| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <CACBanvr+RKf_PrRrvDWiHZ9esi2tonHX8SbLUcgzXbuO_RnH_g@mail.gmail.com>
Date: Thu, 21 Feb 2013 08:24:26 -0800
From: Mandeep Singh Baines <msb@...omium.org>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
Oleg Nesterov <oleg@...hat.com>, Tejun Heo <tj@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v5] lockdep: check that no locks held at freeze time
On Thu, Feb 21, 2013 at 7:42 AM, Rafael J. Wysocki <rjw@...k.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@...il.com> Ingo Molnar
>> * Added a msg string that gets passed in.
>> * LKML: <20130215154449.GD30829@...hat.com> Oleg Nesterov
>> * Check PF_NOFREEZE in try_to_freeze().
>> Changes since v2:
>> * LKML: <20130216170605.GC4910@...hat.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@...hat.com> Oleg Nesterovw
>> * Remove stale vfork comment from commit message.
>> Changes since v4:
>> * LKML: <20130220152446.a65ff84f.akpm@...ux-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@...omium.org>
>> CC: Ingo Molnar <mingo@...hat.com>
>> CC: Oleg Nesterov <oleg@...hat.com>
>> CC: Tejun Heo <tj@...nel.org>
>> CC: Andrew Morton <akpm@...ux-foundation.org>
>> CC: Rafael J. Wysocki <rjw@...k.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.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists