aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorRafael J. Wysocki <rjw@sisk.pl>2012-01-29 20:35:52 +0100
committerRafael J. Wysocki <rjw@sisk.pl>2012-01-29 20:35:52 +0100
commit181e9bdef37bfcaa41f3ab6c948a2a0d60a268b5 (patch)
tree66e69f83b63e8517a47e0eb0e7ae730d8a9a109b
parent0a9626575400879d1d5e6bc8768188b938d7c501 (diff)
downloadlinux-linaro-stable-181e9bdef37bfcaa41f3ab6c948a2a0d60a268b5.tar.gz
PM / Hibernate: Fix s2disk regression related to freezing workqueues
Commit 2aede851ddf08666f68ffc17be446420e9d2a056 PM / Hibernate: Freeze kernel threads after preallocating memory introduced a mechanism by which kernel threads were frozen after the preallocation of hibernate image memory to avoid problems with frozen kernel threads not responding to memory freeing requests. However, it overlooked the s2disk code path in which the SNAPSHOT_CREATE_IMAGE ioctl was run directly after SNAPSHOT_FREE, which caused freeze_workqueues_begin() to BUG(), because it saw that worqueues had been already frozen. Although in principle this issue might be addressed by removing the relevant BUG_ON() from freeze_workqueues_begin(), that would reintroduce the very problem that commit 2aede851ddf08666f68ffc17be4 attempted to avoid into that particular code path. For this reason, to fix the issue at hand, introduce thaw_kernel_threads() and make the SNAPSHOT_FREE ioctl execute it. Special thanks to Srivatsa S. Bhat for detailed analysis of the problem. Reported-and-tested-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Cc: stable@kernel.org
-rw-r--r--include/linux/freezer.h2
-rw-r--r--kernel/power/process.c19
-rw-r--r--kernel/power/user.c9
3 files changed, 30 insertions, 0 deletions
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 0ab54e16a91f..d09af4b67cf1 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -39,6 +39,7 @@ extern bool __refrigerator(bool check_kthr_stop);
extern int freeze_processes(void);
extern int freeze_kernel_threads(void);
extern void thaw_processes(void);
+extern void thaw_kernel_threads(void);
static inline bool try_to_freeze(void)
{
@@ -174,6 +175,7 @@ static inline bool __refrigerator(bool check_kthr_stop) { return false; }
static inline int freeze_processes(void) { return -ENOSYS; }
static inline int freeze_kernel_threads(void) { return -ENOSYS; }
static inline void thaw_processes(void) {}
+static inline void thaw_kernel_threads(void) {}
static inline bool try_to_freeze(void) { return false; }
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 77274c9ba2f1..eeca00311f39 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -188,3 +188,22 @@ void thaw_processes(void)
printk("done.\n");
}
+void thaw_kernel_threads(void)
+{
+ struct task_struct *g, *p;
+
+ pm_nosig_freezing = false;
+ printk("Restarting kernel threads ... ");
+
+ thaw_workqueues();
+
+ read_lock(&tasklist_lock);
+ do_each_thread(g, p) {
+ if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
+ __thaw_task(p);
+ } while_each_thread(g, p);
+ read_unlock(&tasklist_lock);
+
+ schedule();
+ printk("done.\n");
+}
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 6b1ab7a88522..e5a21a857302 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -274,6 +274,15 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
swsusp_free();
memset(&data->handle, 0, sizeof(struct snapshot_handle));
data->ready = 0;
+ /*
+ * It is necessary to thaw kernel threads here, because
+ * SNAPSHOT_CREATE_IMAGE may be invoked directly after
+ * SNAPSHOT_FREE. In that case, if kernel threads were not
+ * thawed, the preallocation of memory carried out by
+ * hibernation_snapshot() might run into problems (i.e. it
+ * might fail or even deadlock).
+ */
+ thaw_kernel_threads();
break;
case SNAPSHOT_PREF_IMAGE_SIZE: