IF YOU WOULD LIKE TO GET AN ACCOUNT, please write an
email to Administrator. User accounts are meant only to access repo
and report issues and/or generate pull requests.
This is a purpose-specific Git hosting for
BaseALT
projects. Thank you for your understanding!
Только зарегистрированные пользователи имеют доступ к сервису!
Для получения аккаунта, обратитесь к администратору.
We make these changes in order to prepare __register_sysctl_table and
its callers for when we remove the sentinel element (empty element at
the end of ctl_table arrays). We don't actually remove any sentinels in
this commit, but we *do* make sure to use ARRAY_SIZE so the table_size
is available when the removal occurs.
We add a table_size argument to __register_sysctl_table and adjust
callers, all of which pass ctl_table pointers and need an explicit call
to ARRAY_SIZE. We implement a size calculation in register_net_sysctl in
order to forward the size of the array pointer received from the network
register calls.
The new table_size argument does not yet have any effect in the
init_header call which is still dependent on the sentinel's presence.
table_size *does* however drive the `kzalloc` allocation in
__register_sysctl_table with no adverse effects as the allocated memory
is either one element greater than the calculated ctl_table array (for
the calls in ipc_sysctl.c, mq_sysctl.c and ucount.c) or the exact size
of the calculated ctl_table array (for the call from sysctl_net.c and
register_sysctl). This approach will allows us to "just" remove the
sentinel without further changes to __register_sysctl_table as
table_size will represent the exact size for all the callers at that
point.
Signed-off-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Fixes following checkpatch.pl issue:
ERROR: trailing statements should be on next line
Signed-off-by: Atul Kumar Pant <atulpant.linux@gmail.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
The patch fixes following checkpatch.pl issue:
ERROR: open brace '{' following function definitions go on the next line
ERROR: do not use assignment in if condition
Signed-off-by: Atul Kumar Pant <atulpant.linux@gmail.com>
[PM: subject line tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Fixes following checkpatch.pl issue:
ERROR: space required before the open parenthesis '('
ERROR: spaces required around that '='
ERROR: spaces required around that '<'
ERROR: spaces required around that '=='
Signed-off-by: Atul Kumar Pant <atulpant.linux@gmail.com>
[PM: subject line tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Currently, if a struct_ops map is loaded with BPF_F_LINK, it must also
define the .validate() and .update() callbacks in its corresponding
struct bpf_struct_ops in the kernel. Enabling struct_ops link is useful
in its own right to ensure that the map is unloaded if an application
crashes. For example, with sched_ext, we want to automatically unload
the host-wide scheduler if the application crashes. We would likely
never support updating elements of a sched_ext struct_ops map, so we'd
have to implement these callbacks showing that they _can't_ support
element updates just to benefit from the basic lifetime management of
struct_ops links.
Let's enable struct_ops maps to work with BPF_F_LINK even if they
haven't defined these callbacks, by assuming that a struct_ops map
element cannot be updated by default.
Acked-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230814185908.700553-2-void@manifault.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
cgroup_namspace_init() just return 0. Therefore, there is no need to
call it during start_kernel. Just remove it.
Fixes: a79a908fd2b0 ("cgroup: introduce cgroup namespaces")
Signed-off-by: Lu Jialin <lujialin4@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Each CPU-specific and unbound kworker kthread conforms to a particular
naming scheme. However, this does not extend to the rescuer kworker.
At present, a rescuer kworker is simply named according to its
workqueue's name. This can be cryptic.
This patch modifies a rescuer to follow the kworker naming scheme.
The "R" is indicative of a rescuer and after "-" is its workqueue's
name e.g. "kworker/R-ext4-rsv-conver".
tj: Use "R" instead of "r" as the prefix to make it more distinctive and
consistent with how highpri pools are marked.
Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Now that torture_random() uses swahw32(), its callers no longer see
not-so-random low-order bits, as these are now swapped up into the upper
16 bits of the torture_random() function's return value. This commit
therefore removes the right-shifting of torture_random() return values.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Now that torture_random() uses swahw32(), its callers no longer see
not-so-random low-order bits, as these are now swapped up into the upper
16 bits of the torture_random() function's return value. This commit
therefore removes the right-shifting of torture_random() return values.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
In order to gain better race coverage, move the test start/stop
waits in stutter_wait() to torture_hrtimeout_jiffies().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
In order to gain better race coverage, move the CPU-migration timed
waits in torture_shuffle() to torture_hrtimeout_jiffies().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
In order to gain better race coverage, move the CPU-hotplug-related
timed waits in torture_onoff() to torture_hrtimeout_jiffies().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Given that it is expected that more code will use torture_hrtimeout_*(),
including for longer timeouts, make it use TASK_IDLE instead of
TASK_UNINTERRUPTIBLE.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds a module parameter that causes the locktorture writer
to run at real-time priority.
To use it:
insmod /lib/modules/torture.ko random_shuffle=1
insmod /lib/modules/locktorture.ko torture_type=mutex_lock rt_boost=1 rt_boost_factor=50 nested_locks=3 writer_fifo=1
^^^^^^^^^^^^^
A predecessor to this patch has been helpful to uncover issues with the
proxy-execution series.
[ paulmck: Remove locktorture-specific code from kernel/torture.c. ]
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: kernel-team@android.com
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
[jstultz: Include header change to build, reword commit message]
Signed-off-by: John Stultz <jstultz@google.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds a kthread-creation callback to the
_torture_create_kthread() function, which allows callers of a new
torture_create_kthread_cb() macro to specify a function to be invoked
after the kthread is created but before it is awakened for the first time.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: kernel-team@android.com
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: John Stultz <jstultz@google.com>
In kernels built with CONFIG_PROVE_RCU=y (for example, lockdep kernels),
the following sequence of events can occur:
o rcu_init_tasks_generic() is invoked just before init is spawned.
It invokes rcu_spawn_tasks_kthread() and friends.
o rcu_spawn_tasks_kthread() invokes rcu_spawn_tasks_kthread_generic(),
which uses kthread_run() to create the needed kthread.
o Control returns to rcu_init_tasks_generic(), which, because this
is a CONFIG_PROVE_RCU=y kernel, invokes the version of the
rcu_tasks_initiate_self_tests() function that actually does
something, including invoking synchronize_rcu_tasks(), which
in turn invokes synchronize_rcu_tasks_generic().
o synchronize_rcu_tasks_generic() sees that the ->kthread_ptr is
still NULL, because the newly spawned kthread has not yet
started.
o The new kthread starts, preempting synchronize_rcu_tasks_generic()
just after its check. This kthread invokes rcu_tasks_one_gp(),
which acquires ->tasks_gp_mutex, and, seeing no work, blocks
in rcuwait_wait_event(). Note that this step requires either
a preemptible kernel or a fault-injection-style sleep at the
beginning of mutex_lock().
o synchronize_rcu_tasks_generic() resumes and invokes rcu_tasks_one_gp().
o rcu_tasks_one_gp() attempts to acquire ->tasks_gp_mutex, which
is still held by the newly spawned kthread's rcu_tasks_one_gp()
function. Deadlock.
Because the only reason for ->tasks_gp_mutex is to handle pre-kthread
synchronous grace periods, this commit avoids this deadlock by having
rcu_tasks_one_gp() momentarily release ->tasks_gp_mutex while invoking
rcuwait_wait_event(). This allows the call to rcu_tasks_one_gp() from
synchronize_rcu_tasks_generic() proceed.
Note that it is not necessary to release the mutex anywhere else in
rcu_tasks_one_gp() because rcuwait_wait_event() is the only function
that can block indefinitely.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Roy Hopkins <rhopkins@suse.de>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Roy Hopkins <rhopkins@suse.de>
Use guards to reduce gotos and simplify control flow.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20230801211811.828443100@infradead.org
The sched_rr_timeslice can be reset to default by writing value that is
<= 0. However after reading from this file we always got the last value
written, which is not useful at all.
$ echo -1 > /proc/sys/kernel/sched_rr_timeslice_ms
$ cat /proc/sys/kernel/sched_rr_timeslice_ms
-1
Fix this by setting the variable that holds the sysctl file value to the
jiffies_to_msecs(RR_TIMESLICE) in case that <= 0 value was written.
Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Tested-by: Petr Vorel <pvorel@suse.cz>
Link: https://lore.kernel.org/r/20230802151906.25258-3-chrubis@suse.cz
There is a 10% rounding error in the intial value of the
sysctl_sched_rr_timeslice with CONFIG_HZ_300=y.
This was found with LTP test sched_rr_get_interval01:
sched_rr_get_interval01.c:57: TPASS: sched_rr_get_interval() passed
sched_rr_get_interval01.c:64: TPASS: Time quantum 0s 99999990ns
sched_rr_get_interval01.c:72: TFAIL: /proc/sys/kernel/sched_rr_timeslice_ms != 100 got 90
sched_rr_get_interval01.c:57: TPASS: sched_rr_get_interval() passed
sched_rr_get_interval01.c:64: TPASS: Time quantum 0s 99999990ns
sched_rr_get_interval01.c:72: TFAIL: /proc/sys/kernel/sched_rr_timeslice_ms != 100 got 90
What this test does is to compare the return value from the
sched_rr_get_interval() and the sched_rr_timeslice_ms sysctl file and
fails if they do not match.
The problem it found is the intial sysctl file value which was computed as:
static int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
which works fine as long as MSEC_PER_SEC is multiple of HZ, however it
introduces 10% rounding error for CONFIG_HZ_300:
(MSEC_PER_SEC / HZ) * (100 * HZ / 1000)
(1000 / 300) * (100 * 300 / 1000)
3 * 30 = 90
This can be easily fixed by reversing the order of the multiplication
and division. After this fix we get:
(MSEC_PER_SEC * (100 * HZ / 1000)) / HZ
(1000 * (100 * 300 / 1000)) / 300
(1000 * 30) / 300 = 100
Fixes: 975e155ed873 ("sched/rt: Show the 'sched_rr_timeslice' SCHED_RR timeslice tuning knob in milliseconds")
Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Tested-by: Petr Vorel <pvorel@suse.cz>
Link: https://lore.kernel.org/r/20230802151906.25258-2-chrubis@suse.cz
If an output buffer size exceeded U16_MAX, the min_t(u16, ...) cast in
copy_data() was causing writes to truncate. This manifested as output
bytes being skipped, seen as %NUL bytes in pstore dumps when the available
record size was larger than 65536. Fix the cast to no longer truncate
the calculation.
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: John Ogness <john.ogness@linutronix.de>
Reported-by: Vijay Balakrishna <vijayb@linux.microsoft.com>
Link: https://lore.kernel.org/lkml/d8bb1ec7-a4c5-43a2-9de0-9643a70b899f@linux.microsoft.com/
Fixes: b6cf8b3f3312 ("printk: add lockless ringbuffer")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Vijay Balakrishna <vijayb@linux.microsoft.com>
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Reviewed-by: Tyler Hicks (Microsoft) <code@tyhicks.com>
Tested-by: Tyler Hicks (Microsoft) <code@tyhicks.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20230811054528.never.165-kees@kernel.org
- Make amd-pstate use device_attributes as expected by the CPU root
kobject (Thomas Weißschuh).
- Restore the previous behavior of resume_store() when hibernation is
not available which is to return the full number of bytes that were
to be written by user space (Vlastimil Babka).
-----BEGIN PGP SIGNATURE-----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=0RaA
-----END PGP SIGNATURE-----
Merge tag 'pm-6.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fixes from Rafael Wysocki:
"These fix an amd-pstate cpufreq driver issues and recently introduced
hibernation-related breakage.
Specifics:
- Make amd-pstate use device_attributes as expected by the CPU root
kobject (Thomas Weißschuh)
- Restore the previous behavior of resume_store() when hibernation is
not available which is to return the full number of bytes that were
to be written by user space (Vlastimil Babka)"
* tag 'pm-6.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpufreq: amd-pstate: fix global sysfs attribute type
PM: hibernate: fix resume_store() return value when hibernation not available
-----BEGIN PGP SIGNATURE-----
iHUEABYIAB0WIQRdM/uy1Ege0+EN1fNar9k/UBDW4wUCZNRx8QAKCRBar9k/UBDW
46MBAQC3YDFsEfPzX4P7ZnlM5Lf1NynjNbso5bYW0TF/dp/Y+gD+M8wdM5Vj2Mb0
Zr56TnwCJei0kGBemiel4sStt3e4qwY=
=+0u+
-----END PGP SIGNATURE-----
Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Martin KaFai Lau says:
====================
pull-request: bpf-next 2023-08-09
We've added 19 non-merge commits during the last 6 day(s) which contain
a total of 25 files changed, 369 insertions(+), 141 deletions(-).
The main changes are:
1) Fix array-index-out-of-bounds access when detaching from an
already empty mprog entry from Daniel Borkmann.
2) Adjust bpf selftest because of a recent llvm change
related to the cpu-v4 ISA from Eduard Zingerman.
3) Add uprobe support for the bpf_get_func_ip helper from Jiri Olsa.
4) Fix a KASAN splat due to the kernel incorrectly accepted
an invalid program using the recent cpu-v4 instruction from
Yonghong Song.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next:
bpf: btf: Remove two unused function declarations
bpf: lru: Remove unused declaration bpf_lru_promote()
selftests/bpf: relax expected log messages to allow emitting BPF_ST
selftests/bpf: remove duplicated functions
bpf, docs: Fix small typo and define semantics of sign extension
selftests/bpf: Add bpf_get_func_ip test for uprobe inside function
selftests/bpf: Add bpf_get_func_ip tests for uprobe on function entry
bpf: Add support for bpf_get_func_ip helper for uprobe program
selftests/bpf: Add a movsx selftest for sign-extension of R10
bpf: Fix an incorrect verification success with movsx insn
bpf, docs: Formalize type notation and function semantics in ISA standard
bpf: change bpf_alu_sign_string and bpf_movsx_string to static
libbpf: Use local includes inside the library
bpf: fix bpf_dynptr_slice() to stop return an ERR_PTR.
bpf: fix inconsistent return types of bpf_xdp_copy_buf().
selftests/bpf: fix the incorrect verification of port numbers.
selftests/bpf: Add test for detachment on empty mprog entry
bpf: Fix mprog detachment for empty mprog entry
bpf: bpf_struct_ops: Remove unnecessary initial values of variables
====================
Link: https://lore.kernel.org/r/20230810055123.109578-1-martin.lau@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Pick up the EEVDF work into the main branch - it's looking good so far.
Conflicts:
kernel/sched/features.h
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Three LSMs register the implementations for the "capget" hook: AppArmor,
SELinux, and the normal capability code. Looking at the function
implementations we may observe that the first parameter "target" is not
changing.
Mark the first argument "target" of LSM hook security_capget() as
"const" since it will not be changing in the LSM hook.
cap_capget() LSM hook declaration exceeds the 80 characters per line
limit. Split the function declaration to multiple lines to decrease the
line length.
Signed-off-by: Khadija Kamran <kamrankhadijadj@gmail.com>
Acked-by: John Johansen <john.johansen@canonical.com>
[PM: align the cap_capget() declaration, spelling fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Tracefs or debugfs maybe cause hundreds to thousands of PATH records,
too many PATH records maybe cause soft lockup.
For example:
1. CONFIG_KASAN=y && CONFIG_PREEMPTION=n
2. auditctl -a exit,always -S open -k key
3. sysctl -w kernel.watchdog_thresh=5
4. mkdir /sys/kernel/debug/tracing/instances/test
There may be a soft lockup as follows:
watchdog: BUG: soft lockup - CPU#45 stuck for 7s! [mkdir:15498]
Kernel panic - not syncing: softlockup: hung tasks
Call trace:
dump_backtrace+0x0/0x30c
show_stack+0x20/0x30
dump_stack+0x11c/0x174
panic+0x27c/0x494
watchdog_timer_fn+0x2bc/0x390
__run_hrtimer+0x148/0x4fc
__hrtimer_run_queues+0x154/0x210
hrtimer_interrupt+0x2c4/0x760
arch_timer_handler_phys+0x48/0x60
handle_percpu_devid_irq+0xe0/0x340
__handle_domain_irq+0xbc/0x130
gic_handle_irq+0x78/0x460
el1_irq+0xb8/0x140
__audit_inode_child+0x240/0x7bc
tracefs_create_file+0x1b8/0x2a0
trace_create_file+0x18/0x50
event_create_dir+0x204/0x30c
__trace_add_new_event+0xac/0x100
event_trace_add_tracer+0xa0/0x130
trace_array_create_dir+0x60/0x140
trace_array_create+0x1e0/0x370
instance_mkdir+0x90/0xd0
tracefs_syscall_mkdir+0x68/0xa0
vfs_mkdir+0x21c/0x34c
do_mkdirat+0x1b4/0x1d4
__arm64_sys_mkdirat+0x4c/0x60
el0_svc_common.constprop.0+0xa8/0x240
do_el0_svc+0x8c/0xc0
el0_svc+0x20/0x30
el0_sync_handler+0xb0/0xb4
el0_sync+0x160/0x180
Therefore, we add cond_resched() to __audit_inode_child() to fix it.
Fixes: 5195d8e217a7 ("audit: dynamically allocate audit_names when not enough space is in the names array")
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Use a simple logical shift and increment to calculate the number of slots
taken by the DMA segment boundary.
At least GCC-13 is not able to optimize the expression, producing this
horrible assembly code on x86:
cmpq $-1, %rcx
je .L364
addq $2048, %rcx
shrq $11, %rcx
movq %rcx, %r13
.L331:
// rest of the function here...
// after function epilogue and return:
.L364:
movabsq $9007199254740992, %r13
jmp .L331
After the optimization, the code looks more reasonable:
shrq $11, %r11
leaq 1(%r11), %rbx
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Move the comment down in front of the loop that actually sets the list
member of struct io_tlb_slot to zero.
Fixes: 26a7e094783d ("swiotlb: refactor swiotlb_tbl_map_single")
Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
While workqueue.default_affinity_scope is writable, it only affects
workqueues which are created afterwards and isn't very useful. Instead,
let's introduce explicit "default" scope and update the effective scope
dynamically when workqueue.default_affinity_scope is changed.
Signed-off-by: Tejun Heo <tj@kernel.org>
An unbound workqueue can be served by multiple worker_pools to improve
locality. The segmentation is achieved by grouping CPUs into pods. By
default, the cache boundaries according to cpus_share_cache() define the
CPUs are grouped. Let's a workqueue is allowed to run on all CPUs and the
system has two L3 caches. The workqueue would be mapped to two worker_pools
each serving one L3 cache domains.
While this improves locality, because the pod boundaries are strict, it
limits the total bandwidth a given issuer can consume. For example, let's
say there is a thread pinned to a CPU issuing enough work items to saturate
the whole machine. With the machine segmented into two pods, no matter how
many work items it issues, it can only use half of the CPUs on the system.
While this limitation has existed for a very long time, it wasn't very
pronounced because the affinity grouping used to be always by NUMA nodes.
With cache boundaries as the default and support for even finer grained
scopes (smt and cpu), it is now an a lot more pressing problem.
This patch implements non-strict affinity scope where the pod boundaries
aren't enforced strictly. Going back to the previous example, the workqueue
would still be mapped to two worker_pools; however, the affinity enforcement
would be soft. The workers in both pools would have their cpus_allowed set
to the whole machine thus allowing the scheduler to migrate them anywhere on
the machine. However, whenever an idle worker is woken up, the workqueue
code asks the scheduler to bring back the task within the pod if the worker
is outside. ie. work items start executing within its affinity scope but can
be migrated outside as the scheduler sees fit. This removes the hard cap on
utilization while maintaining the benefits of affinity scopes.
After the earlier ->__pod_cpumask changes, the implementation is pretty
simple. When non-strict which is the new default:
* pool_allowed_cpus() returns @pool->attrs->cpumask instead of
->__pod_cpumask so that the workers are allowed to run on any CPU that
the associated workqueues allow.
* If the idle worker task's ->wake_cpu is outside the pod, kick_pool() sets
the field to a CPU within the pod.
This would be the first use of task_struct->wake_cpu outside scheduler
proper, so it isn't clear whether this would be acceptable. However, other
methods of migrating tasks are significantly more expensive and are likely
prohibitively so if we want to do this on every work item. This needs
discussion with scheduler folks.
There is also a race window where setting ->wake_cpu wouldn't be effective
as the target task is still on CPU. However, the window is pretty small and
this being a best-effort optimization, it doesn't seem to warrant more
complexity at the moment.
While the non-strict cache affinity scopes seem to be the best option, the
performance picture interacts with the affinity scope and is a bit
complicated to fully discuss in this patch, so the behavior is made easily
selectable through wqattrs and sysfs and the next patch will add
documentation to discuss performance implications.
v2: pool->attrs->affn_strict is set to true for per-cpu worker_pools.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
workqueue_attrs has two uses:
* to specify the required unouned workqueue properties by users
* to match worker_pool's properties to workqueues by core code
For example, if the user wants to restrict a workqueue to run only CPUs 0
and 2, and the two CPUs are on different affinity scopes, the workqueue's
attrs->cpumask would contains CPUs 0 and 2, and the workqueue would be
associated with two worker_pools, one with attrs->cpumask containing just
CPU 0 and the other CPU 2.
Workqueue wants to support non-strict affinity scopes where work items are
started in their matching affinity scopes but the scheduler is free to
migrate them outside the starting scopes, which can enable utilizing the
whole machine while maintaining most of the locality benefits from affinity
scopes.
To enable that, worker_pools need to distinguish the strict affinity that it
has to follow (because that's the restriction coming from the user) and the
soft affinity that it wants to apply when dispatching work items. Note that
two worker_pools with different soft dispatching requirements have to be
separate; otherwise, for example, we'd be ping-ponging worker threads across
NUMA boundaries constantly.
This patch adds workqueue_attrs->__pod_cpumask. The new field is double
underscored as it's only used internally to distinguish worker_pools. A
worker_pool's ->cpumask is now always the same as the online subset of
allowed CPUs of the associated workqueues, and ->__pod_cpumask is the pod's
subset of that ->cpumask. Going back to the example above, both worker_pools
would have ->cpumask containing both CPUs 0 and 2 but one's ->__pod_cpumask
would contain 0 while the other's 2.
* pool_allowed_cpus() is added. It returns the worker_pool's strict cpumask
that the pool's workers must stay within. This is currently always
->__pod_cpumask as all boundaries are still strict.
* As a workqueue_attrs can now track both the associated workqueues' cpumask
and its per-pod subset, wq_calc_pod_cpumask() no longer needs an external
out-argument. Drop @cpumask and instead store the result in
->__pod_cpumask.
* The above also simplifies apply_wqattrs_prepare() as the same
workqueue_attrs can be used to create all pods associated with a
workqueue. tmp_attrs is dropped.
* wq_update_pod() is updated to use wqattrs_equal() to test whether a pwq
update is needed instead of only comparing ->cpumask so that
->__pod_cpumask is compared too. It can directly compare ->__pod_cpumaks
but the code is easier to understand and more robust this way.
The only user-visible behavior change is that two workqueues with different
cpumasks no longer can share worker_pools even when their pod subsets
coincide. Going back to the example, let's say there's another workqueue
with cpumask 0, 2, 3, where 2 and 3 are in the same pod. It would be mapped
to two worker_pools - one with CPU 0, the other with 2 and 3. The former has
the same cpumask as the first pod of the earlier example and would have
shared the same worker_pool but that's no longer the case after this patch.
The worker_pools would have the same ->__pod_cpumask but their ->cpumask's
wouldn't match.
While this is necessary to support non-strict affinity scopes, there can be
further optimizations to maintain sharing among strict affinity scopes.
However, non-strict affinity scopes are going to be preferable for most use
cases and we don't see very diverse mixture of unbound workqueue cpumasks
anyway, so the additional overhead doesn't seem to justify the extra
complexity.
v2: - wq_update_pod() was incorrectly comparing target_attrs->__pod_cpumask
to pool->attrs->cpumask instead of its ->__pod_cpumask. Fix it by
using wqattrs_equal() for comparison instead.
- Per-cpu worker pools weren't initializing ->__pod_cpumask which caused
a subtle problem later on. Set it to cpumask_of(cpu) like ->cpumask.
Signed-off-by: Tejun Heo <tj@kernel.org>
Checking need_more_worker() and calling wake_up_worker() is a repeated
pattern. Let's add kick_pool(), which checks need_more_worker() and
open-code wake_up_worker(), and replace wake_up_worker() uses. The following
conversions aren't one-to-one:
* __queue_work() was using __need_more_work() because it knows that
pool->worklist isn't empty. Switching to kick_pool() adds an extra
list_empty() test.
* create_worker() always needs to wake up the newly minted worker whether
there's more work to do or not to avoid triggering hung task check on the
new task. Keep the current wake_up_process() and still add kick_pool().
This may lead to an extra wakeup which isn't harmful.
* pwq_adjust_max_active() was explicitly checking whether it needs to wake
up a worker or not to avoid spurious wakeups. As kick_pool() only wakes up
a worker when necessary, this explicit check is no longer necessary and
dropped.
* unbind_workers() now calls kick_pool() instead of wake_up_worker() adding
a need_more_worker() test. This avoids spurious wakeups and shouldn't
break anything.
wake_up_worker() is dropped as kick_pool() replaces all its users. After
this patch, all paths that wakes up a non-rescuer worker to initiate work
item execution use kick_pool(). This will enable future changes to improve
locality.
Signed-off-by: Tejun Heo <tj@kernel.org>
The two work execution paths in worker_thread() and rescuer_thread() use
move_linked_works() to claim work items from @pool->worklist. Once claimed,
process_schedule_works() is called which invokes process_one_work() on each
work item. process_one_work() then uses find_worker_executing_work() to
detect and handle collisions - situations where the work item to be executed
is still running on another worker.
This works fine, but, to improve work execution locality, we want to
establish work to worker association earlier and know for sure that the
worker is going to excute the work once asssigned, which requires performing
collision handling earlier while trying to assign the work item to the
worker.
This patch introduces assign_work() which assigns a work item to a worker
using move_linked_works() and then performs collision handling. As collision
handling is handled earlier, process_one_work() no longer needs to worry
about them.
After the this patch, collision checks for linked work items are skipped,
which should be fine as they can't be queued multiple times concurrently.
For work items running from rescuers, the timing of collision handling may
change but the invariant that the work items go through collision handling
before starting execution does not.
This patch shouldn't cause noticeable behavior changes, especially given
that worker_thread() behavior remains the same.
Signed-off-by: Tejun Heo <tj@kernel.org>
Add three more affinity scopes - WQ_AFFN_CPU, SMT and CACHE - and make CACHE
the default. The code changes to actually add the additional scopes are
trivial.
Also add module parameter "workqueue.default_affinity_scope" to override the
default scope and "affinity_scope" sysfs file to configure it per workqueue.
wq_dump.py and documentations are updated accordingly.
This enables significant flexibility in configuring how unbound workqueues
behave. If affinity scope is set to "cpu", it'll behave close to a per-cpu
workqueue. On the other hand, "system" removes all locality boundaries.
Many modern machines have multiple L3 caches often while being mostly
uniform in terms of memory access. Thus, workqueue's previous behavior of
spreading work items in each NUMA node had negative performance implications
from unncessarily crossing L3 boundaries between issue and execution.
However, picking a finer grained affinity scope also has a downside in that
an issuer in one group can't utilize CPUs in other groups.
While dependent on the specifics of workload, there's usually a noticeable
penalty in crossing L3 boundaries, so let's default to CACHE. This issue
will be further addressed and documented with examples in future patches.
Signed-off-by: Tejun Heo <tj@kernel.org>
While wq_pod_type[] can now group CPUs in any aribitrary way, WQ_AFFN_NUM
init is hard coded into workqueue_init_topology(). This patch modularizes
the init path by introducing init_pod_type() which takes a callback to
determine whether two CPUs should share a pod as an argument.
init_pod_type() first scans the CPU combinations testing for sharing to
assign consecutive pod IDs and initialize pod_type->cpu_pod[]. Once
->cpu_pod[] is determined, ->pod_cpus[] and ->pod_node[] are initialized
accordingly. WQ_AFFN_NUMA is now initialized by calling init_pod_type() with
cpus_share_numa() which tests whether the CPU belongs to the same NUMA node.
This patch may change the pod ID assigned to each NUMA node but that
shouldn't cause any behavior changes as the NUMA node to use for allocations
are tracked separately in pod_type->pod_node[]. This makes adding new
affinty types pretty easy.
Signed-off-by: Tejun Heo <tj@kernel.org>
While renamed to pod, the code still assumes that the pods are defined by
NUMA boundaries. Let's generalize it:
* workqueue_attrs->affn_scope is added. Each enum represents the type of
boundaries that define the pods. There are currently two scopes -
WQ_AFFN_NUMA and WQ_AFFN_SYSTEM. The former is the same behavior as before
- one pod per NUMA node. The latter defines one global pod across the
whole system.
* struct wq_pod_type is added which describes how pods are configured for
each affnity scope. For each pod, it lists the member CPUs and the
preferred NUMA node for memory allocations. The reverse mapping from CPU
to pod is also available.
* wq_pod_enabled is dropped. Pod is now always enabled. The previously
disabled behavior is now implemented through WQ_AFFN_SYSTEM.
* get_unbound_pool() wants to determine the NUMA node to allocate memory
from for the new pool. The variables are renamed from node to pod but the
logic still assumes they're one and the same. Clearly distinguish them -
walk the WQ_AFFN_NUMA pods to find the matching pod and then use the pod's
NUMA node.
* wq_calc_pod_cpumask() was taking @pod but assumed that it was the NUMA
node. Take @cpu instead and determine the cpumask to use from the pod_type
matching @attrs.
* apply_wqattrs_prepare() is update to return ERR_PTR() on error instead of
NULL so that it can indicate -EINVAL on invalid affinity scopes.
This patch allows CPUs to be grouped into pods however desired per type.
While this patch causes some internal behavior changes, nothing material
should change for workqueue users.
v2: Trigger WARN_ON_ONCE() in wqattrs_pod_type() if affn_scope is
WQ_AFFN_NR_TYPES which indicates that the function is called with a
worker_pool's attrs instead of a workqueue's.
Signed-off-by: Tejun Heo <tj@kernel.org>
workqueue_attrs can be used for both workqueues and worker_pools. However,
some fields, currently only ->ordered, only apply to workqueues and should
be cleared to the default / invalid values.
Currently, an unbound workqueue explicitly clears attrs->ordered in
get_unbound_pool() after copying the source workqueue attrs, while per-cpu
workqueues rely on the fact that zeroing on allocation gives us the desired
default value for pool->attrs->ordered.
This is fragile. Let's add wqattrs_clear_for_pool() which clears
attrs->ordered and is called from both init_worker_pool() and
get_unbound_pool(). This will ease adding more workqueue-only attrs fields.
In get_unbound_pool(), pool->node initialization is moved upwards for
readability. This shouldn't cause any behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
For an unbound pool, multiple cpumasks are involved.
U: The user-specified cpumask (may be filtered with cpu_possible_mask).
A: The actual cpumask filtered by wq_unbound_cpumask. If the filtering
leaves no CPU, wq_unbound_cpumask is used.
P: Per-pod subsets of #A.
wq->attrs stores #U, wq->dfl_pwq->pool->attrs->cpumask #A, and
wq->cpu_pwq[CPU]->pool->attrs->cpumask #P.
wq_update_pod() is called to update per-pod pwq's during CPU hotplug. To
calculate the new #P for each workqueue, it needs to call
wq_calc_pod_cpumask() with @attrs that contains #A. Currently,
wq_update_pod() achieves this by calling wq_calc_pod_cpumask() with
wq->dfl_pwq->pool->attrs.
This is rather fragile because we're calling wq_calc_pod_cpumask() with
@attrs of a worker_pool rather than the workqueue's actual attrs when what
we want to calculate is the workqueue's cpumask on the pod. While this works
fine currently, future changes will add fields which are used differently
between workqueues and worker_pools and this subtlety will bite us.
This patch factors out #U -> #A calculation from apply_wqattrs_prepare()
into wqattrs_actualize_cpumask and updates wq_update_pod() to copy
wq->unbound_attrs and use the new helper to obtain #A freshly instead of
abusing wq->dfl_pwq->pool_attrs.
This shouldn't cause any behavior changes in the current code.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reference: http://lkml.kernel.org/r/30625cdd-4d61-594b-8db9-6816b017dde3@amd.com
During boot, to initialize unbound CPU pods, wq_pod_init() was called from
workqueue_init(). This is early enough for NUMA nodes to be set up but
before SMP is brought up and CPU topology information is populated.
Workqueue is in the process of improving CPU locality for unbound workqueues
and will need access to topology information during pod init. This adds a
new init function workqueue_init_topology() which is called after CPU
topology information is available and replaces wq_pod_init().
As unbound CPU pods are now initialized after workqueues are activated, we
need to revisit the workqueues to apply the pod configuration. Workqueues
which are created before workqueue_init_topology() are set up so that they
always use the default worker pool. After pods are set up in
workqueue_init_topology(), wq_update_pod() is called on all existing
workqueues to update the pool associations accordingly.
Note that wq_update_pod_attrs_buf allocation is moved to
workqueue_init_early(). This isn't necessary right now but enables further
generalization of pod handling in the future.
This patch changes the initialization sequence but the end result should be
the same.
Signed-off-by: Tejun Heo <tj@kernel.org>
wq_pod_init() is called from workqueue_init() and responsible for
initializing unbound CPU pods according to NUMA node. Workqueue is in the
process of improving affinity awareness and wants to use other topology
information to initialize unbound CPU pods; however, unlike NUMA nodes,
other topology information isn't yet available in workqueue_init().
The next patch will introduce a later stage init function for workqueue
which will be responsible for initializing unbound CPU pods. Relocate
wq_pod_init() below workqueue_init() where the new init function is going to
be located so that the diff can show the content differences.
Just a relocation. No functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
