psi has provisions to shut off the periodic aggregation worker when
there is a period of no task activity - and thus no data that needs
aggregating. However, while developing psi monitoring, Suren noticed
that the aggregation clock currently won't stay shut off for good.
Debugging this revealed a flaw in the idle design: an aggregation run
will see no task activity and decide to go to sleep; shortly thereafter,
the kworker thread that executed the aggregation will go idle and cause
a scheduling change, during which the psi callback will kick the
!pending worker again. This will ping-pong forever, and is equivalent
to having no shut-off logic at all (but with more code!)
Fix this by exempting aggregation workers from psi's clock waking logic
when the state change is them going to sleep. To do this, tag workers
with the last work function they executed, and if in psi we see a worker
going to sleep after aggregating psi data, we will not reschedule the
aggregation work item.
What if the worker is also executing other items before or after?
Any psi state times that were incurred by work items preceding the
aggregation work will have been collected from the per-cpu buckets
during the aggregation itself. If there are work items following the
aggregation work, the worker's last_func tag will be overwritten and the
aggregator will be kept alive to process this genuine new activity.
If the aggregation work is the last thing the worker does, and we decide
to go idle, the brief period of non-idle time incurred between the
aggregation run and the kworker's dequeue will be stranded in the
per-cpu buckets until the clock is woken by later activity. But that
should not be a problem. The buckets can hold 4s worth of time, and
future activity will wake the clock with a 2s delay, giving us 2s worth
of data we can leave behind when disabling aggregation. If it takes a
worker more than two seconds to go idle after it finishes its last work
item, we likely have bigger problems in the system, and won't notice one
sample that was averaged with a bogus per-CPU weight.
Link: http://lkml.kernel.org/r/20190116193501.1910-1-hannes@cmpxchg.org
Fixes: eb414681d5 ("psi: pressure stall information for CPU, memory, and IO")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Provide a new function, queue_work_node, which is meant to schedule work on
a "random" CPU of the requested NUMA node. The main motivation for this is
to help assist asynchronous init to better improve boot times for devices
that are local to a specific node.
For now we just default to the first CPU that is in the intersection of the
cpumask of the node and the online cpumask. The only exception is if the
CPU is local to the node we will just use the current CPU. This should work
for our purposes as we are currently only using this for unbound work so
the CPU will be translated to a node anyway instead of being directly used.
As we are only using the first CPU to represent the NUMA node for now I am
limiting the scope of the function so that it can only be used with unbound
workqueues.
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
syzbot found a flush_work() caller who forgot to call INIT_WORK()
because that work_struct was allocated by kzalloc() [1]. But the message
INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
by lock_map_acquire() is failing to tell that INIT_WORK() is missing.
Since flush_work() without INIT_WORK() is a bug, and INIT_WORK() should
set ->func field to non-zero, let's warn if ->func field is zero.
[1] https://syzkaller.appspot.com/bug?id=a5954455fcfa51c29ca2ab55b203076337e1c770
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Tejun Heo <tj@kernel.org>
Now that call_rcu()'s callback is not invoked until after all
preempt-disable regions of code have completed (in addition to explicitly
marked RCU read-side critical sections), call_rcu() can be used in place
of call_rcu_sched(). This commit therefore makes that change.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Some architectures need to use stop_machine() to patch functions for
ftrace, and the assumption is that the stopped CPUs do not make function
calls to traceable functions when they are in the stopped state.
Commit ce4f06dcbb ("stop_machine: Touch_nmi_watchdog() after
MULTI_STOP_PREPARE") added calls to the watchdog touch functions from
the stopped CPUs and those functions lack notrace annotations. This
leads to crashes when enabling/disabling ftrace on ARM kernels built
with the Thumb-2 instruction set.
Fix it by adding the necessary notrace annotations.
Fixes: ce4f06dcbb ("stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: oleg@redhat.com
Cc: tj@kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180821152507.18313-1-vincent.whitchurch@axis.com
Pull workqueue updates from Tejun Heo:
"Over the lockdep cross-release churn, workqueue lost some of the
existing annotations. Johannes Berg restored it and also improved
them"
* 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: re-add lockdep dependencies for flushing
workqueue: skip lockdep wq dependency in cancel_work_sync()
In flush_work(), we need to create a lockdep dependency so that
the following scenario is appropriately tagged as a problem:
work_function()
{
mutex_lock(&mutex);
...
}
other_function()
{
mutex_lock(&mutex);
flush_work(&work); // or cancel_work_sync(&work);
}
This is a problem since the work might be running and be blocked
on trying to acquire the mutex.
Similarly, in flush_workqueue().
These were removed after cross-release partially caught these
problems, but now cross-release was reverted anyway. IMHO the
removal was erroneous anyway though, since lockdep should be
able to catch potential problems, not just actual ones, and
cross-release would only have caught the problem when actually
invoking wait_for_completion().
Fixes: fd1a5b04df ("workqueue: Remove now redundant lock acquisitions wrt. workqueue flushes")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In cancel_work_sync(), we can only have one of two cases, even
with an ordered workqueue:
* the work isn't running, just cancelled before it started
* the work is running, but then nothing else can be on the
workqueue before it
Thus, we need to skip the lockdep workqueue dependency handling,
otherwise we get false positive reports from lockdep saying that
we have a potential deadlock when the workqueue also has other
work items with locking, e.g.
work1_function() { mutex_lock(&mutex); ... }
work2_function() { /* nothing */ }
other_function() {
queue_work(ordered_wq, &work1);
queue_work(ordered_wq, &work2);
mutex_lock(&mutex);
cancel_work_sync(&work2);
}
As described above, this isn't a problem, but lockdep will
currently flag it as if cancel_work_sync() was flush_work(),
which *is* a problem.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This is mostly updates to the usual drivers: ufs, qedf, mpt3sas, lpfc,
xfcp, hisi_sas, cxlflash, qla2xxx. In the absence of Nic, we're also
taking target updates which are mostly minor except for the tcmu
refactor. The only real core change to worry about is the removal of
high page bouncing (in sas, storvsc and iscsi). This has been well
tested and no problems have shown up so far.
Signed-off-by: James E.J. Bottomley <jejb@linux.vnet.ibm.com>
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Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
Pull SCSI updates from James Bottomley:
"This is mostly updates to the usual drivers: ufs, qedf, mpt3sas, lpfc,
xfcp, hisi_sas, cxlflash, qla2xxx.
In the absence of Nic, we're also taking target updates which are
mostly minor except for the tcmu refactor.
The only real core change to worry about is the removal of high page
bouncing (in sas, storvsc and iscsi). This has been well tested and no
problems have shown up so far"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (268 commits)
scsi: lpfc: update driver version to 12.0.0.4
scsi: lpfc: Fix port initialization failure.
scsi: lpfc: Fix 16gb hbas failing cq create.
scsi: lpfc: Fix crash in blk_mq layer when executing modprobe -r lpfc
scsi: lpfc: correct oversubscription of nvme io requests for an adapter
scsi: lpfc: Fix MDS diagnostics failure (Rx < Tx)
scsi: hisi_sas: Mark PHY as in reset for nexus reset
scsi: hisi_sas: Fix return value when get_free_slot() failed
scsi: hisi_sas: Terminate STP reject quickly for v2 hw
scsi: hisi_sas: Add v2 hw force PHY function for internal ATA command
scsi: hisi_sas: Include TMF elements in struct hisi_sas_slot
scsi: hisi_sas: Try wait commands before before controller reset
scsi: hisi_sas: Init disks after controller reset
scsi: hisi_sas: Create a scsi_host_template per HW module
scsi: hisi_sas: Reset disks when discovered
scsi: hisi_sas: Add LED feature for v3 hw
scsi: hisi_sas: Change common allocation mode of device id
scsi: hisi_sas: change slot index allocation mode
scsi: hisi_sas: Introduce hisi_sas_phy_set_linkrate()
scsi: hisi_sas: fix a typo in hisi_sas_task_prep()
...
- Use overflow helpers in 2-factor allocators (Kees, Rasmus)
- Introduce overflow test module (Rasmus, Kees)
- Introduce saturating size helper functions (Matthew, Kees)
- Treewide use of struct_size() for allocators (Kees)
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Merge tag 'overflow-v4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull overflow updates from Kees Cook:
"This adds the new overflow checking helpers and adds them to the
2-factor argument allocators. And this adds the saturating size
helpers and does a treewide replacement for the struct_size() usage.
Additionally this adds the overflow testing modules to make sure
everything works.
I'm still working on the treewide replacements for allocators with
"simple" multiplied arguments:
*alloc(a * b, ...) -> *alloc_array(a, b, ...)
and
*zalloc(a * b, ...) -> *calloc(a, b, ...)
as well as the more complex cases, but that's separable from this
portion of the series. I expect to have the rest sent before -rc1
closes; there are a lot of messy cases to clean up.
Summary:
- Introduce arithmetic overflow test helper functions (Rasmus)
- Use overflow helpers in 2-factor allocators (Kees, Rasmus)
- Introduce overflow test module (Rasmus, Kees)
- Introduce saturating size helper functions (Matthew, Kees)
- Treewide use of struct_size() for allocators (Kees)"
* tag 'overflow-v4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
treewide: Use struct_size() for devm_kmalloc() and friends
treewide: Use struct_size() for vmalloc()-family
treewide: Use struct_size() for kmalloc()-family
device: Use overflow helpers for devm_kmalloc()
mm: Use overflow helpers in kvmalloc()
mm: Use overflow helpers in kmalloc_array*()
test_overflow: Add memory allocation overflow tests
overflow.h: Add allocation size calculation helpers
test_overflow: Report test failures
test_overflow: macrofy some more, do more tests for free
lib: add runtime test of check_*_overflow functions
compiler.h: enable builtin overflow checkers and add fallback code
One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:
struct foo {
int stuff;
void *entry[];
};
instance = kmalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);
Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:
instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);
This patch makes the changes for kmalloc()-family (and kvmalloc()-family)
uses. It was done via automatic conversion with manual review for the
"CHECKME" non-standard cases noted below, using the following Coccinelle
script:
// pkey_cache = kmalloc(sizeof *pkey_cache + tprops->pkey_tbl_len *
// sizeof *pkey_cache->table, GFP_KERNEL);
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@
- alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT), GFP)
+ alloc(struct_size(VAR, ELEMENT, COUNT), GFP)
// mr = kzalloc(sizeof(*mr) + m * sizeof(mr->map[0]), GFP_KERNEL);
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@
- alloc(sizeof(*VAR) + COUNT * sizeof(VAR->ELEMENT[0]), GFP)
+ alloc(struct_size(VAR, ELEMENT, COUNT), GFP)
// Same pattern, but can't trivially locate the trailing element name,
// or variable name.
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
expression SOMETHING, COUNT, ELEMENT;
@@
- alloc(sizeof(SOMETHING) + COUNT * sizeof(ELEMENT), GFP)
+ alloc(CHECKME_struct_size(&SOMETHING, ELEMENT, COUNT), GFP)
Signed-off-by: Kees Cook <keescook@chromium.org>
In commit 7ee681b252 ("workqueue: Convert to state machine callbacks"),
three new function definitions were added: ‘workqueue_prepare_cpu’,
‘workqueue_online_cpu’ and ‘workqueue_offline_cpu’.
Move these function definitions within a CONFIG_SMP block since they are
not used outside of it. This will match function declarations in header
<include/linux/workqueue.h>, and silence the following gcc warning (W=1):
kernel/workqueue.c:4743:5: warning: no previous prototype for ‘workqueue_prepare_cpu’ [-Wmissing-prototypes]
kernel/workqueue.c:4756:5: warning: no previous prototype for ‘workqueue_online_cpu’ [-Wmissing-prototypes]
kernel/workqueue.c:4783:5: warning: no previous prototype for ‘workqueue_offline_cpu’ [-Wmissing-prototypes]
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
The worker struct could already be freed when wq_worker_comm() tries
to access it for reporting. This patch protects PF_WQ_WORKER
modifications with wq_pool_attach_mutex and makes wq_worker_comm()
test the flag before dereferencing worker from kthread_data(), which
ensures that it only dereferences when the worker struct is valid.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Lai Jiangshan <jiangshanlai@gmail.com>
Fixes: 6b59808bfe ("workqueue: Show the latest workqueue name in /proc/PID/{comm,stat,status}")
There can be a lot of workqueue workers and they all show up with the
cryptic kworker/* names making it difficult to understand which is
doing what and how they came to be.
# ps -ef | grep kworker
root 4 2 0 Feb25 ? 00:00:00 [kworker/0:0H]
root 6 2 0 Feb25 ? 00:00:00 [kworker/u112:0]
root 19 2 0 Feb25 ? 00:00:00 [kworker/1:0H]
root 25 2 0 Feb25 ? 00:00:00 [kworker/2:0H]
root 31 2 0 Feb25 ? 00:00:00 [kworker/3:0H]
...
This patch makes workqueue workers report the latest workqueue it was
executing for through /proc/PID/{comm,stat,status}. The extra
information is appended to the kthread name with intervening '+' if
currently executing, otherwise '-'.
# cat /proc/25/comm
kworker/2:0-events_power_efficient
# cat /proc/25/stat
25 (kworker/2:0-events_power_efficient) I 2 0 0 0 -1 69238880 0 0...
# grep Name /proc/25/status
Name: kworker/2:0-events_power_efficient
Unfortunately, ps(1) truncates comm to 15 characters,
# ps 25
PID TTY STAT TIME COMMAND
25 ? I 0:00 [kworker/2:0-eve]
making it a lot less useful; however, this should be an easy fix from
ps(1) side.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Craig Small <csmall@enc.com.au>
Work functions can use set_worker_desc() to improve the visibility of
what the worker task is doing. Currently, the desc field is unset at
the beginning of each execution and there is a separate field to track
the field is set during the current execution.
Instead of leaving empty till desc is set, worker->desc can be used to
remember the last workqueue the worker worked on by default and users
that use set_worker_desc() can override it to something more
informative as necessary.
This simplifies desc handling and helps tracking the last workqueue
that the worker exected on to improve visibility.
Signed-off-by: Tejun Heo <tj@kernel.org>
For historical reasons, the worker attach/detach functions don't
currently manage worker->pool and the callers are manually and
inconsistently updating it.
This patch moves worker->pool updates into the worker attach/detach
functions. This makes worker->pool consistent and clearly defines how
worker->pool updates are synchronized.
This will help later workqueue visibility improvements by allowing
safe access to workqueue information from worker->task.
Signed-off-by: Tejun Heo <tj@kernel.org>
To improve workqueue visibility, we want to be able to access
workqueue information from worker tasks. The per-pool attach mutex
makes that difficult because there's no way of stabilizing task ->
worker pool association without knowing the pool first.
Worker attach/detach is a slow path and there's no need for different
pools to be able to perform them concurrently. This patch replaces
the per-pool attach_mutex with global wq_pool_attach_mutex to prepare
for visibility improvement changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
As a prerequisite, complement commit 3d1cb2059d ("workqueue: include
workqueue info when printing debug dump of a worker task") to be usable with
kernel modules by exporting the symbol set_worker_desc(). Current built-in
user was introduced with commit ef3b101925 ("writeback: set worker desc to
identify writeback workers in task dumps").
Can help distinguishing work items which do not have adapter scope.
Description is printed out with task dump for debugging on WARN, BUG, panic,
or magic-sysrq [show-task-states(t)].
Example:
$ echo 0 >| /sys/bus/ccw/drivers/zfcp/0.0.1880/0x50050763031bd327/failed &
$ echo 't' >| /proc/sysrq-trigger
$ dmesg
sysrq: SysRq : Show State
task PC stack pid father
...
zfcp_q_0.0.1880 S14640 2165 2 0x02000000
Call Trace:
([<00000000009df464>] __schedule+0xbf4/0xc78)
[<00000000009df57c>] schedule+0x94/0xc0
[<0000000000168654>] rescuer_thread+0x33c/0x3a0
[<000000000016f8be>] kthread+0x166/0x178
[<00000000009e71f2>] kernel_thread_starter+0x6/0xc
[<00000000009e71ec>] kernel_thread_starter+0x0/0xc
no locks held by zfcp_q_0.0.1880/2165.
...
kworker/u512:2 D11280 2193 2 0x02000000
Workqueue: zfcp_q_0.0.1880 zfcp_scsi_rport_work [zfcp] (zrpd-50050763031bd327)
^^^^^^^^^^^^^^^^^^^^^
Call Trace:
([<00000000009df464>] __schedule+0xbf4/0xc78)
[<00000000009df57c>] schedule+0x94/0xc0
[<00000000009e50c0>] schedule_timeout+0x488/0x4d0
[<00000000001e425c>] msleep+0x5c/0x78 >>test code only<<
[<000003ff8008a21e>] zfcp_scsi_rport_work+0xbe/0x100 [zfcp]
[<0000000000167154>] process_one_work+0x3b4/0x718
[<000000000016771c>] worker_thread+0x264/0x408
[<000000000016f8be>] kthread+0x166/0x178
[<00000000009e71f2>] kernel_thread_starter+0x6/0xc
[<00000000009e71ec>] kernel_thread_starter+0x0/0xc
2 locks held by kworker/u512:2/2193:
#0: (name){++++.+}, at: [<0000000000166f4e>] process_one_work+0x1ae/0x718
#1: ((&(&port->rport_work)->work)){+.+.+.}, at: [<0000000000166f4e>] process_one_work+0x1ae/0x718
...
=============================================
Showing busy workqueues and worker pools:
workqueue zfcp_q_0.0.1880: flags=0x2000a
pwq 512: cpus=0-255 flags=0x4 nice=0 active=1/1
in-flight: 2193:zfcp_scsi_rport_work [zfcp]
pool 512: cpus=0-255 flags=0x4 nice=0 hung=0s workers=4 idle: 5 2354 2311
Work items with adapter scope are already identified by the workqueue name
"zfcp_q_<devbusid>" and the work item function name.
Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Pull workqueue updates from Tejun Heo:
"rcu_work addition and a couple trivial changes"
* 'for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: remove the comment about the old manager_arb mutex
workqueue: fix the comments of nr_idle
fs/aio: Use rcu_work instead of explicit rcu and work item
cgroup: Use rcu_work instead of explicit rcu and work item
RCU, workqueue: Implement rcu_work
Since the worker rebinding behavior was refactored, there is
no idle worker off the idle_list now. The comment is outdated
and can be just removed.
It also groups nr_workers and nr_idle together.
Signed-off-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There are cases where RCU callback needs to be bounced to a sleepable
context. This is currently done by the RCU callback queueing a work
item, which can be cumbersome to write and confusing to read.
This patch introduces rcu_work, a workqueue work variant which gets
executed after a RCU grace period, and converts the open coded
bouncing in fs/aio and kernel/cgroup.
v3: Dropped queue_rcu_work_on(). Documented rcu grace period behavior
after queue_rcu_work().
v2: Use rcu_barrier() instead of synchronize_rcu() to wait for
completion of previously queued rcu callback as per Paul.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Found this by accident.
There are no usages of bare cancel_work() in current kernel source.
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Never directly free @dev after calling device_register(), even
if it returned an error! Always use put_device() to give up the
reference initialized in this function instead.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
drivers, a memory leak on non-blocking commits, a crash on color-eviction.
The is also meson and edid fixes, plus a fix for a doc warning.
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Merge tag 'drm-misc-fixes-2018-02-21' of git://anongit.freedesktop.org/drm/drm-misc into drm-fixes
Fixes for 4.16. I contains fixes for deadlock on runtime suspend on few
drivers, a memory leak on non-blocking commits, a crash on color-eviction.
The is also meson and edid fixes, plus a fix for a doc warning.
* tag 'drm-misc-fixes-2018-02-21' of git://anongit.freedesktop.org/drm/drm-misc:
drm/tve200: fix kernel-doc documentation comment include
drm/meson: fix vsync buffer update
drm: Handle unexpected holes in color-eviction
drm/edid: Add 6 bpc quirk for CPT panel in Asus UX303LA
drm/amdgpu: Fix deadlock on runtime suspend
drm/radeon: Fix deadlock on runtime suspend
drm/nouveau: Fix deadlock on runtime suspend
drm: Allow determining if current task is output poll worker
workqueue: Allow retrieval of current task's work struct
drm/atomic: Fix memleak on ERESTARTSYS during non-blocking commits
As we prepare for offloading the residual 1hz scheduler ticks to
workqueue, let's affine those to housekeepers so that they don't
interrupt the CPUs that don't want to be disturbed.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1519186649-3242-5-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Introduce a helper to retrieve the current task's work struct if it is
a workqueue worker.
This allows us to fix a long-standing deadlock in several DRM drivers
wherein the ->runtime_suspend callback waits for a specific worker to
finish and that worker in turn calls a function which waits for runtime
suspend to finish. That function is invoked from multiple call sites
and waiting for runtime suspend to finish is the correct thing to do
except if it's executing in the context of the worker.
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://patchwork.freedesktop.org/patch/msgid/2d8f603074131eb87e588d2b803a71765bd3a2fd.1518338788.git.lukas@wunner.de
Here is the big Staging and IIO driver patches for 4.16-rc1.
There is the normal amount of new IIO drivers added, like all releases.
The networking IPX and the ncpfs filesystem are moved into the staging
tree, as they are on their way out of the kernel due to lack of use
anymore.
The visorbus subsystem finall has started moving out of the staging tree
to the "real" part of the kernel, and the most and fsl-mc codebases are
almost ready to move out, that will probably happen for 4.17-rc1 if all
goes well.
Other than that, there is a bunch of license header cleanups in the
tree, along with the normal amount of coding style churn that we all
know and love for this codebase. I also got frustrated at the
Meltdown/Spectre mess and took it out on the dgnc tty driver, deleting
huge chunks of it that were never even being used.
Full details of everything is in the shortlog.
All of these patches have been in linux-next for a while with no
reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'staging-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
Pull staging/IIO updates from Greg KH:
"Here is the big Staging and IIO driver patches for 4.16-rc1.
There is the normal amount of new IIO drivers added, like all
releases.
The networking IPX and the ncpfs filesystem are moved into the staging
tree, as they are on their way out of the kernel due to lack of use
anymore.
The visorbus subsystem finall has started moving out of the staging
tree to the "real" part of the kernel, and the most and fsl-mc
codebases are almost ready to move out, that will probably happen for
4.17-rc1 if all goes well.
Other than that, there is a bunch of license header cleanups in the
tree, along with the normal amount of coding style churn that we all
know and love for this codebase. I also got frustrated at the
Meltdown/Spectre mess and took it out on the dgnc tty driver, deleting
huge chunks of it that were never even being used.
Full details of everything is in the shortlog.
All of these patches have been in linux-next for a while with no
reported issues"
* tag 'staging-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (627 commits)
staging: rtlwifi: remove redundant initialization of 'cfg_cmd'
staging: rtl8723bs: remove a couple of redundant initializations
staging: comedi: reformat lines to 80 chars or less
staging: lustre: separate a connection destroy from free struct kib_conn
Staging: rtl8723bs: Use !x instead of NULL comparison
Staging: rtl8723bs: Remove dead code
Staging: rtl8723bs: Change names to conform to the kernel code
staging: ccree: Fix missing blank line after declaration
staging: rtl8188eu: remove redundant initialization of 'pwrcfgcmd'
staging: rtlwifi: remove unused RTLHALMAC_ST and RTLPHYDM_ST
staging: fbtft: remove unused FB_TFT_SSD1325 kconfig
staging: comedi: dt2811: remove redundant initialization of 'ns'
staging: wilc1000: fix alignments to match open parenthesis
staging: wilc1000: removed unnecessary defined enums typedef
staging: wilc1000: remove unnecessary use of parentheses
staging: rtl8192u: remove redundant initialization of 'timeout'
staging: sm750fb: fix CamelCase for dispSet var
staging: lustre: lnet/selftest: fix compile error on UP build
staging: rtl8723bs: hal_com_phycfg: Remove unneeded semicolons
staging: rts5208: Fix "seg_no" calculation in reset_ms_card()
...
Pull workqueue updates from Tejun Heo:
"Workqueue has an early init trick where workqueues can be created and
work items queued on them before the workqueue subsystem is online.
This helps simplifying early init and operation of low level
subsystems which use workqueues for managerial things which aren't
depended upon early during boot.
Out of laziness, the early init didn't cover workqueues with
WQ_MEM_RECLAIM, which is inconsistent and confusing because adding the
flag simply makes the system fail to boot. Cover WQ_MEM_RECLAIM too.
This was originally brought up for RCU but RCU didn't actually need
this. I still think it's a good idea to cover it"
* 'for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: allow WQ_MEM_RECLAIM on early init workqueues
workqueue: separate out init_rescuer()
Pull RCU updates from Ingo Molnar:
"The main RCU changes in this cycle were:
- Updates to use cond_resched() instead of cond_resched_rcu_qs()
where feasible (currently everywhere except in kernel/rcu and in
kernel/torture.c). Also a couple of fixes to avoid sending IPIs to
offline CPUs.
- Updates to simplify RCU's dyntick-idle handling.
- Updates to remove almost all uses of smp_read_barrier_depends() and
read_barrier_depends().
- Torture-test updates.
- Miscellaneous fixes"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits)
torture: Save a line in stutter_wait(): while -> for
torture: Eliminate torture_runnable and perf_runnable
torture: Make stutter less vulnerable to compilers and races
locking/locktorture: Fix num reader/writer corner cases
locking/locktorture: Fix rwsem reader_delay
torture: Place all torture-test modules in one MAINTAINERS group
rcutorture/kvm-build.sh: Skip build directory check
rcutorture: Simplify functions.sh include path
rcutorture: Simplify logging
rcutorture/kvm-recheck-*: Improve result directory readability check
rcutorture/kvm.sh: Support execution from any directory
rcutorture/kvm.sh: Use consistent help text for --qemu-args
rcutorture/kvm.sh: Remove unused variable, `alldone`
rcutorture: Remove unused script, config2frag.sh
rcutorture/configinit: Fix build directory error message
rcutorture: Preempt RCU-preempt readers more vigorously
torture: Reduce #ifdefs for preempt_schedule()
rcu: Remove have_rcu_nocb_mask from tree_plugin.h
rcu: Add comment giving debug strategy for double call_rcu()
tracing, rcu: Hide trace event rcu_nocb_wake when not used
...
Instead of the cfs workitem library, use workqueues.
As lnet wants to provide a cpu mask of allowed cpus, it
needs to be a WQ_UNBOUND work queue so that tasks can
run on cpus other than where they were submitted.
This patch also exported apply_workqueue_attrs() which is
a documented part of the workqueue API, that isn't currently
exported. lustre needs it to allow workqueue thread to be limited
to a subset of CPUs.
Acked-by: Tejun Heo <tj@kernel.org> (for export of apply_workqueue_attrs)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show_workqueue_state() can print out a lot of messages while being in
atomic context, e.g. sysrq-t -> show_workqueue_state(). If the console
device is slow it may end up triggering NMI hard lockup watchdog.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v4.5+
Workqueues can be created early during boot before workqueue subsystem
in fully online - work items are queued waiting for later full
initialization. However, early init wasn't supported for
WQ_MEM_RECLAIM workqueues causing unnecessary annoyances for a subset
of users. Expand early init support to include WQ_MEM_RECLAIM
workqueues.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Separate out init_rescuer() from __alloc_workqueue_key() to prepare
for early init support for WQ_MEM_RECLAIM. This patch doesn't
introduce any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Pull RCU updates from Paul E. McKenney:
- Updates to use cond_resched() instead of cond_resched_rcu_qs()
where feasible (currently everywhere except in kernel/rcu and
in kernel/torture.c). Also a couple of fixes to avoid sending
IPIs to offline CPUs.
- Updates to simplify RCU's dyntick-idle handling.
- Updates to remove almost all uses of smp_read_barrier_depends()
and read_barrier_depends().
- Miscellaneous fixes.
- Torture-test updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The filw was converted from print_symbol() to %pf some time
ago (044c782ce3 "workqueue: fix checkpatch issues").
kallsyms does not seem to be needed anymore.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since the cpu/hotplug refactoring, DOWN_FAILED is never called without
preceding DOWN_PREPARE making the workaround unnecessary. Remove it.
Signed-off-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Since the recent cpu/hotplug refactoring, workqueue_offline_cpu() is
guaranteed to run on the local cpu which is going offline.
This also fixes the following deadlock by removing work item
scheduling and flushing from CPU hotplug path.
http://lkml.kernel.org/r/1504764252-29091-1-git-send-email-prsood@codeaurora.org
tj: Description update.
Signed-off-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Now that cond_resched() also provides RCU quiescent states when
needed, it can be used in place of cond_resched_rcu_qs(). This
commit therefore makes this change.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Initialize wq_unbound_cpumask to exclude cpus that were isolated by
the cmdline's isolcpus parameter.
Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
With all callbacks converted, and the timer callback prototype
switched over, the TIMER_FUNC_TYPE cast is no longer needed,
so remove it. Conversion was done with the following scripts:
perl -pi -e 's|\(TIMER_FUNC_TYPE\)||g' \
$(git grep TIMER_FUNC_TYPE | cut -d: -f1 | sort -u)
perl -pi -e 's|\(TIMER_DATA_TYPE\)||g' \
$(git grep TIMER_DATA_TYPE | cut -d: -f1 | sort -u)
The now unused macros are also dropped from include/linux/timer.h.
Signed-off-by: Kees Cook <keescook@chromium.org>
Pull workqueue updates from Tejun Heo:
"There was a commit to make unbound kworkers respect cpu isolation but
it conflicted with the restructuring of cpu isolation and got
reverted, so the only thing left is the trivial comment fix.
Will retry the cpu isolation change after this merge window"
* 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Fix comment for unbound workqueue's attrbutes
Revert "workqueue: respect isolated cpus when queueing an unbound work"
workqueue: respect isolated cpus when queueing an unbound work
Pull timer updates from Thomas Gleixner:
"Yet another big pile of changes:
- More year 2038 work from Arnd slowly reaching the point where we
need to think about the syscalls themself.
- A new timer function which allows to conditionally (re)arm a timer
only when it's either not running or the new expiry time is sooner
than the armed expiry time. This allows to use a single timer for
multiple timeout requirements w/o caring about the first expiry
time at the call site.
- A new NMI safe accessor to clock real time for the printk timestamp
work. Can be used by tracing, perf as well if required.
- A large number of timer setup conversions from Kees which got
collected here because either maintainers requested so or they
simply got ignored. As Kees pointed out already there are a few
trivial merge conflicts and some redundant commits which was
unavoidable due to the size of this conversion effort.
- Avoid a redundant iteration in the timer wheel softirq processing.
- Provide a mechanism to treat RTC implementations depending on their
hardware properties, i.e. don't inflict the write at the 0.5
seconds boundary which originates from the PC CMOS RTC to all RTCs.
No functional change as drivers need to be updated separately.
- The usual small updates to core code clocksource drivers. Nothing
really exciting"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (111 commits)
timers: Add a function to start/reduce a timer
pstore: Use ktime_get_real_fast_ns() instead of __getnstimeofday()
timer: Prepare to change all DEFINE_TIMER() callbacks
netfilter: ipvs: Convert timers to use timer_setup()
scsi: qla2xxx: Convert timers to use timer_setup()
block/aoe: discover_timer: Convert timers to use timer_setup()
ide: Convert timers to use timer_setup()
drbd: Convert timers to use timer_setup()
mailbox: Convert timers to use timer_setup()
crypto: Convert timers to use timer_setup()
drivers/pcmcia: omap1: Fix error in automated timer conversion
ARM: footbridge: Fix typo in timer conversion
drivers/sgi-xp: Convert timers to use timer_setup()
drivers/pcmcia: Convert timers to use timer_setup()
drivers/memstick: Convert timers to use timer_setup()
drivers/macintosh: Convert timers to use timer_setup()
hwrng/xgene-rng: Convert timers to use timer_setup()
auxdisplay: Convert timers to use timer_setup()
sparc/led: Convert timers to use timer_setup()
mips: ip22/32: Convert timers to use timer_setup()
...
Use lockdep to check that IRQs are enabled or disabled as expected. This
way the sanity check only shows overhead when concurrency correctness
debug code is enabled.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: David S . Miller <davem@davemloft.net>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1509980490-4285-4-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This reverts commit b5149873a0.
It conflicts with the following isolcpus change from the sched branch.
edb9382175 ("sched/isolation: Move isolcpus= handling to the housekeeping code")
Let's revert for now.
Signed-off-by: Tejun Heo <tj@kernel.org>
For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't currently harmful.
However, for some features it is necessary to instrument reads and
writes separately, which is not possible with ACCESS_ONCE(). This
distinction is critical to correct operation.
It's possible to transform the bulk of kernel code using the Coccinelle
script below. However, this doesn't handle comments, leaving references
to ACCESS_ONCE() instances which have been removed. As a preparatory
step, this patch converts the workqueue code and comments to use
{READ,WRITE}_ONCE() consistently.
----
virtual patch
@ depends on patch @
expression E1, E2;
@@
- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)
@ depends on patch @
expression E;
@@
- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-12-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Initialize wq_unbound_cpumask to exclude cpus that were isolated by
the cmdline's isolcpus parameter.
Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In preparation for unconditionally passing the struct timer_list pointer
to all timer callbacks, switch to using the new timer_setup() and
from_timer() to pass the timer pointer explicitly. (The prior workqueue
patch missed a few timers.)
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Link: https://lkml.kernel.org/r/20171016225825.GA99101@beast
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Josef reported a HARDIRQ-safe -> HARDIRQ-unsafe lock order detected by
lockdep:
[ 1270.472259] WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
[ 1270.472783] 4.14.0-rc1-xfstests-12888-g76833e8 #110 Not tainted
[ 1270.473240] -----------------------------------------------------
[ 1270.473710] kworker/u5:2/5157 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
[ 1270.474239] (&(&lock->wait_lock)->rlock){+.+.}, at: [<ffffffff8da253d2>] __mutex_unlock_slowpath+0xa2/0x280
[ 1270.474994]
[ 1270.474994] and this task is already holding:
[ 1270.475440] (&pool->lock/1){-.-.}, at: [<ffffffff8d2992f6>] worker_thread+0x366/0x3c0
[ 1270.476046] which would create a new lock dependency:
[ 1270.476436] (&pool->lock/1){-.-.} -> (&(&lock->wait_lock)->rlock){+.+.}
[ 1270.476949]
[ 1270.476949] but this new dependency connects a HARDIRQ-irq-safe lock:
[ 1270.477553] (&pool->lock/1){-.-.}
...
[ 1270.488900] to a HARDIRQ-irq-unsafe lock:
[ 1270.489327] (&(&lock->wait_lock)->rlock){+.+.}
...
[ 1270.494735] Possible interrupt unsafe locking scenario:
[ 1270.494735]
[ 1270.495250] CPU0 CPU1
[ 1270.495600] ---- ----
[ 1270.495947] lock(&(&lock->wait_lock)->rlock);
[ 1270.496295] local_irq_disable();
[ 1270.496753] lock(&pool->lock/1);
[ 1270.497205] lock(&(&lock->wait_lock)->rlock);
[ 1270.497744] <Interrupt>
[ 1270.497948] lock(&pool->lock/1);
, which will cause a irq inversion deadlock if the above lock scenario
happens.
The root cause of this safe -> unsafe lock order is the
mutex_unlock(pool->manager_arb) in manage_workers() with pool->lock
held.
Unlocking mutex while holding an irq spinlock was never safe and this
problem has been around forever but it never got noticed because the
only time the mutex is usually trylocked while holding irqlock making
actual failures very unlikely and lockdep annotation missed the
condition until the recent b9c16a0e1f ("locking/mutex: Fix
lockdep_assert_held() fail").
Using mutex for pool->manager_arb has always been a bit of stretch.
It primarily is an mechanism to arbitrate managership between workers
which can easily be done with a pool flag. The only reason it became
a mutex is that pool destruction path wants to exclude parallel
managing operations.
This patch replaces the mutex with a new pool flag POOL_MANAGER_ACTIVE
and make the destruction path wait for the current manager on a wait
queue.
v2: Drop unnecessary flag clearing before pool destruction as
suggested by Boqun.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: stable@vger.kernel.org
Pull workqueue updates from Tejun Heo:
"Nothing major. I introduced a flag collsion bug during v4.13 cycle
which is fixed in this pull request. Fortunately, the flag is for
debugging / verification and the bug isn't critical"
* 'for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Fix flag collision
workqueue: Use TASK_IDLE
workqueue: fix path to documentation
workqueue: doc change for ST behavior on NUMA systems
Where XHLOCK_{SOFT,HARD} are save/restore points in the xhlocks[] to
ensure the temporal IRQ events don't interact with task state, the
XHLOCK_PROC is a fundament different beast that just happens to share
the interface.
The purpose of XHLOCK_PROC is to annotate independent execution inside
one task. For example workqueues, each work should appear to run in its
own 'pristine' 'task'.
Remove XHLOCK_PROC in favour of its own interface to avoid confusion.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: boqun.feng@gmail.com
Cc: david@fromorbit.com
Cc: johannes@sipsolutions.net
Cc: kernel-team@lge.com
Cc: oleg@redhat.com
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/20170829085939.ggmb6xiohw67micb@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The new completion/crossrelease annotations interact unfavourable with
the extant flush_work()/flush_workqueue() annotations.
The problem is that when a single work class does:
wait_for_completion(&C)
and
complete(&C)
in different executions, we'll build dependencies like:
lock_map_acquire(W)
complete_acquire(C)
and
lock_map_acquire(W)
complete_release(C)
which results in the dependency chain: W->C->W, which lockdep thinks
spells deadlock, even though there is no deadlock potential since
works are ran concurrently.
One possibility would be to change the work 'lock' to recursive-read,
but that would mean hitting a lockdep limitation on recursive locks.
Also, unconditinoally switching to recursive-read here would fail to
detect the actual deadlock on single-threaded workqueues, which do
have a problem with this.
For now, forcefully disregard these locks for crossrelease.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: boqun.feng@gmail.com
Cc: byungchul.park@lge.com
Cc: david@fromorbit.com
Cc: johannes@sipsolutions.net
Cc: oleg@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The flush_work() annotation as introduced by commit:
e159489baa ("workqueue: relax lockdep annotation on flush_work()")
hits on the lockdep problem with recursive read locks.
The situation as described is:
Work W1: Work W2: Task:
ARR(Q) ARR(Q) flush_workqueue(Q)
A(W1) A(W2) A(Q)
flush_work(W2) R(Q)
A(W2)
R(W2)
if (special)
A(Q)
else
ARR(Q)
R(Q)
where: A - acquire, ARR - acquire-read-recursive, R - release.
Where under 'special' conditions we want to trigger a lock recursion
deadlock, but otherwise allow the flush_work(). The allowing is done
by using recursive read locks (ARR), but lockdep is broken for
recursive stuff.
However, there appears to be no need to acquire the lock if we're not
'special', so if we remove the 'else' clause things become much
simpler and no longer need the recursion thing at all.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: boqun.feng@gmail.com
Cc: byungchul.park@lge.com
Cc: david@fromorbit.com
Cc: johannes@sipsolutions.net
Cc: oleg@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Workqueues don't use signals, it (ab)uses TASK_INTERRUPTIBLE to avoid
increasing the loadavg numbers. We've 'recently' introduced TASK_IDLE
for this case:
80ed87c8a9 ("sched/wait: Introduce TASK_NOLOAD and TASK_IDLE")
use it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
With the new lockdep crossrelease feature, which checks completions usage,
a false positive is reported in the workqueue code:
> Worker A : acquired of wfc.work -> wait for cpu_hotplug_lock to be released
> Task B : acquired of cpu_hotplug_lock -> wait for lock#3 to be released
> Task C : acquired of lock#3 -> wait for completion of barr->done
> (Task C is in lru_add_drain_all_cpuslocked())
> Worker D : wait for wfc.work to be released -> will complete barr->done
Such a dead lock can not happen because Task C's barr->done and Worker D's
barr->done can not be the same instance.
The reason of this false positive is we initialize all wq_barrier::done
at insert_wq_barrier() via init_completion(), which makes them belong to
the same lock class, therefore, impossible circles are reported.
To fix this, explicitly initialize the lockdep map for wq_barrier::done
in insert_wq_barrier(), so that the lock class key of wq_barrier::done
is a subkey of the corresponding work_struct, as a result we won't build
a dependency between a wq_barrier with a unrelated work, and we can
differ wq barriers based on the related works, so the false positive
above is avoided.
Also define the empty lockdep_init_map_crosslock() for !CROSSRELEASE
to make the code simple and away from unnecessary #ifdefs.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170817094622.12915-1-boqun.feng@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Lockdep is a runtime locking correctness validator that detects and
reports a deadlock or its possibility by checking dependencies between
locks. It's useful since it does not report just an actual deadlock but
also the possibility of a deadlock that has not actually happened yet.
That enables problems to be fixed before they affect real systems.
However, this facility is only applicable to typical locks, such as
spinlocks and mutexes, which are normally released within the context in
which they were acquired. However, synchronization primitives like page
locks or completions, which are allowed to be released in any context,
also create dependencies and can cause a deadlock.
So lockdep should track these locks to do a better job. The 'crossrelease'
implementation makes these primitives also be tracked.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: boqun.feng@gmail.com
Cc: kernel-team@lge.com
Cc: kirill@shutemov.name
Cc: npiggin@gmail.com
Cc: walken@google.com
Cc: willy@infradead.org
Link: http://lkml.kernel.org/r/1502089981-21272-6-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is an underlying assumption/trade-off in many layers of the Linux
system that CPU <-> node mapping is static. This is despite the presence
of features like NUMA and 'hotplug' that support the dynamic addition/
removal of fundamental system resources like CPUs and memory. PowerPC
systems, however, do provide extensive features for the dynamic change
of resources available to a system.
Currently, there is little or no synchronization protection around the
updating of the CPU <-> node mapping, and the export/update of this
information for other layers / modules. In systems which can change
this mapping during 'hotplug', like PowerPC, the information is changing
underneath all layers that might reference it.
This patch attempts to ensure that a valid, usable cpumask attribute
is used by the workqueue infrastructure when setting up new resource
pools. It prevents a crash that has been observed when an 'empty'
cpumask is passed along to the worker/task scheduling code. It is
intended as a temporary workaround until a more fundamental review and
correction of the issue can be done.
[With additions to the patch provided by Tejun Hao <tj@kernel.org>]
Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
5c0338c687 ("workqueue: restore WQ_UNBOUND/max_active==1 to be
ordered") automatically enabled ordered attribute for unbound
workqueues w/ max_active == 1. Because ordered workqueues reject
max_active and some attribute changes, this implicit ordered mode
broke cases where the user creates an unbound workqueue w/ max_active
== 1 and later explicitly changes the related attributes.
This patch distinguishes explicit and implicit ordered setting and
overrides from attribute changes if implict.
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 5c0338c687 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered")
The combination of WQ_UNBOUND and max_active == 1 used to imply
ordered execution. After NUMA affinity 4c16bd327c ("workqueue:
implement NUMA affinity for unbound workqueues"), this is no longer
true due to per-node worker pools.
While the right way to create an ordered workqueue is
alloc_ordered_workqueue(), the documentation has been misleading for a
long time and people do use WQ_UNBOUND and max_active == 1 for ordered
workqueues which can lead to subtle bugs which are very difficult to
trigger.
It's unlikely that we'd see noticeable performance impact by enforcing
ordering on WQ_UNBOUND / max_active == 1 workqueues. Let's
automatically set __WQ_ORDERED for those workqueues.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Christoph Hellwig <hch@infradead.org>
Reported-by: Alexei Potashnik <alexei@purestorage.com>
Fixes: 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues")
Cc: stable@vger.kernel.org # v3.10+
Rename:
wait_queue_t => wait_queue_entry_t
'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue",
but in reality it's a queue *entry*. The 'real' queue is the wait queue head,
which had to carry the name.
Start sorting this out by renaming it to 'wait_queue_entry_t'.
This also allows the real structure name 'struct __wait_queue' to
lose its double underscore and become 'struct wait_queue_entry',
which is the more canonical nomenclature for such data types.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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>
Pull workqueue update from Tejun Heo:
"One trivial patch to use setup_deferrable_timer() instead of
open-coding the initialization"
* 'for-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: use setup_deferrable_timer
work_on_cpu() is not protected against CPU hotplug. For code which requires
to be either executed on an online CPU or to fail if the CPU is not
available the callsite would have to protect against CPU hotplug.
Provide a function which does get/put_online_cpus() around the call to
work_on_cpu() and fails the call with -ENODEV if the target CPU is not
online.
Preparatory patch to convert several racy task affinity manipulations.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Len Brown <lenb@kernel.org>
Link: http://lkml.kernel.org/r/20170412201042.262610721@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Use setup_deferrable_timer() instead of init_timer_deferrable() to
simplify the code.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
If queue_delayed_work() gets called with NULL @wq, the kernel will
oops asynchronuosly on timer expiration which isn't too helpful in
tracking down the offender. This actually happened with smc.
__queue_delayed_work() already does several input sanity checks
synchronously. Add NULL @wq check.
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Link: http://lkml.kernel.org/r/20170227171439.jshx3qplflyrgcv7@codemonkey.org.uk
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently CONFIG_TIMER_STATS exposes process information across namespaces:
kernel/time/timer_list.c print_timer():
SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);
/proc/timer_list:
#11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570
Given that the tracer can give the same information, this patch entirely
removes CONFIG_TIMER_STATS.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: linux-doc@vger.kernel.org
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Xing Gao <xgao01@email.wm.edu>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jessica Frazelle <me@jessfraz.com>
Cc: kernel-hardening@lists.openwall.com
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Michal Marek <mmarek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Cc: Arjan van de Ven <arjan@linux.intel.com>
Link: http://lkml.kernel.org/r/20170208192659.GA32582@beast
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
While splitting up workqueue initialization into two parts,
ac8f73400782 ("workqueue: make workqueue available early during boot")
put wq_numa_init() into workqueue_init_early(). Unfortunately, on
some archs including power and arm64, cpu to node mapping isn't yet
established by the time the early init is called leading to incorrect
NUMA initialization and subsequently the following oops due to zero
cpumask on node-specific unbound pools.
Unable to handle kernel paging request for data at address 0x00000038
Faulting instruction address: 0xc0000000000fc0cc
Oops: Kernel access of bad area, sig: 11 [#1]
SMP NR_CPUS=2048 NUMA PowerNV
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.0-compiler_gcc-6.2.0-next-20161005 #94
task: c0000007f5400000 task.stack: c000001ffc084000
NIP: c0000000000fc0cc LR: c0000000000ed928 CTR: c0000000000fbfd0
REGS: c000001ffc087780 TRAP: 0300 Not tainted (4.8.0-compiler_gcc-6.2.0-next-20161005)
MSR: 9000000002009033 <SF,HV,VEC,EE,ME,IR,DR,RI,LE> CR: 48000424 XER: 00000000
CFAR: c0000000000089dc DAR: 0000000000000038 DSISR: 40000000 SOFTE: 0
GPR00: c0000000000ed928 c000001ffc087a00 c000000000e63200 c000000010d6d600
GPR04: c0000007f5409200 0000000000000021 000000000748e08c 000000000000001f
GPR08: 0000000000000000 0000000000000021 000000000748f1f8 0000000000000000
GPR12: 0000000028000422 c00000000fb80000 c00000000000e0c8 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000021 0000000000000001
GPR20: ffffffffafb50401 0000000000000000 c000000010d6d600 000000000000ba7e
GPR24: 000000000000ba7e c000000000d8bc58 afb504000afb5041 0000000000000001
GPR28: 0000000000000000 0000000000000004 c0000007f5409280 0000000000000000
NIP [c0000000000fc0cc] enqueue_task_fair+0xfc/0x18b0
LR [c0000000000ed928] activate_task+0x78/0xe0
Call Trace:
[c000001ffc087a00] [c0000007f5409200] 0xc0000007f5409200 (unreliable)
[c000001ffc087b10] [c0000000000ed928] activate_task+0x78/0xe0
[c000001ffc087b50] [c0000000000ede58] ttwu_do_activate+0x68/0xc0
[c000001ffc087b90] [c0000000000ef1b8] try_to_wake_up+0x208/0x4f0
[c000001ffc087c10] [c0000000000d3484] create_worker+0x144/0x250
[c000001ffc087cb0] [c000000000cd72d0] workqueue_init+0x124/0x150
[c000001ffc087d00] [c000000000cc0e74] kernel_init_freeable+0x158/0x360
[c000001ffc087dc0] [c00000000000e0e4] kernel_init+0x24/0x160
[c000001ffc087e30] [c00000000000bfa0] ret_from_kernel_thread+0x5c/0xbc
Instruction dump:
62940401 3b800000 3aa00000 7f17c378 3a600001 3b600001 60000000 60000000
60420000 72490021 ebfe0150 2f890001 <ebbf0038> 419e0de0 7fbee840 419e0e58
---[ end trace 0000000000000000 ]---
Fix it by moving wq_numa_init() to workqueue_init(). As this means
that the early intialization may not have full NUMA info for per-cpu
pools and ignores NUMA affinity for unbound pools, fix them up from
workqueue_init() after wq_numa_init().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Link: http://lkml.kernel.org/r/87twck5wqo.fsf@concordia.ellerman.id.au
Fixes: ac8f73400782 ("workqueue: make workqueue available early during boot")
Signed-off-by: Tejun Heo <tj@kernel.org>
Patch series "kthread: Kthread worker API improvements"
The intention of this patchset is to make it easier to manipulate and
maintain kthreads. Especially, I want to replace all the custom main
cycles with a generic one. Also I want to make the kthreads sleep in a
consistent state in a common place when there is no work.
This patch (of 11):
A good practice is to prefix the names of functions by the name of the
subsystem.
This patch fixes the name of probe_kthread_data(). The other wrong
functions names are part of the kthread worker API and will be fixed
separately.
Link: http://lkml.kernel.org/r/1470754545-17632-2-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Workqueue is currently initialized in an early init call; however,
there are cases where early boot code has to be split and reordered to
come after workqueue initialization or the same code path which makes
use of workqueues is used both before workqueue initailization and
after. The latter cases have to gate workqueue usages with
keventd_up() tests, which is nasty and easy to get wrong.
Workqueue usages have become widespread and it'd be a lot more
convenient if it can be used very early from boot. This patch splits
workqueue initialization into two steps. workqueue_init_early() which
sets up the basic data structures so that workqueues can be created
and work items queued, and workqueue_init() which actually brings up
workqueues online and starts executing queued work items. The former
step can be done very early during boot once memory allocation,
cpumasks and idr are initialized. The latter right after kthreads
become available.
This allows work item queueing and canceling from very early boot
which is what most of these use cases want.
* As systemd_wq being initialized doesn't indicate that workqueue is
fully online anymore, update keventd_up() to test wq_online instead.
The follow-up patches will get rid of all its usages and the
function itself.
* Flushing doesn't make sense before workqueue is fully initialized.
The flush functions trigger WARN and return immediately before fully
online.
* Work items are never in-flight before fully online. Canceling can
always succeed by skipping the flush step.
* Some code paths can no longer assume to be called with irq enabled
as irq is disabled during early boot. Use irqsave/restore
operations instead.
v2: Watchdog init, which requires timer to be running, moved from
workqueue_init_early() to workqueue_init().
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/CA+55aFx0vPuMuxn00rBSM192n-Du5uxy+4AvKa0SBSOVJeuCGg@mail.gmail.com
destroy_workqueue() performs a number of sanity checks to ensure that
the workqueue is empty before proceeding with destruction. However,
it's not always easy to tell what's going on just from the warning
message. Let's dump workqueue state after sanity check failures to
help debugging.
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/CACT4Y+Zs6vkjHo9qHb4TrEiz3S4+quvvVQ9VWvj2Mx6pETGb9Q@mail.gmail.com
Cc: Dmitry Vyukov <dvyukov@google.com>
Pull smp hotplug updates from Thomas Gleixner:
"This is the next part of the hotplug rework.
- Convert all notifiers with a priority assigned
- Convert all CPU_STARTING/DYING notifiers
The final removal of the STARTING/DYING infrastructure will happen
when the merge window closes.
Another 700 hundred line of unpenetrable maze gone :)"
* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits)
timers/core: Correct callback order during CPU hot plug
leds/trigger/cpu: Move from CPU_STARTING to ONLINE level
powerpc/numa: Convert to hotplug state machine
arm/perf: Fix hotplug state machine conversion
irqchip/armada: Avoid unused function warnings
ARC/time: Convert to hotplug state machine
clocksource/atlas7: Convert to hotplug state machine
clocksource/armada-370-xp: Convert to hotplug state machine
clocksource/exynos_mct: Convert to hotplug state machine
clocksource/arm_global_timer: Convert to hotplug state machine
rcu: Convert rcutree to hotplug state machine
KVM/arm/arm64/vgic-new: Convert to hotplug state machine
smp/cfd: Convert core to hotplug state machine
x86/x2apic: Convert to CPU hotplug state machine
profile: Convert to hotplug state machine
timers/core: Convert to hotplug state machine
hrtimer: Convert to hotplug state machine
x86/tboot: Convert to hotplug state machine
arm64/armv8 deprecated: Convert to hotplug state machine
hwtracing/coresight-etm4x: Convert to hotplug state machine
...
* pm-sleep:
PM / hibernate: Introduce test_resume mode for hibernation
x86 / hibernate: Use hlt_play_dead() when resuming from hibernation
PM / hibernate: Image data protection during restoration
PM / hibernate: Add missing braces in __register_nosave_region()
PM / hibernate: Clean up comments in snapshot.c
PM / hibernate: Clean up function headers in snapshot.c
PM / hibernate: Add missing braces in hibernate_setup()
PM / hibernate: Recycle safe pages after image restoration
PM / hibernate: Simplify mark_unsafe_pages()
PM / hibernate: Do not free preallocated safe pages during image restore
PM / suspend: show workqueue state in suspend flow
PM / sleep: make PM notifiers called symmetrically
PM / sleep: Make pm_prepare_console() return void
PM / Hibernate: Don't let kasan instrument snapshot.c
* pm-tools:
PM / tools: scripts: AnalyzeSuspend v4.2
tools/turbostat: allow user to alter DESTDIR and PREFIX
Get rid of the prio ordering of the separate notifiers and use a proper state
callback pair.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153335.197083890@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If freezable workqueue aborts suspend flow, show
workqueue state for debug purpose.
Signed-off-by: Roger Lu <roger.lu@mediatek.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
With commit e9d867a67f ("sched: Allow per-cpu kernel threads to
run on online && !active"), __set_cpus_allowed_ptr() expects that only
strict per-cpu kernel threads can have affinity to an online CPU which
is not yet active.
This assumption is currently broken in the CPU_ONLINE notification
handler for the workqueues where restore_unbound_workers_cpumask()
calls set_cpus_allowed_ptr() when the first cpu in the unbound
worker's pool->attr->cpumask comes online. Since
set_cpus_allowed_ptr() is called with pool->attr->cpumask in which
only one CPU is online which is not yet active, we get the following
WARN_ON during an CPU online operation.
------------[ cut here ]------------
WARNING: CPU: 40 PID: 248 at kernel/sched/core.c:1166
__set_cpus_allowed_ptr+0x228/0x2e0
Modules linked in:
CPU: 40 PID: 248 Comm: cpuhp/40 Not tainted 4.6.0-autotest+ #4
<..snip..>
Call Trace:
[c000000f273ff920] [c00000000010493c] __set_cpus_allowed_ptr+0x2cc/0x2e0 (unreliable)
[c000000f273ffac0] [c0000000000ed4b0] workqueue_cpu_up_callback+0x2c0/0x470
[c000000f273ffb70] [c0000000000f5c58] notifier_call_chain+0x98/0x100
[c000000f273ffbc0] [c0000000000c5ed0] __cpu_notify+0x70/0xe0
[c000000f273ffc00] [c0000000000c6028] notify_online+0x38/0x50
[c000000f273ffc30] [c0000000000c5214] cpuhp_invoke_callback+0x84/0x250
[c000000f273ffc90] [c0000000000c562c] cpuhp_up_callbacks+0x5c/0x120
[c000000f273ffce0] [c0000000000c64d4] cpuhp_thread_fun+0x184/0x1c0
[c000000f273ffd20] [c0000000000fa050] smpboot_thread_fn+0x290/0x2a0
[c000000f273ffd80] [c0000000000f45b0] kthread+0x110/0x130
[c000000f273ffe30] [c000000000009570] ret_from_kernel_thread+0x5c/0x6c
---[ end trace 00f1456578b2a3b2 ]---
This patch fixes this by limiting the mask to the intersection of
the pool affinity and online CPUs.
Changelog-cribbed-from: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.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>
Update the return type to use bool instead of int, corresponding to
change (debugobjects: make fixup functions return bool instead of int)
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>
Pull workqueue fix from Tejun Heo:
"CPU hotplug callbacks can invoke DOWN_FAILED w/o preceding
DOWN_PREPARE which can trigger a WARN_ON() in workqueue.
The bug has been there for a very long time. It only triggers if CPU
down fails at a specific point and I don't think it has adverse
effects other than the warning messages. The fix is very low impact"
* 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: fix rebind bound workers warning
------------[ cut here ]------------
WARNING: CPU: 0 PID: 16 at kernel/workqueue.c:4559 rebind_workers+0x1c0/0x1d0
Modules linked in:
CPU: 0 PID: 16 Comm: cpuhp/0 Not tainted 4.6.0-rc4+ #31
Hardware name: IBM IBM System x3550 M4 Server -[7914IUW]-/00Y8603, BIOS -[D7E128FUS-1.40]- 07/23/2013
0000000000000000 ffff881037babb58 ffffffff8139d885 0000000000000010
0000000000000000 0000000000000000 0000000000000000 ffff881037babba8
ffffffff8108505d ffff881037ba0000 000011cf3e7d6e60 0000000000000046
Call Trace:
dump_stack+0x89/0xd4
__warn+0xfd/0x120
warn_slowpath_null+0x1d/0x20
rebind_workers+0x1c0/0x1d0
workqueue_cpu_up_callback+0xf5/0x1d0
notifier_call_chain+0x64/0x90
? trace_hardirqs_on_caller+0xf2/0x220
? notify_prepare+0x80/0x80
__raw_notifier_call_chain+0xe/0x10
__cpu_notify+0x35/0x50
notify_down_prepare+0x5e/0x80
? notify_prepare+0x80/0x80
cpuhp_invoke_callback+0x73/0x330
? __schedule+0x33e/0x8a0
cpuhp_down_callbacks+0x51/0xc0
cpuhp_thread_fun+0xc1/0xf0
smpboot_thread_fn+0x159/0x2a0
? smpboot_create_threads+0x80/0x80
kthread+0xef/0x110
? wait_for_completion+0xf0/0x120
? schedule_tail+0x35/0xf0
ret_from_fork+0x22/0x50
? __init_kthread_worker+0x70/0x70
---[ end trace eb12ae47d2382d8f ]---
notify_down_prepare: attempt to take down CPU 0 failed
This bug can be reproduced by below config w/ nohz_full= all cpus:
CONFIG_BOOTPARAM_HOTPLUG_CPU0=y
CONFIG_DEBUG_HOTPLUG_CPU0=y
CONFIG_NO_HZ_FULL=y
As Thomas pointed out:
| If a down prepare callback fails, then DOWN_FAILED is invoked for all
| callbacks which have successfully executed DOWN_PREPARE.
|
| But, workqueue has actually two notifiers. One which handles
| UP/DOWN_FAILED/ONLINE and one which handles DOWN_PREPARE.
|
| Now look at the priorities of those callbacks:
|
| CPU_PRI_WORKQUEUE_UP = 5
| CPU_PRI_WORKQUEUE_DOWN = -5
|
| So the call order on DOWN_PREPARE is:
|
| CB 1
| CB ...
| CB workqueue_up() -> Ignores DOWN_PREPARE
| CB ...
| CB X ---> Fails
|
| So we call up to CB X with DOWN_FAILED
|
| CB 1
| CB ...
| CB workqueue_up() -> Handles DOWN_FAILED
| CB ...
| CB X-1
|
| So the problem is that the workqueue stuff handles DOWN_FAILED in the up
| callback, while it should do it in the down callback. Which is not a good idea
| either because it wants to be called early on rollback...
|
| Brilliant stuff, isn't it? The hotplug rework will solve this problem because
| the callbacks become symetric, but for the existing mess, we need some
| workaround in the workqueue code.
The boot CPU handles housekeeping duty(unbound timers, workqueues,
timekeeping, ...) on behalf of full dynticks CPUs. It must remain
online when nohz full is enabled. There is a priority set to every
notifier_blocks:
workqueue_cpu_up > tick_nohz_cpu_down > workqueue_cpu_down
So tick_nohz_cpu_down callback failed when down prepare cpu 0, and
notifier_blocks behind tick_nohz_cpu_down will not be called any
more, which leads to workers are actually not unbound. Then hotplug
state machine will fallback to undo and online cpu 0 again. Workers
will be rebound unconditionally even if they are not unbound and
trigger the warning in this progress.
This patch fix it by catching !DISASSOCIATED to avoid rebind bound
workers.
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: stable@vger.kernel.org
Suggested-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Pull workqueue fix from Tejun Heo:
"So, it turns out we had a silly bug in the most fundamental part of
workqueue for a very long time. AFAICS, this dates back to pre-git
era and has quite likely been there from the time workqueue was first
introduced.
A work item uses its PENDING bit to synchronize multiple queuers.
Anyone who wins the PENDING bit owns the pending state of the work
item. Whether a queuer wins or loses the race, one thing should be
guaranteed - there will soon be at least one execution of the work
item - where "after" means that the execution instance would be able
to see all the changes that the queuer has made prior to the queueing
attempt.
Unfortunately, we were missing a smp_mb() after clearing PENDING for
execution, so nothing guaranteed visibility of the changes that a
queueing loser has made, which manifested as a reproducible blk-mq
stall.
Lots of kudos to Roman for debugging the problem. The patch for
-stable is the minimal one. For v3.7, Peter is working on a patch to
make the code path slightly more efficient and less fragile"
* 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: fix ghost PENDING flag while doing MQ IO
The bug in a workqueue leads to a stalled IO request in MQ ctx->rq_list
with the following backtrace:
[ 601.347452] INFO: task kworker/u129:5:1636 blocked for more than 120 seconds.
[ 601.347574] Tainted: G O 4.4.5-1-storage+ #6
[ 601.347651] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 601.348142] kworker/u129:5 D ffff880803077988 0 1636 2 0x00000000
[ 601.348519] Workqueue: ibnbd_server_fileio_wq ibnbd_dev_file_submit_io_worker [ibnbd_server]
[ 601.348999] ffff880803077988 ffff88080466b900 ffff8808033f9c80 ffff880803078000
[ 601.349662] ffff880807c95000 7fffffffffffffff ffffffff815b0920 ffff880803077ad0
[ 601.350333] ffff8808030779a0 ffffffff815b01d5 0000000000000000 ffff880803077a38
[ 601.350965] Call Trace:
[ 601.351203] [<ffffffff815b0920>] ? bit_wait+0x60/0x60
[ 601.351444] [<ffffffff815b01d5>] schedule+0x35/0x80
[ 601.351709] [<ffffffff815b2dd2>] schedule_timeout+0x192/0x230
[ 601.351958] [<ffffffff812d43f7>] ? blk_flush_plug_list+0xc7/0x220
[ 601.352208] [<ffffffff810bd737>] ? ktime_get+0x37/0xa0
[ 601.352446] [<ffffffff815b0920>] ? bit_wait+0x60/0x60
[ 601.352688] [<ffffffff815af784>] io_schedule_timeout+0xa4/0x110
[ 601.352951] [<ffffffff815b3a4e>] ? _raw_spin_unlock_irqrestore+0xe/0x10
[ 601.353196] [<ffffffff815b093b>] bit_wait_io+0x1b/0x70
[ 601.353440] [<ffffffff815b056d>] __wait_on_bit+0x5d/0x90
[ 601.353689] [<ffffffff81127bd0>] wait_on_page_bit+0xc0/0xd0
[ 601.353958] [<ffffffff81096db0>] ? autoremove_wake_function+0x40/0x40
[ 601.354200] [<ffffffff81127cc4>] __filemap_fdatawait_range+0xe4/0x140
[ 601.354441] [<ffffffff81127d34>] filemap_fdatawait_range+0x14/0x30
[ 601.354688] [<ffffffff81129a9f>] filemap_write_and_wait_range+0x3f/0x70
[ 601.354932] [<ffffffff811ced3b>] blkdev_fsync+0x1b/0x50
[ 601.355193] [<ffffffff811c82d9>] vfs_fsync_range+0x49/0xa0
[ 601.355432] [<ffffffff811cf45a>] blkdev_write_iter+0xca/0x100
[ 601.355679] [<ffffffff81197b1a>] __vfs_write+0xaa/0xe0
[ 601.355925] [<ffffffff81198379>] vfs_write+0xa9/0x1a0
[ 601.356164] [<ffffffff811c59d8>] kernel_write+0x38/0x50
The underlying device is a null_blk, with default parameters:
queue_mode = MQ
submit_queues = 1
Verification that nullb0 has something inflight:
root@pserver8:~# cat /sys/block/nullb0/inflight
0 1
root@pserver8:~# find /sys/block/nullb0/mq/0/cpu* -name rq_list -print -exec cat {} \;
...
/sys/block/nullb0/mq/0/cpu2/rq_list
CTX pending:
ffff8838038e2400
...
During debug it became clear that stalled request is always inserted in
the rq_list from the following path:
save_stack_trace_tsk + 34
blk_mq_insert_requests + 231
blk_mq_flush_plug_list + 281
blk_flush_plug_list + 199
wait_on_page_bit + 192
__filemap_fdatawait_range + 228
filemap_fdatawait_range + 20
filemap_write_and_wait_range + 63
blkdev_fsync + 27
vfs_fsync_range + 73
blkdev_write_iter + 202
__vfs_write + 170
vfs_write + 169
kernel_write + 56
So blk_flush_plug_list() was called with from_schedule == true.
If from_schedule is true, that means that finally blk_mq_insert_requests()
offloads execution of __blk_mq_run_hw_queue() and uses kblockd workqueue,
i.e. it calls kblockd_schedule_delayed_work_on().
That means, that we race with another CPU, which is about to execute
__blk_mq_run_hw_queue() work.
Further debugging shows the following traces from different CPUs:
CPU#0 CPU#1
---------------------------------- -------------------------------
reqeust A inserted
STORE hctx->ctx_map[0] bit marked
kblockd_schedule...() returns 1
<schedule to kblockd workqueue>
request B inserted
STORE hctx->ctx_map[1] bit marked
kblockd_schedule...() returns 0
*** WORK PENDING bit is cleared ***
flush_busy_ctxs() is executed, but
bit 1, set by CPU#1, is not observed
As a result request B pended forever.
This behaviour can be explained by speculative LOAD of hctx->ctx_map on
CPU#0, which is reordered with clear of PENDING bit and executed _before_
actual STORE of bit 1 on CPU#1.
The proper fix is an explicit full barrier <mfence>, which guarantees
that clear of PENDING bit is to be executed before all possible
speculative LOADS or STORES inside actual work function.
Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com>
Cc: Gioh Kim <gi-oh.kim@profitbricks.com>
Cc: Michael Wang <yun.wang@profitbricks.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull workqueue updates from Tejun Heo:
"Three trivial workqueue changes"
* 'for-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Fix comment for work_on_cpu()
sched/core: Get rid of 'cpu' argument in wq_worker_sleeping()
workqueue: Replace usage of init_name with dev_set_name()
$ make tags
GEN tags
ctags: Warning: drivers/acpi/processor_idle.c:64: null expansion of name pattern "\1"
ctags: Warning: drivers/xen/events/events_2l.c:41: null expansion of name pattern "\1"
ctags: Warning: kernel/locking/lockdep.c:151: null expansion of name pattern "\1"
ctags: Warning: kernel/rcu/rcutorture.c:133: null expansion of name pattern "\1"
ctags: Warning: kernel/rcu/rcutorture.c:135: null expansion of name pattern "\1"
ctags: Warning: kernel/workqueue.c:323: null expansion of name pattern "\1"
ctags: Warning: net/ipv4/syncookies.c:53: null expansion of name pattern "\1"
ctags: Warning: net/ipv6/syncookies.c:44: null expansion of name pattern "\1"
ctags: Warning: net/rds/page.c:45: null expansion of name pattern "\1"
Which are all the result of the DEFINE_PER_CPU pattern:
scripts/tags.sh:200: '/\<DEFINE_PER_CPU([^,]*, *\([[:alnum:]_]*\)/\1/v/'
scripts/tags.sh:201: '/\<DEFINE_PER_CPU_SHARED_ALIGNED([^,]*, *\([[:alnum:]_]*\)/\1/v/'
The below cures them. All except the workqueue one are within reasonable
distance of the 80 char limit. TJ do you have any preference on how to
fix the wq one, or shall we just not care its too long?
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Function is processed in thread context, not in user context.
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
Given that wq_worker_sleeping() could only be called for a
CPU it is running on, we do not need passing a CPU ID as an
argument.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The init_name property of the device struct is sort of a hack and should
only be used for statically allocated devices. Since the device is
dynamically allocated here it is safe to use the proper way to set a
devices name by calling dev_set_name().
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
When looking up the pool_workqueue to use for an unbound workqueue,
workqueue assumes that the target CPU is always bound to a valid NUMA
node. However, currently, when a CPU goes offline, the mapping is
destroyed and cpu_to_node() returns NUMA_NO_NODE.
This has always been broken but hasn't triggered often enough before
874bbfe600 ("workqueue: make sure delayed work run in local cpu").
After the commit, workqueue forcifully assigns the local CPU for
delayed work items without explicit target CPU to fix a different
issue. This widens the window where CPU can go offline while a
delayed work item is pending causing delayed work items dispatched
with target CPU set to an already offlined CPU. The resulting
NUMA_NO_NODE mapping makes workqueue try to queue the work item on a
NULL pool_workqueue and thus crash.
While 874bbfe600 has been reverted for a different reason making the
bug less visible again, it can still happen. Fix it by mapping
NUMA_NO_NODE to the default pool_workqueue from unbound_pwq_by_node().
This is a temporary workaround. The long term solution is keeping CPU
-> NODE mapping stable across CPU off/online cycles which is being
worked on.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/g/1454424264.11183.46.camel@gmail.com
Link: http://lkml.kernel.org/g/1453702100-2597-1-git-send-email-tangchen@cn.fujitsu.com
