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Date:	Sat, 27 Nov 2010 00:10:04 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Ondrej Zary <linux@...nbow-software.org>
Cc:	Hugh Dickins <hughd@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.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 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@...k.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@...gle.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?

Rafael

---
 kernel/power/hibernate.c |   36 ++++++++++++++++++++++++++----------
 kernel/power/power.h     |    1 +
 kernel/power/user.c      |    1 +
 3 files changed, 28 insertions(+), 10 deletions(-)

Index: linux-2.6/kernel/power/hibernate.c
===================================================================
--- linux-2.6.orig/kernel/power/hibernate.c
+++ linux-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 nocompress = 0;
 static int noresume = 0;
 static char resume_file[256] = CONFIG_PM_STD_PARTITION;
@@ -327,7 +342,6 @@ 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 +353,7 @@ 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;
@@ -348,7 +362,10 @@ 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 +374,10 @@ 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);
@@ -452,17 +472,16 @@ 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;
@@ -476,7 +495,6 @@ int hibernation_restore(int platform_mod
 int hibernation_platform_enter(void)
 {
 	int error;
-	gfp_t saved_mask;
 
 	if (!hibernation_ops)
 		return -ENOSYS;
@@ -492,7 +510,6 @@ 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 +553,6 @@ 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: linux-2.6/kernel/power/power.h
===================================================================
--- linux-2.6.orig/kernel/power/power.h
+++ linux-2.6/kernel/power/power.h
@@ -52,6 +52,7 @@ 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);
 
 #else /* !CONFIG_HIBERNATION */
 
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;
+		hibernate_restore_gfp_mask();
 		thaw_processes();
 		usermodehelper_enable();
 		data->frozen = 0;
--
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