linux-stable.git/kernel, branch v4.4.196

alarmtimer: Use EOPNOTSUPP instead of ENOTSUPP

2019-10-05T10:27:53+00:00

commit f18ddc13af981ce3c7b7f26925f099e7c6929aba upstream.

ENOTSUPP is not supposed to be returned to userspace. This was found on an
OpenPower machine, where the RTC does not support set_alarm.

On that system, a clock_nanosleep(CLOCK_REALTIME_ALARM, ...) results in
"524 Unknown error 524"

Replace it with EOPNOTSUPP which results in the expected "95 Operation not
supported" error.

Fixes: 1c6b39ad3f01 (alarmtimers: Return -ENOTSUPP if no RTC device is present)
Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Thomas Gleixner 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190903171802.28314-1-cascardo@canonical.com
Signed-off-by: Greg Kroah-Hartman

printk: Do not lose last line in kmsg buffer dump

2019-10-05T10:27:51+00:00

[ Upstream commit b46eff55ad5bd98e746c0a7022fe7ee071de5fee ]

kmsg_dump_get_buffer() is supposed to select all the youngest log
messages which fit into the provided buffer.  It determines the correct
start index by using msg_print_text() with a NULL buffer to calculate
the size of each entry.  However, when performing the actual writes,
msg_print_text() only writes the entry to the buffer if the written len
is lesser than the size of the buffer.  So if the lengths of the
selected youngest log messages happen to precisely fill up the provided
buffer, the last log message is not included.

We don't want to modify msg_print_text() to fill up the buffer and start
returning a length which is equal to the size of the buffer, since
callers of its other users, such as kmsg_dump_get_line(), depend upon
the current behaviour.

Instead, fix kmsg_dump_get_buffer() to compensate for this.

For example, with the following two final prints:

[    6.427502] AAAAAAAAAAAAA
[    6.427769] BBBBBBBB12345

A dump of a 64-byte buffer filled by kmsg_dump_get_buffer(), before this
patch:

 00000000: 3c 30 3e 5b 20 20 20 20 36 2e 35 32 32 31 39 37  <0>[    6.522197
 00000010: 5d 20 41 41 41 41 41 41 41 41 41 41 41 41 41 0a  ] AAAAAAAAAAAAA.
 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................

After this patch:

 00000000: 3c 30 3e 5b 20 20 20 20 36 2e 34 35 36 36 37 38  <0>[    6.456678
 00000010: 5d 20 42 42 42 42 42 42 42 42 31 32 33 34 35 0a  ] BBBBBBBB12345.
 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................

Link: http://lkml.kernel.org/r/20190711142937.4083-1-vincent.whitchurch@axis.com
Fixes: e2ae715d66bf4bec ("kmsg - kmsg_dump() use iterator to receive log buffer content")
To: rostedt@goodmis.org
Cc: linux-kernel@vger.kernel.org
Cc:  # v3.5+
Signed-off-by: Vincent Whitchurch 
Reviewed-by: Sergey Senozhatsky 
Signed-off-by: Petr Mladek 
Signed-off-by: Sasha Levin

kprobes: Prohibit probing on BUG() and WARN() address

2019-10-05T10:27:50+00:00

[ Upstream commit e336b4027775cb458dc713745e526fa1a1996b2a ]

Since BUG() and WARN() may use a trap (e.g. UD2 on x86) to
get the address where the BUG() has occurred, kprobes can not
do single-step out-of-line that instruction. So prohibit
probing on such address.

Without this fix, if someone put a kprobe on WARN(), the
kernel will crash with invalid opcode error instead of
outputing warning message, because kernel can not find
correct bug address.

Signed-off-by: Masami Hiramatsu 
Acked-by: Steven Rostedt (VMware) 
Acked-by: Naveen N. Rao 
Cc: Anil S Keshavamurthy 
Cc: David S . Miller 
Cc: Linus Torvalds 
Cc: Naveen N . Rao 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Link: https://lkml.kernel.org/r/156750890133.19112.3393666300746167111.stgit@devnote2
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

sched/core: Fix CPU controller for !RT_GROUP_SCHED

2019-10-05T10:27:45+00:00

[ Upstream commit a07db5c0865799ebed1f88be0df50c581fb65029 ]

On !CONFIG_RT_GROUP_SCHED configurations it is currently not possible to
move RT tasks between cgroups to which CPU controller has been attached;
but it is oddly possible to first move tasks around and then make them
RT (setschedule to FIFO/RR).

E.g.:

  # mkdir /sys/fs/cgroup/cpu,cpuacct/group1
  # chrt -fp 10 $$
  # echo $$ > /sys/fs/cgroup/cpu,cpuacct/group1/tasks
  bash: echo: write error: Invalid argument
  # chrt -op 0 $$
  # echo $$ > /sys/fs/cgroup/cpu,cpuacct/group1/tasks
  # chrt -fp 10 $$
  # cat /sys/fs/cgroup/cpu,cpuacct/group1/tasks
  2345
  2598
  # chrt -p 2345
  pid 2345's current scheduling policy: SCHED_FIFO
  pid 2345's current scheduling priority: 10

Also, as Michal noted, it is currently not possible to enable CPU
controller on unified hierarchy with !CONFIG_RT_GROUP_SCHED (if there
are any kernel RT threads in root cgroup, they can't be migrated to the
newly created CPU controller's root in cgroup_update_dfl_csses()).

Existing code comes with a comment saying the "we don't support RT-tasks
being in separate groups". Such comment is however stale and belongs to
pre-RT_GROUP_SCHED times. Also, it doesn't make much sense for
!RT_GROUP_ SCHED configurations, since checks related to RT bandwidth
are not performed at all in these cases.

Make moving RT tasks between CPU controller groups viable by removing
special case check for RT (and DEADLINE) tasks.

Signed-off-by: Juri Lelli 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Michal Koutný 
Reviewed-by: Daniel Bristot de Oliveira 
Acked-by: Tejun Heo 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: rostedt@goodmis.org
Link: https://lkml.kernel.org/r/20190719063455.27328-1-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

sched/fair: Fix imbalance due to CPU affinity

2019-10-05T10:27:45+00:00

[ Upstream commit f6cad8df6b30a5d2bbbd2e698f74b4cafb9fb82b ]

The load_balance() has a dedicated mecanism to detect when an imbalance
is due to CPU affinity and must be handled at parent level. In this case,
the imbalance field of the parent's sched_group is set.

The description of sg_imbalanced() gives a typical example of two groups
of 4 CPUs each and 4 tasks each with a cpumask covering 1 CPU of the first
group and 3 CPUs of the second group. Something like:

	{ 0 1 2 3 } { 4 5 6 7 }
	        *     * * *

But the load_balance fails to fix this UC on my octo cores system
made of 2 clusters of quad cores.

Whereas the load_balance is able to detect that the imbalanced is due to
CPU affinity, it fails to fix it because the imbalance field is cleared
before letting parent level a chance to run. In fact, when the imbalance is
detected, the load_balance reruns without the CPU with pinned tasks. But
there is no other running tasks in the situation described above and
everything looks balanced this time so the imbalance field is immediately
cleared.

The imbalance field should not be cleared if there is no other task to move
when the imbalance is detected.

Signed-off-by: Vincent Guittot 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: https://lkml.kernel.org/r/1561996022-28829-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

locking/lockdep: Add debug_locks check in __lock_downgrade()

2019-10-05T10:27:39+00:00

[ Upstream commit 513e1073d52e55b8024b4f238a48de7587c64ccf ]

Tetsuo Handa had reported he saw an incorrect "downgrading a read lock"
warning right after a previous lockdep warning. It is likely that the
previous warning turned off lock debugging causing the lockdep to have
inconsistency states leading to the lock downgrade warning.

Fix that by add a check for debug_locks at the beginning of
__lock_downgrade().

Reported-by: Tetsuo Handa 
Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com
Signed-off-by: Waiman Long 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Link: https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

genirq: Prevent NULL pointer dereference in resend_irqs()

2019-09-21T05:12:43+00:00

commit eddf3e9c7c7e4d0707c68d1bb22cc6ec8aef7d4a upstream.

The following crash was observed:

  Unable to handle kernel NULL pointer dereference at 0000000000000158
  Internal error: Oops: 96000004 [#1] SMP
  pc : resend_irqs+0x68/0xb0
  lr : resend_irqs+0x64/0xb0
  ...
  Call trace:
   resend_irqs+0x68/0xb0
   tasklet_action_common.isra.6+0x84/0x138
   tasklet_action+0x2c/0x38
   __do_softirq+0x120/0x324
   run_ksoftirqd+0x44/0x60
   smpboot_thread_fn+0x1ac/0x1e8
   kthread+0x134/0x138
   ret_from_fork+0x10/0x18

The reason for this is that the interrupt resend mechanism happens in soft
interrupt context, which is a asynchronous mechanism versus other
operations on interrupts. free_irq() does not take resend handling into
account. Thus, the irq descriptor might be already freed before the resend
tasklet is executed. resend_irqs() does not check the return value of the
interrupt descriptor lookup and derefences the return value
unconditionally.

  1):
  __setup_irq
    irq_startup
      check_irq_resend  // activate softirq to handle resend irq
  2):
  irq_domain_free_irqs
    irq_free_descs
      free_desc
        call_rcu(&desc->rcu, delayed_free_desc)
  3):
  __do_softirq
    tasklet_action
      resend_irqs
        desc = irq_to_desc(irq)
        desc->handle_irq(desc)  // desc is NULL --> Ooops

Fix this by adding a NULL pointer check in resend_irqs() before derefencing
the irq descriptor.

Fixes: a4633adcdbc1 ("[PATCH] genirq: add genirq sw IRQ-retrigger")
Signed-off-by: Yunfeng Ye 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Zhiqiang Liu 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1630ae13-5c8e-901e-de09-e740b6a426a7@huawei.com
Signed-off-by: Greg Kroah-Hartman

cgroup: Disable IRQs while holding css_set_lock

2019-09-06T08:18:11+00:00

commit 82d6489d0fed2ec8a8c48c19e8d8a04ac8e5bb26 upstream.

While testing the deadline scheduler + cgroup setup I hit this
warning.

[  132.612935] ------------[ cut here ]------------
[  132.612951] WARNING: CPU: 5 PID: 0 at kernel/softirq.c:150 __local_bh_enable_ip+0x6b/0x80
[  132.612952] Modules linked in: (a ton of modules...)
[  132.612981] CPU: 5 PID: 0 Comm: swapper/5 Not tainted 4.7.0-rc2 #2
[  132.612981] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.2-20150714_191134- 04/01/2014
[  132.612982]  0000000000000086 45c8bb5effdd088b ffff88013fd43da0 ffffffff813d229e
[  132.612984]  0000000000000000 0000000000000000 ffff88013fd43de0 ffffffff810a652b
[  132.612985]  00000096811387b5 0000000000000200 ffff8800bab29d80 ffff880034c54c00
[  132.612986] Call Trace:
[  132.612987]    [] dump_stack+0x63/0x85
[  132.612994]  [] __warn+0xcb/0xf0
[  132.612997]  [] ? push_dl_task.part.32+0x170/0x170
[  132.612999]  [] warn_slowpath_null+0x1d/0x20
[  132.613000]  [] __local_bh_enable_ip+0x6b/0x80
[  132.613008]  [] _raw_write_unlock_bh+0x1a/0x20
[  132.613010]  [] _raw_spin_unlock_bh+0xe/0x10
[  132.613015]  [] put_css_set+0x5c/0x60
[  132.613016]  [] cgroup_free+0x7f/0xa0
[  132.613017]  [] __put_task_struct+0x42/0x140
[  132.613018]  [] dl_task_timer+0xca/0x250
[  132.613027]  [] ? push_dl_task.part.32+0x170/0x170
[  132.613030]  [] __hrtimer_run_queues+0xee/0x270
[  132.613031]  [] hrtimer_interrupt+0xa8/0x190
[  132.613034]  [] local_apic_timer_interrupt+0x38/0x60
[  132.613035]  [] smp_apic_timer_interrupt+0x3d/0x50
[  132.613037]  [] apic_timer_interrupt+0x8c/0xa0
[  132.613038]    [] ? native_safe_halt+0x6/0x10
[  132.613043]  [] default_idle+0x1e/0xd0
[  132.613044]  [] arch_cpu_idle+0xf/0x20
[  132.613046]  [] default_idle_call+0x2a/0x40
[  132.613047]  [] cpu_startup_entry+0x2e7/0x340
[  132.613048]  [] start_secondary+0x155/0x190
[  132.613049] ---[ end trace f91934d162ce9977 ]---

The warn is the spin_(lock|unlock)_bh(&css_set_lock) in the interrupt
context. Converting the spin_lock_bh to spin_lock_irq(save) to avoid
this problem - and other problems of sharing a spinlock with an
interrupt.

Cc: Tejun Heo 
Cc: Li Zefan 
Cc: Johannes Weiner 
Cc: Juri Lelli 
Cc: Steven Rostedt 
Cc: cgroups@vger.kernel.org
Cc: stable@vger.kernel.org # 4.5+
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Rik van Riel 
Reviewed-by: "Luis Claudio R. Goncalves" 
Signed-off-by: Daniel Bristot de Oliveira 
Acked-by: Zefan Li 
Signed-off-by: Tejun Heo 
Signed-off-by: Zubin Mithra 
Signed-off-by: Greg Kroah-Hartman

perf/core: Fix creating kernel counters for PMUs that override event->cpu

2019-08-25T08:52:51+00:00

[ Upstream commit 4ce54af8b33d3e21ca935fc1b89b58cbba956051 ]

Some hardware PMU drivers will override perf_event.cpu inside their
event_init callback. This causes a lockdep splat when initialized through
the kernel API:

 WARNING: CPU: 0 PID: 250 at kernel/events/core.c:2917 ctx_sched_out+0x78/0x208
 pc : ctx_sched_out+0x78/0x208
 Call trace:
  ctx_sched_out+0x78/0x208
  __perf_install_in_context+0x160/0x248
  remote_function+0x58/0x68
  generic_exec_single+0x100/0x180
  smp_call_function_single+0x174/0x1b8
  perf_install_in_context+0x178/0x188
  perf_event_create_kernel_counter+0x118/0x160

Fix this by calling perf_install_in_context with event->cpu, just like
perf_event_open

Signed-off-by: Leonard Crestez 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Mark Rutland 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Frank Li 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Link: https://lkml.kernel.org/r/c4ebe0503623066896d7046def4d6b1e06e0eb2e.1563972056.git.leonard.crestez@nxp.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

kernel/module.c: Only return -EEXIST for modules that have finished loading

2019-08-06T16:28:25+00:00

[ Upstream commit 6e6de3dee51a439f76eb73c22ae2ffd2c9384712 ]

Microsoft HyperV disables the X86_FEATURE_SMCA bit on AMD systems, and
linux guests boot with repeated errors:

amd64_edac_mod: Unknown symbol amd_unregister_ecc_decoder (err -2)
amd64_edac_mod: Unknown symbol amd_register_ecc_decoder (err -2)
amd64_edac_mod: Unknown symbol amd_report_gart_errors (err -2)
amd64_edac_mod: Unknown symbol amd_unregister_ecc_decoder (err -2)
amd64_edac_mod: Unknown symbol amd_register_ecc_decoder (err -2)
amd64_edac_mod: Unknown symbol amd_report_gart_errors (err -2)

The warnings occur because the module code erroneously returns -EEXIST
for modules that have failed to load and are in the process of being
removed from the module list.

module amd64_edac_mod has a dependency on module edac_mce_amd.  Using
modules.dep, systemd will load edac_mce_amd for every request of
amd64_edac_mod.  When the edac_mce_amd module loads, the module has
state MODULE_STATE_UNFORMED and once the module load fails and the state
becomes MODULE_STATE_GOING.  Another request for edac_mce_amd module
executes and add_unformed_module() will erroneously return -EEXIST even
though the previous instance of edac_mce_amd has MODULE_STATE_GOING.
Upon receiving -EEXIST, systemd attempts to load amd64_edac_mod, which
fails because of unknown symbols from edac_mce_amd.

add_unformed_module() must wait to return for any case other than
MODULE_STATE_LIVE to prevent a race between multiple loads of
dependent modules.

Signed-off-by: Prarit Bhargava 
Signed-off-by: Barret Rhoden 
Cc: David Arcari 
Cc: Jessica Yu 
Cc: Heiko Carstens 
Signed-off-by: Jessica Yu 
Signed-off-by: Sasha Levin