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patches
Signed-off-by: Ingo Molnar <[email protected]>
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Currently, a schedule while atomic error prints the stack trace to the
kernel log and the system continue running.
Although it is possible to collect the kernel log messages and analyze
it, often more information are needed. Furthermore, keep the system
running is not always the best choice. For example, when the preempt
count underflows the system will not stop to complain about scheduling
while atomic, so the kernel log can wrap around overwriting the first
stack trace, tuning the analysis even more challenging.
This patch uses the kernel.panic_on_warn sysctl to help out on these
more complex situations.
When kernel.panic_on_warn is set to 1, the kernel will panic() in the
schedule while atomic detection.
The default value of the sysctl is 0, maintaining the current behavior.
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Reviewed-by: Luis Claudio R. Goncalves <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Luis Claudio R. Goncalves <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/e8f7b80f353aa22c63bd8557208163989af8493d.1464983675.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <[email protected]>
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In current code, we can get cpuacct data from several files,
but each file has various limitations.
For example:
- We can get CPU usage in user and kernel mode via cpuacct.stat,
but we can't get detailed data about each CPU.
- We can get each CPU's kernel mode usage in cpuacct.usage_percpu_sys,
but we can't get user mode usage data at the same time.
This patch introduces cpuacct.usage_all, to show all detailed CPU
accounting data together:
# cat cpuacct.usage_all
cpu user system
0 3809760299 5807968992
1 3250329855 454612211
..
Signed-off-by: Zhao Lei <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/7744460969edd7caaf0e903592ee52353ed9bdd6.1466415271.git.zhaolei@cn.fujitsu.com
Signed-off-by: Ingo Molnar <[email protected]>
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In cpuacct_stats_show() we currently we have copies of similar code,
for each cpustat(system/user) variant.
Use a loop instead to consolidate the code. This will also work better
if we extend the CPUACCT_STAT_NSTATS type.
Signed-off-by: Zhao Lei <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/b0597d4224655e9f333f1a6224ed9654c7d7d36a.1466415271.git.zhaolei@cn.fujitsu.com
Signed-off-by: Ingo Molnar <[email protected]>
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These two types have similar function, no need to separate them.
Signed-off-by: Zhao Lei <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/436748885270d64363c7dc67167507d486c2057a.1466415271.git.zhaolei@cn.fujitsu.com
Signed-off-by: Ingo Molnar <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
"Two load-balancing fixes for cgroups-intense workloads"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Fix calc_cfs_shares() fixed point arithmetics width confusion
sched/fair: Fix effective_load() to consistently use smoothed load
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The following commit:
66eb579e66ec ("perf: allow for PMU-specific event filtering")
added the pmu::filter_match() callback. This was intended to
avoid HW constraints on events from resulting in extremely
pessimistic scheduling.
However, pmu::filter_match() is only called for the leader of each event
group. When the leader is a SW event, we do not filter the groups, and
may fail at pmu::add() time, and when this happens we'll give up on
scheduling any event groups later in the list until they are rotated
ahead of the failing group.
This can result in extremely sub-optimal event scheduling behaviour,
e.g. if running the following on a big.LITTLE platform:
$ taskset -c 0 ./perf stat \
-e 'a57{context-switches,armv8_cortex_a57/config=0x11/}' \
-e 'a53{context-switches,armv8_cortex_a53/config=0x11/}' \
ls
<not counted> context-switches (0.00%)
<not counted> armv8_cortex_a57/config=0x11/ (0.00%)
24 context-switches (37.36%)
57589154 armv8_cortex_a53/config=0x11/ (37.36%)
Here the 'a53' event group was always eligible to be scheduled, but
the 'a57' group never eligible to be scheduled, as the task was always
affine to a Cortex-A53 CPU. The SW (group leader) event in the 'a57'
group was eligible, but the HW event failed at pmu::add() time,
resulting in ctx_flexible_sched_in giving up on scheduling further
groups with HW events.
One way of avoiding this is to check pmu::filter_match() on siblings
as well as the group leader. If any of these fail their
pmu::filter_match() call, we must skip the entire group before
attempting to add any events.
Signed-off-by: Mark Rutland <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Fixes: 66eb579e66ec ("perf: allow for PMU-specific event filtering")
Link: http://lkml.kernel.org/r/[email protected]
[ Small readability edits. ]
Signed-off-by: Ingo Molnar <[email protected]>
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Pull audit fixes from Paul Moore:
"Two small patches to fix audit problems in 4.7-rcX: the first fixes a
potential kref leak, the second removes some header file noise.
The first is an important bug fix that really should go in before 4.7
is released, the second is not critical, but falls into the very-nice-
to-have category so I'm including in the pull request.
Both patches are straightforward, self-contained, and pass our
testsuite without problem"
* 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit:
audit: move audit_get_tty to reduce scope and kabi changes
audit: move calcs after alloc and check when logging set loginuid
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Pull networking fixes from David Miller:
"I've been traveling so this accumulates more than week or so of bug
fixing. It perhaps looks a little worse than it really is.
1) Fix deadlock in ath10k driver, from Ben Greear.
2) Increase scan timeout in iwlwifi, from Luca Coelho.
3) Unbreak STP by properly reinjecting STP packets back into the
stack. Regression fix from Ido Schimmel.
4) Mediatek driver fixes (missing malloc failure checks, leaking of
scratch memory, wrong indexing when mapping TX buffers, etc.) from
John Crispin.
5) Fix endianness bug in icmpv6_err() handler, from Hannes Frederic
Sowa.
6) Fix hashing of flows in UDP in the ruseport case, from Xuemin Su.
7) Fix netlink notifications in ovs for tunnels, delete link messages
are never emitted because of how the device registry state is
handled. From Nicolas Dichtel.
8) Conntrack module leaks kmemcache on unload, from Florian Westphal.
9) Prevent endless jump loops in nft rules, from Liping Zhang and
Pablo Neira Ayuso.
10) Not early enough spinlock initialization in mlx4, from Eric
Dumazet.
11) Bind refcount leak in act_ipt, from Cong WANG.
12) Missing RCU locking in HTB scheduler, from Florian Westphal.
13) Several small MACSEC bug fixes from Sabrina Dubroca (missing RCU
barrier, using heap for SG and IV, and erroneous use of async flag
when allocating AEAD conext.)
14) RCU handling fix in TIPC, from Ying Xue.
15) Pass correct protocol down into ipv4_{update_pmtu,redirect}() in
SIT driver, from Simon Horman.
16) Socket timer deadlock fix in TIPC from Jon Paul Maloy.
17) Fix potential deadlock in team enslave, from Ido Schimmel.
18) Memory leak in KCM procfs handling, from Jiri Slaby.
19) ESN generation fix in ipv4 ESP, from Herbert Xu.
20) Fix GFP_KERNEL allocations with locks held in act_ife, from Cong
WANG.
21) Use after free in netem, from Eric Dumazet.
22) Uninitialized last assert time in multicast router code, from Tom
Goff.
23) Skip raw sockets in sock_diag destruction broadcast, from Willem
de Bruijn.
24) Fix link status reporting in thunderx, from Sunil Goutham.
25) Limit resegmentation of retransmit queue so that we do not
retransmit too large GSO frames. From Eric Dumazet.
26) Delay bpf program release after grace period, from Daniel
Borkmann"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (141 commits)
openvswitch: fix conntrack netlink event delivery
qed: Protect the doorbell BAR with the write barriers.
neigh: Explicitly declare RCU-bh read side critical section in neigh_xmit()
e1000e: keep VLAN interfaces functional after rxvlan off
cfg80211: fix proto in ieee80211_data_to_8023 for frames without LLC header
qlcnic: use the correct ring in qlcnic_83xx_process_rcv_ring_diag()
bpf, perf: delay release of BPF prog after grace period
net: bridge: fix vlan stats continue counter
tcp: do not send too big packets at retransmit time
ibmvnic: fix to use list_for_each_safe() when delete items
net: thunderx: Fix TL4 configuration for secondary Qsets
net: thunderx: Fix link status reporting
net/mlx5e: Reorganize ethtool statistics
net/mlx5e: Fix number of PFC counters reported to ethtool
net/mlx5e: Prevent adding the same vxlan port
net/mlx5e: Check for BlueFlame capability before allocating SQ uar
net/mlx5e: Change enum to better reflect usage
net/mlx5: Add ConnectX-5 PCIe 4.0 to list of supported devices
net/mlx5: Update command strings
net: marvell: Add separate config ANEG function for Marvell 88E1111
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
"Three fix patches. Two are for cgroup / css init failure path. The
last one makes css_set_lock irq-safe as the deadline scheduler ends up
calling put_css_set() from irq context"
* 'for-4.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: Disable IRQs while holding css_set_lock
cgroup: set css->id to -1 during init
cgroup: remove redundant cleanup in css_create
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Commit dead9f29ddcc ("perf: Fix race in BPF program unregister") moved
destruction of BPF program from free_event_rcu() callback to __free_event(),
which is problematic if used with tail calls: if prog A is attached as
trace event directly, but at the same time present in a tail call map used
by another trace event program elsewhere, then we need to delay destruction
via RCU grace period since it can still be in use by the program doing the
tail call (the prog first needs to be dropped from the tail call map, then
trace event with prog A attached destroyed, so we get immediate destruction).
Fixes: dead9f29ddcc ("perf: Fix race in BPF program unregister")
Signed-off-by: Daniel Borkmann <[email protected]>
Acked-by: Alexei Starovoitov <[email protected]>
Cc: Jann Horn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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The only users of audit_get_tty and audit_put_tty are internal to
audit, so move it out of include/linux/audit.h to kernel.h and create
a proper function rather than inlining it. This also reduces kABI
changes.
Suggested-by: Paul Moore <[email protected]>
Signed-off-by: Richard Guy Briggs <[email protected]>
[PM: line wrapped description]
Signed-off-by: Paul Moore <[email protected]>
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Move the calculations of values after the allocation in case the
allocation fails. This avoids wasting effort in the rare case that it
fails, but more importantly saves us extra logic to release the tty
ref.
Signed-off-by: Richard Guy Briggs <[email protected]>
Signed-off-by: Paul Moore <[email protected]>
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Since we already take rq->lock when creating a cgroup, use it to also
sync the throttle_count and avoid the extra state and enqueue path
branch.
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
[ Fixed build warning. ]
Signed-off-by: Ingo Molnar <[email protected]>
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Previous version was probably written referencing the man page for
glibc's wrapper, but the wrapper's behavior differs from that of the
syscall itself in this case.
Signed-off-by: Zev Weiss <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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A future patch needs rq->lock held _after_ we link the task_group into
the hierarchy. In order to avoid taking every rq->lock twice, reorder
things a little and create online_fair_sched_group() to be called
after we link the task_group.
All this code is still ran from css_alloc() so css_online() isn't in
fact used for this.
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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One additional 'rule' for using update_cfs_rq_load_avg() is that one
should call update_tg_load_avg() if it returns true.
Add a bunch of comments to hopefully clarify some of the rules:
o You need to update cfs_rq _before_ any entity attach/detach,
this is important, because while for mathmatical consisency this
isn't strictly needed, it is required for the physical
interpretation of the model, you attach/detach _now_.
o When you modify the cfs_rq avg, you have to then call
update_tg_load_avg() in order to propagate changes upwards.
o (Fair) entities are always attached, switched_{to,from}_fair()
deal with !fair. This directly follows from the definition of the
cfs_rq averages, namely that they are a direct sum of all
(runnable or blocked) entities on that rq.
It is the second rule that this patch enforces, but it adds comments
pertaining to all of them.
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Vincent and Yuyang found another few scenarios in which entity
tracking goes wobbly.
The scenarios are basically due to the fact that new tasks are not
immediately attached and thereby differ from the normal situation -- a
task is always attached to a cfs_rq load average (such that it
includes its blocked contribution) and are explicitly
detached/attached on migration to another cfs_rq.
Scenario 1: switch to fair class
p->sched_class = fair_class;
if (queued)
enqueue_task(p);
...
enqueue_entity()
enqueue_entity_load_avg()
migrated = !sa->last_update_time (true)
if (migrated)
attach_entity_load_avg()
check_class_changed()
switched_from() (!fair)
switched_to() (fair)
switched_to_fair()
attach_entity_load_avg()
If @p is a new task that hasn't been fair before, it will have
!last_update_time and, per the above, end up in
attach_entity_load_avg() _twice_.
Scenario 2: change between cgroups
sched_move_group(p)
if (queued)
dequeue_task()
task_move_group_fair()
detach_task_cfs_rq()
detach_entity_load_avg()
set_task_rq()
attach_task_cfs_rq()
attach_entity_load_avg()
if (queued)
enqueue_task();
...
enqueue_entity()
enqueue_entity_load_avg()
migrated = !sa->last_update_time (true)
if (migrated)
attach_entity_load_avg()
Similar as with scenario 1, if @p is a new task, it will have
!load_update_time and we'll end up in attach_entity_load_avg()
_twice_.
Furthermore, notice how we do a detach_entity_load_avg() on something
that wasn't attached to begin with.
As stated above; the problem is that the new task isn't yet attached
to the load tracking and thereby violates the invariant assumption.
This patch remedies this by ensuring a new task is indeed properly
attached to the load tracking on creation, through
post_init_entity_util_avg().
Of course, this isn't entirely as straightforward as one might think,
since the task is hashed before we call wake_up_new_task() and thus
can be poked at. We avoid this by adding TASK_NEW and teaching
cpu_cgroup_can_attach() to refuse such tasks.
Reported-by: Yuyang Du <[email protected]>
Reported-by: Vincent Guittot <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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A new fair task is detached and attached from/to task_group with:
cgroup_post_fork()
ss->fork(child) := cpu_cgroup_fork()
sched_move_task()
task_move_group_fair()
Which is wrong, because at this point in fork() the task isn't fully
initialized and it cannot 'move' to another group, because its not
attached to any group as yet.
In fact, cpu_cgroup_fork() needs a small part of sched_move_task() so we
can just call this small part directly instead sched_move_task(). And
the task doesn't really migrate because it is not yet attached so we
need the following sequence:
do_fork()
sched_fork()
__set_task_cpu()
cgroup_post_fork()
set_task_rq() # set task group and runqueue
wake_up_new_task()
select_task_rq() can select a new cpu
__set_task_cpu
post_init_entity_util_avg
attach_task_cfs_rq()
activate_task
enqueue_task
This patch makes that happen.
Signed-off-by: Vincent Guittot <[email protected]>
[ Added TASK_SET_GROUP to set depth properly. ]
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Vincent reported that when a new task is moved into a new cgroup it
gets attached twice to the load tracking:
sched_move_task()
task_move_group_fair()
detach_task_cfs_rq()
set_task_rq()
attach_task_cfs_rq()
attach_entity_load_avg()
se->avg.last_load_update = cfs_rq->avg.last_load_update // == 0
enqueue_entity()
enqueue_entity_load_avg()
update_cfs_rq_load_avg()
now = clock()
__update_load_avg(&cfs_rq->avg)
cfs_rq->avg.last_load_update = now
// ages load/util for: now - 0, load/util -> 0
if (migrated)
attach_entity_load_avg()
se->avg.last_load_update = cfs_rq->avg.last_load_update; // now != 0
The problem is that we don't update cfs_rq load_avg before all
entity attach/detach operations. Only enqueue_task() and migrate_task()
do this.
By fixing this, the above will not happen, because the
sched_move_task() attach will have updated cfs_rq's last_load_update
time before attach, and in turn the attach will have set the entity's
last_load_update stamp.
Note that there is a further problem with sched_move_task() calling
detach on a task that hasn't yet been attached; this will be taken
care of in a subsequent patch.
Reported-by: Vincent Guittot <[email protected]>
Tested-by: Vincent Guittot <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Yuyang Du <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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The task_fork_fair() callback already calls __set_task_cpu() and takes
rq->lock.
If we move the sched_class::task_fork callback in sched_fork() under
the existing p->pi_lock, right after its set_task_cpu() call, we can
avoid doing two such calls and omit the IRQ disabling on the rq->lock.
Change to __set_task_cpu() to skip the migration bits, this is a new
task, not a migration. Similarly, make wake_up_new_task() use
__set_task_cpu() for the same reason, the task hasn't actually
migrated as it hasn't ever ran.
This cures the problem of calling migrate_task_rq_fair(), which does
remove_entity_from_load_avg() on tasks that have never been added to
the load avg to begin with.
This bug would result in transiently messed up load_avg values, averaged
out after a few dozen milliseconds. This is probably the reason why
this bug was not found for such a long time.
Reported-by: Vincent Guittot <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Signed-off-by: Ingo Molnar <[email protected]>
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Commit:
fde7d22e01aa ("sched/fair: Fix overly small weight for interactive group entities")
did something non-obvious but also did it buggy yet latent.
The problem was exposed for real by a later commit in the v4.7 merge window:
2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels")
... after which tg->load_avg and cfs_rq->load.weight had different
units (10 bit fixed point and 20 bit fixed point resp.).
Add a comment to explain the use of cfs_rq->load.weight over the
'natural' cfs_rq->avg.load_avg and add scale_load_down() to correct
for the difference in unit.
Since this is (now, as per a previous commit) the only user of
calc_tg_weight(), collapse it.
The effects of this bug should be randomly inconsistent SMP-balancing
of cgroups workloads.
Reported-by: Jirka Hladky <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels")
Fixes: fde7d22e01aa ("sched/fair: Fix overly small weight for interactive group entities")
Signed-off-by: Ingo Molnar <[email protected]>
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Starting with the following commit:
fde7d22e01aa ("sched/fair: Fix overly small weight for interactive group entities")
calc_tg_weight() doesn't compute the right value as expected by effective_load().
The difference is in the 'correction' term. In order to ensure \Sum
rw_j >= rw_i we cannot use tg->load_avg directly, since that might be
lagging a correction on the current cfs_rq->avg.load_avg value.
Therefore we use tg->load_avg - cfs_rq->tg_load_avg_contrib +
cfs_rq->avg.load_avg.
Now, per the referenced commit, calc_tg_weight() doesn't use
cfs_rq->avg.load_avg, as is later used in @w, but uses
cfs_rq->load.weight instead.
So stop using calc_tg_weight() and do it explicitly.
The effects of this bug are wake_affine() making randomly
poor choices in cgroup-intense workloads.
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: <[email protected]> # v4.3+
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: fde7d22e01aa ("sched/fair: Fix overly small weight for interactive group entities")
Signed-off-by: Ingo Molnar <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Thomas Gleixner:
"A couple of scheduler fixes:
- force watchdog reset while processing sysrq-w
- fix a deadlock when enabling trace events in the scheduler
- fixes to the throttled next buddy logic
- fixes for the average accounting (missing serialization and
underflow handling)
- allow kernel threads for fallback to online but not active cpus"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/core: Allow kthreads to fall back to online && !active cpus
sched/fair: Do not announce throttled next buddy in dequeue_task_fair()
sched/fair: Initialize throttle_count for new task-groups lazily
sched/fair: Fix cfs_rq avg tracking underflow
kernel/sysrq, watchdog, sched/core: Reset watchdog on all CPUs while processing sysrq-w
sched/debug: Fix deadlock when enabling sched events
sched/fair: Fix post_init_entity_util_avg() serialization
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fix from Thomas Gleixner:
"A single fix to address a race in the static key logic"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/static_key: Fix concurrent static_key_slow_inc()
|
|
Commit b235beea9e99 ("Clarify naming of thread info/stack allocators")
breaks the build on some powerpc configs, where THREAD_SIZE < PAGE_SIZE:
kernel/fork.c:235:2: error: implicit declaration of function 'free_thread_stack'
kernel/fork.c:355:8: error: assignment from incompatible pointer type
stack = alloc_thread_stack_node(tsk, node);
^
Fix it by renaming free_stack() to free_thread_stack(), and updating the
return type of alloc_thread_stack_node().
Fixes: b235beea9e99 ("Clarify naming of thread info/stack allocators")
Signed-off-by: Michael Ellerman <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
Merge misc fixes from Andrew Morton:
"Two weeks worth of fixes here"
* emailed patches from Andrew Morton <[email protected]>: (41 commits)
init/main.c: fix initcall_blacklisted on ia64, ppc64 and parisc64
autofs: don't get stuck in a loop if vfs_write() returns an error
mm/page_owner: avoid null pointer dereference
tools/vm/slabinfo: fix spelling mistake: "Ocurrences" -> "Occurrences"
fs/nilfs2: fix potential underflow in call to crc32_le
oom, suspend: fix oom_reaper vs. oom_killer_disable race
ocfs2: disable BUG assertions in reading blocks
mm, compaction: abort free scanner if split fails
mm: prevent KASAN false positives in kmemleak
mm/hugetlb: clear compound_mapcount when freeing gigantic pages
mm/swap.c: flush lru pvecs on compound page arrival
memcg: css_alloc should return an ERR_PTR value on error
memcg: mem_cgroup_migrate() may be called with irq disabled
hugetlb: fix nr_pmds accounting with shared page tables
Revert "mm: disable fault around on emulated access bit architecture"
Revert "mm: make faultaround produce old ptes"
mailmap: add Boris Brezillon's email
mailmap: add Antoine Tenart's email
mm, sl[au]b: add __GFP_ATOMIC to the GFP reclaim mask
mm: mempool: kasan: don't poot mempool objects in quarantine
...
|
|
Tetsuo has reported the following potential oom_killer_disable vs.
oom_reaper race:
(1) freeze_processes() starts freezing user space threads.
(2) Somebody (maybe a kenrel thread) calls out_of_memory().
(3) The OOM killer calls mark_oom_victim() on a user space thread
P1 which is already in __refrigerator().
(4) oom_killer_disable() sets oom_killer_disabled = true.
(5) P1 leaves __refrigerator() and enters do_exit().
(6) The OOM reaper calls exit_oom_victim(P1) before P1 can call
exit_oom_victim(P1).
(7) oom_killer_disable() returns while P1 not yet finished
(8) P1 perform IO/interfere with the freezer.
This situation is unfortunate. We cannot move oom_killer_disable after
all the freezable kernel threads are frozen because the oom victim might
depend on some of those kthreads to make a forward progress to exit so
we could deadlock. It is also far from trivial to teach the oom_reaper
to not call exit_oom_victim() because then we would lose a guarantee of
the OOM killer and oom_killer_disable forward progress because
exit_mm->mmput might block and never call exit_oom_victim.
It seems the easiest way forward is to workaround this race by calling
try_to_freeze_tasks again after oom_killer_disable. This will make sure
that all the tasks are frozen or it bails out.
Fixes: 449d777d7ad6 ("mm, oom_reaper: clear TIF_MEMDIE for all tasks queued for oom_reaper")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michal Hocko <[email protected]>
Reported-by: Tetsuo Handa <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
We've had the thread info allocated together with the thread stack for
most architectures for a long time (since the thread_info was split off
from the task struct), but that is about to change.
But the patches that move the thread info to be off-stack (and a part of
the task struct instead) made it clear how confused the allocator and
freeing functions are.
Because the common case was that we share an allocation with the thread
stack and the thread_info, the two pointers were identical. That
identity then meant that we would have things like
ti = alloc_thread_info_node(tsk, node);
...
tsk->stack = ti;
which certainly _worked_ (since stack and thread_info have the same
value), but is rather confusing: why are we assigning a thread_info to
the stack? And if we move the thread_info away, the "confusing" code
just gets to be entirely bogus.
So remove all this confusion, and make it clear that we are doing the
stack allocation by renaming and clarifying the function names to be
about the stack. The fact that the thread_info then shares the
allocation is an implementation detail, and not really about the
allocation itself.
This is a pure renaming and type fix: we pass in the same pointer, it's
just that we clarify what the pointer means.
The ia64 code that actually only has one single allocation (for all of
task_struct, thread_info and kernel thread stack) now looks a bit odd,
but since "tsk->stack" is actually not even used there, that oddity
doesn't matter. It would be a separate thing to clean that up, I
intentionally left the ia64 changes as a pure brute-force renaming and
type change.
Acked-by: Andy Lutomirski <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
During CPU hotplug, CPU_ONLINE callbacks are run while the CPU is
online but not active. A CPU_ONLINE callback may create or bind a
kthread so that its cpus_allowed mask only allows the CPU which is
being brought online. The kthread may start executing before the CPU
is made active and can end up in select_fallback_rq().
In such cases, the expected behavior is selecting the CPU which is
coming online; however, because select_fallback_rq() only chooses from
active CPUs, it determines that the task doesn't have any viable CPU
in its allowed mask and ends up overriding it to cpu_possible_mask.
CPU_ONLINE callbacks should be able to put kthreads on the CPU which
is coming online. Update select_fallback_rq() so that it follows
cpu_online() rather than cpu_active() for kthreads.
Reported-by: Gautham R Shenoy <[email protected]>
Tested-by: Gautham R. Shenoy <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Abdul Haleem <[email protected]>
Cc: Aneesh Kumar <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
|
|
Hierarchy could be already throttled at this point. Throttled next
buddy could trigger a NULL pointer dereference in pick_next_task_fair().
Signed-off-by: Konstantin Khlebnikov <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Ben Segall <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzz
Signed-off-by: Ingo Molnar <[email protected]>
|
|
Cgroup created inside throttled group must inherit current throttle_count.
Broken throttle_count allows to nominate throttled entries as a next buddy,
later this leads to null pointer dereference in pick_next_task_fair().
This patch initialize cfs_rq->throttle_count at first enqueue: laziness
allows to skip locking all rq at group creation. Lazy approach also allows
to skip full sub-tree scan at throttling hierarchy (not in this patch).
Signed-off-by: Konstantin Khlebnikov <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/146608182119.21870.8439834428248129633.stgit@buzz
Signed-off-by: Ingo Molnar <[email protected]>
|
|
The following scenario is possible:
CPU 1 CPU 2
static_key_slow_inc()
atomic_inc_not_zero()
-> key.enabled == 0, no increment
jump_label_lock()
atomic_inc_return()
-> key.enabled == 1 now
static_key_slow_inc()
atomic_inc_not_zero()
-> key.enabled == 1, inc to 2
return
** static key is wrong!
jump_label_update()
jump_label_unlock()
Testing the static key at the point marked by (**) will follow the
wrong path for jumps that have not been patched yet. This can
actually happen when creating many KVM virtual machines with userspace
LAPIC emulation; just run several copies of the following program:
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/kvm.h>
int main(void)
{
for (;;) {
int kvmfd = open("/dev/kvm", O_RDONLY);
int vmfd = ioctl(kvmfd, KVM_CREATE_VM, 0);
close(ioctl(vmfd, KVM_CREATE_VCPU, 1));
close(vmfd);
close(kvmfd);
}
return 0;
}
Every KVM_CREATE_VCPU ioctl will attempt a static_key_slow_inc() call.
The static key's purpose is to skip NULL pointer checks and indeed one
of the processes eventually dereferences NULL.
As explained in the commit that introduced the bug:
706249c222f6 ("locking/static_keys: Rework update logic")
jump_label_update() needs key.enabled to be true. The solution adopted
here is to temporarily make key.enabled == -1, and use go down the
slow path when key.enabled <= 0.
Reported-by: Dmitry Vyukov <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: <[email protected]> # v4.3+
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: 706249c222f6 ("locking/static_keys: Rework update logic")
Link: http://lkml.kernel.org/r/[email protected]
[ Small stylistic edits to the changelog and the code. ]
Signed-off-by: Ingo Molnar <[email protected]>
|
|
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] <IRQ> [<ffffffff813d229e>] dump_stack+0x63/0x85
[ 132.612994] [<ffffffff810a652b>] __warn+0xcb/0xf0
[ 132.612997] [<ffffffff810e76a0>] ? push_dl_task.part.32+0x170/0x170
[ 132.612999] [<ffffffff810a665d>] warn_slowpath_null+0x1d/0x20
[ 132.613000] [<ffffffff810aba5b>] __local_bh_enable_ip+0x6b/0x80
[ 132.613008] [<ffffffff817d6c8a>] _raw_write_unlock_bh+0x1a/0x20
[ 132.613010] [<ffffffff817d6c9e>] _raw_spin_unlock_bh+0xe/0x10
[ 132.613015] [<ffffffff811388ac>] put_css_set+0x5c/0x60
[ 132.613016] [<ffffffff8113dc7f>] cgroup_free+0x7f/0xa0
[ 132.613017] [<ffffffff810a3912>] __put_task_struct+0x42/0x140
[ 132.613018] [<ffffffff810e776a>] dl_task_timer+0xca/0x250
[ 132.613027] [<ffffffff810e76a0>] ? push_dl_task.part.32+0x170/0x170
[ 132.613030] [<ffffffff8111371e>] __hrtimer_run_queues+0xee/0x270
[ 132.613031] [<ffffffff81113ec8>] hrtimer_interrupt+0xa8/0x190
[ 132.613034] [<ffffffff81051a58>] local_apic_timer_interrupt+0x38/0x60
[ 132.613035] [<ffffffff817d9b0d>] smp_apic_timer_interrupt+0x3d/0x50
[ 132.613037] [<ffffffff817d7c5c>] apic_timer_interrupt+0x8c/0xa0
[ 132.613038] <EOI> [<ffffffff81063466>] ? native_safe_halt+0x6/0x10
[ 132.613043] [<ffffffff81037a4e>] default_idle+0x1e/0xd0
[ 132.613044] [<ffffffff810381cf>] arch_cpu_idle+0xf/0x20
[ 132.613046] [<ffffffff810e8fda>] default_idle_call+0x2a/0x40
[ 132.613047] [<ffffffff810e92d7>] cpu_startup_entry+0x2e7/0x340
[ 132.613048] [<ffffffff81050235>] 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 <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: [email protected]
Cc: [email protected] # 4.5+
Cc: [email protected]
Reviewed-by: Rik van Riel <[email protected]>
Reviewed-by: "Luis Claudio R. Goncalves" <[email protected]>
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Acked-by: Zefan Li <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
|
|
None of the code actually wants a thread_info, it all wants a
task_struct, and it's just converting back and forth between the two
("ti->task" to get the task_struct from the thread_info, and
"task_thread_info(task)" to go the other way).
No semantic change.
Acked-by: Peter Zijlstra <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
"Two fixes for the tracing system:
- When trace_printk() is used with a non constant format descriptor,
it adds a NULL pointer into the trace format section, and the code
isn't prepared to deal with it. This bug appeared by a change that
was added in v3.5.
- The ftracetest (selftests section) can't handle testing histograms
when histograms are not configured. Currently it shows that they
fail the test, when they should state that they are unsupported.
This bug was added in the 4.7 merge window with the addition of the
historgram code"
* tag 'trace-v4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftracetest: Fix hist unsupported result in hist selftests
tracing: Handle NULL formats in hold_module_trace_bprintk_format()
|
|
If a task uses a non constant string for the format parameter in
trace_printk(), then the trace_printk_fmt variable is set to NULL. This
variable is then saved in the __trace_printk_fmt section.
The function hold_module_trace_bprintk_format() checks to see if duplicate
formats are used by modules, and reuses them if so (saves them to the list
if it is new). But this function calls lookup_format() that does a strcmp()
to the value (which is now NULL) and can cause a kernel oops.
This wasn't an issue till 3debb0a9ddb ("tracing: Fix trace_printk() to print
when not using bprintk()") which added "__used" to the trace_printk_fmt
variable, and before that, the kernel simply optimized it out (no NULL value
was saved).
The fix is simply to handle the NULL pointer in lookup_format() and have the
caller ignore the value if it was NULL.
Link: http://lkml.kernel.org/r/[email protected]
Reported-by: xingzhen <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Fixes: 3debb0a9ddb ("tracing: Fix trace_printk() to print when not using bprintk()")
Cc: [email protected] # v3.5+
Signed-off-by: Steven Rostedt <[email protected]>
|
|
As per commit:
b7fa30c9cc48 ("sched/fair: Fix post_init_entity_util_avg() serialization")
> the code generated from update_cfs_rq_load_avg():
>
> if (atomic_long_read(&cfs_rq->removed_load_avg)) {
> s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0);
> sa->load_avg = max_t(long, sa->load_avg - r, 0);
> sa->load_sum = max_t(s64, sa->load_sum - r * LOAD_AVG_MAX, 0);
> removed_load = 1;
> }
>
> turns into:
>
> ffffffff81087064: 49 8b 85 98 00 00 00 mov 0x98(%r13),%rax
> ffffffff8108706b: 48 85 c0 test %rax,%rax
> ffffffff8108706e: 74 40 je ffffffff810870b0 <update_blocked_averages+0xc0>
> ffffffff81087070: 4c 89 f8 mov %r15,%rax
> ffffffff81087073: 49 87 85 98 00 00 00 xchg %rax,0x98(%r13)
> ffffffff8108707a: 49 29 45 70 sub %rax,0x70(%r13)
> ffffffff8108707e: 4c 89 f9 mov %r15,%rcx
> ffffffff81087081: bb 01 00 00 00 mov $0x1,%ebx
> ffffffff81087086: 49 83 7d 70 00 cmpq $0x0,0x70(%r13)
> ffffffff8108708b: 49 0f 49 4d 70 cmovns 0x70(%r13),%rcx
>
> Which you'll note ends up with sa->load_avg -= r in memory at
> ffffffff8108707a.
So I _should_ have looked at other unserialized users of ->load_avg,
but alas. Luckily nikbor reported a similar /0 from task_h_load() which
instantly triggered recollection of this here problem.
Aside from the intermediate value hitting memory and causing problems,
there's another problem: the underflow detection relies on the signed
bit. This reduces the effective width of the variables, IOW its
effectively the same as having these variables be of signed type.
This patch changes to a different means of unsigned underflow
detection to not rely on the signed bit. This allows the variables to
use the 'full' unsigned range. And it does so with explicit LOAD -
STORE to ensure any intermediate value will never be visible in
memory, allowing these unserialized loads.
Note: GCC generates crap code for this, might warrant a look later.
Note2: I say 'full' above, if we end up at U*_MAX we'll still explode;
maybe we should do clamping on add too.
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Yuyang Du <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Fixes: 9d89c257dfb9 ("sched/fair: Rewrite runnable load and utilization average tracking")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
|
|
If percpu_ref initialization fails during css_create(), the free path
can end up trying to free css->id of zero. As ID 0 is unused, it
doesn't cause a critical breakage but it does trigger a warning
message. Fix it by setting css->id to -1 from init_and_link_css().
Signed-off-by: Tejun Heo <[email protected]>
Cc: Wenwei Tao <[email protected]>
Fixes: 01e586598b22 ("cgroup: release css->id after css_free")
Cc: [email protected] # v4.0+
Signed-off-by: Tejun Heo <[email protected]>
|
|
similar to bpf_perf_event_output() the bpf_perf_event_read() helper
needs to check the type of the perf_event before reading the counter.
Fixes: a43eec304259 ("bpf: introduce bpf_perf_event_output() helper")
Reported-by: Daniel Borkmann <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
Acked-by: Daniel Borkmann <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
|
|
The ctx structure passed into bpf programs is different depending on bpf
program type. The verifier incorrectly marked ctx->data and ctx->data_end
access based on ctx offset only. That caused loads in tracing programs
int bpf_prog(struct pt_regs *ctx) { .. ctx->ax .. }
to be incorrectly marked as PTR_TO_PACKET which later caused verifier
to reject the program that was actually valid in tracing context.
Fix this by doing program type specific matching of ctx offsets.
Fixes: 969bf05eb3ce ("bpf: direct packet access")
Reported-by: Sasha Goldshtein <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
Acked-by: Daniel Borkmann <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
|
|
Since commit 49d200deaa68 ("debugfs: prevent access to removed files'
private data"), a debugfs file's file_operations methods get proxied
through lifetime aware wrappers.
However, only a certain subset of the file_operations members is supported
by debugfs and ->mmap isn't among them -- it appears to be NULL from the
VFS layer's perspective.
This behaviour breaks the /sys/kernel/debug/kcov file introduced
concurrently with commit 5c9a8750a640 ("kernel: add kcov code coverage").
Since that file never gets removed, there is no file removal race and thus,
a lifetime checking proxy isn't needed.
Avoid the proxying for /sys/kernel/debug/kcov by creating it via
debugfs_create_file_unsafe() rather than debugfs_create_file().
Fixes: 49d200deaa68 ("debugfs: prevent access to removed files' private data")
Fixes: 5c9a8750a640 ("kernel: add kcov code coverage")
Reported-by: Sasha Levin <[email protected]>
Signed-off-by: Nicolai Stange <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
|
|
processing sysrq-w
Lengthy output of sysrq-w may take a lot of time on slow serial console.
Currently we reset NMI-watchdog on the current CPU to avoid spurious
lockup messages. Sometimes this doesn't work since softlockup watchdog
might trigger on another CPU which is waiting for an IPI to proceed.
We reset softlockup watchdogs on all CPUs, but we do this only after
listing all tasks, and this may be too late on a busy system.
So, reset watchdogs CPUs earlier, in for_each_process_thread() loop.
Signed-off-by: Andrey Ryabinin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
|
|
I see a hang when enabling sched events:
echo 1 > /sys/kernel/debug/tracing/events/sched/enable
The printk buffer shows:
BUG: spinlock recursion on CPU#1, swapper/1/0
lock: 0xffff88007d5d8c00, .magic: dead4ead, .owner: swapper/1/0, .owner_cpu: 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.7.0-rc2+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014
...
Call Trace:
<IRQ> [<ffffffff8143d663>] dump_stack+0x85/0xc2
[<ffffffff81115948>] spin_dump+0x78/0xc0
[<ffffffff81115aea>] do_raw_spin_lock+0x11a/0x150
[<ffffffff81891471>] _raw_spin_lock+0x61/0x80
[<ffffffff810e5466>] ? try_to_wake_up+0x256/0x4e0
[<ffffffff810e5466>] try_to_wake_up+0x256/0x4e0
[<ffffffff81891a0a>] ? _raw_spin_unlock_irqrestore+0x4a/0x80
[<ffffffff810e5705>] wake_up_process+0x15/0x20
[<ffffffff810cebb4>] insert_work+0x84/0xc0
[<ffffffff810ced7f>] __queue_work+0x18f/0x660
[<ffffffff810cf9a6>] queue_work_on+0x46/0x90
[<ffffffffa00cd95b>] drm_fb_helper_dirty.isra.11+0xcb/0xe0 [drm_kms_helper]
[<ffffffffa00cdac0>] drm_fb_helper_sys_imageblit+0x30/0x40 [drm_kms_helper]
[<ffffffff814babcd>] soft_cursor+0x1ad/0x230
[<ffffffff814ba379>] bit_cursor+0x649/0x680
[<ffffffff814b9d30>] ? update_attr.isra.2+0x90/0x90
[<ffffffff814b5e6a>] fbcon_cursor+0x14a/0x1c0
[<ffffffff81555ef8>] hide_cursor+0x28/0x90
[<ffffffff81558b6f>] vt_console_print+0x3bf/0x3f0
[<ffffffff81122c63>] call_console_drivers.constprop.24+0x183/0x200
[<ffffffff811241f4>] console_unlock+0x3d4/0x610
[<ffffffff811247f5>] vprintk_emit+0x3c5/0x610
[<ffffffff81124bc9>] vprintk_default+0x29/0x40
[<ffffffff811e965b>] printk+0x57/0x73
[<ffffffff810f7a9e>] enqueue_entity+0xc2e/0xc70
[<ffffffff810f7b39>] enqueue_task_fair+0x59/0xab0
[<ffffffff8106dcd9>] ? kvm_sched_clock_read+0x9/0x20
[<ffffffff8103fb39>] ? sched_clock+0x9/0x10
[<ffffffff810e3fcc>] activate_task+0x5c/0xa0
[<ffffffff810e4514>] ttwu_do_activate+0x54/0xb0
[<ffffffff810e5cea>] sched_ttwu_pending+0x7a/0xb0
[<ffffffff810e5e51>] scheduler_ipi+0x61/0x170
[<ffffffff81059e7f>] smp_trace_reschedule_interrupt+0x4f/0x2a0
[<ffffffff81893ba6>] trace_reschedule_interrupt+0x96/0xa0
<EOI> [<ffffffff8106e0d6>] ? native_safe_halt+0x6/0x10
[<ffffffff8110fb1d>] ? trace_hardirqs_on+0xd/0x10
[<ffffffff81040ac0>] default_idle+0x20/0x1a0
[<ffffffff8104147f>] arch_cpu_idle+0xf/0x20
[<ffffffff81102f8f>] default_idle_call+0x2f/0x50
[<ffffffff8110332e>] cpu_startup_entry+0x37e/0x450
[<ffffffff8105af70>] start_secondary+0x160/0x1a0
Note the hang only occurs when echoing the above from a physical serial
console, not from an ssh session.
The bug is caused by a deadlock where the task is trying to grab the rq
lock twice because printk()'s aren't safe in sched code.
Signed-off-by: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Matt Fleming <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Srikar Dronamraju <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Fixes: cb2517653fcc ("sched/debug: Make schedstats a runtime tunable that is disabled by default")
Link: http://lkml.kernel.org/r/20160613073209.gdvdybiruljbkn3p@treble
Signed-off-by: Ingo Molnar <[email protected]>
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This patch adds guest steal-time support to full dynticks CPU
time accounting. After the following commit:
ff9a9b4c4334 ("sched, time: Switch VIRT_CPU_ACCOUNTING_GEN to jiffy granularity")
... time sampling became jiffy based, even if we do the sampling from the
context tracking code, so steal_account_process_tick() can be reused
to account how many 'ticks' are stolen-time, after the last accumulation.
Signed-off-by: Wanpeng Li <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Paolo Bonzini <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Radim Krčmář <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Commit:
e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug")
... set rq->prev_* to 0 after a CPU hotplug comes back, in order to
fix the case where (after CPU hotplug) steal time is smaller than
rq->prev_steal_time.
However, this should never happen. Steal time was only smaller because of the
KVM-specific bug fixed by the previous patch. Worse, the previous patch
triggers a bug on CPU hot-unplug/plug operation: because
rq->prev_steal_time is cleared, all of the CPU's past steal time will be
accounted again on hot-plug.
Since the root cause has been fixed, we can just revert commit e9532e69b8d1.
Signed-off-by: Wanpeng Li <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Paolo Bonzini <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Radim Krčmář <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: 'commit e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug")'
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Signed-off-by: Ingo Molnar <[email protected]>
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Chris Wilson reported a divide by 0 at:
post_init_entity_util_avg():
> 725 if (cfs_rq->avg.util_avg != 0) {
> 726 sa->util_avg = cfs_rq->avg.util_avg * se->load.weight;
> -> 727 sa->util_avg /= (cfs_rq->avg.load_avg + 1);
> 728
> 729 if (sa->util_avg > cap)
> 730 sa->util_avg = cap;
> 731 } else {
Which given the lack of serialization, and the code generated from
update_cfs_rq_load_avg() is entirely possible:
if (atomic_long_read(&cfs_rq->removed_load_avg)) {
s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0);
sa->load_avg = max_t(long, sa->load_avg - r, 0);
sa->load_sum = max_t(s64, sa->load_sum - r * LOAD_AVG_MAX, 0);
removed_load = 1;
}
turns into:
ffffffff81087064: 49 8b 85 98 00 00 00 mov 0x98(%r13),%rax
ffffffff8108706b: 48 85 c0 test %rax,%rax
ffffffff8108706e: 74 40 je ffffffff810870b0
ffffffff81087070: 4c 89 f8 mov %r15,%rax
ffffffff81087073: 49 87 85 98 00 00 00 xchg %rax,0x98(%r13)
ffffffff8108707a: 49 29 45 70 sub %rax,0x70(%r13)
ffffffff8108707e: 4c 89 f9 mov %r15,%rcx
ffffffff81087081: bb 01 00 00 00 mov $0x1,%ebx
ffffffff81087086: 49 83 7d 70 00 cmpq $0x0,0x70(%r13)
ffffffff8108708b: 49 0f 49 4d 70 cmovns 0x70(%r13),%rcx
Which you'll note ends up with 'sa->load_avg - r' in memory at
ffffffff8108707a.
By calling post_init_entity_util_avg() under rq->lock we're sure to be
fully serialized against PELT updates and cannot observe intermediate
state like this.
Reported-by: Chris Wilson <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Yuyang Du <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Fixes: 2b8c41daba32 ("sched/fair: Initiate a new task's util avg to a bounded value")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Merge filesystem stacking fixes from Jann Horn.
* emailed patches from Jann Horn <[email protected]>:
sched: panic on corrupted stack end
ecryptfs: forbid opening files without mmap handler
proc: prevent stacking filesystems on top
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