linux-stable.git/kernel, branch v4.9.207

kernel/module.c: wakeup processes in module_wq on module unload

2019-12-21T09:42:21+00:00

[ Upstream commit 5d603311615f612320bb77bd2a82553ef1ced5b7 ]

Fix the race between load and unload a kernel module.

sys_delete_module()
 try_stop_module()
  mod->state = _GOING
					add_unformed_module()
					 old = find_module_all()
					 (old->state == _GOING =>
					  wait_event_interruptible())

					 During pre-condition
					 finished_loading() rets 0
					 schedule()
					 (never gets waken up later)
 free_module()
  mod->state = _UNFORMED
   list_del_rcu(&mod->list)
   (dels mod from "modules" list)

return

The race above leads to modprobe hanging forever on loading
a module.

Error paths on loading module call wake_up_all(&module_wq) after
freeing module, so let's do the same on straight module unload.

Fixes: 6e6de3dee51a ("kernel/module.c: Only return -EEXIST for modules that have finished loading")
Reviewed-by: Prarit Bhargava 
Signed-off-by: Konstantin Khorenko 
Signed-off-by: Jessica Yu 
Signed-off-by: Sasha Levin

workqueue: Fix missing kfree(rescuer) in destroy_workqueue()

2019-12-21T09:42:19+00:00

commit 8efe1223d73c218ce7e8b2e0e9aadb974b582d7f upstream.

Signed-off-by: Tejun Heo 
Reported-by: Qian Cai 
Fixes: def98c84b6cd ("workqueue: Fix spurious sanity check failures in destroy_workqueue()")
Cc: Nobuhiro Iwamatsu 
Signed-off-by: Greg Kroah-Hartman

cgroup: pids: use atomic64_t for pids->limit

2019-12-21T09:42:02+00:00

commit a713af394cf382a30dd28a1015cbe572f1b9ca75 upstream.

Because pids->limit can be changed concurrently (but we don't want to
take a lock because it would be needlessly expensive), use atomic64_ts
instead.

Fixes: commit 49b786ea146f ("cgroup: implement the PIDs subsystem")
Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: Aleksa Sarai 
Signed-off-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

workqueue: Fix pwq ref leak in rescuer_thread()

2019-12-21T09:42:01+00:00

commit e66b39af00f426b3356b96433d620cb3367ba1ff upstream.

008847f66c3 ("workqueue: allow rescuer thread to do more work.") made
the rescuer worker requeue the pwq immediately if there may be more
work items which need rescuing instead of waiting for the next mayday
timer expiration.  Unfortunately, it doesn't check whether the pwq is
already on the mayday list and unconditionally gets the ref and moves
it onto the list.  This doesn't corrupt the list but creates an
additional reference to the pwq.  It got queued twice but will only be
removed once.

This leak later can trigger pwq refcnt warning on workqueue
destruction and prevent freeing of the workqueue.

Signed-off-by: Tejun Heo 
Cc: "Williams, Gerald S" 
Cc: NeilBrown 
Cc: stable@vger.kernel.org # v3.19+
Signed-off-by: Greg Kroah-Hartman

workqueue: Fix spurious sanity check failures in destroy_workqueue()

2019-12-21T09:42:01+00:00

commit def98c84b6cdf2eeea19ec5736e90e316df5206b upstream.

Before actually destrying a workqueue, destroy_workqueue() checks
whether it's actually idle.  If it isn't, it prints out a bunch of
warning messages and leaves the workqueue dangling.  It unfortunately
has a couple issues.

* Mayday list queueing increments pwq's refcnts which gets detected as
  busy and fails the sanity checks.  However, because mayday list
  queueing is asynchronous, this condition can happen without any
  actual work items left in the workqueue.

* Sanity check failure leaves the sysfs interface behind too which can
  lead to init failure of newer instances of the workqueue.

This patch fixes the above two by

* If a workqueue has a rescuer, disable and kill the rescuer before
  sanity checks.  Disabling and killing is guaranteed to flush the
  existing mayday list.

* Remove sysfs interface before sanity checks.

Signed-off-by: Tejun Heo 
Reported-by: Marcin Pawlowski 
Reported-by: "Williams, Gerald S" 
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman

sched/fair: Scale bandwidth quota and period without losing quota/period ratio precision

2019-12-21T09:41:28+00:00

commit 4929a4e6faa0f13289a67cae98139e727f0d4a97 upstream.

The quota/period ratio is used to ensure a child task group won't get
more bandwidth than the parent task group, and is calculated as:

  normalized_cfs_quota() = [(quota_us << 20) / period_us]

If the quota/period ratio was changed during this scaling due to
precision loss, it will cause inconsistency between parent and child
task groups.

See below example:

A userspace container manager (kubelet) does three operations:

 1) Create a parent cgroup, set quota to 1,000us and period to 10,000us.
 2) Create a few children cgroups.
 3) Set quota to 1,000us and period to 10,000us on a child cgroup.

These operations are expected to succeed. However, if the scaling of
147/128 happens before step 3, quota and period of the parent cgroup
will be changed:

  new_quota: 1148437ns,   1148us
 new_period: 11484375ns, 11484us

And when step 3 comes in, the ratio of the child cgroup will be
104857, which will be larger than the parent cgroup ratio (104821),
and will fail.

Scaling them by a factor of 2 will fix the problem.

Tested-by: Phil Auld 
Signed-off-by: Xuewei Zhang 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Phil Auld 
Cc: Anton Blanchard 
Cc: Ben Segall 
Cc: Dietmar Eggemann 
Cc: Juri Lelli 
Cc: Linus Torvalds 
Cc: Mel Gorman 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: Vincent Guittot 
Fixes: 2e8e19226398 ("sched/fair: Limit sched_cfs_period_timer() loop to avoid hard lockup")
Link: https://lkml.kernel.org/r/20191004001243.140897-1-xueweiz@google.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

audit_get_nd(): don't unlock parent too early

2019-12-21T09:40:48+00:00

[ Upstream commit 69924b89687a2923e88cc42144aea27868913d0e ]

if the child has been negative and just went positive
under us, we want coherent d_is_positive() and ->d_inode.
Don't unlock the parent until we'd done that work...

Signed-off-by: Al Viro 
Signed-off-by: Sasha Levin

audit: print empty EXECVE args

2019-11-28T17:28:55+00:00

[ Upstream commit ea956d8be91edc702a98b7fe1f9463e7ca8c42ab ]

Empty executable arguments were being skipped when printing out the list
of arguments in an EXECVE record, making it appear they were somehow
lost.  Include empty arguments as an itemized empty string.

Reproducer:
	autrace /bin/ls "" "/etc"
	ausearch --start recent -m execve -i | grep EXECVE
	type=EXECVE msg=audit(10/03/2018 13:04:03.208:1391) : argc=3 a0=/bin/ls a2=/etc

With fix:
	type=EXECVE msg=audit(10/03/2018 21:51:38.290:194) : argc=3 a0=/bin/ls a1= a2=/etc
	type=EXECVE msg=audit(1538617898.290:194): argc=3 a0="/bin/ls" a1="" a2="/etc"

Passes audit-testsuite.  GH issue tracker at
https://github.com/linux-audit/audit-kernel/issues/99

Signed-off-by: Richard Guy Briggs 
[PM: cleaned up the commit metadata]
Signed-off-by: Paul Moore 
Signed-off-by: Sasha Levin

sched/fair: Don't increase sd->balance_interval on newidle balance

2019-11-28T17:28:55+00:00

[ Upstream commit 3f130a37c442d5c4d66531b240ebe9abfef426b5 ]

When load_balance() fails to move some load because of task affinity,
we end up increasing sd->balance_interval to delay the next periodic
balance in the hopes that next time we look, that annoying pinned
task(s) will be gone.

However, idle_balance() pays no attention to sd->balance_interval, yet
it will still lead to an increase in balance_interval in case of
pinned tasks.

If we're going through several newidle balances (e.g. we have a
periodic task), this can lead to a huge increase of the
balance_interval in a very small amount of time.

To prevent that, don't increase the balance interval when going
through a newidle balance.

This is a similar approach to what is done in commit 58b26c4c0257
("sched: Increment cache_nice_tries only on periodic lb"), where we
disregard newidle balance and rely on periodic balance for more stable
results.

Signed-off-by: Valentin Schneider 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: patrick.bellasi@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1537974727-30788-2-git-send-email-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

printk: fix integer overflow in setup_log_buf()

2019-11-28T17:28:15+00:00

[ Upstream commit d2130e82e9454304e9b91ba9da551b5989af8c27 ]

The way we calculate logbuf free space percentage overflows signed
integer:

	int free;

	free = __LOG_BUF_LEN - log_next_idx;
	pr_info("early log buf free: %u(%u%%)\n",
		free, (free * 100) / __LOG_BUF_LEN);

We support LOG_BUF_LEN of up to 1<<25 bytes. Since setup_log_buf() is
called during early init, logbuf is mostly empty, so

	__LOG_BUF_LEN - log_next_idx

is close to 1<<25. Thus when we multiply it by 100, we overflow signed
integer value range: 100 is 2^6 + 2^5 + 2^2.

Example, booting with LOG_BUF_LEN 1<<25 and log_buf_len=2G
boot param:

[    0.075317] log_buf_len: -2147483648 bytes
[    0.075319] early log buf free: 33549896(-28%)

Make "free" unsigned integer and use appropriate printk() specifier.

Link: http://lkml.kernel.org/r/20181010113308.9337-1-sergey.senozhatsky@gmail.com
To: Steven Rostedt 
Cc: linux-kernel@vger.kernel.org
Cc: Sergey Senozhatsky 
Signed-off-by: Sergey Senozhatsky 
Signed-off-by: Petr Mladek 
Signed-off-by: Sasha Levin