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authorRafael J. Wysocki <rjw@sisk.pl>2011-09-26 20:32:27 +0200
committerRafael J. Wysocki <rjw@sisk.pl>2011-10-16 23:28:52 +0200
commit2aede851ddf08666f68ffc17be446420e9d2a056 (patch)
treef63a0477c9fe618cd374065bac4cb5f172aaf7db /kernel/power/process.c
parent8f88893c05f2f677f18f2ce5591b4bed5d4a7535 (diff)
PM / Hibernate: Freeze kernel threads after preallocating memory
There is a problem with the current ordering of hibernate code which leads to deadlocks in some filesystems' memory shrinkers. Namely, some filesystems use freezable kernel threads that are inactive when the hibernate memory preallocation is carried out. Those same filesystems use memory shrinkers that may be triggered by the hibernate memory preallocation. If those memory shrinkers wait for the frozen kernel threads, the hibernate process deadlocks (this happens with XFS, for one example). Apparently, it is not technically viable to redesign the filesystems in question to avoid the situation described above, so the only possible solution of this issue is to defer the freezing of kernel threads until the hibernate memory preallocation is done, which is implemented by this change. Unfortunately, this requires the memory preallocation to be done before the "prepare" stage of device freeze, so after this change the only way drivers can allocate additional memory for their freeze routines in a clean way is to use PM notifiers. Reported-by: Christoph <cr2005@u-club.de> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'kernel/power/process.c')
-rw-r--r--kernel/power/process.c30
1 files changed, 20 insertions, 10 deletions
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 0cf3a27a6c9d..addbbe5531bc 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -135,7 +135,7 @@ static int try_to_freeze_tasks(bool sig_only)
}
/**
- * freeze_processes - tell processes to enter the refrigerator
+ * freeze_processes - Signal user space processes to enter the refrigerator.
*/
int freeze_processes(void)
{
@@ -143,20 +143,30 @@ int freeze_processes(void)
printk("Freezing user space processes ... ");
error = try_to_freeze_tasks(true);
- if (error)
- goto Exit;
- printk("done.\n");
+ if (!error) {
+ printk("done.");
+ oom_killer_disable();
+ }
+ printk("\n");
+ BUG_ON(in_atomic());
+
+ return error;
+}
+
+/**
+ * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
+ */
+int freeze_kernel_threads(void)
+{
+ int error;
printk("Freezing remaining freezable tasks ... ");
error = try_to_freeze_tasks(false);
- if (error)
- goto Exit;
- printk("done.");
+ if (!error)
+ printk("done.");
- oom_killer_disable();
- Exit:
- BUG_ON(in_atomic());
printk("\n");
+ BUG_ON(in_atomic());
return error;
}