linux-toradex.git/kernel/locking/lockdep.c, branch v4.17

lockdep: Make the lock debug output more useful

2018-03-29T12:41:40+00:00

The lock debug output in print_lock() has a few shortcomings:

 - It prints the hlock->acquire_ip field in %px and %pS format. That's
   redundant information.

 - It lacks information about the lock object itself. The lock class is
   not helpful to identify a particular instance of a lock.

Change the output so it prints:

 - hlock->instance to allow identification of a particular lock instance.

 - only the %pS format of hlock->ip_acquire which is sufficient to decode
   the actual code line with faddr2line.

The resulting output is:

3 locks held by a.out/31106:
#0: 00000000b0f753ba (&mm->mmap_sem){++++}, at: copy_process.part.41+0x10d5/0x1fe0
#1: 00000000ef64d539 (&mm->mmap_sem/1){+.+.}, at: copy_process.part.41+0x10fe/0x1fe0
#2: 00000000b41a282e (&mapping->i_mmap_rwsem){++++}, at: copy_process.part.41+0x12f2/0x1fe0

[ tglx: Massaged changelog ]

Signed-off-by: Tetsuo Handa 
Signed-off-by: Thomas Gleixner 
Acked-by: Michal Hocko 
Acked-by: David Rientjes 
Acked-by: Peter Zijlstra 
Cc: linux-mm@kvack.org
Cc: Borislav Petkov 
Link: https://lkml.kernel.org/r/201803271941.GBE57310.tVSOJLQOFFOHFM@I-love.SAKURA.ne.jp

locking/lockdep: Show unadorned pointers

2018-02-28T14:25:44+00:00

Show unadorned pointers in lockdep reports - lockdep is a debugging
facility and hashing pointers there doesn't make a whole lotta sense.

Signed-off-by: Borislav Petkov 
Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Link: https://lkml.kernel.org/r/20180226134926.23069-1-bp@alien8.de

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-01-30T18:44:56+00:00

Pull locking updates from Ingo Molnar:
 "The main changes relate to making lock_is_held() et al (and external
  wrappers of them) work on const data types - this requires const
  propagation through the depths of lockdep.

  This removes a number of ugly type hacks the external helpers used"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep: Convert some users to const
  lockdep: Make lockdep checking constant
  lockdep: Assign lock keys on registration

locking/lockdep: Avoid triggering hardlockup from debug_show_all_locks()

2018-01-24T09:00:09+00:00

debug_show_all_locks() iterates all tasks and print held locks whole
holding tasklist_lock.  This can take a while on a slow console device
and may end up triggering NMI hardlockup detector if someone else ends
up waiting for tasklist_lock.

Touch the NMI watchdog while printing the held locks to avoid
spuriously triggering the hardlockup detector.

Signed-off-by: Tejun Heo 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: kernel-team@fb.com
Link: http://lkml.kernel.org/r/20180122220055.GB1771050@devbig577.frc2.facebook.com
Signed-off-by: Ingo Molnar

lockdep: Make lockdep checking constant

2018-01-18T10:56:48+00:00

There are several places in the kernel which would like to pass a const
pointer to lockdep_is_held().  Constify the entire path so nobody has to
trick the compiler.

Signed-off-by: Matthew Wilcox 
Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra (Intel) 
Cc: "David S. Miller" 
Link: https://lkml.kernel.org/r/20180117151414.23686-3-willy@infradead.org

lockdep: Assign lock keys on registration

2018-01-18T10:56:48+00:00

Lockdep is assigning lock keys when a lock was looked up.  This is
unnecessary; if the lock has never been registered then it is known that it
is not locked.  It also complicates the calling convention.  Switch to
assigning the lock key in register_lock_class().

Signed-off-by: Matthew Wilcox 
Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra (Intel) 
Cc: "David S. Miller" 
Link: https://lkml.kernel.org/r/20180117151414.23686-2-willy@infradead.org

locking/lockdep: Remove the cross-release locking checks

2017-12-12T11:38:51+00:00

This code (CONFIG_LOCKDEP_CROSSRELEASE=y and CONFIG_LOCKDEP_COMPLETIONS=y),
while it found a number of old bugs initially, was also causing too many
false positives that caused people to disable lockdep - which is arguably
a worse overall outcome.

If we disable cross-release by default but keep the code upstream then
in practice the most likely outcome is that we'll allow the situation
to degrade gradually, by allowing entropy to introduce more and more
false positives, until it overwhelms maintenance capacity.

Another bad side effect was that people were trying to work around
the false positives by uglifying/complicating unrelated code. There's
a marked difference between annotating locking operations and
uglifying good code just due to bad lock debugging code ...

This gradual decrease in quality happened to a number of debugging
facilities in the kernel, and lockdep is pretty complex already,
so we cannot risk this outcome.

Either cross-release checking can be done right with no false positives,
or it should not be included in the upstream kernel.

( Note that it might make sense to maintain it out of tree and go through
  the false positives every now and then and see whether new bugs were
  introduced. )

Cc: Byungchul Park 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

locking/lockdep: Fix possible NULL deref

2017-12-06T18:29:56+00:00

We can't invalidate xhlocks when we've not yet allocated any.

Reported-by: Dmitry Vyukov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Fixes: f52be5708076 ("locking/lockdep: Untangle xhlock history save/restore from task independence")
Signed-off-by: Ingo Molnar

kmemcheck: remove annotations

2017-11-16T02:21:04+00:00

Patch series "kmemcheck: kill kmemcheck", v2.

As discussed at LSF/MM, kill kmemcheck.

KASan is a replacement that is able to work without the limitation of
kmemcheck (single CPU, slow).  KASan is already upstream.

We are also not aware of any users of kmemcheck (or users who don't
consider KASan as a suitable replacement).

The only objection was that since KASAN wasn't supported by all GCC
versions provided by distros at that time we should hold off for 2
years, and try again.

Now that 2 years have passed, and all distros provide gcc that supports
KASAN, kill kmemcheck again for the very same reasons.

This patch (of 4):

Remove kmemcheck annotations, and calls to kmemcheck from the kernel.

[alexander.levin@verizon.com: correctly remove kmemcheck call from dma_map_sg_attrs]
  Link: http://lkml.kernel.org/r/20171012192151.26531-1-alexander.levin@verizon.com
Link: http://lkml.kernel.org/r/20171007030159.22241-2-alexander.levin@verizon.com
Signed-off-by: Sasha Levin 
Cc: Alexander Potapenko 
Cc: Eric W. Biederman 
Cc: Michal Hocko 
Cc: Pekka Enberg 
Cc: Steven Rostedt 
Cc: Tim Hansen 
Cc: Vegard Nossum 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

locking/lockdep: Introduce CONFIG_BOOTPARAM_LOCKDEP_CROSSRELEASE_FULLSTACK=y

2017-10-25T10:19:02+00:00

Add a Kconfig knob that enables the lockdep "crossrelease_fullstack" boot parameter.

Suggested-by: Ingo Molnar 
Signed-off-by: Byungchul Park 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: amir73il@gmail.com
Cc: axboe@kernel.dk
Cc: darrick.wong@oracle.com
Cc: david@fromorbit.com
Cc: hch@infradead.org
Cc: idryomov@gmail.com
Cc: johan@kernel.org
Cc: johannes.berg@intel.com
Cc: kernel-team@lge.com
Cc: linux-block@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Cc: oleg@redhat.com
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/1508921765-15396-7-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar