Mostly changes from Petr to improve warning and error reporting. Workqueue
now reports more of the relevant failures with better context which should
help debugging.
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Merge tag 'wq-for-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue updates from Tejun Heo:
"Mostly changes from Petr to improve warning and error reporting.
Workqueue now reports more of the relevant failures with better
context which should help debugging"
* tag 'wq-for-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Introduce show_freezable_workqueues
workqueue: Print backtraces from CPUs with hung CPU bound workqueues
workqueue: Warn when a rescuer could not be created
workqueue: Interrupted create_worker() is not a repeated event
workqueue: Warn when a new worker could not be created
workqueue: Fix hung time report of worker pools
workqueue: Simplify a pr_warn() call in wq_select_unbound_cpu()
MAINTAINERS: Add workqueue_internal.h to the WORKQUEUE entry
Currently show_all_workqueue is called if freeze fails at the time of
freeze the workqueues, which shows the status of all workqueues and of
all worker pools. In this cases we may only need to dump state of only
workqueues that are freezable and busy.
This patch defines show_freezable_workqueues, which uses
show_one_workqueue, a granular function that shows the state of individual
workqueues, so that dump only the state of freezable workqueues
at that time.
tj: Minor message adjustment.
Signed-off-by: Jungseung Lee <js07.lee@samsung.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The workqueue watchdog reports a lockup when there was not any progress
in the worker pool for a long time. The progress means that a pending
work item starts being proceed.
Worker pools for unbound workqueues always wake up an idle worker and
try to process the work immediately. The last idle worker has to create
new worker first. The stall might happen only when a new worker could
not be created in which case an error should get printed. Another problem
might be too high load. In this case, workers are victims of a global
system problem.
Worker pools for CPU bound workqueues are designed for lightweight
work items that do not need much CPU time. They are proceed one by
one on a single worker. New worker is used only when a work is sleeping.
It creates one additional scenario. The stall might happen when
the CPU-bound workqueue is used for CPU-intensive work.
More precisely, the stall is detected when a CPU-bound worker is in
the TASK_RUNNING state for too long. In this case, it might be useful
to see the backtrace from the problematic worker.
The information how long a worker is in the running state is not available.
But the CPU-bound worker pools do not have many workers in the running
state by definition. And only few pools are typically blocked.
It should be acceptable to print backtraces from all workers in
TASK_RUNNING state in the stalled worker pools. The number of false
positives should be very low.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Rescuers are created when a workqueue with WQ_MEM_RECLAIM is allocated.
It typically happens during the system boot.
systemd switches the root filesystem from initrd to the booted system
during boot. It kills processes that block the switch for too long.
One of the process might be modprobe that tries to create a workqueue.
These problems are hard to reproduce. Also alloc_workqueue() does not
pass the error code. Make the debugging easier by printing an error,
similar to create_worker().
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
kthread_create_on_node() might get interrupted(). It is rare but realistic.
For example, when an unbound workqueue is allocated in module_init()
callback. It is done in the context of the "modprobe" process. And,
for example, systemd might kill pending processes when switching root
from initrd to the booted system.
The interrupt is a one-off event and the race might be hard to reproduce.
It is always worth printing.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The workqueue watchdog reports a lockup when there was not any progress
in the worker pool for a long time. The progress means that a pending
work item starts being proceed.
The progress is guaranteed by using idle workers or creating new workers
for pending work items.
There are several reasons why a new worker could not be created:
+ there is not enough memory
+ there is no free pool ID (IDR API)
+ the system reached PID limit
+ the process creating the new worker was interrupted
+ the last idle worker (manager) has not been scheduled for a long
time. It was not able to even start creating the kthread.
None of these failures is reported at the moment. The only clue is that
show_one_worker_pool() prints that there is a manager. It is the last
idle worker that is responsible for creating a new one. But it is not
clear if create_worker() is failing and why.
Make the debugging easier by printing errors in create_worker().
The error code is important, especially from kthread_create_on_node().
It helps to distinguish the various reasons. For example, reaching
memory limit (-ENOMEM), other system limits (-EAGAIN), or process
interrupted (-EINTR).
Use pr_once() to avoid repeating the same error every CREATE_COOLDOWN
for each stuck worker pool.
Ratelimited printk() might be better. It would help to know if the problem
remains. It would be more clear if the create_worker() errors and workqueue
stalls are related. Also old messages might get lost when the internal log
buffer is full. The problem is that printk() might touch the watchdog.
For example, see touch_nmi_watchdog() in serial8250_console_write().
It would require synchronization of the begin and length of the ratelimit
interval with the workqueue watchdog. Otherwise, the error messages
might break the watchdog. This does not look worth the complexity.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The workqueue watchdog prints a warning when there is no progress in
a worker pool. Where the progress means that the pool started processing
a pending work item.
Note that it is perfectly fine to process work items much longer.
The progress should be guaranteed by waking up or creating idle
workers.
show_one_worker_pool() prints state of non-idle worker pool. It shows
a delay since the last pool->watchdog_ts.
The timestamp is updated when a first pending work is queued in
__queue_work(). Also it is updated when a work is dequeued for
processing in worker_thread() and rescuer_thread().
The delay is misleading when there is no pending work item. In this
case it shows how long the last work item is being proceed. Show
zero instead. There is no stall if there is no pending work.
Fixes: 82607adcf9 ("workqueue: implement lockup detector")
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Use pr_warn_once() to achieve the same thing. It's simpler.
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Direct access to the struct bus_type dev_root pointer is going away soon
so replace that with a call to bus_get_dev_root() instead, which is what
it is there for.
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230313182918.1312597-8-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
!CONFIG_SMP builds complain about rebind_worker() being unused. Its only
user, rebind_workers() is indeed only defined for CONFIG_SMP, so just fold
the two lines back up there.
Link: http://lore.kernel.org/r/20230113143102.2e94d74f@canb.auug.org.au
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
It has been reported that isolated CPUs can suffer from interference due to
per-CPU kworkers waking up just to die.
A surge of workqueue activity during initial setup of a latency-sensitive
application (refresh_vm_stats() being one of the culprits) can cause extra
per-CPU kworkers to be spawned. Then, said latency-sensitive task can be
running merrily on an isolated CPU only to be interrupted sometime later by
a kworker marked for death (cf. IDLE_WORKER_TIMEOUT, 5 minutes after last
kworker activity).
Prevent this by affining kworkers to the wq_unbound_cpumask (which doesn't
contain isolated CPUs, cf. HK_TYPE_WQ) before waking them up after marking
them with WORKER_DIE.
Changing the affinity does require a sleepable context, leverage the newly
introduced pool->idle_cull_work to get that.
Remove dying workers from pool->workers and keep track of them in a
separate list. This intentionally prevents for_each_loop_worker() from
iterating over workers that are marked for death.
Rename destroy_worker() to set_working_dying() to better reflect its
effects and relationship with wake_dying_workers().
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
put_unbound_pool() currently passes wq_manager_inactive() as exit condition
to rcuwait_wait_event(), which grabs pool->lock to check for
pool->flags & POOL_MANAGER_ACTIVE
A later patch will require destroy_worker() to be invoked with
wq_pool_attach_mutex held, which needs to be acquired before
pool->lock. A mutex cannot be acquired within rcuwait_wait_event(), as
it could clobber the task state set by rcuwait_wait_event()
Instead, restructure the waiting logic to acquire any necessary lock
outside of rcuwait_wait_event().
Since further work cannot be inserted into unbound pwqs that have reached
->refcnt==0, this is bound to make forward progress as eventually the
worklist will be drained and need_more_worker(pool) will remain false,
preventing any worker from stealing the manager position from us.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
A later patch will require a sleepable context in the idle worker timeout
function. Converting worker_pool.idle_timer to a delayed_work gives us just
that, however this would imply turning all idle_timer expiries into
scheduler events (waking up a worker to handle the dwork).
Instead, implement a "custom dwork" where the timer callback does some
extra checks before queuing the associated work.
No change in functionality intended.
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Later patches will reuse this code, move it into reusable functions.
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
When unbind_workers() reads wq_unbound_cpumask to set the affinity of
freshly-unbound kworkers, it only holds wq_pool_attach_mutex. This isn't
sufficient as wq_unbound_cpumask is only protected by wq_pool_mutex.
Make wq_unbound_cpumask protected with wq_pool_attach_mutex and also
remove the need of temporary saved_cpumask.
Fixes: 10a5a651e3 ("workqueue: Restrict kworker in the offline CPU pool running on housekeeping CPUs")
Reported-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The show_pwq() function dumps out a pool_workqueue structure's activity,
including the pending work-queue handlers:
Showing busy workqueues and worker pools:
workqueue events: flags=0x0
pwq 0: cpus=0 node=0 flags=0x1 nice=0 active=10/256 refcnt=11
in-flight: 7:test_work_func, 64:test_work_func, 249:test_work_func
pending: test_work_func, test_work_func, test_work_func1, test_work_func1, test_work_func1, test_work_func1, test_work_func1
When large systems are facing certain types of hang conditions, it is not
unusual for this "pending" list to contain runs of hundreds of identical
function names. This "wall of text" is difficult to read, and worse yet,
it can be interleaved with other output such as stack traces.
Therefore, make show_pwq() use run-length encoding so that the above
printout instead looks like this:
Showing busy workqueues and worker pools:
workqueue events: flags=0x0
pwq 0: cpus=0 node=0 flags=0x1 nice=0 active=10/256 refcnt=11
in-flight: 7:test_work_func, 64:test_work_func, 249:test_work_func
pending: 2*test_work_func, 5*test_work_func1
When no comma would be printed, including the WORK_STRUCT_LINKED case,
a new run is started unconditionally.
This output is more readable, places less stress on the hardware,
firmware, and software on the console-log path, and reduces interference
with other output.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently if the user queues a new work item unintentionally
into a wq after the destroy_workqueue(wq), the work still can
be queued and scheduled without any noticeable kernel message
before the end of a RCU grace period.
As a debug-aid facility, this commit adds a new flag
__WQ_DESTROYING to spot that issue by triggering a kernel WARN
message.
Signed-off-by: Richard Clark <richard.xnu.clark@gmail.com>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Earlier commits in this series allow battery-powered systems to build
their kernels with the default-disabled CONFIG_RCU_LAZY=y Kconfig option.
This Kconfig option causes call_rcu() to delay its callbacks in order
to batch them. This means that a given RCU grace period covers more
callbacks, thus reducing the number of grace periods, in turn reducing
the amount of energy consumed, which increases battery lifetime which
can be a very good thing. This is not a subtle effect: In some important
use cases, the battery lifetime is increased by more than 10%.
This CONFIG_RCU_LAZY=y option is available only for CPUs that offload
callbacks, for example, CPUs mentioned in the rcu_nocbs kernel boot
parameter passed to kernels built with CONFIG_RCU_NOCB_CPU=y.
Delaying callbacks is normally not a problem because most callbacks do
nothing but free memory. If the system is short on memory, a shrinker
will kick all currently queued lazy callbacks out of their laziness,
thus freeing their memory in short order. Similarly, the rcu_barrier()
function, which blocks until all currently queued callbacks are invoked,
will also kick lazy callbacks, thus enabling rcu_barrier() to complete
in a timely manner.
However, there are some cases where laziness is not a good option.
For example, synchronize_rcu() invokes call_rcu(), and blocks until
the newly queued callback is invoked. It would not be a good for
synchronize_rcu() to block for ten seconds, even on an idle system.
Therefore, synchronize_rcu() invokes call_rcu_hurry() instead of
call_rcu(). The arrival of a non-lazy call_rcu_hurry() callback on a
given CPU kicks any lazy callbacks that might be already queued on that
CPU. After all, if there is going to be a grace period, all callbacks
might as well get full benefit from it.
Yes, this could be done the other way around by creating a
call_rcu_lazy(), but earlier experience with this approach and
feedback at the 2022 Linux Plumbers Conference shifted the approach
to call_rcu() being lazy with call_rcu_hurry() for the few places
where laziness is inappropriate.
And another call_rcu() instance that cannot be lazy is the one
in queue_rcu_work(), given that callers to queue_rcu_work() are
not necessarily OK with long delays.
Therefore, make queue_rcu_work() use call_rcu_hurry() in order to revert
to the old behavior.
[ paulmck: Apply s/call_rcu_flush/call_rcu_hurry/ feedback from Tejun Heo. ]
Signed-off-by: Uladzislau Rezki <urezki@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This replaces the prior support for Clang's standard Control Flow
Integrity (CFI) instrumentation, which has required a lot of special
conditions (e.g. LTO) and work-arounds. The current implementation
("Kernel CFI") is specific to C, directly designed for the Linux kernel,
and takes advantage of architectural features like x86's IBT. This
series retains arm64 support and adds x86 support. Additional "generic"
architectural support is expected soon:
https://github.com/samitolvanen/llvm-project/commits/kcfi_generic
- treewide: Remove old CFI support details
- arm64: Replace Clang CFI support with Clang KCFI support
- x86: Introduce Clang KCFI support
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Merge tag 'kcfi-v6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull kcfi updates from Kees Cook:
"This replaces the prior support for Clang's standard Control Flow
Integrity (CFI) instrumentation, which has required a lot of special
conditions (e.g. LTO) and work-arounds.
The new implementation ("Kernel CFI") is specific to C, directly
designed for the Linux kernel, and takes advantage of architectural
features like x86's IBT. This series retains arm64 support and adds
x86 support.
GCC support is expected in the future[1], and additional "generic"
architectural support is expected soon[2].
Summary:
- treewide: Remove old CFI support details
- arm64: Replace Clang CFI support with Clang KCFI support
- x86: Introduce Clang KCFI support"
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107048 [1]
Link: https://github.com/samitolvanen/llvm-project/commits/kcfi_generic [2]
* tag 'kcfi-v6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (22 commits)
x86: Add support for CONFIG_CFI_CLANG
x86/purgatory: Disable CFI
x86: Add types to indirectly called assembly functions
x86/tools/relocs: Ignore __kcfi_typeid_ relocations
kallsyms: Drop CONFIG_CFI_CLANG workarounds
objtool: Disable CFI warnings
objtool: Preserve special st_shndx indexes in elf_update_symbol
treewide: Drop __cficanonical
treewide: Drop WARN_ON_FUNCTION_MISMATCH
treewide: Drop function_nocfi
init: Drop __nocfi from __init
arm64: Drop unneeded __nocfi attributes
arm64: Add CFI error handling
arm64: Add types to indirect called assembly functions
psci: Fix the function type for psci_initcall_t
lkdtm: Emit an indirect call for CFI tests
cfi: Add type helper macros
cfi: Switch to -fsanitize=kcfi
cfi: Drop __CFI_ADDRESSABLE
cfi: Remove CONFIG_CFI_CLANG_SHADOW
...
CONFIG_CFI_CLANG no longer breaks cross-module function address
equality, which makes WARN_ON_FUNCTION_MISMATCH unnecessary. Remove
the definition and switch back to WARN_ON_ONCE.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220908215504.3686827-15-samitolvanen@google.com
Like Hillf Danton mentioned
syzbot should have been able to catch cancel_work_sync() in work context
by checking lockdep_map in __flush_work() for both flush and cancel.
in [1], being unable to report an obvious deadlock scenario shown below is
broken. From locking dependency perspective, sync version of cancel request
should behave as if flush request, for it waits for completion of work if
that work has already started execution.
----------
#include <linux/module.h>
#include <linux/sched.h>
static DEFINE_MUTEX(mutex);
static void work_fn(struct work_struct *work)
{
schedule_timeout_uninterruptible(HZ / 5);
mutex_lock(&mutex);
mutex_unlock(&mutex);
}
static DECLARE_WORK(work, work_fn);
static int __init test_init(void)
{
schedule_work(&work);
schedule_timeout_uninterruptible(HZ / 10);
mutex_lock(&mutex);
cancel_work_sync(&work);
mutex_unlock(&mutex);
return -EINVAL;
}
module_init(test_init);
MODULE_LICENSE("GPL");
----------
The check this patch restores was added by commit 0976dfc1d0
("workqueue: Catch more locking problems with flush_work()").
Then, lockdep's crossrelease feature was added by commit b09be676e0
("locking/lockdep: Implement the 'crossrelease' feature"). As a result,
this check was once removed by commit fd1a5b04df ("workqueue: Remove
now redundant lock acquisitions wrt. workqueue flushes").
But lockdep's crossrelease feature was removed by commit e966eaeeb6
("locking/lockdep: Remove the cross-release locking checks"). At this
point, this check should have been restored.
Then, commit d6e89786be ("workqueue: skip lockdep wq dependency in
cancel_work_sync()") introduced a boolean flag in order to distinguish
flush_work() and cancel_work_sync(), for checking "struct workqueue_struct"
dependency when called from cancel_work_sync() was causing false positives.
Then, commit 87915adc3f ("workqueue: re-add lockdep dependencies for
flushing") tried to restore "struct work_struct" dependency check, but by
error checked this boolean flag. Like an example shown above indicates,
"struct work_struct" dependency needs to be checked for both flush_work()
and cancel_work_sync().
Link: https://lkml.kernel.org/r/20220504044800.4966-1-hdanton@sina.com [1]
Reported-by: Hillf Danton <hdanton@sina.com>
Suggested-by: Lai Jiangshan <jiangshanlai@gmail.com>
Fixes: 87915adc3f ("workqueue: re-add lockdep dependencies for flushing")
Cc: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Tejun Heo <tj@kernel.org>
New driver:
- logicvc
vfio:
- use aperture API
core:
- of: Add data-lane helpers and convert drivers
- connector: Remove deprecated ida_simple_get()
media:
- Add various RGB666 and RGB888 format constants
panel:
- Add HannStar HSD101PWW
- Add ETML0700Y5DHA
dma-buf:
- add sync-file API
- set dma mask for udmabuf devices
fbcon:
- Improve scrolling performance
- Sanitize input
fbdev:
- device unregistering fixes
- vesa: Support COMPILE_TEST
- Disable firmware-device registration when first native driver loads
aperture:
- fix segfault during hot-unplug
- export for use with other subsystems
client:
- use driver validated modes
dp:
- aux: make probing more reliable
- mst: Read extended DPCD capabilities during system resume
- Support waiting for HDP signal
- Port-validation fixes
edid:
- CEA data-block iterators
- struct drm_edid introduction
- implement HF-EEODB extension
gem:
- don't use fb format non-existing planes
probe-helper:
- use 640x480 as displayport fallback
scheduler:
- don't kill jobs in interrupt context
bridge:
- Add support for i.MX8qxp and i.MX8qm
- lots of fixes/cleanups
- Add TI-DLPC3433
- fy07024di26a30d: Optional GPIO reset
- ldb: Add reg and reg-name properties to bindings, Kconfig fixes
- lt9611: Fix display sensing;
- tc358767: DSI/DPI refactoring and DSI-to-eDP support, DSI lane handling
- tc358775: Fix clock settings
- ti-sn65dsi83: Allow GPIO to sleep
- adv7511: I2C fixes
- anx7625: Fix error handling; DPI fixes; Implement HDP timeout via callback
- fsl-ldb: Drop DE flip
- ti-sn65dsi86: Convert to atomic modesetting
amdgpu:
- use atomic fence helpers in DM
- fix VRAM address calculations
- export CRTC bpc via debugfs
- Initial devcoredump support
- Enable high priority gfx queue on asics which support it
- Adjust GART size on newer APUs for S/G display
- Soft reset for GFX 11 / SDMA 6
- Add gfxoff status query for vangogh
- Fix timestamps for cursor only commits
- Adjust GART size on newer APUs for S/G display
- fix buddy memory corruption
amdkfd:
- MMU notifier fixes
- P2P DMA support using dma-buf
- Add available memory IOCTL
- HMM profiler support
- Simplify GPUVM validation
- Unified memory for CWSR save/restore area
i915:
- General driver clean-up
- DG2 enabling (still under force probe)
- DG2 small BAR memory support
- HuC loading support
- DG2 workarounds
- DG2/ATS-M device IDs added
- Ponte Vecchio prep work and new blitter engines
- add Meteorlake support
- Fix sparse warnings
- DMC MMIO range checks
- Audio related fixes
- Runtime PM fixes
- PSR fixes
- Media freq factor and per-gt enhancements
- DSI fixes for ICL+
- Disable DMC flip queue handlers
- ADL_P voltage swing updates
- Use more the VBT for panel information
- Fix on Type-C ports with TBT mode
- Improve fastset and allow seamless M/N changes
- Accept more fixed modes with VRR/DMRRS panels
- Disable connector polling for a headless SKU
- ADL-S display PLL w/a
- Enable THP on Icelake and beyond
- Fix i915_gem_object_ggtt_pin_ww regression on old platforms
- Expose per tile media freq factor in sysfs
- Fix dma_resv fence handling in multi-batch execbuf
- Improve on suspend / resume time with VT-d enabled
- export CRTC bpc settings via debugfs
msm:
- gpu: a619 support
- gpu: Fix for unclocked GMU register access
- gpu: Devcore dump enhancements
- client utilization via fdinfo support
- fix fence rollover issue
- gem: Lockdep false-positive warning fix
- gem: Switch to pfn mappings
- WB support on sc7180
- dp: dropped custom bulk clock implementation
- fix link retraining on resolution change
- hdmi: dropped obsolete GPIO support
tegra:
- context isolation for host1x engines
- tegra234 soc support
mediatek:
- add vdosys0/1 for mt8195
- add MT8195 dp_intf driver
exynos:
- Fix resume function issue of exynos decon driver by calling
clk_disable_unprepare() properly if clk_prepare_enable() failed.
nouveau:
- set of misc fixes/cleanups
- display cleanups
gma500:
- Cleanup connector I2C handling
hyperv:
- Unify VRAM allocation of Gen1 and Gen2
meson:
- Support YUV422 output; Refcount fixes
mgag200:
- Support damage clipping
- Support gamma handling
- Protect concurrent HW access
- Fixes to connector
- Store model-specific limits in device-info structure
- fix PCI register init
panfrost:
- Valhall support
r128:
- Fix bit-shift overflow
rockchip:
- Locking fixes in error path
ssd130x:
- Fix built-in linkage
udl:
- Always advertize VGA connector
ast:
- Support multiple outputs
- fix black screen on resume
sun4i:
- HDMI PHY cleanups
vc4:
- Add support for BCM2711
vkms:
- Allocate output buffer with vmalloc()
mcde:
- Fix ref-count leak
mxsfb/lcdif:
- Support i.MX8MP LCD controller
stm/ltdc:
- Support dynamic Z order
- Support mirroring
ingenic:
- Fix display at maximum resolution
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Merge tag 'drm-next-2022-08-03' of git://anongit.freedesktop.org/drm/drm
Pull drm updates from Dave Airlie:
"Highlights:
- New driver for logicvc - which is a display IP core.
- EDID parser rework to add new extensions
- fbcon scrolling improvements
- i915 has some more DG2 work but not enabled by default, but should
have enough features for userspace to work now.
Otherwise it's lots of work all over the place. Detailed summary:
New driver:
- logicvc
vfio:
- use aperture API
core:
- of: Add data-lane helpers and convert drivers
- connector: Remove deprecated ida_simple_get()
media:
- Add various RGB666 and RGB888 format constants
panel:
- Add HannStar HSD101PWW
- Add ETML0700Y5DHA
dma-buf:
- add sync-file API
- set dma mask for udmabuf devices
fbcon:
- Improve scrolling performance
- Sanitize input
fbdev:
- device unregistering fixes
- vesa: Support COMPILE_TEST
- Disable firmware-device registration when first native driver loads
aperture:
- fix segfault during hot-unplug
- export for use with other subsystems
client:
- use driver validated modes
dp:
- aux: make probing more reliable
- mst: Read extended DPCD capabilities during system resume
- Support waiting for HDP signal
- Port-validation fixes
edid:
- CEA data-block iterators
- struct drm_edid introduction
- implement HF-EEODB extension
gem:
- don't use fb format non-existing planes
probe-helper:
- use 640x480 as displayport fallback
scheduler:
- don't kill jobs in interrupt context
bridge:
- Add support for i.MX8qxp and i.MX8qm
- lots of fixes/cleanups
- Add TI-DLPC3433
- fy07024di26a30d: Optional GPIO reset
- ldb: Add reg and reg-name properties to bindings, Kconfig fixes
- lt9611: Fix display sensing;
- tc358767: DSI/DPI refactoring and DSI-to-eDP support, DSI lane handling
- tc358775: Fix clock settings
- ti-sn65dsi83: Allow GPIO to sleep
- adv7511: I2C fixes
- anx7625: Fix error handling; DPI fixes; Implement HDP timeout via callback
- fsl-ldb: Drop DE flip
- ti-sn65dsi86: Convert to atomic modesetting
amdgpu:
- use atomic fence helpers in DM
- fix VRAM address calculations
- export CRTC bpc via debugfs
- Initial devcoredump support
- Enable high priority gfx queue on asics which support it
- Adjust GART size on newer APUs for S/G display
- Soft reset for GFX 11 / SDMA 6
- Add gfxoff status query for vangogh
- Fix timestamps for cursor only commits
- Adjust GART size on newer APUs for S/G display
- fix buddy memory corruption
amdkfd:
- MMU notifier fixes
- P2P DMA support using dma-buf
- Add available memory IOCTL
- HMM profiler support
- Simplify GPUVM validation
- Unified memory for CWSR save/restore area
i915:
- General driver clean-up
- DG2 enabling (still under force probe)
- DG2 small BAR memory support
- HuC loading support
- DG2 workarounds
- DG2/ATS-M device IDs added
- Ponte Vecchio prep work and new blitter engines
- add Meteorlake support
- Fix sparse warnings
- DMC MMIO range checks
- Audio related fixes
- Runtime PM fixes
- PSR fixes
- Media freq factor and per-gt enhancements
- DSI fixes for ICL+
- Disable DMC flip queue handlers
- ADL_P voltage swing updates
- Use more the VBT for panel information
- Fix on Type-C ports with TBT mode
- Improve fastset and allow seamless M/N changes
- Accept more fixed modes with VRR/DMRRS panels
- Disable connector polling for a headless SKU
- ADL-S display PLL w/a
- Enable THP on Icelake and beyond
- Fix i915_gem_object_ggtt_pin_ww regression on old platforms
- Expose per tile media freq factor in sysfs
- Fix dma_resv fence handling in multi-batch execbuf
- Improve on suspend / resume time with VT-d enabled
- export CRTC bpc settings via debugfs
msm:
- gpu: a619 support
- gpu: Fix for unclocked GMU register access
- gpu: Devcore dump enhancements
- client utilization via fdinfo support
- fix fence rollover issue
- gem: Lockdep false-positive warning fix
- gem: Switch to pfn mappings
- WB support on sc7180
- dp: dropped custom bulk clock implementation
- fix link retraining on resolution change
- hdmi: dropped obsolete GPIO support
tegra:
- context isolation for host1x engines
- tegra234 soc support
mediatek:
- add vdosys0/1 for mt8195
- add MT8195 dp_intf driver
exynos:
- Fix resume function issue of exynos decon driver by calling
clk_disable_unprepare() properly if clk_prepare_enable() failed.
nouveau:
- set of misc fixes/cleanups
- display cleanups
gma500:
- Cleanup connector I2C handling
hyperv:
- Unify VRAM allocation of Gen1 and Gen2
meson:
- Support YUV422 output; Refcount fixes
mgag200:
- Support damage clipping
- Support gamma handling
- Protect concurrent HW access
- Fixes to connector
- Store model-specific limits in device-info structure
- fix PCI register init
panfrost:
- Valhall support
r128:
- Fix bit-shift overflow
rockchip:
- Locking fixes in error path
ssd130x:
- Fix built-in linkage
udl:
- Always advertize VGA connector
ast:
- Support multiple outputs
- fix black screen on resume
sun4i:
- HDMI PHY cleanups
vc4:
- Add support for BCM2711
vkms:
- Allocate output buffer with vmalloc()
mcde:
- Fix ref-count leak
mxsfb/lcdif:
- Support i.MX8MP LCD controller
stm/ltdc:
- Support dynamic Z order
- Support mirroring
ingenic:
- Fix display at maximum resolution"
* tag 'drm-next-2022-08-03' of git://anongit.freedesktop.org/drm/drm: (1480 commits)
drm/amd/display: Fix a compilation failure on PowerPC caused by FPU code
drm/amdgpu: enable support for psp 13.0.4 block
drm/amdgpu: add files for PSP 13.0.4
drm/amdgpu: add header files for MP 13.0.4
drm/amdgpu: correct RLC_RLCS_BOOTLOAD_STATUS offset and index
drm/amdgpu: send msg to IMU for the front-door loading
drm/amdkfd: use time_is_before_jiffies(a + b) to replace "jiffies - a > b"
drm/amdgpu: fix hive reference leak when reflecting psp topology info
drm/amd/pm: enable GFX ULV feature support for SMU13.0.0
drm/amd/pm: update driver if header for SMU 13.0.0
drm/amdgpu: move mes self test after drm sched re-started
drm/amdgpu: drop non-necessary call trace dump
drm/amdgpu: enable VCN cg and JPEG cg/pg
drm/amdgpu: vcn_4_0_2 video codec query
drm/amdgpu: add VCN_4_0_2 firmware support
drm/amdgpu: add VCN function in NBIO v7.7
drm/amdgpu: fix a vcn4 boot poll bug in emulation mode
drm/amd/amdgpu: add memory training support for PSP_V13
drm/amdkfd: remove an unnecessary amdgpu_bo_ref
drm/amd/pm: Add get_gfx_off_status interface for yellow carp
...
Doing set_cpus_allowed_ptr() with wq_unbound_cpumask can be possible
fails and trigger the false warning.
Use cpu_possible_mask instead when wq_unbound_cpumask has no active CPUs.
It is very easy to trigger the warning:
Set wq_unbound_cpumask to a small set of CPUs.
Offline all the CPUs of wq_unbound_cpumask.
Offline an extra CPU and trigger the warning.
Fixes: 10a5a651e3 ("workqueue: Restrict kworker in the offline CPU pool running on housekeeping CPUs")
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This reverts commit 6417250d3f.
amdpgu need this function in order to prematurly stop pending
reset works when another reset work already in progress.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Lai Jiangshan<jiangshanlai@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Since flush operation synchronously waits for completion, flushing
system-wide WQs (e.g. system_wq) might introduce possibility of deadlock
due to unexpected locking dependency. Tejun Heo commented at [1] that it
makes no sense at all to call flush_workqueue() on the shared WQs as the
caller has no idea what it's gonna end up waiting for.
Although there is flush_scheduled_work() which flushes system_wq WQ with
"Think twice before calling this function! It's very easy to get into
trouble if you don't take great care." warning message, syzbot found a
circular locking dependency caused by flushing system_wq WQ [2].
Therefore, let's change the direction to that developers had better use
their local WQs if flush_scheduled_work()/flush_workqueue(system_*_wq) is
inevitable.
Steps for converting system-wide WQs into local WQs are explained at [3],
and a conversion to stop flushing system-wide WQs is in progress. Now we
want some mechanism for preventing developers who are not aware of this
conversion from again start flushing system-wide WQs.
Since I found that WARN_ON() is complete but awkward approach for teaching
developers about this problem, let's use __compiletime_warning() for
incomplete but handy approach. For completeness, we will also insert
WARN_ON() into __flush_workqueue() after all in-tree users stopped calling
flush_scheduled_work().
Link: https://lore.kernel.org/all/YgnQGZWT%2Fn3VAITX@slm.duckdns.org/ [1]
Link: https://syzkaller.appspot.com/bug?extid=bde0f89deacca7c765b8 [2]
Link: https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@I-love.SAKURA.ne.jp [3]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Tejun Heo <tj@kernel.org>
When a CPU is going offline, all workers on the CPU's pool will have their
cpus_allowed cleared to cpu_possible_mask and can run on any CPUs including
the isolated ones. Instead, set cpus_allowed to wq_unbound_cpumask so that
the can avoid isolated CPUs.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull workqueue updates from Tejun Heo:
"Nothing major. Just follow-up cleanups from Lai after the earlier
synchronization simplification"
* 'for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Convert the type of pool->nr_running to int
workqueue: Use wake_up_worker() in wq_worker_sleeping() instead of open code
workqueue: Change the comments of the synchronization about the idle_list
workqueue: Remove the mb() pair between wq_worker_sleeping() and insert_work()
Refer to housekeeping APIs using single feature types instead of flags.
This prevents from passing multiple isolation features at once to
housekeeping interfaces, which soon won't be possible anymore as each
isolation features will have their own cpumask.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lore.kernel.org/r/20220207155910.527133-5-frederic@kernel.org
To prepare for supporting each feature of the housekeeping cpumask
toward cpuset, prepare each of the HK_FLAG_* entries to move to their
own cpumask with enforcing to fetch them individually. The new
constraint is that multiple HK_FLAG_* entries can't be mixed together
anymore in a single call to housekeeping cpumask().
This will later allow, for example, to runtime modify the cpulist passed
through "isolcpus=", "nohz_full=" and "rcu_nocbs=" kernel boot
parameters.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220207155910.527133-3-frederic@kernel.org
It is only modified in associated CPU, so it doesn't need to be atomic.
tj: Comment updated.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The wakeup code in wq_worker_sleeping() is the same as wake_up_worker().
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The access to idle_list in wq_worker_sleeping() is changed to be
protected by pool->lock, so the comments above idle_list can be changed
to "L:" which is the meaning of "access with pool->lock held".
And the outdated comments in wq_worker_sleeping() is removed since
the function is not called with rq lock held any more, idle_list is
dereferenced with pool lock now.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In wq_worker_sleeping(), the access to worklist is protected by the
pool->lock, so the memory barrier is unneeded.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
for-5.16-fixes contains two subtle race conditions which were introduced by
scheduler side code cleanups. The branch didn't get pushed out, so merge
into for-5.17.
nr_running is never modified remotely after the schedule callback in
wakeup path is removed.
Rather nr_running is often accessed with other fields in the pool
together, so the cacheline_aligned for nr_running isn't needed.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
In unbind_workers(), there are two pool->lock held sections separated
by the code of zapping nr_running. wake_up_worker() needs to be in
pool->lock held section and after zapping nr_running. And zapping
nr_running had to be after schedule() when the local wake up
functionality was in use. Now, the call to schedule() has been removed
along with the local wake up functionality, so the code can be merged
into the same pool->lock held section.
The diffstat shows that it is other code moved down because the diff
tools can not know the meaning of merging lock sections by swapping
two code blocks.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The commit 6d25be5782 ("sched/core, workqueues: Distangle worker
accounting from rq lock") changed the schedule callbacks for workqueue
and moved the schedule callback from the wakeup code to at end of
schedule() in the worker's process context.
It means that the callback wq_worker_running() is guaranteed that
it sees the %WORKER_UNBOUND flag after scheduled since unbind_workers()
is running on the same CPU that all the pool's workers bound to.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Long time before, workers are not ALL bound after CPU_ONLINE, they can
still be running in other CPUs before self rebinding.
But the commit a9ab775bca ("workqueue: directly restore CPU affinity
of workers from CPU_ONLINE") makes rebind_workers() bind them all.
So all workers are on the CPU before the CPU is down.
And the comment in unbind_workers() refers to the workers "which are
still executing works from before the last CPU down" is outdated.
Just removed it.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The commit 6d25be5782 ("sched/core, workqueues: Distangle worker
accounting from rq lock") changed the schedule callbacks for workqueue
and removed the local-wake-up functionality.
Now the wakingup of workers is done by normal fashion and workers not
yet migrated to the specific CPU in concurrency managed pool can also
be woken up by workers that already bound to the specific cpu now.
So this advanced kicking of the idle workers to migrate them to the
associated CPU is unneeded now.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
At CPU-hotplug time, unbind_workers() may preempt a worker while it is
going to sleep. In that case the following scenario can happen:
unbind_workers() wq_worker_sleeping()
-------------- -------------------
if (worker->flags & WORKER_NOT_RUNNING)
return;
//PREEMPTED by unbind_workers
worker->flags |= WORKER_UNBOUND;
[...]
atomic_set(&pool->nr_running, 0);
//resume to worker
atomic_dec_and_test(&pool->nr_running);
After unbind_worker() resets pool->nr_running, the value is expected to
remain 0 until the pool ever gets rebound in case cpu_up() is called on
the target CPU in the future. But here the race leaves pool->nr_running
with a value of -1, triggering the following warning when the worker goes
idle:
WARNING: CPU: 3 PID: 34 at kernel/workqueue.c:1823 worker_enter_idle+0x95/0xc0
Modules linked in:
CPU: 3 PID: 34 Comm: kworker/3:0 Not tainted 5.16.0-rc1+ #34
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
Workqueue: 0x0 (rcu_par_gp)
RIP: 0010:worker_enter_idle+0x95/0xc0
Code: 04 85 f8 ff ff ff 39 c1 7f 09 48 8b 43 50 48 85 c0 74 1b 83 e2 04 75 99 8b 43 34 39 43 30 75 91 8b 83 00 03 00 00 85 c0 74 87 <0f> 0b 5b c3 48 8b 35 70 f1 37 01 48 8d 7b 48 48 81 c6 e0 93 0
RSP: 0000:ffff9b7680277ed0 EFLAGS: 00010086
RAX: 00000000ffffffff RBX: ffff93465eae9c00 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff9346418a0000 RDI: ffff934641057140
RBP: ffff934641057170 R08: 0000000000000001 R09: ffff9346418a0080
R10: ffff9b768027fdf0 R11: 0000000000002400 R12: ffff93465eae9c20
R13: ffff93465eae9c20 R14: ffff93465eae9c70 R15: ffff934641057140
FS: 0000000000000000(0000) GS:ffff93465eac0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000001cc0c000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
worker_thread+0x89/0x3d0
? process_one_work+0x400/0x400
kthread+0x162/0x190
? set_kthread_struct+0x40/0x40
ret_from_fork+0x22/0x30
</TASK>
Also due to this incorrect "nr_running == -1", all sorts of hazards can
happen, starting with queued works being ignored because no workers are
awaken at insert_work() time.
Fix this with checking again the worker flags while pool->lock is locked.
Fixes: b945efcdd0 ("sched: Remove pointless preemption disable in sched_submit_work()")
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
At CPU-hotplug time, unbind_worker() may preempt a worker while it is
waking up. In that case the following scenario can happen:
unbind_workers() wq_worker_running()
-------------- -------------------
if (!(worker->flags & WORKER_NOT_RUNNING))
//PREEMPTED by unbind_workers
worker->flags |= WORKER_UNBOUND;
[...]
atomic_set(&pool->nr_running, 0);
//resume to worker
atomic_inc(&worker->pool->nr_running);
After unbind_worker() resets pool->nr_running, the value is expected to
remain 0 until the pool ever gets rebound in case cpu_up() is called on
the target CPU in the future. But here the race leaves pool->nr_running
with a value of 1, triggering the following warning when the worker goes
idle:
WARNING: CPU: 3 PID: 34 at kernel/workqueue.c:1823 worker_enter_idle+0x95/0xc0
Modules linked in:
CPU: 3 PID: 34 Comm: kworker/3:0 Not tainted 5.16.0-rc1+ #34
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
Workqueue: 0x0 (rcu_par_gp)
RIP: 0010:worker_enter_idle+0x95/0xc0
Code: 04 85 f8 ff ff ff 39 c1 7f 09 48 8b 43 50 48 85 c0 74 1b 83 e2 04 75 99 8b 43 34 39 43 30 75 91 8b 83 00 03 00 00 85 c0 74 87 <0f> 0b 5b c3 48 8b 35 70 f1 37 01 48 8d 7b 48 48 81 c6 e0 93 0
RSP: 0000:ffff9b7680277ed0 EFLAGS: 00010086
RAX: 00000000ffffffff RBX: ffff93465eae9c00 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff9346418a0000 RDI: ffff934641057140
RBP: ffff934641057170 R08: 0000000000000001 R09: ffff9346418a0080
R10: ffff9b768027fdf0 R11: 0000000000002400 R12: ffff93465eae9c20
R13: ffff93465eae9c20 R14: ffff93465eae9c70 R15: ffff934641057140
FS: 0000000000000000(0000) GS:ffff93465eac0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000001cc0c000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
worker_thread+0x89/0x3d0
? process_one_work+0x400/0x400
kthread+0x162/0x190
? set_kthread_struct+0x40/0x40
ret_from_fork+0x22/0x30
</TASK>
Also due to this incorrect "nr_running == 1", further queued work may
end up not being served, because no worker is awaken at work insert time.
This raises rcutorture writer stalls for example.
Fix this with disabling preemption in the right place in
wq_worker_running().
It's worth noting that if the worker migrates and runs concurrently with
unbind_workers(), it is guaranteed to see the WORKER_UNBOUND flag update
due to set_cpus_allowed_ptr() acquiring/releasing rq->lock.
Fixes: 6d25be5782 ("sched/core, workqueues: Distangle worker accounting from rq lock")
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The current queue_work_on() docbook comment says that the caller must
ensure that the specified CPU can't go away, but does not spell out the
consequences, which turn out to be quite mild. Therefore expand this
comment to explicitly say that the penalty for failing to nail down the
specified CPU is that the workqueue handler might find itself executing
on some other CPU.
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Merge misc updates from Andrew Morton:
"257 patches.
Subsystems affected by this patch series: scripts, ocfs2, vfs, and
mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache,
gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc,
pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools,
memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm,
vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram,
cleanups, kfence, and damon)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (257 commits)
mm/damon: remove return value from before_terminate callback
mm/damon: fix a few spelling mistakes in comments and a pr_debug message
mm/damon: simplify stop mechanism
Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions
Docs/admin-guide/mm/damon/start: simplify the content
Docs/admin-guide/mm/damon/start: fix a wrong link
Docs/admin-guide/mm/damon/start: fix wrong example commands
mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on
mm/damon: remove unnecessary variable initialization
Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM
mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)
selftests/damon: support watermarks
mm/damon/dbgfs: support watermarks
mm/damon/schemes: activate schemes based on a watermarks mechanism
tools/selftests/damon: update for regions prioritization of schemes
mm/damon/dbgfs: support prioritization weights
mm/damon/vaddr,paddr: support pageout prioritization
mm/damon/schemes: prioritize regions within the quotas
mm/damon/selftests: support schemes quotas
mm/damon/dbgfs: support quotas of schemes
...
Shuah Khan reported:
| When CONFIG_PROVE_RAW_LOCK_NESTING=y and CONFIG_KASAN are enabled,
| kasan_record_aux_stack() runs into "BUG: Invalid wait context" when
| it tries to allocate memory attempting to acquire spinlock in page
| allocation code while holding workqueue pool raw_spinlock.
|
| There are several instances of this problem when block layer tries
| to __queue_work(). Call trace from one of these instances is below:
|
| kblockd_mod_delayed_work_on()
| mod_delayed_work_on()
| __queue_delayed_work()
| __queue_work() (rcu_read_lock, raw_spin_lock pool->lock held)
| insert_work()
| kasan_record_aux_stack()
| kasan_save_stack()
| stack_depot_save()
| alloc_pages()
| __alloc_pages()
| get_page_from_freelist()
| rm_queue()
| rm_queue_pcplist()
| local_lock_irqsave(&pagesets.lock, flags);
| [ BUG: Invalid wait context triggered ]
The default kasan_record_aux_stack() calls stack_depot_save() with
GFP_NOWAIT, which in turn can then call alloc_pages(GFP_NOWAIT, ...).
In general, however, it is not even possible to use either GFP_ATOMIC
nor GFP_NOWAIT in certain non-preemptive contexts, including
raw_spin_locks (see gfp.h and commmit ab00db216c).
Fix it by instructing stackdepot to not expand stack storage via
alloc_pages() in case it runs out by using
kasan_record_aux_stack_noalloc().
While there is an increased risk of failing to insert the stack trace,
this is typically unlikely, especially if the same insertion had already
succeeded previously (stack depot hit).
For frequent calls from the same location, it therefore becomes
extremely unlikely that kasan_record_aux_stack_noalloc() fails.
Link: https://lkml.kernel.org/r/20210902200134.25603-1-skhan@linuxfoundation.org
Link: https://lkml.kernel.org/r/20210913112609.2651084-7-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Reported-by: Shuah Khan <skhan@linuxfoundation.org>
Tested-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Taras Madan <tarasmadan@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: Walter Wu <walter-zh.wu@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently show_workqueue_state shows the state of all workqueues and of
all worker pools. In certain cases we may need to dump state of only a
specific workqueue or worker pool. For example in destroy_workqueue we
only need to show state of the workqueue which is getting destroyed.
So rename show_workqueue_state to show_all_workqueues(to signify it
dumps state of all busy workqueues) and divide it into more granular
functions (show_one_workqueue and show_one_worker_pool), that would show
states of individual workqueues and worker pools and can be used in
cases such as the one mentioned above.
Also, as mentioned earlier, make destroy_workqueue dump data pertaining
to only the workqueue that is being destroyed and make user(s) of
earlier interface(show_workqueue_state), use new interface
(show_all_workqueues).
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Some unfriendly component, such as dpdk, write the same mask to
unbound kworker cpumask again and again. Every time it write to
this interface some work is queue to cpu, even though the mask
is same with the original mask.
So, fix it by return success and do nothing if the cpumask is
equal with the old one.
Signed-off-by: Mengen Sun <mengensun@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Console drivers often queue work while holding locks also taken in their
console write paths, something which can lead to deadlocks on SMP when
dumping workqueue state (e.g. sysrq-t or on suspend failures).
For serial console drivers this could look like:
CPU0 CPU1
---- ----
show_workqueue_state();
lock(&pool->lock); <IRQ>
lock(&port->lock);
schedule_work();
lock(&pool->lock);
printk();
lock(console_owner);
lock(&port->lock);
where workqueues are, for example, used to push data to the line
discipline, process break signals and handle modem-status changes. Line
disciplines and serdev drivers can also queue work on write-wakeup
notifications, etc.
Reworking every console driver to avoid queuing work while holding locks
also taken in their write paths would complicate drivers and is neither
desirable or feasible.
Instead use the deferred-printk mechanism to avoid printing while
holding pool locks when dumping workqueue state.
Note that there are a few WARN_ON() assertions in the workqueue code
which could potentially also trigger a deadlock. Hopefully the ongoing
printk rework will provide a general solution for this eventually.
This was originally reported after a lockdep splat when executing
sysrq-t with the imx serial driver.
Fixes: 3494fc3084 ("workqueue: dump workqueues on sysrq-t")
Cc: stable@vger.kernel.org # 4.0
Reported-by: Fabio Estevam <festevam@denx.de>
Tested-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
There was no strong reason to or not to flush barrier work items in
flush_workqueue(). And we have to make barrier work items not participate
in nr_active so we had been using WORK_NO_COLOR for them which also makes
them can't be flushed by flush_workqueue().
And the users of flush_workqueue() often do not intend to wait barrier work
items issued by flush_work(). That made the choice sound perfect.
But barrier work items have reference to internal structure (pool_workqueue)
and the worker thread[s] is/are still busy for the workqueue user when the
barrrier work items are not done. So it is reasonable to make flush_workqueue()
also watch for flush_work() to make it more robust.
And a problem[1] reported by Li Zhe shows that we need such robustness.
The warning logs are listed below:
WARNING: CPU: 0 PID: 19336 at kernel/workqueue.c:4430 destroy_workqueue+0x11a/0x2f0
*****
destroy_workqueue: test_workqueue9 has the following busy pwq
pwq 4: cpus=2 node=0 flags=0x0 nice=0 active=0/1 refcnt=2
in-flight: 5658:wq_barrier_func
Showing busy workqueues and worker pools:
*****
It shows that even after drain_workqueue() returns, the barrier work item
is still in flight and the pwq (and a worker) is still busy on it.
The problem is caused by flush_workqueue() not watching flush_work():
Thread A Worker
/* normal work item with linked */
process_scheduled_works()
destroy_workqueue() process_one_work()
drain_workqueue() /* run normal work item */
/-- pwq_dec_nr_in_flight()
flush_workqueue() <---/
/* the last normal work item is done */
sanity_check process_one_work()
/-- raw_spin_unlock_irq(&pool->lock)
raw_spin_lock_irq(&pool->lock) <-/ /* maybe preempt */
*WARNING* wq_barrier_func()
/* maybe preempt by cond_resched() */
Thread A can get the pool lock after the Worker unlocks the pool lock before
running wq_barrier_func(). And if there is any preemption happen around
wq_barrier_func(), destroy_workqueue()'s sanity check is more likely to
get the lock and catch it. (Note: preemption is not necessary to cause the bug,
the unlocking is enough to possibly trigger the WARNING.)
A simple solution might be just executing all linked barrier work items
once without releasing pool lock after the head work item's
pwq_dec_nr_in_flight(). But this solution has two problems:
1) the head work item might also be barrier work item when the user-queued
work item is cancelled. For example:
thread 1: thread 2:
queue_work(wq, &my_work)
flush_work(&my_work)
cancel_work_sync(&my_work);
/* Neiter my_work nor the barrier work is scheduled. */
destroy_workqueue(wq);
/* This is an easier way to catch the WARNING. */
2) there might be too much linked barrier work items and running them
all once without releasing pool lock just causes trouble.
The only solution is to make flush_workqueue() aslo watch barrier work
items. So we have to assign a color to these barrier work items which
is the color of the head (user-queued) work item.
Assigning a color doesn't cause any problem in ative management, because
the prvious patch made barrier work items not participate in nr_active
via WORK_STRUCT_INACTIVE rather than reliance on the (old) WORK_NO_COLOR.
[1]: https://lore.kernel.org/lkml/20210812083814.32453-1-lizhe.67@bytedance.com/
Reported-by: Li Zhe <lizhe.67@bytedance.com>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
