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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 /include/linux/freezer.h
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 'include/linux/freezer.h')
-rw-r--r--include/linux/freezer.h4
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 1effc8b56b4e..aa56cf31f7ff 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -49,6 +49,7 @@ extern int thaw_process(struct task_struct *p);
extern void refrigerator(void);
extern int freeze_processes(void);
+extern int freeze_kernel_threads(void);
extern void thaw_processes(void);
static inline int try_to_freeze(void)
@@ -171,7 +172,8 @@ static inline void clear_freeze_flag(struct task_struct *p) {}
static inline int thaw_process(struct task_struct *p) { return 1; }
static inline void refrigerator(void) {}
-static inline int freeze_processes(void) { BUG(); return 0; }
+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 int try_to_freeze(void) { return 0; }