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authorMandeep Singh Baines <msb@chromium.org>2013-02-27 17:03:18 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-27 19:10:11 -0800
commit6aa9707099c4b25700940eb3d016f16c4434360d (patch)
tree6996f5789a3c0a09eea2fe57d318c1d387c24f3a
parentc2c1b089b44b783bd50fae4bccaa6f367f92e492 (diff)
lockdep: check that no locks held at freeze time
We shouldn't try_to_freeze if locks are held. Holding a lock can cause a deadlock if the lock is later acquired in the suspend or hibernate path (e.g. by dpm). Holding a lock can also cause a deadlock in the case of cgroup_freezer if a lock is held inside a frozen cgroup that is later acquired by a process outside that group. [akpm@linux-foundation.org: export debug_check_no_locks_held] Signed-off-by: Mandeep Singh Baines <msb@chromium.org> Cc: Ben Chan <benchan@chromium.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/debug_locks.h4
-rw-r--r--include/linux/freezer.h3
-rw-r--r--kernel/exit.c2
-rw-r--r--kernel/lockdep.c17
4 files changed, 14 insertions, 12 deletions
diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h
index 3bd46f766751..a975de1ff59f 100644
--- a/include/linux/debug_locks.h
+++ b/include/linux/debug_locks.h
@@ -51,7 +51,7 @@ struct task_struct;
extern void debug_show_all_locks(void);
extern void debug_show_held_locks(struct task_struct *task);
extern void debug_check_no_locks_freed(const void *from, unsigned long len);
-extern void debug_check_no_locks_held(struct task_struct *task);
+extern void debug_check_no_locks_held(void);
#else
static inline void debug_show_all_locks(void)
{
@@ -67,7 +67,7 @@ debug_check_no_locks_freed(const void *from, unsigned long len)
}
static inline void
-debug_check_no_locks_held(struct task_struct *task)
+debug_check_no_locks_held(void)
{
}
#endif
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index e70df40d84f6..043a5cf8b5ba 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -3,6 +3,7 @@
#ifndef FREEZER_H_INCLUDED
#define FREEZER_H_INCLUDED
+#include <linux/debug_locks.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/atomic.h>
@@ -48,6 +49,8 @@ extern void thaw_kernel_threads(void);
static inline bool try_to_freeze(void)
{
+ if (!(current->flags & PF_NOFREEZE))
+ debug_check_no_locks_held();
might_sleep();
if (likely(!freezing(current)))
return false;
diff --git a/kernel/exit.c b/kernel/exit.c
index 7dd20408707c..aaf97c122e8a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -835,7 +835,7 @@ void do_exit(long code)
/*
* Make sure we are holding no locks:
*/
- debug_check_no_locks_held(tsk);
+ debug_check_no_locks_held();
/*
* We can do this unlocked here. The futex code uses this flag
* just to verify whether the pi state cleanup has been done
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 8a0efac4f99d..259db207b5d9 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -4088,7 +4088,7 @@ void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
}
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
-static void print_held_locks_bug(struct task_struct *curr)
+static void print_held_locks_bug(void)
{
if (!debug_locks_off())
return;
@@ -4097,22 +4097,21 @@ static void print_held_locks_bug(struct task_struct *curr)
printk("\n");
printk("=====================================\n");
- printk("[ BUG: lock held at task exit time! ]\n");
+ printk("[ BUG: %s/%d still has locks held! ]\n",
+ current->comm, task_pid_nr(current));
print_kernel_ident();
printk("-------------------------------------\n");
- printk("%s/%d is exiting with locks still held!\n",
- curr->comm, task_pid_nr(curr));
- lockdep_print_held_locks(curr);
-
+ lockdep_print_held_locks(current);
printk("\nstack backtrace:\n");
dump_stack();
}
-void debug_check_no_locks_held(struct task_struct *task)
+void debug_check_no_locks_held(void)
{
- if (unlikely(task->lockdep_depth > 0))
- print_held_locks_bug(task);
+ if (unlikely(current->lockdep_depth > 0))
+ print_held_locks_bug();
}
+EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
void debug_show_all_locks(void)
{