The allocated debug objects are either on the free list or in the
hashed bucket lists. So they won't get lost. However if both debug
objects and kmemleak are enabled and kmemleak scanning is done
while some of the debug objects are transitioning from one list to
the others, false negative reporting of memory leaks may happen for
those objects. For example,
[38687.275678] kmemleak: 12 new suspected memory leaks (see
/sys/kernel/debug/kmemleak)
unreferenced object 0xffff92e98aabeb68 (size 40):
comm "ksmtuned", pid 4344, jiffies 4298403600 (age 906.430s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 d0 bc db 92 e9 92 ff ff ................
01 00 00 00 00 00 00 00 38 36 8a 61 e9 92 ff ff ........86.a....
backtrace:
[<ffffffff8fa5378a>] kmemleak_alloc+0x4a/0xa0
[<ffffffff8f47c019>] kmem_cache_alloc+0xe9/0x320
[<ffffffff8f62ed96>] __debug_object_init+0x3e6/0x400
[<ffffffff8f62ef01>] debug_object_activate+0x131/0x210
[<ffffffff8f330d9f>] __call_rcu+0x3f/0x400
[<ffffffff8f33117d>] call_rcu_sched+0x1d/0x20
[<ffffffff8f4a183c>] put_object+0x2c/0x40
[<ffffffff8f4a188c>] __delete_object+0x3c/0x50
[<ffffffff8f4a18bd>] delete_object_full+0x1d/0x20
[<ffffffff8fa535c2>] kmemleak_free+0x32/0x80
[<ffffffff8f47af07>] kmem_cache_free+0x77/0x350
[<ffffffff8f453912>] unlink_anon_vmas+0x82/0x1e0
[<ffffffff8f440341>] free_pgtables+0xa1/0x110
[<ffffffff8f44af91>] exit_mmap+0xc1/0x170
[<ffffffff8f29db60>] mmput+0x80/0x150
[<ffffffff8f2a7609>] do_exit+0x2a9/0xd20
The references in the debug objects may also hide a real memory leak.
As there is no point in having kmemleak to track debug object
allocations, kmemleak checking is now disabled for debug objects.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1502718733-8527-1-git-send-email-longman@redhat.com
We are going to split <linux/sched/task_stack.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/task_stack.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On a large SMP system with many CPUs, the global pool_lock may become
a performance bottleneck as all the CPUs that need to allocate or
free debug objects have to take the lock. That can sometimes cause
soft lockups like:
NMI watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [rcuos/1:21]
...
RIP: 0010:[<ffffffff817c216b>] [<ffffffff817c216b>]
_raw_spin_unlock_irqrestore+0x3b/0x60
...
Call Trace:
[<ffffffff813f40d1>] free_object+0x81/0xb0
[<ffffffff813f4f33>] debug_check_no_obj_freed+0x193/0x220
[<ffffffff81101a59>] ? trace_hardirqs_on_caller+0xf9/0x1c0
[<ffffffff81284996>] ? file_free_rcu+0x36/0x60
[<ffffffff81251712>] kmem_cache_free+0xd2/0x380
[<ffffffff81284960>] ? fput+0x90/0x90
[<ffffffff81284996>] file_free_rcu+0x36/0x60
[<ffffffff81124c23>] rcu_nocb_kthread+0x1b3/0x550
[<ffffffff81124b71>] ? rcu_nocb_kthread+0x101/0x550
[<ffffffff81124a70>] ? sync_exp_work_done.constprop.63+0x50/0x50
[<ffffffff810c59d1>] kthread+0x101/0x120
[<ffffffff81101a59>] ? trace_hardirqs_on_caller+0xf9/0x1c0
[<ffffffff817c2d32>] ret_from_fork+0x22/0x50
To reduce the amount of contention on the pool_lock, the actual
kmem_cache_free() of the debug objects will be delayed if the pool_lock
is busy. This will temporarily increase the amount of free objects
available at the free pool when the system is busy. As a result,
the number of kmem_cache allocation and freeing is reduced.
To further reduce the lock operations free debug objects in batches of
four.
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Du Changbin" <changbin.du@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Stancek <jstancek@redhat.com>
Link: http://lkml.kernel.org/r/1483647425-4135-4-git-send-email-longman@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
On a large SMP systems with hundreds of CPUs, the current thresholds
for allocating and freeing debug objects (256 and 1024 respectively)
may not work well. This can cause a lot of needless calls to
kmem_aloc() and kmem_free() on those systems.
To alleviate this thrashing problem, the object freeing threshold
is now increased to "1024 + # of CPUs * 32". Whereas the object
allocation threshold is increased to "256 + # of CPUs * 4". That
should make the debug objects subsystem scale better with the number
of CPUs available in the system.
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Du Changbin" <changbin.du@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Stancek <jstancek@redhat.com>
Link: http://lkml.kernel.org/r/1483647425-4135-3-git-send-email-longman@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull workqueue updates from Tejun Heo:
"Mostly patches to initialize workqueue subsystem earlier and get rid
of keventd_up().
The patches were headed for the last merge cycle but got delayed due
to a bug found late minute, which is fixed now.
Also, to help debugging, destroy_workqueue() is more chatty now on a
sanity check failure."
* 'for-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: move wq_numa_init() to workqueue_init()
workqueue: remove keventd_up()
debugobj, workqueue: remove keventd_up() usage
slab, workqueue: remove keventd_up() usage
power, workqueue: remove keventd_up() usage
tty, workqueue: remove keventd_up() usage
mce, workqueue: remove keventd_up() usage
workqueue: make workqueue available early during boot
workqueue: dump workqueue state on sanity check failures in destroy_workqueue()
Drivers, or other modules, that use a mixture of objects (especially
objects embedded within other objects) would like to take advantage of
the debugobjects facilities to help catch misuse. Currently, the
debugobjects interface is only available to builtin drivers and requires
a set of EXPORT_SYMBOL_GPL for use by modules.
I am using the debugobjects in i915.ko to try and catch some invalid
operations on embedded objects. The problem currently only presents
itself across module unload so forcing i915 to be builtin is not an
option.
Link: http://lkml.kernel.org/r/20161122143039.6433-1-chris@chris-wilson.co.uk
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: "Du, Changbin" <changbin.du@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that workqueue can handle work item queueing from very early
during boot, there is no need to gate schedule_work() while
!keventd_up(). Remove it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
When activating a static object we need make sure that the object is
tracked in the object tracker. If it is a non-static object then the
activation is illegal.
In previous implementation, each subsystem need take care of this in
their fixup callbacks. Actually we can put it into debugobjects core.
Thus we can save duplicated code, and have *pure* fixup callbacks.
To achieve this, a new callback "is_static_object" is introduced to let
the type specific code decide whether a object is static or not. If
yes, we take it into object tracker, otherwise give warning and invoke
fixup callback.
This change has paassed debugobjects selftest, and I also do some test
with all debugobjects supports enabled.
At last, I have a concern about the fixups that can it change the object
which is in incorrect state on fixup? Because the 'addr' may not point
to any valid object if a non-static object is not tracked. Then Change
such object can overwrite someone's memory and cause unexpected
behaviour. For example, the timer_fixup_activate bind timer to function
stub_timer.
Link: http://lkml.kernel.org/r/1462576157-14539-1-git-send-email-changbin.du@intel.com
[changbin.du@intel.com: improve code comments where invoke the new is_static_object callback]
Link: http://lkml.kernel.org/r/1462777431-8171-1-git-send-email-changbin.du@intel.com
Signed-off-by: Du, Changbin <changbin.du@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I am going to introduce debugobjects infrastructure to USB subsystem.
But before this, I found the code of debugobjects could be improved.
This patchset will make fixup functions return bool type instead of int.
Because fixup only need report success or no. boolean is the 'real'
type.
This patch (of 7):
The object debugging infrastructure core provides some fixup callbacks
for the subsystem who use it. These callbacks are called from the debug
code whenever a problem in debug_object_init is detected. And
debugobjects core suppose them returns 1 when the fixup was successful,
otherwise 0. So the return type is boolean.
A bad thing is that debug_object_fixup use the return value for
arithmetic operation. It confused me that what is the reall return
type.
Reading over the whole code, I found some place do use the return value
incorrectly(see next patch). So why use bool type instead?
Signed-off-by: Du, Changbin <changbin.du@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On my bigger s390 systems I always get "Out of memory.
ODEBUG disabled". Since the number of objects is needed at
compile time, we can not change the size dynamically before
the caches etc are available. Doubling the size seems to
do the trick. Since it is init data it will be freed anyway,
this should be ok.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Link: http://lkml.kernel.org/r/1453905478-13409-1-git-send-email-borntraeger@de.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Direct conversion of one KERN_DEBUG message without DEBUG definition
(suggested by Josh Triplett)
That message will now be disabled by default. (see
Documentation/CodingStyle Chapter 13)
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I'm not sure why, but the hlist for each entry iterators were conceived
list_for_each_entry(pos, head, member)
The hlist ones were greedy and wanted an extra parameter:
hlist_for_each_entry(tpos, pos, head, member)
Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.
Besides the semantic patch, there was some manual work required:
- Fix up the actual hlist iterators in linux/list.h
- Fix up the declaration of other iterators based on the hlist ones.
- A very small amount of places were using the 'node' parameter, this
was modified to use 'obj->member' instead.
- Coccinelle didn't handle the hlist_for_each_entry_safe iterator
properly, so those had to be fixed up manually.
The semantic patch which is mostly the work of Peter Senna Tschudin is here:
@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;
type T;
expression a,c,d,e;
identifier b;
statement S;
@@
-T b;
<+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
...+>
[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
debugobjects is now printing a warning when a fixup for a NOTAVAILABLE
object is run. This causes the selftest to fail like:
ODEBUG: selftest warnings failed 4 != 5
We could just increase the number of warnings that the selftest is
expecting to see because that is actually what has changed. But, it turns
out that fixup_activate() was written with inverted logic and thus a fixup
for a static object returned 1 indicating the object had been fixed, and 0
otherwise. Fix the logic to be correct and update the counts to reflect
that nothing needed fixing for a static object.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Calling del_timer_sync() on an uninitialized timer leads to a
never ending loop in lock_timer_base() that spins checking for a
non-NULL timer base. Add an assertion to debugobjects to catch
usage of uninitialized objects so that we can initialize timers
in the del_timer_sync() path before it calls lock_timer_base().
[ sboyd@codeaurora.org: Clarify commit message ]
Signed-off-by: Christine Chan <cschan@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1320724108-20788-3-git-send-email-sboyd@codeaurora.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Make debugobjects use the return code from the fixup function. That
allows us better diagnostics in the activate check than relying on a
WARN_ON() in the object specific code.
[ tglx@linutronix.de: Split out the debugobjects vs. the timer change ]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Christine Chan <cschan@codeaurora.org>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1320724108-20788-2-git-send-email-sboyd@codeaurora.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
