linux-stable.git/kernel, branch v5.0.8

sched/fair: Do not re-read ->h_load_next during hierarchical load calculation

2019-04-17T06:39:52+00:00

commit 0e9f02450da07fc7b1346c8c32c771555173e397 upstream.

A NULL pointer dereference bug was reported on a distribution kernel but
the same issue should be present on mainline kernel. It occured on s390
but should not be arch-specific.  A partial oops looks like:

  Unable to handle kernel pointer dereference in virtual kernel address space
  ...
  Call Trace:
    ...
    try_to_wake_up+0xfc/0x450
    vhost_poll_wakeup+0x3a/0x50 [vhost]
    __wake_up_common+0xbc/0x178
    __wake_up_common_lock+0x9e/0x160
    __wake_up_sync_key+0x4e/0x60
    sock_def_readable+0x5e/0x98

The bug hits any time between 1 hour to 3 days. The dereference occurs
in update_cfs_rq_h_load when accumulating h_load. The problem is that
cfq_rq->h_load_next is not protected by any locking and can be updated
by parallel calls to task_h_load. Depending on the compiler, code may be
generated that re-reads cfq_rq->h_load_next after the check for NULL and
then oops when reading se->avg.load_avg. The dissassembly showed that it
was possible to reread h_load_next after the check for NULL.

While this does not appear to be an issue for later compilers, it's still
an accident if the correct code is generated. Full locking in this path
would have high overhead so this patch uses READ_ONCE to read h_load_next
only once and check for NULL before dereferencing. It was confirmed that
there were no further oops after 10 days of testing.

As Peter pointed out, it is also necessary to use WRITE_ONCE() to avoid any
potential problems with store tearing.

Signed-off-by: Mel Gorman 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Valentin Schneider 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: 
Fixes: 685207963be9 ("sched: Move h_load calculation to task_h_load()")
Link: https://lkml.kernel.org/r/20190319123610.nsivgf3mjbjjesxb@techsingularity.net
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

genirq: Initialize request_mutex if CONFIG_SPARSE_IRQ=n

2019-04-17T06:39:50+00:00

commit e8458e7afa855317b14915d7b86ab3caceea7eb6 upstream.

When CONFIG_SPARSE_IRQ is disable, the request_mutex in struct irq_desc
is not initialized which causes malfunction.

Fixes: 9114014cf4e6 ("genirq: Add mutex to irq desc to serialize request/free_irq()")
Signed-off-by: Kefeng Wang 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Mukesh Ojha 
Cc: Marc Zyngier 
Cc: 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190404074512.145533-1-wangkefeng.wang@huawei.com
Signed-off-by: Greg Kroah-Hartman

genirq: Respect IRQCHIP_SKIP_SET_WAKE in irq_chip_set_wake_parent()

2019-04-17T06:39:50+00:00

commit 325aa19598e410672175ed50982f902d4e3f31c5 upstream.

If a child irqchip calls irq_chip_set_wake_parent() but its parent irqchip
has the IRQCHIP_SKIP_SET_WAKE flag set an error is returned.

This is inconsistent behaviour vs. set_irq_wake_real() which returns 0 when
the irqchip has the IRQCHIP_SKIP_SET_WAKE flag set. It doesn't attempt to
walk the chain of parents and set irq wake on any chips that don't have the
flag set either. If the intent is to call the .irq_set_wake() callback of
the parent irqchip, then we expect irqchip implementations to omit the
IRQCHIP_SKIP_SET_WAKE flag and implement an .irq_set_wake() function that
calls irq_chip_set_wake_parent().

The problem has been observed on a Qualcomm sdm845 device where set wake
fails on any GPIO interrupts after applying work in progress wakeup irq
patches to the GPIO driver. The chain of chips looks like this:

     QCOM GPIO -> QCOM PDC (SKIP) -> ARM GIC (SKIP)

The GPIO controllers parent is the QCOM PDC irqchip which in turn has ARM
GIC as parent.  The QCOM PDC irqchip has the IRQCHIP_SKIP_SET_WAKE flag
set, and so does the grandparent ARM GIC.

The GPIO driver doesn't know if the parent needs to set wake or not, so it
unconditionally calls irq_chip_set_wake_parent() causing this function to
return a failure because the parent irqchip (PDC) doesn't have the
.irq_set_wake() callback set. Returning 0 instead makes everything work and
irqs from the GPIO controller can be configured for wakeup.

Make it consistent by returning 0 (success) from irq_chip_set_wake_parent()
when a parent chip has IRQCHIP_SKIP_SET_WAKE set.

[ tglx: Massaged changelog ]

Fixes: 08b55e2a9208e ("genirq: Add irqchip_set_wake_parent")
Signed-off-by: Stephen Boyd 
Signed-off-by: Thomas Gleixner 
Acked-by: Marc Zyngier 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-gpio@vger.kernel.org
Cc: Lina Iyer 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190325181026.247796-1-swboyd@chromium.org
Signed-off-by: Greg Kroah-Hartman

alarmtimer: Return correct remaining time

2019-04-17T06:39:48+00:00

commit 07d7e12091f4ab869cc6a4bb276399057e73b0b3 upstream.

To calculate a remaining time, it's required to subtract the current time
from the expiration time. In alarm_timer_remaining() the arguments of
ktime_sub are swapped.

Fixes: d653d8457c76 ("alarmtimer: Implement remaining callback")
Signed-off-by: Andrei Vagin 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Mukesh Ojha 
Cc: Stephen Boyd 
Cc: John Stultz 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190408041542.26338-1-avagin@gmail.com
Signed-off-by: Greg Kroah-Hartman

audit: hand taken context to audit_kill_trees for syscall logging

2019-04-05T20:34:51+00:00

[ Upstream commit 9e36a5d49c3a6fc4a2e0ba2dc11b27c4a8ae6303 ]

Since the context is derived from the task parameter handed to
__audit_free(), hand the context to audit_kill_trees() so it can be used
to associate with a syscall record.  This requires adding the context
parameter to kill_rules() rather than using the current audit_context.

The callers of trim_marked() and evict_chunk() still have their context.

The EOE record was being issued prior to the pruning of the killed_tree
list.

Move the kill_trees call before the audit_log_exit call in
__audit_free() and __audit_syscall_exit() so that any pruned trees
CONFIG_CHANGE records are included with the associated syscall event by
the user library due to the EOE record flagging the end of the event.

See: https://github.com/linux-audit/audit-kernel/issues/50
See: https://github.com/linux-audit/audit-kernel/issues/59

Signed-off-by: Richard Guy Briggs 
[PM: fixed merge fuzz in kernel/audit_tree.c]
Signed-off-by: Paul Moore 
Signed-off-by: Sasha Levin

cpu/hotplug: Mute hotplug lockdep during init

2019-04-05T20:34:49+00:00

[ Upstream commit ce48c457b95316b9a01b5aa9d4456ce820df94b4 ]

Since we've had:

  commit cb538267ea1e ("jump_label/lockdep: Assert we hold the hotplug lock for _cpuslocked() operations")

we've been getting some lockdep warnings during init, such as on HiKey960:

[    0.820495] WARNING: CPU: 4 PID: 0 at kernel/cpu.c:316 lockdep_assert_cpus_held+0x3c/0x48
[    0.820498] Modules linked in:
[    0.820509] CPU: 4 PID: 0 Comm: swapper/4 Tainted: G S                4.20.0-rc5-00051-g4cae42a #34
[    0.820511] Hardware name: HiKey960 (DT)
[    0.820516] pstate: 600001c5 (nZCv dAIF -PAN -UAO)
[    0.820520] pc : lockdep_assert_cpus_held+0x3c/0x48
[    0.820523] lr : lockdep_assert_cpus_held+0x38/0x48
[    0.820526] sp : ffff00000a9cbe50
[    0.820528] x29: ffff00000a9cbe50 x28: 0000000000000000
[    0.820533] x27: 00008000b69e5000 x26: ffff8000bff4cfe0
[    0.820537] x25: ffff000008ba69e0 x24: 0000000000000001
[    0.820541] x23: ffff000008fce000 x22: ffff000008ba70c8
[    0.820545] x21: 0000000000000001 x20: 0000000000000003
[    0.820548] x19: ffff00000a35d628 x18: ffffffffffffffff
[    0.820552] x17: 0000000000000000 x16: 0000000000000000
[    0.820556] x15: ffff00000958f848 x14: 455f3052464d4d34
[    0.820559] x13: 00000000769dde98 x12: ffff8000bf3f65a8
[    0.820564] x11: 0000000000000000 x10: ffff00000958f848
[    0.820567] x9 : ffff000009592000 x8 : ffff00000958f848
[    0.820571] x7 : ffff00000818ffa0 x6 : 0000000000000000
[    0.820574] x5 : 0000000000000000 x4 : 0000000000000001
[    0.820578] x3 : 0000000000000000 x2 : 0000000000000001
[    0.820582] x1 : 00000000ffffffff x0 : 0000000000000000
[    0.820587] Call trace:
[    0.820591]  lockdep_assert_cpus_held+0x3c/0x48
[    0.820598]  static_key_enable_cpuslocked+0x28/0xd0
[    0.820606]  arch_timer_check_ool_workaround+0xe8/0x228
[    0.820610]  arch_timer_starting_cpu+0xe4/0x2d8
[    0.820615]  cpuhp_invoke_callback+0xe8/0xd08
[    0.820619]  notify_cpu_starting+0x80/0xb8
[    0.820625]  secondary_start_kernel+0x118/0x1d0

We've also had a similar warning in sched_init_smp() for every
asymmetric system that would enable the sched_asym_cpucapacity static
key, although that was singled out in:

  commit 40fa3780bac2 ("sched/core: Take the hotplug lock in sched_init_smp()")

Those warnings are actually harmless, since we cannot have hotplug
operations at the time they appear. Instead of starting to sprinkle
useless hotplug lock operations in the init codepaths, mute the
warnings until they start warning about real problems.

Suggested-by: Peter Zijlstra 
Signed-off-by: Valentin Schneider 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: cai@gmx.us
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: longman@redhat.com
Cc: marc.zyngier@arm.com
Cc: mark.rutland@arm.com
Link: https://lkml.kernel.org/r/1545243796-23224-2-git-send-email-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

cgroup/pids: turn cgroup_subsys->free() into cgroup_subsys->release() to fix the accounting

2019-04-05T20:34:46+00:00

[ Upstream commit 51bee5abeab2058ea5813c5615d6197a23dbf041 ]

The only user of cgroup_subsys->free() callback is pids_cgrp_subsys which
needs pids_free() to uncharge the pid.

However, ->free() is called from __put_task_struct()->cgroup_free() and this
is too late. Even the trivial program which does

	for (;;) {
		int pid = fork();
		assert(pid >= 0);
		if (pid)
			wait(NULL);
		else
			exit(0);
	}

can run out of limits because release_task()->call_rcu(delayed_put_task_struct)
implies an RCU gp after the task/pid goes away and before the final put().

Test-case:

	mkdir -p /tmp/CG
	mount -t cgroup2 none /tmp/CG
	echo '+pids' > /tmp/CG/cgroup.subtree_control

	mkdir /tmp/CG/PID
	echo 2 > /tmp/CG/PID/pids.max

	perl -e 'while ($p = fork) { wait; } $p // die "fork failed: $!\n"' &
	echo $! > /tmp/CG/PID/cgroup.procs

Without this patch the forking process fails soon after migration.

Rename cgroup_subsys->free() to cgroup_subsys->release() and move the callsite
into the new helper, cgroup_release(), called by release_task() which actually
frees the pid(s).

Reported-by: Herton R. Krzesinski 
Reported-by: Jan Stancek 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Tejun Heo 
Signed-off-by: Sasha Levin

sched/core: Use READ_ONCE()/WRITE_ONCE() in move_queued_task()/task_rq_lock()

2019-04-05T20:34:43+00:00

[ Upstream commit c546951d9c9300065bad253ecdf1ac59ce9d06c8 ]

move_queued_task() synchronizes with task_rq_lock() as follows:

	move_queued_task()		task_rq_lock()

	[S] ->on_rq = MIGRATING		[L] rq = task_rq()
	WMB (__set_task_cpu())		ACQUIRE (rq->lock);
	[S] ->cpu = new_cpu		[L] ->on_rq

where "[L] rq = task_rq()" is ordered before "ACQUIRE (rq->lock)" by an
address dependency and, in turn, "ACQUIRE (rq->lock)" is ordered before
"[L] ->on_rq" by the ACQUIRE itself.

Use READ_ONCE() to load ->cpu in task_rq() (c.f., task_cpu()) to honor
this address dependency.  Also, mark the accesses to ->cpu and ->on_rq
with READ_ONCE()/WRITE_ONCE() to comply with the LKMM.

Signed-off-by: Andrea Parri 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alan Stern 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Link: https://lkml.kernel.org/r/20190121155240.27173-1-andrea.parri@amarulasolutions.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

sched/debug: Initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK

2019-04-05T20:34:43+00:00

[ Upstream commit 1ca4fa3ab604734e38e2a3000c9abf788512ffa7 ]

register_sched_domain_sysctl() copies the cpu_possible_mask into
sd_sysctl_cpus, but only if sd_sysctl_cpus hasn't already been
allocated (ie, CONFIG_CPUMASK_OFFSTACK is set).  However, when
CONFIG_CPUMASK_OFFSTACK is not set, sd_sysctl_cpus is left
uninitialized (all zeroes) and the kernel may fail to initialize
sched_domain sysctl entries for all possible CPUs.

This is visible to the user if the kernel is booted with maxcpus=n, or
if ACPI tables have been modified to leave CPUs offline, and then
checking for missing /proc/sys/kernel/sched_domain/cpu* entries.

Fix this by separating the allocation and initialization, and adding a
flag to initialize the possible CPU entries while system booting only.

Tested-by: Syuuichirou Ishii 
Tested-by: Tarumizu, Kohei 
Signed-off-by: Hidetoshi Seto 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Masayoshi Mizuma 
Acked-by: Joe Lawrence 
Cc: Linus Torvalds 
Cc: Masayoshi Mizuma 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: https://lkml.kernel.org/r/20190129151245.5073-1-msys.mizuma@gmail.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

perf/aux: Make perf_event accessible to setup_aux()

2019-04-05T20:34:42+00:00

[ Upstream commit 840018668ce2d96783356204ff282d6c9b0e5f66 ]

When pmu::setup_aux() is called the coresight PMU needs to know which
sink to use for the session by looking up the information in the
event's attr::config2 field.

As such simply replace the cpu information by the complete perf_event
structure and change all affected customers.

Signed-off-by: Mathieu Poirier 
Reviewed-by: Suzuki Poulouse 
Acked-by: Peter Zijlstra 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Alexei Starovoitov 
Cc: Greg Kroah-Hartman 
Cc: H. Peter Anvin 
Cc: Heiko Carstens 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Martin Schwidefsky 
Cc: Namhyung Kim 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Link: http://lkml.kernel.org/r/20190131184714.20388-2-mathieu.poirier@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin