seems to be caused by
> > > > > > > > > b77c254d8d66e5e9aa81239fedba9f3d568097d9.
> > > > > > >
> > > > > > > commit b77c254d8d66e5e9aa81239fedba9f3d568097d9
> > > > > > > Author: Hugh Dickins <hughd@google.com>
> > > > > > > Date:   Thu Sep 9 16:38:09 2010 -0700
> > > > > > >
> > > > > > >     swap: prevent reuse during hibernation
> > > >
> > > > Embarrassing: I suspect that I've been confused, not for the first
> > > > time, by the fork-like nature of hibernation and its images.
> > > > I wonder if this patch below fixes it, Ondrej?
> > > >
> > > > (And is it kernel swsusp or user swsusp that you're using?  May not
> > > > matter at all, but will help us to think more clearly about it,
> > > > if the corruption remains after this patch.)
> > > >
> > > > Rafael, do you agree that this patch was actually required even for
> > > > your original commit 452aa6999e6703ffbddd7f6ea124d3968915f3e3
> > > > mm/pm: force GFP_NOIO during suspend/hibernation and resume?
> > > >
> > > > Or am I still just as confused?  Or if not, are there more forking
> > > > places which require a similar patch?
> > > >
> > > > Not signing it off yet,
> > > > Hugh
> > >
> > > Could you please do that? The patch fixes the problem.
> >
> > 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.

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;
+	}
+}
+
 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();
 	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();
+
 	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();
 	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();
 	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);
 	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);
 	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();
 		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);
 		if (!error)
 			error = put_user(in_suspend, (int __user *)arg);