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>
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c2c1b089b4
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@ -51,7 +51,7 @@ struct task_struct;
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extern void debug_show_all_locks(void);
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extern void debug_show_all_locks(void);
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extern void debug_show_held_locks(struct task_struct *task);
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extern void debug_show_held_locks(struct task_struct *task);
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extern void debug_check_no_locks_freed(const void *from, unsigned long len);
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extern void debug_check_no_locks_freed(const void *from, unsigned long len);
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extern void debug_check_no_locks_held(struct task_struct *task);
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extern void debug_check_no_locks_held(void);
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#else
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#else
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static inline void debug_show_all_locks(void)
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static inline void debug_show_all_locks(void)
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{
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{
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@ -67,7 +67,7 @@ debug_check_no_locks_freed(const void *from, unsigned long len)
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}
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}
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static inline void
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static inline void
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debug_check_no_locks_held(struct task_struct *task)
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debug_check_no_locks_held(void)
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{
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{
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}
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}
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#endif
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#endif
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@ -3,6 +3,7 @@
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#ifndef FREEZER_H_INCLUDED
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#ifndef FREEZER_H_INCLUDED
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#define FREEZER_H_INCLUDED
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#define FREEZER_H_INCLUDED
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#include <linux/debug_locks.h>
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#include <linux/sched.h>
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#include <linux/sched.h>
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#include <linux/wait.h>
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#include <linux/wait.h>
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#include <linux/atomic.h>
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#include <linux/atomic.h>
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@ -48,6 +49,8 @@ extern void thaw_kernel_threads(void);
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static inline bool try_to_freeze(void)
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static inline bool try_to_freeze(void)
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{
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{
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if (!(current->flags & PF_NOFREEZE))
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debug_check_no_locks_held();
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might_sleep();
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might_sleep();
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if (likely(!freezing(current)))
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if (likely(!freezing(current)))
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return false;
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return false;
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@ -835,7 +835,7 @@ void do_exit(long code)
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/*
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/*
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* Make sure we are holding no locks:
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* Make sure we are holding no locks:
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*/
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*/
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debug_check_no_locks_held(tsk);
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debug_check_no_locks_held();
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/*
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/*
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* We can do this unlocked here. The futex code uses this flag
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* We can do this unlocked here. The futex code uses this flag
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* just to verify whether the pi state cleanup has been done
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* just to verify whether the pi state cleanup has been done
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@ -4088,7 +4088,7 @@ void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
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}
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}
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EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
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EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
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static void print_held_locks_bug(struct task_struct *curr)
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static void print_held_locks_bug(void)
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{
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{
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if (!debug_locks_off())
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if (!debug_locks_off())
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return;
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return;
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@ -4097,22 +4097,21 @@ static void print_held_locks_bug(struct task_struct *curr)
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printk("\n");
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printk("\n");
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printk("=====================================\n");
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printk("=====================================\n");
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printk("[ BUG: lock held at task exit time! ]\n");
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printk("[ BUG: %s/%d still has locks held! ]\n",
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current->comm, task_pid_nr(current));
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print_kernel_ident();
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print_kernel_ident();
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printk("-------------------------------------\n");
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printk("-------------------------------------\n");
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printk("%s/%d is exiting with locks still held!\n",
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lockdep_print_held_locks(current);
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curr->comm, task_pid_nr(curr));
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lockdep_print_held_locks(curr);
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printk("\nstack backtrace:\n");
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printk("\nstack backtrace:\n");
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dump_stack();
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dump_stack();
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}
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}
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void debug_check_no_locks_held(struct task_struct *task)
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void debug_check_no_locks_held(void)
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{
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{
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if (unlikely(task->lockdep_depth > 0))
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if (unlikely(current->lockdep_depth > 0))
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print_held_locks_bug(task);
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print_held_locks_bug();
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}
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}
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EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
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void debug_show_all_locks(void)
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void debug_show_all_locks(void)
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{
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{
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