We shouldn't try_to_freeze if locks are held. Verified that
I get no lockdep warnings after applying this patch and
"vfork: don't freezer_count() for in-kernel users of CLONE_VFORK".
Changes since v1:
* LKML: <20130215111635.ga26...@gmail.com> Ingo Molnar
* Added a msg string that gets passed in.
* LKML: <20130215154449.gd30...@redhat.com> Oleg Nesterov
* Check PF_NOFREEZE in try_to_freeze().
Signed-off-by: Mandeep Singh Baines <m...@chromium.org>
CC: Oleg Nesterov <o...@redhat.com>
CC: Tejun Heo <t...@kernel.org>
CC: Andrew Morton <a...@linux-foundation.org>
CC: Rafael J. Wysocki <r...@sisk.pl>
CC: Ingo Molnar <mi...@redhat.com>
---
include/linux/debug_locks.h | 5 +++--
include/linux/freezer.h | 4 ++++
kernel/exit.c | 2 +-
kernel/lockdep.c | 12 ++++++------
4 files changed, 14 insertions(+), 9 deletions(-)
diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h
index 3bd46f7..e6c3c85 100644
--- a/include/linux/debug_locks.h
+++ b/include/linux/debug_locks.h
@@ -51,7 +51,8 @@ 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(struct task_struct *task,
+ const char *msg);
#else
static inline void debug_show_all_locks(void)
{
@@ -67,7 +68,7 @@ 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(struct task_struct *task, const char *msg)
{
}
#endif
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index e4238ce..e6f8256 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>
@@ -43,6 +44,9 @@ extern void thaw_kernel_threads(void);
static inline bool try_to_freeze(void)
{
+ if (current->flags & PF_NOFREEZE)
+ return false;
+ debug_check_no_locks_held(current, "lock held while trying to freeze");
might_sleep();
if (likely(!freezing(current)))
return false;
diff --git a/kernel/exit.c b/kernel/exit.c
index b4df219..88a706c 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -833,7 +833,7 @@ void do_exit(long code)
/*
* Make sure we are holding no locks:
*/
- debug_check_no_locks_held(tsk);
+ debug_check_no_locks_held(tsk, "lock held at task exit time");
/*
* 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 7981e5b..2d4cfbf 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -4083,7 +4083,7 @@ 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(struct task_struct *curr, const char *msg)
{
if (!debug_locks_off())
return;
@@ -4091,10 +4091,10 @@ static void print_held_locks_bug(struct task_struct
*curr)
return;
printk("\n");
- printk("=====================================\n");
- printk("[ BUG: lock held at task exit time! ]\n");
+ printk("=======================================\n");
+ printk("[ BUG: %s! ]\n", msg);
print_kernel_ident();
- printk("-------------------------------------\n");
+ printk("---------------------------------------\n");
printk("%s/%d is exiting with locks still held!\n",
curr->comm, task_pid_nr(curr));
lockdep_print_held_locks(curr);
@@ -4103,10 +4103,10 @@ static void print_held_locks_bug(struct task_struct
*curr)
dump_stack();
}
-void debug_check_no_locks_held(struct task_struct *task)
+void debug_check_no_locks_held(struct task_struct *task, const char *msg)
{
if (unlikely(task->lockdep_depth > 0))
- print_held_locks_bug(task);
+ print_held_locks_bug(task, msg);
}
void debug_show_all_locks(void)
--
1.7.12.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
