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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core fixes from Greg KH:
"Here are a number of small driver core fixes for 5.7-rc5 to resolve a
bunch of reported issues with the current tree.
Biggest here are the reverts and patches from John Stultz to resolve a
bunch of deferred probe regressions we have been seeing in 5.7-rc
right now.
Along with those are some other smaller fixes:
- coredump crash fix
- devlink fix for when permissive mode was enabled
- amba and platform device dma_parms fixes
- component error silenced for when deferred probe happens
All of these have been in linux-next for a while with no reported
issues"
* tag 'driver-core-5.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
regulator: Revert "Use driver_deferred_probe_timeout for regulator_init_complete_work"
driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires
driver core: Use dev_warn() instead of dev_WARN() for deferred_probe_timeout warnings
driver core: Revert default driver_deferred_probe_timeout value to 0
component: Silence bind error on -EPROBE_DEFER
driver core: Fix handling of fw_devlink=permissive
coredump: fix crash when umh is disabled
amba: Initialize dma_parms for amba devices
driver core: platform: Initialize dma_parms for platform devices
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Merge misc fixes from Andrew Morton:
"14 fixes and one selftest to verify the ipc fixes herein"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
mm: limit boost_watermark on small zones
ubsan: disable UBSAN_ALIGNMENT under COMPILE_TEST
mm/vmscan: remove unnecessary argument description of isolate_lru_pages()
epoll: atomically remove wait entry on wake up
kselftests: introduce new epoll60 testcase for catching lost wakeups
percpu: make pcpu_alloc() aware of current gfp context
mm/slub: fix incorrect interpretation of s->offset
scripts/gdb: repair rb_first() and rb_last()
eventpoll: fix missing wakeup for ovflist in ep_poll_callback
arch/x86/kvm/svm/sev.c: change flag passed to GUP fast in sev_pin_memory()
scripts/decodecode: fix trapping instruction formatting
kernel/kcov.c: fix typos in kcov_remote_start documentation
mm/page_alloc: fix watchdog soft lockups during set_zone_contiguous()
mm, memcg: fix error return value of mem_cgroup_css_alloc()
ipc/mqueue.c: change __do_notify() to bypass check_kill_permission()
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Jan reported an issue where an interaction between sign-extending clone's
flag argument on ppc64le and the new CLONE_INTO_CGROUP feature causes
clone() to consistently fail with EBADF.
The whole story is a little longer. The legacy clone() syscall is odd in a
bunch of ways and here two things interact. First, legacy clone's flag
argument is word-size dependent, i.e. it's an unsigned long whereas most
system calls with flag arguments use int or unsigned int. Second, legacy
clone() ignores unknown and deprecated flags. The two of them taken
together means that users on 64bit systems can pass garbage for the upper
32bit of the clone() syscall since forever and things would just work fine.
Just try this on a 64bit kernel prior to v5.7-rc1 where this will succeed
and on v5.7-rc1 where this will fail with EBADF:
int main(int argc, char *argv[])
{
pid_t pid;
/* Note that legacy clone() has different argument ordering on
* different architectures so this won't work everywhere.
*
* Only set the upper 32 bits.
*/
pid = syscall(__NR_clone, 0xffffffff00000000 | SIGCHLD,
NULL, NULL, NULL, NULL);
if (pid < 0)
exit(EXIT_FAILURE);
if (pid == 0)
exit(EXIT_SUCCESS);
if (wait(NULL) != pid)
exit(EXIT_FAILURE);
exit(EXIT_SUCCESS);
}
Since legacy clone() couldn't be extended this was not a problem so far and
nobody really noticed or cared since nothing in the kernel ever bothered to
look at the upper 32 bits.
But once we introduced clone3() and expanded the flag argument in struct
clone_args to 64 bit we opened this can of worms. With the first flag-based
extension to clone3() making use of the upper 32 bits of the flag argument
we've effectively made it possible for the legacy clone() syscall to reach
clone3() only flags. The sign extension scenario is just the odd
corner-case that we needed to figure this out.
The reason we just realized this now and not already when we introduced
CLONE_CLEAR_SIGHAND was that CLONE_INTO_CGROUP assumes that a valid cgroup
file descriptor has been given. So the sign extension (or the user
accidently passing garbage for the upper 32 bits) caused the
CLONE_INTO_CGROUP bit to be raised and the kernel to error out when it
didn't find a valid cgroup file descriptor.
Let's fix this by always capping the upper 32 bits for all codepaths that
are not aware of clone3() features. This ensures that we can't reach
clone3() only features by accident via legacy clone as with the sign
extension case and also that legacy clone() works exactly like before, i.e.
ignoring any unknown flags. This solution risks no regressions and is also
pretty clean.
Fixes: 7f192e3cd316 ("fork: add clone3")
Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups")
Reported-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Cc: Florian Weimer <fw@deneb.enyo.de>
Cc: libc-alpha@sourceware.org
Cc: stable@vger.kernel.org # 5.3+
Link: https://sourceware.org/pipermail/libc-alpha/2020-May/113596.html
Link: https://lore.kernel.org/r/20200507103214.77218-1-christian.brauner@ubuntu.com
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Signed-off-by: Maciej Grochowski <maciej.grochowski@pm.me>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Link: http://lkml.kernel.org/r/20200420030259.31674-1-maciek.grochowski@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
- Fix bootconfig causing kernels to fail with CONFIG_BLK_DEV_RAM
enabled
- Fix allocation leaks in bootconfig tool
- Fix a double initialization of a variable
- Fix API bootconfig usage from kprobe boot time events
- Reject NULL location for kprobes
- Fix crash caused by preempt delay module not cleaning up kthread
correctly
- Add vmalloc_sync_mappings() to prevent x86_64 page faults from
recursively faulting from tracing page faults
- Fix comment in gpu/trace kerneldoc header
- Fix documentation of how to create a trace event class
- Make the local tracing_snapshot_instance_cond() function static
* tag 'trace-v5.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tools/bootconfig: Fix resource leak in apply_xbc()
tracing: Make tracing_snapshot_instance_cond() static
tracing: Fix doc mistakes in trace sample
gpu/trace: Minor comment updates for gpu_mem_total tracepoint
tracing: Add a vmalloc_sync_mappings() for safe measure
tracing: Wait for preempt irq delay thread to finish
tracing/kprobes: Reject new event if loc is NULL
tracing/boottime: Fix kprobe event API usage
tracing/kprobes: Fix a double initialization typo
bootconfig: Fix to remove bootconfig data from initrd while boot
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Fix the following sparse warning:
kernel/trace/trace.c:950:6: warning: symbol 'tracing_snapshot_instance_cond'
was not declared. Should it be static?
Link: http://lkml.kernel.org/r/1587614905-48692-1-git-send-email-zou_wei@huawei.com
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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x86_64 lazily maps in the vmalloc pages, and the way this works with per_cpu
areas can be complex, to say the least. Mappings may happen at boot up, and
if nothing synchronizes the page tables, those page mappings may not be
synced till they are used. This causes issues for anything that might touch
one of those mappings in the path of the page fault handler. When one of
those unmapped mappings is touched in the page fault handler, it will cause
another page fault, which in turn will cause a page fault, and leave us in
a loop of page faults.
Commit 763802b53a42 ("x86/mm: split vmalloc_sync_all()") split
vmalloc_sync_all() into vmalloc_sync_unmappings() and
vmalloc_sync_mappings(), as on system exit, it did not need to do a full
sync on x86_64 (although it still needed to be done on x86_32). By chance,
the vmalloc_sync_all() would synchronize the page mappings done at boot up
and prevent the per cpu area from being a problem for tracing in the page
fault handler. But when that synchronization in the exit of a task became a
nop, it caused the problem to appear.
Link: https://lore.kernel.org/r/20200429054857.66e8e333@oasis.local.home
Cc: stable@vger.kernel.org
Fixes: 737223fbca3b1 ("tracing: Consolidate buffer allocation code")
Reported-by: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
Suggested-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Running on a slower machine, it is possible that the preempt delay kernel
thread may still be executing if the module was immediately removed after
added, and this can cause the kernel to crash as the kernel thread might be
executing after its code has been removed.
There's no reason that the caller of the code shouldn't just wait for the
delay thread to finish, as the thread can also be created by a trigger in
the sysfs code, which also has the same issues.
Link: http://lore.kernel.org/r/5EA2B0C8.2080706@cn.fujitsu.com
Cc: stable@vger.kernel.org
Fixes: 793937236d1ee ("lib: Add module for testing preemptoff/irqsoff latency tracers")
Reported-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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'rcu-tasks.2020.04.27a', 'stall.2020.04.27a' and 'torture.2020.05.07a' into HEAD
fixes.2020.04.27a: Miscellaneous fixes.
kfree_rcu.2020.04.27a: Changes related to kfree_rcu().
rcu-tasks.2020.04.27a: Addition of new RCU-tasks flavors.
stall.2020.04.27a: RCU CPU stall-warning updates.
torture.2020.05.07a: Torture-test updates.
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This commit converts three ULONG_CMP_LT() invocations in rcutorture to
time_before() to reflect the fact that they are comparing timestamps to
the jiffies counter.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit fixes the following sparse warning:
kernel/rcu/rcutorture.c:1695:16: warning: symbol 'rcu_fwds' was not declared. Should it be static?
kernel/rcu/rcutorture.c:1696:6: warning: symbol 'rcu_fwd_emergency_stop' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit provides an rcutorture.stall_gp_kthread module parameter
to allow rcutorture to starve the grace-period kthread. This allows
testing the code that detects such starvation.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit aids testing of RCU task stall warning messages by adding
an rcutorture.stall_cpu_block module parameter that results in the
induced stall sleeping within the RCU read-side critical section.
Spinning with interrupts disabled is still available via the
rcutorture.stall_cpu_irqsoff module parameter, and specifying neither
of these two module parameters will spin with preemption disabled.
Note that sleeping (as opposed to preemption) results in additional
complaints from RCU at context-switch time, so yet more testing.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Reject the new event which has NULL location for kprobes.
For kprobes, user must specify at least the location.
Link: http://lkml.kernel.org/r/158779376597.6082.1411212055469099461.stgit@devnote2
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 2a588dd1d5d6 ("tracing: Add kprobe event command generation functions")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Fix boottime kprobe events to use API correctly for
multiple events.
For example, when we set a multiprobe kprobe events in
bootconfig like below,
ftrace.event.kprobes.myevent {
probes = "vfs_read $arg1 $arg2", "vfs_write $arg1 $arg2"
}
This cause an error;
trace_boot: Failed to add probe: p:kprobes/myevent (null) vfs_read $arg1 $arg2 vfs_write $arg1 $arg2
This shows the 1st argument becomes NULL and multiprobes
are merged to 1 probe.
Link: http://lkml.kernel.org/r/158779375766.6082.201939936008972838.stgit@devnote2
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 29a154810546 ("tracing: Change trace_boot to use kprobe_event interface")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Fix a typo that resulted in an unnecessary double
initialization to addr.
Link: http://lkml.kernel.org/r/158779374968.6082.2337484008464939919.stgit@devnote2
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Fixes: c7411a1a126f ("tracing/kprobe: Check whether the non-suffixed symbol is notrace")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Currently root_task_group.shares and cfs_bandwidth are initialized for
each online cpu, which not necessary.
Let's take it out to do it only once.
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200423214443.29994-1-richard.weiyang@gmail.com
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The code is executed with preemption(and interrupts) disabled,
so it's safe to use __this_cpu_write().
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200421144123.33580-1-songmuchun@bytedance.com
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In the CPU-offline process, it calls mmdrop() after idle entry and the
subsequent call to cpuhp_report_idle_dead(). Once execution passes the
call to rcu_report_dead(), RCU is ignoring the CPU, which results in
lockdep complaining when mmdrop() uses RCU from either memcg or
debugobjects below.
Fix it by cleaning up the active_mm state from BP instead. Every arch
which has CONFIG_HOTPLUG_CPU should have already called idle_task_exit()
from AP. The only exception is parisc because it switches them to
&init_mm unconditionally (see smp_boot_one_cpu() and smp_cpu_init()),
but the patch will still work there because it calls mmgrab(&init_mm) in
smp_cpu_init() and then should call mmdrop(&init_mm) in finish_cpu().
WARNING: suspicious RCU usage
-----------------------------
kernel/workqueue.c:710 RCU or wq_pool_mutex should be held!
other info that might help us debug this:
RCU used illegally from offline CPU!
Call Trace:
dump_stack+0xf4/0x164 (unreliable)
lockdep_rcu_suspicious+0x140/0x164
get_work_pool+0x110/0x150
__queue_work+0x1bc/0xca0
queue_work_on+0x114/0x120
css_release+0x9c/0xc0
percpu_ref_put_many+0x204/0x230
free_pcp_prepare+0x264/0x570
free_unref_page+0x38/0xf0
__mmdrop+0x21c/0x2c0
idle_task_exit+0x170/0x1b0
pnv_smp_cpu_kill_self+0x38/0x2e0
cpu_die+0x48/0x64
arch_cpu_idle_dead+0x30/0x50
do_idle+0x2f4/0x470
cpu_startup_entry+0x38/0x40
start_secondary+0x7a8/0xa80
start_secondary_resume+0x10/0x14
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Link: https://lkml.kernel.org/r/20200401214033.8448-1-cai@lca.pw
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Function sched_init_granularity() is only called from __init
functions, so mark it __init as well.
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/20200406074750.56533-1-songmuchun@bytedance.com
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In order to prevent possible hardlockup of sched_cfs_period_timer()
loop, loop count is introduced to denote whether to scale quota and
period or not. However, scale is done between forwarding period timer
and refilling cfs bandwidth runtime, which means that period timer is
forwarded with old "period" while runtime is refilled with scaled
"quota".
Move do_sched_cfs_period_timer() before scaling to solve this.
Fixes: 2e8e19226398 ("sched/fair: Limit sched_cfs_period_timer() loop to avoid hard lockup")
Signed-off-by: Huaixin Chang <changhuaixin@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/20200420024421.22442-3-changhuaixin@linux.alibaba.com
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Introduce a new function put_prev_task_balance() to do the balance
when necessary, and then put previous task back to the run queue.
This function is extracted from pick_next_task() to prepare for
future usage by other type of task picking logic.
No functional change.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/5a99860cf66293db58a397d6248bcb2eee326776.1587464698.git.yu.c.chen@intel.com
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After Commit 6e2df0581f56 ("sched: Fix pick_next_task() vs 'change'
pattern race"), there is no need to expose newidle_balance() as it
is only used within fair.c file. Change this function back to static again.
No functional change.
Reported-by: kbuild test robot <lkp@intel.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/83cd3030b031ca5d646cd5e225be10e7a0fdd8f5.1587464698.git.yu.c.chen@intel.com
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That flag is set unconditionally in sd_init(), and no one checks for it
anymore. Remove it.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200415210512.805-5-valentin.schneider@arm.com
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The SD_LOAD_BALANCE flag is set unconditionally for all domains in
sd_init(). By making the sched_domain->flags syctl interface read-only, we
have removed the last piece of code that could clear that flag - as such,
it will now be always present. Rather than to keep carrying it along, we
can work towards getting rid of it entirely.
cpusets don't need it because they can make CPUs be attached to the NULL
domain (e.g. cpuset with sched_load_balance=0), or to a partitioned
root_domain, i.e. a sched_domain hierarchy that doesn't span the entire
system (e.g. root cpuset with sched_load_balance=0 and sibling cpusets with
sched_load_balance=1).
isolcpus apply the same "trick": isolated CPUs are explicitly taken out of
the sched_domain rebuild (using housekeeping_cpumask()), so they get the
NULL domain treatment as well.
Remove the checks against SD_LOAD_BALANCE.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200415210512.805-4-valentin.schneider@arm.com
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Writing to the sysctl of a sched_domain->flags directly updates the value of
the field, and goes nowhere near update_top_cache_domain(). This means that
the cached domain pointers can end up containing stale data (e.g. the
domain pointed to doesn't have the relevant flag set anymore).
Explicit domain walks that check for flags will be affected by
the write, but this won't be in sync with the cached pointers which will
still point to the domains that were cached at the last sched_domain
build.
In other words, writing to this interface is playing a dangerous game. It
could be made to trigger an update of the cached sched_domain pointers when
written to, but this does not seem to be worth the trouble. Make it
read-only.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200415210512.805-3-valentin.schneider@arm.com
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The last use of that parameter was removed by commit
57abff067a08 ("sched/fair: Rework find_idlest_group()")
Get rid of the parameter.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20200415210512.805-2-valentin.schneider@arm.com
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With CONFIG_DEBUG_ATOMIC_SLEEP=y and CONFIG_CGROUPS=y, kernel oopses in
non-preemptible context look untidy; after the main oops, the kernel prints
a "sleeping function called from invalid context" report because
exit_signals() -> cgroup_threadgroup_change_begin() -> percpu_down_read()
can sleep, and that happens before the preempt_count_set(PREEMPT_ENABLED)
fixup.
It looks like the same thing applies to profile_task_exit() and
kcov_task_exit().
Fix it by moving the preemption fixup up and the calls to
profile_task_exit() and kcov_task_exit() down.
Fixes: 1dc0fffc48af ("sched/core: Robustify preemption leak checks")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200305220657.46800-1-jannh@google.com
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We only consider group_balance_cpu() after there is no idle
cpu. So, just do comparison before return at these two cases.
Signed-off-by: Peng Wang <rocking@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/245c792f0e580b3ca342ad61257f4c066ee0f84f.1586594833.git.rocking@linux.alibaba.com
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This is mostly a revert of commit:
baa9be4ffb55 ("sched/fair: Fix throttle_list starvation with low CFS quota")
The primary use of distribute_running was to determine whether to add
throttled entities to the head or the tail of the throttled list. Now
that we always add to the tail, we can remove this field.
The other use of distribute_running is in the slack_timer, so that we
don't start a distribution while one is already running. However, even
in the event that this race occurs, it is fine to have two distributions
running (especially now that distribute grabs the cfs_b->lock to
determine remaining quota before assigning).
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Tested-by: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/20200410225208.109717-3-joshdon@google.com
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There is a race window in which an entity begins throttling before quota
is added to the pool, but does not finish throttling until after we have
finished with distribute_cfs_runtime(). This entity is not observed by
distribute_cfs_runtime() because it was not on the throttled list at the
time that distribution was running. This race manifests as rare
period-length statlls for such entities.
Rather than heavy-weight the synchronization with the progress of
distribution, we can fix this by aborting throttling if bandwidth has
become available. Otherwise, we immediately add the entity to the
throttled list so that it can be observed by a subsequent distribution.
Additionally, we can remove the case of adding the throttled entity to
the head of the throttled list, and simply always add to the tail.
Thanks to 26a8b12747c97, distribute_cfs_runtime() no longer holds onto
its own pool of runtime. This means that if we do hit the !assign and
distribute_running case, we know that distribution is about to end.
Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/20200410225208.109717-2-joshdon@google.com
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Ensure leave one space between state and task name.
w/o patch:
runnable tasks:
S task PID tree-key switches prio wait
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200414125721.195801-1-xiexiuqi@huawei.com
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Fix to return negative error code -EFAULT from the copy_to_user() error
handling case instead of 0, as done elsewhere in this function.
Fixes: bd513cd08f10 ("bpf: add MAP_LOOKUP_AND_DELETE_ELEM syscall")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200430081851.166996-1-weiyongjun1@huawei.com
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Commit 64e90a8acb859 ("Introduce STATIC_USERMODEHELPER to mediate
call_usermodehelper()") added the optiont to disable all
call_usermodehelper() calls by setting STATIC_USERMODEHELPER_PATH to
an empty string. When this is done, and crashdump is triggered, it
will crash on null pointer dereference, since we make assumptions
over what call_usermodehelper_exec() did.
This has been reported by Sergey when one triggers a a coredump
with the following configuration:
```
CONFIG_STATIC_USERMODEHELPER=y
CONFIG_STATIC_USERMODEHELPER_PATH=""
kernel.core_pattern = |/usr/lib/systemd/systemd-coredump %P %u %g %s %t %c %h %e
```
The way disabling the umh was designed was that call_usermodehelper_exec()
would just return early, without an error. But coredump assumes
certain variables are set up for us when this happens, and calls
ile_start_write(cprm.file) with a NULL file.
[ 2.819676] BUG: kernel NULL pointer dereference, address: 0000000000000020
[ 2.819859] #PF: supervisor read access in kernel mode
[ 2.820035] #PF: error_code(0x0000) - not-present page
[ 2.820188] PGD 0 P4D 0
[ 2.820305] Oops: 0000 [#1] SMP PTI
[ 2.820436] CPU: 2 PID: 89 Comm: a Not tainted 5.7.0-rc1+ #7
[ 2.820680] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190711_202441-buildvm-armv7-10.arm.fedoraproject.org-2.fc31 04/01/2014
[ 2.821150] RIP: 0010:do_coredump+0xd80/0x1060
[ 2.821385] Code: e8 95 11 ed ff 48 c7 c6 cc a7 b4 81 48 8d bd 28 ff
ff ff 89 c2 e8 70 f1 ff ff 41 89 c2 85 c0 0f 84 72 f7 ff ff e9 b4 fe ff
ff <48> 8b 57 20 0f b7 02 66 25 00 f0 66 3d 00 8
0 0f 84 9c 01 00 00 44
[ 2.822014] RSP: 0000:ffffc9000029bcb8 EFLAGS: 00010246
[ 2.822339] RAX: 0000000000000000 RBX: ffff88803f860000 RCX: 000000000000000a
[ 2.822746] RDX: 0000000000000009 RSI: 0000000000000282 RDI: 0000000000000000
[ 2.823141] RBP: ffffc9000029bde8 R08: 0000000000000000 R09: ffffc9000029bc00
[ 2.823508] R10: 0000000000000001 R11: ffff88803dec90be R12: ffffffff81c39da0
[ 2.823902] R13: ffff88803de84400 R14: 0000000000000000 R15: 0000000000000000
[ 2.824285] FS: 00007fee08183540(0000) GS:ffff88803e480000(0000) knlGS:0000000000000000
[ 2.824767] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2.825111] CR2: 0000000000000020 CR3: 000000003f856005 CR4: 0000000000060ea0
[ 2.825479] Call Trace:
[ 2.825790] get_signal+0x11e/0x720
[ 2.826087] do_signal+0x1d/0x670
[ 2.826361] ? force_sig_info_to_task+0xc1/0xf0
[ 2.826691] ? force_sig_fault+0x3c/0x40
[ 2.826996] ? do_trap+0xc9/0x100
[ 2.827179] exit_to_usermode_loop+0x49/0x90
[ 2.827359] prepare_exit_to_usermode+0x77/0xb0
[ 2.827559] ? invalid_op+0xa/0x30
[ 2.827747] ret_from_intr+0x20/0x20
[ 2.827921] RIP: 0033:0x55e2c76d2129
[ 2.828107] Code: 2d ff ff ff e8 68 ff ff ff 5d c6 05 18 2f 00 00 01
c3 0f 1f 80 00 00 00 00 c3 0f 1f 80 00 00 00 00 e9 7b ff ff ff 55 48 89
e5 <0f> 0b b8 00 00 00 00 5d c3 66 2e 0f 1f 84 0
0 00 00 00 00 0f 1f 40
[ 2.828603] RSP: 002b:00007fffeba5e080 EFLAGS: 00010246
[ 2.828801] RAX: 000055e2c76d2125 RBX: 0000000000000000 RCX: 00007fee0817c718
[ 2.829034] RDX: 00007fffeba5e188 RSI: 00007fffeba5e178 RDI: 0000000000000001
[ 2.829257] RBP: 00007fffeba5e080 R08: 0000000000000000 R09: 00007fee08193c00
[ 2.829482] R10: 0000000000000009 R11: 0000000000000000 R12: 000055e2c76d2040
[ 2.829727] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[ 2.829964] CR2: 0000000000000020
[ 2.830149] ---[ end trace ceed83d8c68a1bf1 ]---
```
Cc: <stable@vger.kernel.org> # v4.11+
Fixes: 64e90a8acb85 ("Introduce STATIC_USERMODEHELPER to mediate call_usermodehelper()")
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=199795
Reported-by: Tony Vroon <chainsaw@gentoo.org>
Reported-by: Sergey Kvachonok <ravenexp@gmail.com>
Tested-by: Sergei Trofimovich <slyfox@gentoo.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20200416162859.26518-1-mcgrof@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The n_barrier_successes, n_barrier_attempts, and
n_rcu_torture_barrier_error variables are updated (without access
markings) by the main rcu_barrier() test kthread, and accessed (also
without access markings) by the rcu_torture_stats() kthread. This of
course can result in KCSAN complaints.
Because the accesses are in diagnostic prints, this commit uses
data_race() to excuse the diagnostic prints from the data race. If this
were to ever cause bogus statistics prints (for example, due to store
tearing), any misleading information would be disambiguated by the
presence or absence of an rcutorture splat.
This data race was reported by KCSAN. Not appropriate for backporting
due to failure being unlikely and due to the mild consequences of the
failure, namely a confusing rcutorture console message.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
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This commit adds stubs for KCSAN's data_race(), ASSERT_EXCLUSIVE_WRITER(),
and ASSERT_EXCLUSIVE_ACCESS() macros to allow code using these macros to
move ahead.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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When all quiescent states have been seen, it is normally the grace-period
kthread that is in trouble. Although the existing stack trace from
the current CPU might possibly provide useful information, experience
indicates that there is too much noise for this to be worthwhile.
This commit therefore removes this stack trace from the output.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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If the grace-period kthread is starved, idle threads' extended quiescent
states are not reported. These idle threads thus wrongly appear to
be blocking the current grace period. This commit therefore tags such
idle threads as probable false positives when the grace-period kthread
is being starved.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Although the accesses used to determine whether or not an expedited
stall should be printed are an integral part of the concurrency algorithm
governing use of the corresponding variables, the values that are simply
printed are ancillary. As such, it is best to use data_race() for these
accesses in order to provide the greatest latitude in the use of KCSAN
for the other accesses that are an integral part of the algorithm. This
commit therefore changes the relevant uses of READ_ONCE() to data_race().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit replaces the schedule_on_each_cpu(ftrace_sync) instances
with synchronize_rcu_tasks_rude().
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
[ paulmck: Make Kconfig adjustments noted by kbuild test robot. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit allows TASKS_TRACE_RCU to be used independently of TASKS_RCU
and vice versa.
[ paulmck: Fix conditional compilation per kbuild test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds a failure-return count for smp_call_function_single(),
and adds this to the console messages for rcutorture writer stalls and at
the end of rcutorture testing.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds a counter for the number of times the quiescent state
was an idle task associated with an offline CPU, and prints this count
at the end of rcutorture runs and at stall time.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds counts of the number of calls and number of successful
calls to rcu_dynticks_zero_in_eqs(), which are printed at the end
of rcutorture runs and at stall time. This allows evaluation of the
effectiveness of rcu_dynticks_zero_in_eqs().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit scans the CPUs, adding each CPU's idle task to the list of
tasks that need quiescent states.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The idle task corresponding to an offline CPU can appear to be running
while that CPU is offline. This commit therefore adds checks for this
situation, treating it as a quiescent state. Because the tasklist scan
and the holdout-list scan now exclude CPU-hotplug operations, readers
on the CPU-hotplug paths are still waited for.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit disables CPU hotplug across RCU tasks trace scans, which
is a first step towards correctly recognizing idle tasks "running" on
offline CPUs.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_read_unlock_trace() can invoke rcu_read_unlock_trace_special(),
which in turn can call wake_up(). Therefore, if any scheduler lock is
held across a call to rcu_read_unlock_trace(), self-deadlock can occur.
This commit therefore uses the irq_work facility to defer the wake_up()
to a clean environment where no scheduler locks will be held.
Reported-by: Steven Rostedt <rostedt@goodmis.org>
[ paulmck: Update #includes for m68k per kbuild test robot. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Systems running CPU-bound real-time task do not want IPIs sent to CPUs
executing nohz_full userspace tasks. Battery-powered systems don't
want IPIs sent to idle CPUs in low-power mode. Unfortunately, RCU tasks
trace can and will send such IPIs in some cases.
Both of these situations occur only when the target CPU is in RCU
dyntick-idle mode, in other words, when RCU is not watching the
target CPU. This suggests that CPUs in dyntick-idle mode should use
memory barriers in outermost invocations of rcu_read_lock_trace()
and rcu_read_unlock_trace(), which would allow the RCU tasks trace
grace period to directly read out the target CPU's read-side state.
One challenge is that RCU tasks trace is not targeting a specific
CPU, but rather a task. And that task could switch from one CPU to
another at any time.
This commit therefore uses try_invoke_on_locked_down_task()
and checks for task_curr() in trc_inspect_reader_notrunning().
When this condition holds, the target task is running and cannot move.
If CONFIG_TASKS_TRACE_RCU_READ_MB=y, the new rcu_dynticks_zero_in_eqs()
function can be used to check if the specified integer (in this case,
t->trc_reader_nesting) is zero while the target CPU remains in that same
dyntick-idle sojourn. If so, the target task is in a quiescent state.
If not, trc_read_check_handler() must indicate failure so that the
grace-period kthread can take appropriate action or retry after an
appropriate delay, as the case may be.
With this change, given CONFIG_TASKS_TRACE_RCU_READ_MB=y, if a given
CPU remains idle or a given task continues executing in nohz_full mode,
the RCU tasks trace grace-period kthread will detect this without the
need to send an IPI.
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit provides a new TASKS_TRACE_RCU_READ_MB Kconfig option that
enables use of read-side memory barriers by both rcu_read_lock_trace()
and rcu_read_unlock_trace() when the are executed with the
current->trc_reader_special.b.need_mb flag set. This flag is currently
never set. Doing that is the subject of a later commit.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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