Messages in this thread | | | Date | Thu, 21 Feb 2013 08:24:26 -0800 | Subject | Re: [PATCH v5] lockdep: check that no locks held at freeze time | From | Mandeep Singh Baines <> |
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On Thu, Feb 21, 2013 at 7:42 AM, Rafael J. Wysocki <rjw@sisk.pl> wrote: > On Wednesday, February 20, 2013 07:17:07 PM Mandeep Singh Baines wrote: >> We shouldn't try_to_freeze if locks are held. > > Has Ingo acked one of the previous versions or is my memory doing tricks? >
Yes, Ingo had acked a previous version. However, the patch has changed non-trivially since his ack. I wasn't really sure what do in this situation. Is it OK to keep the ack?
> Anyway, can you please write something more about what the patch is doing > in the changelog? While the statement above is correct, it doesn't really > explain why it will be a good idea to apply your patch, does it? >
k, will do
> Rafael > > >> Changes since v1: >> * LKML: <20130215111635.GA26955@gmail.com> Ingo Molnar >> * Added a msg string that gets passed in. >> * LKML: <20130215154449.GD30829@redhat.com> Oleg Nesterov >> * Check PF_NOFREEZE in try_to_freeze(). >> Changes since v2: >> * LKML: <20130216170605.GC4910@redhat.com> Oleg Nesterovw >> * Avoid unnecessary PF_NOFREEZE check when !CONFIG_LOCKDEP. >> * Mandeep Singh Baines >> * Generalize an exit specific printk. >> Changes since v3: >> * LKML: <20130220223013.GA15760@redhat.com> Oleg Nesterovw >> * Remove stale vfork comment from commit message. >> Changes since v4: >> * LKML: <20130220152446.a65ff84f.akpm@linux-foundation.org> Andrew Morton >> * Remove tsk param since tsk is always current. >> * Remove msg param, dump_stack() should tell us all we need to know. >> >> Signed-off-by: Mandeep Singh Baines <msb@chromium.org> >> CC: Ingo Molnar <mingo@redhat.com> >> CC: Oleg Nesterov <oleg@redhat.com> >> CC: Tejun Heo <tj@kernel.org> >> CC: Andrew Morton <akpm@linux-foundation.org> >> CC: Rafael J. Wysocki <rjw@sisk.pl> >> --- >> include/linux/debug_locks.h | 4 ++-- >> include/linux/freezer.h | 3 +++ >> kernel/exit.c | 2 +- >> kernel/lockdep.c | 16 +++++++--------- >> 4 files changed, 13 insertions(+), 12 deletions(-) >> >> diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h >> index 3bd46f7..a975de1 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 e4238ce..c5bd118 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 +44,8 @@ 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 b4df219..aff5bdb 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(); >> /* >> * 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..8e28f56 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(void) >> { >> if (!debug_locks_off()) >> return; >> @@ -4092,21 +4092,19 @@ 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(); >> } >> >> void debug_show_all_locks(void) >> > -- > I speak only for myself. > Rafael J. Wysocki, Intel Open Source Technology Center.
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