linux-toradex.git/kernel, branch v4.9.47

locking/spinlock/debug: Remove spinlock lockup detection code

2017-09-02T05:07:54+00:00

commit bc88c10d7e6900916f5e1ba3829d66a9de92b633 upstream.

The current spinlock lockup detection code can sometimes produce false
positives because of the unfairness of the locking algorithm itself.

So the lockup detection code is now removed. Instead, we are relying
on the NMI watchdog to detect potential lockup. We won't have lockup
detection if the watchdog isn't running.

The commented-out read-write lock lockup detection code are also
removed.

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: Sasha Levin 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1486583208-11038-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar 
Cc: Geert Uytterhoeven 
Signed-off-by: Greg Kroah-Hartman

gcov: support GCC 7.1

2017-09-02T05:07:53+00:00

commit 05384213436ab690c46d9dfec706b80ef8d671ab upstream.

Starting from GCC 7.1, __gcov_exit is a new symbol expected to be
implemented in a profiling runtime.

[akpm@linux-foundation.org: coding-style fixes]
[mliska@suse.cz: v2]
  Link: http://lkml.kernel.org/r/e63a3c59-0149-c97e-4084-20ca8f146b26@suse.cz
Link: http://lkml.kernel.org/r/8c4084fa-3885-29fe-5fc4-0d4ca199c785@suse.cz
Signed-off-by: Martin Liska 
Acked-by: Peter Oberparleiter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

timers: Fix excessive granularity of new timers after a nohz idle

2017-08-30T08:21:51+00:00

commit 2fe59f507a65dbd734b990a11ebc7488f6f87a24 upstream.

When a timer base is idle, it is forwarded when a new timer is added
to ensure that granularity does not become excessive. When not idle,
the timer tick is expected to increment the base.

However there are several problems:

- If an existing timer is modified, the base is forwarded only after
  the index is calculated.

- The base is not forwarded by add_timer_on.

- There is a window after a timer is restarted from a nohz idle, after
  it is marked not-idle and before the timer tick on this CPU, where a
  timer may be added but the ancient base does not get forwarded.

These result in excessive granularity (a 1 jiffy timeout can blow out
to 100s of jiffies), which cause the rcu lockup detector to trigger,
among other things.

Fix this by keeping track of whether the timer base has been idle
since it was last run or forwarded, and if so then forward it before
adding a new timer.

There is still a case where mod_timer optimises the case of a pending
timer mod with the same expiry time, where the timer can see excessive
granularity relative to the new, shorter interval. A comment is added,
but it's not changed because it is an important fastpath for
networking.

This has been tested and found to fix the RCU softlockup messages.

Testing was also done with tracing to measure requested versus
achieved wakeup latencies for all non-deferrable timers in an idle
system (with no lockup watchdogs running). Wakeup latency relative to
absolute latency is calculated (note this suffers from round-up skew
at low absolute times) and analysed:

             max     avg      std
upstream   506.0    1.20     4.68
patched      2.0    1.08     0.15

The bug was noticed due to the lockup detector Kconfig changes
dropping it out of people's .configs and resulting in larger base
clk skew When the lockup detectors are enabled, no CPU can go idle for
longer than 4 seconds, which limits the granularity errors.
Sub-optimal timer behaviour is observable on a smaller scale in that
case:

	     max     avg      std
upstream     9.0    1.05     0.19
patched      2.0    1.04     0.11

Fixes: Fixes: a683f390b93f ("timers: Forward the wheel clock whenever possible")
Signed-off-by: Nicholas Piggin 
Signed-off-by: Thomas Gleixner 
Tested-by: Jonathan Cameron 
Tested-by: David Miller 
Cc: dzickus@redhat.com
Cc: sfr@canb.auug.org.au
Cc: mpe@ellerman.id.au
Cc: Stephen Boyd 
Cc: linuxarm@huawei.com
Cc: abdhalee@linux.vnet.ibm.com
Cc: John Stultz 
Cc: akpm@linux-foundation.org
Cc: paulmck@linux.vnet.ibm.com
Cc: torvalds@linux-foundation.org
Link: http://lkml.kernel.org/r/20170822084348.21436-1-npiggin@gmail.com
Signed-off-by: Greg Kroah-Hartman

perf/core: Fix group {cpu,task} validation

2017-08-30T08:21:50+00:00

commit 64aee2a965cf2954a038b5522f11d2cd2f0f8f3e upstream.

Regardless of which events form a group, it does not make sense for the
events to target different tasks and/or CPUs, as this leaves the group
inconsistent and impossible to schedule. The core perf code assumes that
these are consistent across (successfully intialised) groups.

Core perf code only verifies this when moving SW events into a HW
context. Thus, we can violate this requirement for pure SW groups and
pure HW groups, unless the relevant PMU driver happens to perform this
verification itself. These mismatched groups subsequently wreak havoc
elsewhere.

For example, we handle watchpoints as SW events, and reserve watchpoint
HW on a per-CPU basis at pmu::event_init() time to ensure that any event
that is initialised is guaranteed to have a slot at pmu::add() time.
However, the core code only checks the group leader's cpu filter (via
event_filter_match()), and can thus install follower events onto CPUs
violating thier (mismatched) CPU filters, potentially installing them
into a CPU without sufficient reserved slots.

This can be triggered with the below test case, resulting in warnings
from arch backends.

  #define _GNU_SOURCE
  #include 
  #include 
  #include 
  #include 
  #include 
  #include 
  #include 

  static int perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu,
			   int group_fd, unsigned long flags)
  {
	return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags);
  }

  char watched_char;

  struct perf_event_attr wp_attr = {
	.type = PERF_TYPE_BREAKPOINT,
	.bp_type = HW_BREAKPOINT_RW,
	.bp_addr = (unsigned long)&watched_char,
	.bp_len = 1,
	.size = sizeof(wp_attr),
  };

  int main(int argc, char *argv[])
  {
	int leader, ret;
	cpu_set_t cpus;

	/*
	 * Force use of CPU0 to ensure our CPU0-bound events get scheduled.
	 */
	CPU_ZERO(&cpus);
	CPU_SET(0, &cpus);
	ret = sched_setaffinity(0, sizeof(cpus), &cpus);
	if (ret) {
		printf("Unable to set cpu affinity\n");
		return 1;
	}

	/* open leader event, bound to this task, CPU0 only */
	leader = perf_event_open(&wp_attr, 0, 0, -1, 0);
	if (leader < 0) {
		printf("Couldn't open leader: %d\n", leader);
		return 1;
	}

	/*
	 * Open a follower event that is bound to the same task, but a
	 * different CPU. This means that the group should never be possible to
	 * schedule.
	 */
	ret = perf_event_open(&wp_attr, 0, 1, leader, 0);
	if (ret < 0) {
		printf("Couldn't open mismatched follower: %d\n", ret);
		return 1;
	} else {
		printf("Opened leader/follower with mismastched CPUs\n");
	}

	/*
	 * Open as many independent events as we can, all bound to the same
	 * task, CPU0 only.
	 */
	do {
		ret = perf_event_open(&wp_attr, 0, 0, -1, 0);
	} while (ret >= 0);

	/*
	 * Force enable/disble all events to trigger the erronoeous
	 * installation of the follower event.
	 */
	printf("Opened all events. Toggling..\n");
	for (;;) {
		prctl(PR_TASK_PERF_EVENTS_DISABLE, 0, 0, 0, 0);
		prctl(PR_TASK_PERF_EVENTS_ENABLE, 0, 0, 0, 0);
	}

	return 0;
  }

Fix this by validating this requirement regardless of whether we're
moving events.

Signed-off-by: Mark Rutland 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Zhou Chengming 
Link: http://lkml.kernel.org/r/1498142498-15758-1-git-send-email-mark.rutland@arm.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

ftrace: Check for null ret_stack on profile function graph entry function

2017-08-30T08:21:50+00:00

commit a8f0f9e49956a74718874b800251455680085600 upstream.

There's a small race when function graph shutsdown and the calling of the
registered function graph entry callback. The callback must not reference
the task's ret_stack without first checking that it is not NULL. Note, when
a ret_stack is allocated for a task, it stays allocated until the task exits.
The problem here, is that function_graph is shutdown, and a new task was
created, which doesn't have its ret_stack allocated. But since some of the
functions are still being traced, the callbacks can still be called.

The normal function_graph code handles this, but starting with commit
8861dd303c ("ftrace: Access ret_stack->subtime only in the function
profiler") the profiler code references the ret_stack on function entry, but
doesn't check if it is NULL first.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=196611

Fixes: 8861dd303c ("ftrace: Access ret_stack->subtime only in the function profiler")
Reported-by: lilydjwg@gmail.com
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix freeing of filter in create_filter() when set_str is false

2017-08-30T08:21:49+00:00

commit 8b0db1a5bdfcee0dbfa89607672598ae203c9045 upstream.

Performing the following task with kmemleak enabled:

 # cd /sys/kernel/tracing/events/irq/irq_handler_entry/
 # echo 'enable_event:kmem:kmalloc:3 if irq >' > trigger
 # echo 'enable_event:kmem:kmalloc:3 if irq > 31' > trigger
 # echo scan > /sys/kernel/debug/kmemleak
 # cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff8800b9290308 (size 32):
  comm "bash", pid 1114, jiffies 4294848451 (age 141.139s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [] kmemleak_alloc+0x4a/0xa0
    [] kmem_cache_alloc_trace+0x158/0x290
    [] create_filter_start.constprop.28+0x99/0x940
    [] create_filter+0xa9/0x160
    [] create_event_filter+0xc/0x10
    [] set_trigger_filter+0xe5/0x210
    [] event_enable_trigger_func+0x324/0x490
    [] event_trigger_write+0x1a2/0x260
    [] __vfs_write+0xd7/0x380
    [] vfs_write+0x101/0x260
    [] SyS_write+0xab/0x130
    [] entry_SYSCALL_64_fastpath+0x1f/0xbe
    [] 0xffffffffffffffff

The function create_filter() is passed a 'filterp' pointer that gets
allocated, and if "set_str" is true, it is up to the caller to free it, even
on error. The problem is that the pointer is not freed by create_filter()
when set_str is false. This is a bug, and it is not up to the caller to free
the filter on error if it doesn't care about the string.

Link: http://lkml.kernel.org/r/1502705898-27571-2-git-send-email-chuhu@redhat.com

Fixes: 38b78eb85 ("tracing: Factorize filter creation")
Reported-by: Chunyu Hu 
Tested-by: Chunyu Hu 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix kmemleak in tracing_map_array_free()

2017-08-30T08:21:49+00:00

commit 475bb3c69ab05df2a6ecef6acc2393703d134180 upstream.

kmemleak reported the below leak when I was doing clear of the hist
trigger. With this patch, the kmeamleak is gone.

unreferenced object 0xffff94322b63d760 (size 32):
  comm "bash", pid 1522, jiffies 4403687962 (age 2442.311s)
  hex dump (first 32 bytes):
    00 01 00 00 04 00 00 00 08 00 00 00 ff 00 00 00  ................
    10 00 00 00 00 00 00 00 80 a8 7a f2 31 94 ff ff  ..........z.1...
  backtrace:
    [] kmemleak_alloc+0x4a/0xa0
    [] kmem_cache_alloc_trace+0xca/0x1d0
    [] tracing_map_array_alloc+0x26/0x140
    [] kretprobe_trampoline+0x0/0x50
    [] create_hist_data+0x535/0x750
    [] event_hist_trigger_func+0x1f7/0x420
    [] event_trigger_write+0xfd/0x1a0
    [] __vfs_write+0x37/0x170
    [] vfs_write+0xb2/0x1b0
    [] SyS_write+0x55/0xc0
    [] do_syscall_64+0x67/0x150
    [] return_from_SYSCALL_64+0x0/0x6a
    [] 0xffffffffffffffff
unreferenced object 0xffff9431f27aa880 (size 128):
  comm "bash", pid 1522, jiffies 4403687962 (age 2442.311s)
  hex dump (first 32 bytes):
    00 00 8c 2a 32 94 ff ff 00 f0 8b 2a 32 94 ff ff  ...*2......*2...
    00 e0 8b 2a 32 94 ff ff 00 d0 8b 2a 32 94 ff ff  ...*2......*2...
  backtrace:
    [] kmemleak_alloc+0x4a/0xa0
    [] __kmalloc+0xe8/0x220
    [] tracing_map_array_alloc+0xb1/0x140
    [] kretprobe_trampoline+0x0/0x50
    [] create_hist_data+0x535/0x750
    [] event_hist_trigger_func+0x1f7/0x420
    [] event_trigger_write+0xfd/0x1a0
    [] __vfs_write+0x37/0x170
    [] vfs_write+0xb2/0x1b0
    [] SyS_write+0x55/0xc0
    [] do_syscall_64+0x67/0x150
    [] return_from_SYSCALL_64+0x0/0x6a
    [] 0xffffffffffffffff

Link: http://lkml.kernel.org/r/1502705898-27571-1-git-send-email-chuhu@redhat.com

Fixes: 08d43a5fa063 ("tracing: Add lock-free tracing_map")
Signed-off-by: Chunyu Hu 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing: Call clear_boot_tracer() at lateinit_sync

2017-08-30T08:21:48+00:00

commit 4bb0f0e73c8c30917d169c4a0f1ac083690c545b upstream.

The clear_boot_tracer function is used to reset the default_bootup_tracer
string to prevent it from being accessed after boot, as it originally points
to init data. But since clear_boot_tracer() is called via the
init_lateinit() call, it races with the initcall for registering the hwlat
tracer. If someone adds "ftrace=hwlat" to the kernel command line, depending
on how the linker sets up the text, the saved command line may be cleared,
and the hwlat tracer never is initialized.

Simply have the clear_boot_tracer() be called by initcall_lateinit_sync() as
that's for tasks to be called after lateinit.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=196551

Fixes: e7c15cd8a ("tracing: Added hardware latency tracer")
Reported-by: Zamir SUN 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

fork: fix incorrect fput of ->exe_file causing use-after-free

2017-08-30T08:21:47+00:00

commit 2b7e8665b4ff51c034c55df3cff76518d1a9ee3a upstream.

Commit 7c051267931a ("mm, fork: make dup_mmap wait for mmap_sem for
write killable") made it possible to kill a forking task while it is
waiting to acquire its ->mmap_sem for write, in dup_mmap().

However, it was overlooked that this introduced an new error path before
a reference is taken on the mm_struct's ->exe_file.  Since the
->exe_file of the new mm_struct was already set to the old ->exe_file by
the memcpy() in dup_mm(), it was possible for the mmput() in the error
path of dup_mm() to drop a reference to ->exe_file which was never
taken.

This caused the struct file to later be freed prematurely.

Fix it by updating mm_init() to NULL out the ->exe_file, in the same
place it clears other things like the list of mmaps.

This bug was found by syzkaller.  It can be reproduced using the
following C program:

    #define _GNU_SOURCE
    #include 
    #include 
    #include 
    #include 
    #include 
    #include 

    static void *mmap_thread(void *_arg)
    {
        for (;;) {
            mmap(NULL, 0x1000000, PROT_READ,
                 MAP_POPULATE|MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
        }
    }

    static void *fork_thread(void *_arg)
    {
        usleep(rand() % 10000);
        fork();
    }

    int main(void)
    {
        fork();
        fork();
        fork();
        for (;;) {
            if (fork() == 0) {
                pthread_t t;

                pthread_create(&t, NULL, mmap_thread, NULL);
                pthread_create(&t, NULL, fork_thread, NULL);
                usleep(rand() % 10000);
                syscall(__NR_exit_group, 0);
            }
            wait(NULL);
        }
    }

No special kernel config options are needed.  It usually causes a NULL
pointer dereference in __remove_shared_vm_struct() during exit, or in
dup_mmap() (which is usually inlined into copy_process()) during fork.
Both are due to a vm_area_struct's ->vm_file being used after it's
already been freed.

Google Bug Id: 64772007

Link: http://lkml.kernel.org/r/20170823211408.31198-1-ebiggers3@gmail.com
Fixes: 7c051267931a ("mm, fork: make dup_mmap wait for mmap_sem for write killable")
Signed-off-by: Eric Biggers 
Tested-by: Mark Rutland 
Acked-by: Michal Hocko 
Cc: Dmitry Vyukov 
Cc: Ingo Molnar 
Cc: Konstantin Khlebnikov 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

bpf/verifier: fix min/max handling in BPF_SUB

2017-08-30T08:21:44+00:00

[ Upstream commit 9305706c2e808ae59f1eb201867f82f1ddf6d7a6 ]

We have to subtract the src max from the dst min, and vice-versa, since
 (e.g.) the smallest result comes from the largest subtrahend.

Fixes: 484611357c19 ("bpf: allow access into map value arrays")
Signed-off-by: Edward Cree 
Acked-by: Daniel Borkmann 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman