linux-kernel - Re: [PATCH] PM / Hibernation: Fix *massive* memory leak at early exits in hibernation

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Message-Id: <201111212325.39330.rjw@sisk.pl>
Date:	Mon, 21 Nov 2011 23:25:39 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Cc:	pavel@....cz, len.brown@...el.com, tj@...nel.org,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH] PM / Hibernation: Fix *massive* memory leak at early exits in hibernation

On Monday, November 21, 2011, Srivatsa S. Bhat wrote:
> At some of the early exit points during hibernation (exiting either due
> to failure or after a successful hibernation test, the memory pre-allocated
> for hibernation is not freed up. And this is *very* serious, because, during
> pre-allocation, it could have allocated upto a few *gigabytes* of memory!
> And hence, if a hibernation fails or even if we run some hibernation tests
> using the 'pm_test' framework, the system is rendered unstable due to memory
> becoming signifantly lower. Fix this bug.

While the observation is valid, I'd prefer to do something like the patch
below.

Thanks,
Rafael

---
From: Rafael J. Wysocki <rjw@...k.pl>
Subject: PM / Hibernate: Do not leak memory in error/test code paths

The hibernation core code forgets to release memory preallocated
for hibernation if there's an error in its early stages or if test
modes causing hibernation_snapshot() to return early are used.  This
causes the system to be hardly usable, because the amount of
preallocated memory is usually huge.  Fix this problem.

Reported-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
 kernel/power/hibernate.c |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

Index: linux/kernel/power/hibernate.c
===================================================================
--- linux.orig/kernel/power/hibernate.c
+++ linux/kernel/power/hibernate.c
@@ -347,7 +347,7 @@ int hibernation_snapshot(int platform_mo
 
 	error = freeze_kernel_threads();
 	if (error)
-		goto Close;
+		goto Cleanup;
 
 	if (hibernation_test(TEST_FREEZER) ||
 		hibernation_testmode(HIBERNATION_TESTPROC)) {
@@ -357,12 +357,14 @@ int hibernation_snapshot(int platform_mo
 		 * successful freezer test.
 		 */
 		freezer_test_done = true;
-		goto Close;
+		goto Cleanup;
 	}
 
 	error = dpm_prepare(PMSG_FREEZE);
-	if (error)
-		goto Complete_devices;
+	if (error) {
+		dpm_complete(msg);
+		goto Cleanup;
+	}
 
 	suspend_console();
 	pm_restrict_gfp_mask();
@@ -391,8 +393,6 @@ int hibernation_snapshot(int platform_mo
 		pm_restore_gfp_mask();
 
 	resume_console();
-
- Complete_devices:
 	dpm_complete(msg);
 
  Close:
@@ -402,6 +402,10 @@ int hibernation_snapshot(int platform_mo
  Recover_platform:
 	platform_recover(platform_mode);
 	goto Resume_devices;
+
+ Cleanup:
+	swsusp_free();
+	goto Close;
 }
 
 /**
--
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