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Groups > linux.kernel > #1367068
| From | Boqun Feng <boqun.feng@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 |
| Date | 2016-03-30 12:10 +0200 |
| Message-ID | <rilez-3Ki-13@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <rheIa-5IK-1@gated-at.bofh.it> <rhhG1-85z-1@gated-at.bofh.it> <rhpNf-56p-1@gated-at.bofh.it> <rhXvz-3qM-1@gated-at.bofh.it> <rikLx-3iV-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
[Multipart message — attachments visible in raw view] - view raw
Hi Peter,
On Wed, Mar 30, 2016 at 11:36:59AM +0200, Peter Zijlstra wrote:
> On Tue, Mar 29, 2016 at 10:47:02AM +0200, Ingo Molnar wrote:
>
> > > You are right; this is lockdep running into a hash collision; which is a new
> > > DEBUG_LOCKDEP test. See 9e4e7554e755 ("locking/lockdep: Detect chain_key
> > > collisions").
> >
> > I've Cc:-ed Alfredo Alvarez Fernandez who added that test.
>
> OK, so while the code in check_no_collision() seems sensible, it relies
> on borken bits.
>
> The whole chain_hlocks and /proc/lockdep_chains stuff appears to have
> been buggered from the start.
>
> The below patch should fix this.
>
> Furthermore, our hash function has definite room for improvement.
>
> ---
> include/linux/lockdep.h | 8 +++++---
> kernel/locking/lockdep.c | 30 ++++++++++++++++++++++++------
> kernel/locking/lockdep_proc.c | 2 ++
> 3 files changed, 31 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
> index d026b190c530..2568c120513b 100644
> --- a/include/linux/lockdep.h
> +++ b/include/linux/lockdep.h
> @@ -196,9 +196,11 @@ struct lock_list {
> * We record lock dependency chains, so that we can cache them:
> */
> struct lock_chain {
> - u8 irq_context;
> - u8 depth;
> - u16 base;
> + /* see BUILD_BUG_ON()s in lookup_chain_cache() */
> + unsigned int irq_context : 2,
> + depth : 6,
> + base : 24;
> + /* 4 byte hole */
> struct hlist_node entry;
> u64 chain_key;
> };
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 53ab2f85d77e..91a4b7780afb 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
[...]
> @@ -2860,11 +2882,6 @@ static int separate_irq_context(struct task_struct *curr,
> {
> unsigned int depth = curr->lockdep_depth;
>
> - /*
> - * Keep track of points where we cross into an interrupt context:
> - */
> - hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
> - curr->softirq_context;
> if (depth) {
> struct held_lock *prev_hlock;
>
> @@ -3164,6 +3181,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
> hlock->acquire_ip = ip;
> hlock->instance = lock;
> hlock->nest_lock = nest_lock;
> + hlock->irq_context = 2*(!!curr->hardirq_context) + !!curr->softirq_context;
> hlock->trylock = trylock;
> hlock->read = read;
> hlock->check = check;
This is just for cleaning up, right? However ->hardirq_context and
->softirq_context only defined when CONFIG_TRACE_IRQFLAGS=y.
So we should use macro like current_hardirq_context() here? Or
considering the two helpers introduced in my RFC:
http://lkml.kernel.org/g/1455602265-16490-2-git-send-email-boqun.feng@gmail.com
if you don't think that overkills ;-)
Regards,
Boqun
[...]
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Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Linus Torvalds <torvalds@linux-foundation.org> - 2016-03-27 14:10 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Boqun Feng <boqun.feng@gmail.com> - 2016-03-27 15:40 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Theodore Ts'o <tytso@mit.edu> - 2016-03-27 20:30 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Sedat Dilek <sedat.dilek@gmail.com> - 2016-03-27 21:50 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Sedat Dilek <sedat.dilek@gmail.com> - 2016-03-27 22:30 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Peter Zijlstra <peterz@infradead.org> - 2016-03-27 22:50 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Sedat Dilek <sedat.dilek@gmail.com> - 2016-03-27 23:50 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Peter Zijlstra <peterz@infradead.org> - 2016-03-28 08:40 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Ingo Molnar <mingo@kernel.org> - 2016-03-29 10:50 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Peter Zijlstra <peterz@infradead.org> - 2016-03-30 11:40 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Sedat Dilek <sedat.dilek@gmail.com> - 2016-03-30 12:00 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Peter Zijlstra <peterz@infradead.org> - 2016-03-30 14:50 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Sedat Dilek <sedat.dilek@gmail.com> - 2016-03-30 14:50 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Peter Zijlstra <peterz@infradead.org> - 2016-03-30 15:20 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Peter Zijlstra <peterz@infradead.org> - 2016-03-30 12:00 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Boqun Feng <boqun.feng@gmail.com> - 2016-03-30 12:10 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Peter Zijlstra <peterz@infradead.org> - 2016-03-30 12:40 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Sedat Dilek <sedat.dilek@gmail.com> - 2016-03-30 13:10 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Peter Zijlstra <peterz@infradead.org> - 2016-03-31 17:50 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Boqun Feng <boqun.feng@gmail.com> - 2016-03-31 18:00 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Sedat Dilek <sedat.dilek@gmail.com> - 2016-04-02 08:30 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Peter Zijlstra <peterz@infradead.org> - 2016-03-30 16:10 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Sedat Dilek <sedat.dilek@gmail.com> - 2016-03-30 17:30 +0200
[PATCH] lockdep: print chain_key collision information Alfredo Alvarez Fernandez <alfredoalvarezfernandez@gmail.com> - 2016-03-30 19:10 +0200
Re: [PATCH] lockdep: print chain_key collision information Peter Zijlstra <peterz@infradead.org> - 2016-03-30 19:20 +0200
[tip:core/urgent] locking/lockdep: Print chain_key collision information tip-bot for Alfredo Alvarez Fernandez <tipbot@zytor.com> - 2016-04-01 08:40 +0200
Re: [Linux-v4.6-rc1] ext4: WARNING: CPU: 2 PID: 2692 at kernel/locking/lockdep.c:2017 __lock_acquire+0x180e/0x2260 Sedat Dilek <sedat.dilek@gmail.com> - 2016-03-30 11:40 +0200
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