commit 8d67743653 upstream.
The recent futex inode life time fix changed the ordering of the futex key
union struct members, but forgot to adjust the hash function accordingly,
As a result the hashing omits the leading 64bit and even hashes beyond the
futex key causing a bad hash distribution which led to a ~100% performance
regression.
Hand in the futex key pointer instead of a random struct member and make
the size calculation based of the struct offset.
Fixes: 8019ad13ef ("futex: Fix inode life-time issue")
Reported-by: Rong Chen <rong.a.chen@intel.com>
Decoded-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Rong Chen <rong.a.chen@intel.com>
Link: https://lkml.kernel.org/r/87h7yy90ve.fsf@nanos.tec.linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8019ad13ef upstream.
As reported by Jann, ihold() does not in fact guarantee inode
persistence. And instead of making it so, replace the usage of inode
pointers with a per boot, machine wide, unique inode identifier.
This sequence number is global, but shared (file backed) futexes are
rare enough that this should not become a performance issue.
Reported-by: Jann Horn <jannh@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit fda31c5029 ]
When queueing a signal, we increment both the users count of pending
signals (for RLIMIT_SIGPENDING tracking) and we increment the refcount
of the user struct itself (because we keep a reference to the user in
the signal structure in order to correctly account for it when freeing).
That turns out to be fairly expensive, because both of them are atomic
updates, and particularly under extreme signal handling pressure on big
machines, you can get a lot of cache contention on the user struct.
That can then cause horrid cacheline ping-pong when you do these
multiple accesses.
So change the reference counting to only pin the user for the _first_
pending signal, and to unpin it when the last pending signal is
dequeued. That means that when a user sees a lot of concurrent signal
queuing - which is the only situation when this matters - the only
atomic access needed is generally the 'sigpending' count update.
This was noticed because of a particularly odd timing artifact on a
dual-socket 96C/192T Cascade Lake platform: when you get into bad
contention, on that machine for some reason seems to be much worse when
the contention happens in the upper 32-byte half of the cacheline.
As a result, the kernel test robot will-it-scale 'signal1' benchmark had
an odd performance regression simply due to random alignment of the
'struct user_struct' (and pointed to a completely unrelated and
apparently nonsensical commit for the regression).
Avoiding the double increments (and decrements on the dequeueing side,
of course) makes for much less contention and hugely improved
performance on that will-it-scale microbenchmark.
Quoting Feng Tang:
"It makes a big difference, that the performance score is tripled! bump
from original 17000 to 54000. Also the gap between 5.0-rc6 and
5.0-rc6+Jiri's patch is reduced to around 2%"
[ The "2% gap" is the odd cacheline placement difference on that
platform: under the extreme contention case, the effect of which half
of the cacheline was hot was 5%, so with the reduced contention the
odd timing artifact is reduced too ]
It does help in the non-contended case too, but is not nearly as
noticeable.
Reported-and-tested-by: Feng Tang <feng.tang@intel.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Philip Li <philip.li@intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit aa202f1f56 upstream.
wq_select_unbound_cpu() is designed for unbound workqueues only, but
it's wrongly called when using a bound workqueue too.
Fixing this ensures work queued to a bound workqueue with
cpu=WORK_CPU_UNBOUND always runs on the local CPU.
Before, that would happen only if wq_unbound_cpumask happened to include
it (likely almost always the case), or was empty, or we got lucky with
forced round-robin placement. So restricting
/sys/devices/virtual/workqueue/cpumask to a small subset of a machine's
CPUs would cause some bound work items to run unexpectedly there.
Fixes: ef55718044 ("workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs")
Cc: stable@vger.kernel.org # v4.5+
Signed-off-by: Hillf Danton <hdanton@sina.com>
[dj: massage changelog]
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit e876ecc67d ]
We are testing network memory accounting in our setup and noticed
inconsistent network memory usage and often unrelated cgroups network
usage correlates with testing workload. On further inspection, it
seems like mem_cgroup_sk_alloc() and cgroup_sk_alloc() are broken in
irq context specially for cgroup v1.
mem_cgroup_sk_alloc() and cgroup_sk_alloc() can be called in irq context
and kind of assumes that this can only happen from sk_clone_lock()
and the source sock object has already associated cgroup. However in
cgroup v1, where network memory accounting is opt-in, the source sock
can be unassociated with any cgroup and the new cloned sock can get
associated with unrelated interrupted cgroup.
Cgroup v2 can also suffer if the source sock object was created by
process in the root cgroup or if sk_alloc() is called in irq context.
The fix is to just do nothing in interrupt.
WARNING: Please note that about half of the TCP sockets are allocated
from the IRQ context, so, memory used by such sockets will not be
accouted by the memcg.
The stack trace of mem_cgroup_sk_alloc() from IRQ-context:
CPU: 70 PID: 12720 Comm: ssh Tainted: 5.6.0-smp-DEV #1
Hardware name: ...
Call Trace:
<IRQ>
dump_stack+0x57/0x75
mem_cgroup_sk_alloc+0xe9/0xf0
sk_clone_lock+0x2a7/0x420
inet_csk_clone_lock+0x1b/0x110
tcp_create_openreq_child+0x23/0x3b0
tcp_v6_syn_recv_sock+0x88/0x730
tcp_check_req+0x429/0x560
tcp_v6_rcv+0x72d/0xa40
ip6_protocol_deliver_rcu+0xc9/0x400
ip6_input+0x44/0xd0
? ip6_protocol_deliver_rcu+0x400/0x400
ip6_rcv_finish+0x71/0x80
ipv6_rcv+0x5b/0xe0
? ip6_sublist_rcv+0x2e0/0x2e0
process_backlog+0x108/0x1e0
net_rx_action+0x26b/0x460
__do_softirq+0x104/0x2a6
do_softirq_own_stack+0x2a/0x40
</IRQ>
do_softirq.part.19+0x40/0x50
__local_bh_enable_ip+0x51/0x60
ip6_finish_output2+0x23d/0x520
? ip6table_mangle_hook+0x55/0x160
__ip6_finish_output+0xa1/0x100
ip6_finish_output+0x30/0xd0
ip6_output+0x73/0x120
? __ip6_finish_output+0x100/0x100
ip6_xmit+0x2e3/0x600
? ipv6_anycast_cleanup+0x50/0x50
? inet6_csk_route_socket+0x136/0x1e0
? skb_free_head+0x1e/0x30
inet6_csk_xmit+0x95/0xf0
__tcp_transmit_skb+0x5b4/0xb20
__tcp_send_ack.part.60+0xa3/0x110
tcp_send_ack+0x1d/0x20
tcp_rcv_state_process+0xe64/0xe80
? tcp_v6_connect+0x5d1/0x5f0
tcp_v6_do_rcv+0x1b1/0x3f0
? tcp_v6_do_rcv+0x1b1/0x3f0
__release_sock+0x7f/0xd0
release_sock+0x30/0xa0
__inet_stream_connect+0x1c3/0x3b0
? prepare_to_wait+0xb0/0xb0
inet_stream_connect+0x3b/0x60
__sys_connect+0x101/0x120
? __sys_getsockopt+0x11b/0x140
__x64_sys_connect+0x1a/0x20
do_syscall_64+0x51/0x200
entry_SYSCALL_64_after_hwframe+0x44/0xa9
The stack trace of mem_cgroup_sk_alloc() from IRQ-context:
Fixes: 2d75807383 ("mm: memcontrol: consolidate cgroup socket tracking")
Fixes: d979a39d72 ("cgroup: duplicate cgroup reference when cloning sockets")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 2ad3e17ebf upstream.
Commit 219ca39427 ("audit: use union for audit_field values since
they are mutually exclusive") combined a number of separate fields in
the audit_field struct into a single union. Generally this worked
just fine because they are generally mutually exclusive.
Unfortunately in audit_data_to_entry() the overlap can be a problem
when a specific error case is triggered that causes the error path
code to attempt to cleanup an audit_field struct and the cleanup
involves attempting to free a stored LSM string (the lsm_str field).
Currently the code always has a non-NULL value in the
audit_field.lsm_str field as the top of the for-loop transfers a
value into audit_field.val (both .lsm_str and .val are part of the
same union); if audit_data_to_entry() fails and the audit_field
struct is specified to contain a LSM string, but the
audit_field.lsm_str has not yet been properly set, the error handling
code will attempt to free the bogus audit_field.lsm_str value that
was set with audit_field.val at the top of the for-loop.
This patch corrects this by ensuring that the audit_field.val is only
set when needed (it is cleared when the audit_field struct is
allocated with kcalloc()). It also corrects a few other issues to
ensure that in case of error the proper error code is returned.
Cc: stable@vger.kernel.org
Fixes: 219ca39427 ("audit: use union for audit_field values since they are mutually exclusive")
Reported-by: syzbot+1f4d90ead370d72e450b@syzkaller.appspotmail.com
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 6722b23e7a ]
if seq_file .next fuction does not change position index,
read after some lseek can generate unexpected output.
Without patch:
# dd bs=30 skip=1 if=/sys/kernel/tracing/events/sched/sched_switch/trigger
dd: /sys/kernel/tracing/events/sched/sched_switch/trigger: cannot skip to specified offset
n traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist
# Available triggers:
# traceon traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist
6+1 records in
6+1 records out
206 bytes copied, 0.00027916 s, 738 kB/s
Notice the printing of "# Available triggers:..." after the line.
With the patch:
# dd bs=30 skip=1 if=/sys/kernel/tracing/events/sched/sched_switch/trigger
dd: /sys/kernel/tracing/events/sched/sched_switch/trigger: cannot skip to specified offset
n traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist
2+1 records in
2+1 records out
88 bytes copied, 0.000526867 s, 167 kB/s
It only prints the end of the file, and does not restart.
Link: http://lkml.kernel.org/r/3c35ee24-dd3a-8119-9c19-552ed253388a@virtuozzo.comhttps://bugzilla.kernel.org/show_bug.cgi?id=206283
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e4075e8bdf ]
if seq_file .next fuction does not change position index,
read after some lseek can generate unexpected output.
Without patch:
# dd bs=4 skip=1 if=/sys/kernel/tracing/set_ftrace_pid
dd: /sys/kernel/tracing/set_ftrace_pid: cannot skip to specified offset
id
no pid
2+1 records in
2+1 records out
10 bytes copied, 0.000213285 s, 46.9 kB/s
Notice the "id" followed by "no pid".
With the patch:
# dd bs=4 skip=1 if=/sys/kernel/tracing/set_ftrace_pid
dd: /sys/kernel/tracing/set_ftrace_pid: cannot skip to specified offset
id
0+1 records in
0+1 records out
3 bytes copied, 0.000202112 s, 14.8 kB/s
Notice that it only prints "id" and not the "no pid" afterward.
Link: http://lkml.kernel.org/r/4f87c6ad-f114-30bb-8506-c32274ce2992@virtuozzo.comhttps://bugzilla.kernel.org/show_bug.cgi?id=206283
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit dfb6cd1e65 ]
Looking through old emails in my INBOX, I came across a patch from Luis
Henriques that attempted to fix a race of two stat tracers registering the
same stat trace (extremely unlikely, as this is done in the kernel, and
probably doesn't even exist). The submitted patch wasn't quite right as it
needed to deal with clean up a bit better (if two stat tracers were the
same, it would have the same files).
But to make the code cleaner, all we needed to do is to keep the
all_stat_sessions_mutex held for most of the registering function.
Link: http://lkml.kernel.org/r/1410299375-20068-1-git-send-email-luis.henriques@canonical.com
Fixes: 002bb86d8d ("tracing/ftrace: separate events tracing and stats tracing engine")
Reported-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 45178ac0ce ]
Paul reported a very sporadic, rcutorture induced, workqueue failure.
When the planets align, the workqueue rescuer's self-migrate fails and
then triggers a WARN for running a work on the wrong CPU.
Tejun then figured that set_cpus_allowed_ptr()'s stop_one_cpu() call
could be ignored! When stopper->enabled is false, stop_machine will
insta complete the work, without actually doing the work. Worse, it
will not WARN about this (we really should fix this).
It turns out there is a small window where a freshly online'ed CPU is
marked 'online' but doesn't yet have the stopper task running:
BP AP
bringup_cpu()
__cpu_up(cpu, idle) --> start_secondary()
...
cpu_startup_entry()
bringup_wait_for_ap()
wait_for_ap_thread() <-- cpuhp_online_idle()
while (1)
do_idle()
... available to run kthreads ...
stop_machine_unpark()
stopper->enable = true;
Close this by moving the stop_machine_unpark() into
cpuhp_online_idle(), such that the stopper thread is ready before we
start the idle loop and schedule.
Reported-by: "Paul E. McKenney" <paulmck@kernel.org>
Debugged-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 07928d9bfc upstream.
The function padata_flush_queues is fundamentally broken because
it cannot force padata users to complete the request that is
underway. IOW padata has to passively wait for the completion
of any outstanding work.
As it stands flushing is used in two places. Its use in padata_stop
is simply unnecessary because nothing depends on the queues to
be flushed afterwards.
The other use in padata_replace is more substantial as we depend
on it to free the old pd structure. This patch instead uses the
pd->refcnt to dynamically free the pd structure once all requests
are complete.
Fixes: 2b73b07ab8 ("padata: Flush the padata queues actively")
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
[dj: leave "pd->pinst = pinst" assignment in padata_alloc_pd()]
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit febac332a8 upstream.
Kernel crashes inside QEMU/KVM are observed:
kernel BUG at kernel/time/timer.c:1154!
BUG_ON(timer_pending(timer) || !timer->function) in add_timer_on().
At the same time another cpu got:
general protection fault: 0000 [#1] SMP PTI of poinson pointer 0xdead000000000200 in:
__hlist_del at include/linux/list.h:681
(inlined by) detach_timer at kernel/time/timer.c:818
(inlined by) expire_timers at kernel/time/timer.c:1355
(inlined by) __run_timers at kernel/time/timer.c:1686
(inlined by) run_timer_softirq at kernel/time/timer.c:1699
Unfortunately kernel logs are badly scrambled, stacktraces are lost.
Printing the timer->function before the BUG_ON() pointed to
clocksource_watchdog().
The execution of clocksource_watchdog() can race with a sequence of
clocksource_stop_watchdog() .. clocksource_start_watchdog():
expire_timers()
detach_timer(timer, true);
timer->entry.pprev = NULL;
raw_spin_unlock_irq(&base->lock);
call_timer_fn
clocksource_watchdog()
clocksource_watchdog_kthread() or
clocksource_unbind()
spin_lock_irqsave(&watchdog_lock, flags);
clocksource_stop_watchdog();
del_timer(&watchdog_timer);
watchdog_running = 0;
spin_unlock_irqrestore(&watchdog_lock, flags);
spin_lock_irqsave(&watchdog_lock, flags);
clocksource_start_watchdog();
add_timer_on(&watchdog_timer, ...);
watchdog_running = 1;
spin_unlock_irqrestore(&watchdog_lock, flags);
spin_lock(&watchdog_lock);
add_timer_on(&watchdog_timer, ...);
BUG_ON(timer_pending(timer) || !timer->function);
timer_pending() -> true
BUG()
I.e. inside clocksource_watchdog() watchdog_timer could be already armed.
Check timer_pending() before calling add_timer_on(). This is sufficient as
all operations are synchronized by watchdog_lock.
Fixes: 75c5158f70 ("timekeeping: Update clocksource with stop_machine")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/158048693917.4378.13823603769948933793.stgit@buzz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 33da8e7c81 ]
My recent to change to only use force_sig for a synchronous events
wound up breaking signal reception cifs and drbd. I had overlooked
the fact that by default kthreads start out with all signals set to
SIG_IGN. So a change I thought was safe turned out to have made it
impossible for those kernel thread to catch their signals.
Reverting the work on force_sig is a bad idea because what the code
was doing was very much a misuse of force_sig. As the way force_sig
ultimately allowed the signal to happen was to change the signal
handler to SIG_DFL. Which after the first signal will allow userspace
to send signals to these kernel threads. At least for
wake_ack_receiver in drbd that does not appear actively wrong.
So correct this problem by adding allow_kernel_signal that will allow
signals whose siginfo reports they were sent by the kernel through,
but will not allow userspace generated signals, and update cifs and
drbd to call allow_kernel_signal in an appropriate place so that their
thread can receive this signal.
Fixing things this way ensures that userspace won't be able to send
signals and cause problems, that it is clear which signals the
threads are expecting to receive, and it guarantees that nothing
else in the system will be affected.
This change was partly inspired by similar cifs and drbd patches that
added allow_signal.
Reported-by: ronnie sahlberg <ronniesahlberg@gmail.com>
Reported-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Tested-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Cc: Steve French <smfrench@gmail.com>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Fixes: 247bc9470b ("cifs: fix rmmod regression in cifs.ko caused by force_sig changes")
Fixes: 72abe3bcf0 ("signal/cifs: Fix cifs_put_tcp_session to call send_sig instead of force_sig")
Fixes: fee109901f ("signal/drbd: Use send_sig not force_sig")
Fixes: 3cf5d076fb ("signal: Remove task parameter from force_sig")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit b586627e10 ]
The "whichcpu" comes from argv[3]. The cpu_online() macro looks up the
cpu in a bitmap of online cpus, but if the value is too high then it
could read beyond the end of the bitmap and possibly Oops.
Fixes: 5d5314d679 ("kdb: core for kgdb back end (1 of 2)")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 1a365e8223 ]
This fixes various data races in spinlock_debug. By testing with KCSAN,
it is observable that the console gets spammed with data races reports,
suggesting these are extremely frequent.
Example data race report:
read to 0xffff8ab24f403c48 of 4 bytes by task 221 on cpu 2:
debug_spin_lock_before kernel/locking/spinlock_debug.c:85 [inline]
do_raw_spin_lock+0x9b/0x210 kernel/locking/spinlock_debug.c:112
__raw_spin_lock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_lock+0x39/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:338 [inline]
get_partial_node.isra.0.part.0+0x32/0x2f0 mm/slub.c:1873
get_partial_node mm/slub.c:1870 [inline]
<snip>
write to 0xffff8ab24f403c48 of 4 bytes by task 167 on cpu 3:
debug_spin_unlock kernel/locking/spinlock_debug.c:103 [inline]
do_raw_spin_unlock+0xc9/0x1a0 kernel/locking/spinlock_debug.c:138
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:159 [inline]
_raw_spin_unlock_irqrestore+0x2d/0x50 kernel/locking/spinlock.c:191
spin_unlock_irqrestore include/linux/spinlock.h:393 [inline]
free_debug_processing+0x1b3/0x210 mm/slub.c:1214
__slab_free+0x292/0x400 mm/slub.c:2864
<snip>
As a side-effect, with KCSAN, this eventually locks up the console, most
likely due to deadlock, e.g. .. -> printk lock -> spinlock_debug ->
KCSAN detects data race -> kcsan_print_report() -> printk lock ->
deadlock.
This fix will 1) avoid the data races, and 2) allow using lock debugging
together with KCSAN.
Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Marco Elver <elver@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/20191120155715.28089-1-elver@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 106f41f5a3 upstream.
The compare functions of the histogram code would be specific for the size
of the value being compared (byte, short, int, long long). It would
reference the value from the array via the type of the compare, but the
value was stored in a 64 bit number. This is fine for little endian
machines, but for big endian machines, it would end up comparing zeros or
all ones (depending on the sign) for anything but 64 bit numbers.
To fix this, first derference the value as a u64 then convert it to the type
being compared.
Link: http://lkml.kernel.org/r/20191211103557.7bed6928@gandalf.local.home
Cc: stable@vger.kernel.org
Fixes: 08d43a5fa0 ("tracing: Add lock-free tracing_map")
Acked-by: Tom Zanussi <zanussi@kernel.org>
Reported-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 84029fd04c upstream.
The cred_jar kmem_cache is already memcg accounted in the current kernel
but cred->security is not. Account cred->security to kmemcg.
Recently we saw high root slab usage on our production and on further
inspection, we found a buggy application leaking processes. Though that
buggy application was contained within its memcg but we observe much
more system memory overhead, couple of GiBs, during that period. This
overhead can adversely impact the isolation on the system.
One source of high overhead we found was cred->security objects, which
have a lifetime of at least the life of the process which allocated
them.
Link: http://lkml.kernel.org/r/20191205223721.40034-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 0b8d616fb5 ]
When assiging and testing taskstats in taskstats_exit() there's a race
when setting up and reading sig->stats when a thread-group with more
than one thread exits:
write to 0xffff8881157bbe10 of 8 bytes by task 7951 on cpu 0:
taskstats_tgid_alloc kernel/taskstats.c:567 [inline]
taskstats_exit+0x6b7/0x717 kernel/taskstats.c:596
do_exit+0x2c2/0x18e0 kernel/exit.c:864
do_group_exit+0xb4/0x1c0 kernel/exit.c:983
get_signal+0x2a2/0x1320 kernel/signal.c:2734
do_signal+0x3b/0xc00 arch/x86/kernel/signal.c:815
exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:159
prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
do_syscall_64+0x2d7/0x2f0 arch/x86/entry/common.c:299
entry_SYSCALL_64_after_hwframe+0x44/0xa9
read to 0xffff8881157bbe10 of 8 bytes by task 7949 on cpu 1:
taskstats_tgid_alloc kernel/taskstats.c:559 [inline]
taskstats_exit+0xb2/0x717 kernel/taskstats.c:596
do_exit+0x2c2/0x18e0 kernel/exit.c:864
do_group_exit+0xb4/0x1c0 kernel/exit.c:983
__do_sys_exit_group kernel/exit.c:994 [inline]
__se_sys_exit_group kernel/exit.c:992 [inline]
__x64_sys_exit_group+0x2e/0x30 kernel/exit.c:992
do_syscall_64+0xcf/0x2f0 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fix this by using smp_load_acquire() and smp_store_release().
Reported-by: syzbot+c5d03165a1bd1dead0c1@syzkaller.appspotmail.com
Fixes: 34ec12349c ("taskstats: cleanup ->signal->stats allocation")
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Will Deacon <will@kernel.org>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Link: https://lore.kernel.org/r/20191009114809.8643-1-christian.brauner@ubuntu.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit da6043fe85 ]
When looking for a bit by number we make use of the cached result from the
preceding lookup to speed up operation. Firstly we check if the requested
pfn is within the cached zone and if not lookup the new zone. We then
check if the offset for that pfn falls within the existing cached node.
This happens regardless of whether the node is within the zone we are
now scanning. With certain memory layouts it is possible for this to
false trigger creating a temporary alias for the pfn to a different bit.
This leads the hibernation code to free memory which it was never allocated
with the expected fallout.
Ensure the zone we are scanning matches the cached zone before considering
the cached node.
Deep thanks go to Andrea for many, many, many hours of hacking and testing
that went into cornering this bug.
Reported-by: Andrea Righi <andrea.righi@canonical.com>
Tested-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 204cb79ad4 ]
Currently, the drop_caches proc file and sysctl read back the last value
written, suggesting this is somehow a stateful setting instead of a
one-time command. Make it write-only, like e.g. compact_memory.
While mitigating a VM problem at scale in our fleet, there was confusion
about whether writing to this file will permanently switch the kernel into
a non-caching mode. This influences the decision making in a tense
situation, where tens of people are trying to fix tens of thousands of
affected machines: Do we need a rollback strategy? What are the
performance implications of operating in a non-caching state for several
days? It also caused confusion when the kernel team said we may need to
write the file several times to make sure it's effective ("But it already
reads back 3?").
Link: http://lkml.kernel.org/r/20191031221602.9375-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 5d60331161 ]
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: 6e6de3dee5 ("kernel/module.c: Only return -EEXIST for modules that have finished loading")
Reviewed-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit a713af394c 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 49b786ea14 ("cgroup: implement the PIDs subsystem")
Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e66b39af00 upstream.
008847f66c ("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 <tj@kernel.org>
Cc: "Williams, Gerald S" <gerald.s.williams@intel.com>
Cc: NeilBrown <neilb@suse.de>
Cc: stable@vger.kernel.org # v3.19+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit def98c84b6 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 <tj@kernel.org>
Reported-by: Marcin Pawlowski <mpawlowski@fb.com>
Reported-by: "Williams, Gerald S" <gerald.s.williams@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4929a4e6fa 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 <pauld@redhat.com>
Signed-off-by: Xuewei Zhang <xueweiz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Phil Auld <pauld@redhat.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Fixes: 2e8e192263 ("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 <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 69924b8968 ]
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 <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit ea956d8be9 ]
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 <rgb@redhat.com>
[PM: cleaned up the commit metadata]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 3f130a37c4 ]
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 58b26c4c02
("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 <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
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 <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit d2130e82e9 ]
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 <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 55a3235fc7 ]
For userspace to tell the difference between a random signal and an
exception, the exception must include siginfo information.
Using SEND_SIG_FORCED for SIGILL is thus wrong, and it will result
in userspace seeing si_code == SI_USER (like a random signal) instead
of si_code == SI_KERNEL or a more specific si_code as all exceptions
deliver.
Therefore replace force_sig_info(SIGILL, SEND_SIG_FORCE, current)
with force_sig(SIG_ILL, current) which gets this right and is
shorter and easier to type.
Fixes: 014940bad8 ("uprobes/x86: Send SIGILL if arch_uprobe_post_xol() fails")
Fixes: 0b5256c7f1 ("uprobes: Send SIGILL if handle_trampoline() fails")
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 86989c41b5 ]
If the first process started (aka /sbin/init) receives a SIGKILL it
will panic the system if it is delivered. Making the system unusable
and undebugable. It isn't much better if the first process started
receives SIGSTOP.
So always ignore SIGSTOP and SIGKILL sent to init.
This is done in a separate clause in sig_task_ignored as force_sig_info
can clear SIG_UNKILLABLE and this protection should work even then.
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 731dc9df97 upstream.
A kernel module may need to check the value of the "mitigations=" kernel
command line parameter as part of its setup when the module needs
to perform software mitigations for a CPU flaw.
Uninline and export the helper functions surrounding the cpu_mitigations
enum to allow for their usage from a module.
Lastly, privatize the enum and cpu_mitigations variable since the value of
cpu_mitigations can be checked with the exported helper functions.
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit d303de1fcf ]
A customer reported the following softlockup:
[899688.160002] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [test.sh:16464]
[899688.160002] CPU: 0 PID: 16464 Comm: test.sh Not tainted 4.12.14-6.23-azure #1 SLE12-SP4
[899688.160002] RIP: 0010:up_write+0x1a/0x30
[899688.160002] Kernel panic - not syncing: softlockup: hung tasks
[899688.160002] RIP: 0010:up_write+0x1a/0x30
[899688.160002] RSP: 0018:ffffa86784d4fde8 EFLAGS: 00000257 ORIG_RAX: ffffffffffffff12
[899688.160002] RAX: ffffffff970fea00 RBX: 0000000000000001 RCX: 0000000000000000
[899688.160002] RDX: ffffffff00000001 RSI: 0000000000000080 RDI: ffffffff970fea00
[899688.160002] RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000
[899688.160002] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8b59014720d8
[899688.160002] R13: ffff8b59014720c0 R14: ffff8b5901471090 R15: ffff8b5901470000
[899688.160002] tracing_read_pipe+0x336/0x3c0
[899688.160002] __vfs_read+0x26/0x140
[899688.160002] vfs_read+0x87/0x130
[899688.160002] SyS_read+0x42/0x90
[899688.160002] do_syscall_64+0x74/0x160
It caught the process in the middle of trace_access_unlock(). There is
no loop. So, it must be looping in the caller tracing_read_pipe()
via the "waitagain" label.
Crashdump analyze uncovered that iter->seq was completely zeroed
at this point, including iter->seq.seq.size. It means that
print_trace_line() was never able to print anything and
there was no forward progress.
The culprit seems to be in the code:
/* reset all but tr, trace, and overruns */
memset(&iter->seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
It was added by the commit 53d0aa7730 ("ftrace:
add logic to record overruns"). It was v2.6.27-rc1.
It was the time when iter->seq looked like:
struct trace_seq {
unsigned char buffer[PAGE_SIZE];
unsigned int len;
};
There was no "size" variable and zeroing was perfectly fine.
The solution is to reinitialize the structure after or without
zeroing.
Link: http://lkml.kernel.org/r/20191011142134.11997-1-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 194c2c74f5 upstream.
As instances may have different tracers available, we need to look at the
trace_array descriptor that shows the list of the available tracers for the
instance. But there's a race between opening the file and an admin
deleting the instance. The trace_array_get() needs to be called before
accessing the trace_array.
Cc: stable@vger.kernel.org
Fixes: 607e2ea167 ("tracing: Set up infrastructure to allow tracers for instances")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
