Messages in this thread Patch in this message | | | From | Mandeep Singh Baines <> | Subject | [PATCH 2/5] lockdep: check that no locks held at freeze time | Date | Sat, 16 Feb 2013 01:53:23 -0800 |
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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.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().
Signed-off-by: Mandeep Singh Baines <msb@chromium.org> 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> CC: Ingo Molnar <mingo@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
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