Some call sites of cpuhp_setup/remove_state[_nocalls]() are within a
cpus_read locked region.
cpuhp_setup/remove_state[_nocalls]() call cpus_read_lock() as well, which
is possible in the current implementation but prevents converting the
hotplug locking to a percpu rwsem.
Provide locked versions of the interfaces to avoid nested calls to
cpus_read_lock().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081547.239600868@linutronix.de
The counting 'rwsem' hackery of get|put_online_cpus() is going to be
replaced by percpu rwsem.
Rename the functions to make it clear that it's locking and not some
refcount style interface. These new functions will be used for the
preparatory patches which make the code ready for the percpu rwsem
conversion.
Rename all instances in the cpu hotplug code while at it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170524081547.080397752@linutronix.de
Saw these compile errors on SPARC when queued rwlock feature is enabled.
CC kernel/locking/qrwlock.o
kernel/locking/qrwlock.c: In function ‘queued_read_lock_slowpath’:
kernel/locking/qrwlock.c:89: error: implicit declaration of function ‘arch_spin_lock’
kernel/locking/qrwlock.c:102: error: implicit declaration of function ‘arch_spin_unlock’
make[4]: *** [kernel/locking/qrwlock.o] Error 1
Include spinlock.h in qrwlock.c to fix it.
Signed-off-by: Babu Moger <babu.moger@oracle.com>
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>
Reviewed-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Reviewed-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
trie_alloc() always needs to have BPF_F_NO_PREALLOC passed in via
attr->map_flags, since it does not support preallocation yet. We
check the flag, but we never copy the flag into trie->map.map_flags,
which is later on exposed into fdinfo and used by loaders such as
iproute2. Latter uses this in bpf_map_selfcheck_pinned() to test
whether a pinned map has the same spec as the one from the BPF obj
file and if not, bails out, which is currently the case for lpm
since it exposes always 0 as flags.
Also copy over flags in array_map_alloc() and stack_map_alloc().
They always have to be 0 right now, but we should make sure to not
miss to copy them over at a later point in time when we add actual
flags for them to use.
Fixes: b95a5c4db0 ("bpf: add a longest prefix match trie map implementation")
Reported-by: Jarno Rajahalme <jarno@covalent.io>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, after performing helper calls, we clear all caller saved
registers, that is r0 - r5 and fill r0 depending on struct bpf_func_proto
specification. The way we reset these regs can affect pruning decisions
in later paths, since we only reset register's imm to 0 and type to
NOT_INIT. However, we leave out clearing of other variables such as id,
min_value, max_value, etc, which can later on lead to pruning mismatches
due to stale data.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, when we enforce alignment tracking on direct packet access,
the verifier lets the following program pass despite doing a packet
write with unaligned access:
0: (61) r2 = *(u32 *)(r1 +76)
1: (61) r3 = *(u32 *)(r1 +80)
2: (61) r7 = *(u32 *)(r1 +8)
3: (bf) r0 = r2
4: (07) r0 += 14
5: (25) if r7 > 0x1 goto pc+4
R0=pkt(id=0,off=14,r=0) R1=ctx R2=pkt(id=0,off=0,r=0)
R3=pkt_end R7=inv,min_value=0,max_value=1 R10=fp
6: (2d) if r0 > r3 goto pc+1
R0=pkt(id=0,off=14,r=14) R1=ctx R2=pkt(id=0,off=0,r=14)
R3=pkt_end R7=inv,min_value=0,max_value=1 R10=fp
7: (63) *(u32 *)(r0 -4) = r0
8: (b7) r0 = 0
9: (95) exit
from 6 to 8:
R0=pkt(id=0,off=14,r=0) R1=ctx R2=pkt(id=0,off=0,r=0)
R3=pkt_end R7=inv,min_value=0,max_value=1 R10=fp
8: (b7) r0 = 0
9: (95) exit
from 5 to 10:
R0=pkt(id=0,off=14,r=0) R1=ctx R2=pkt(id=0,off=0,r=0)
R3=pkt_end R7=inv,min_value=2 R10=fp
10: (07) r0 += 1
11: (05) goto pc-6
6: safe <----- here, wrongly found safe
processed 15 insns
However, if we enforce a pruning mismatch by adding state into r8
which is then being mismatched in states_equal(), we find that for
the otherwise same program, the verifier detects a misaligned packet
access when actually walking that path:
0: (61) r2 = *(u32 *)(r1 +76)
1: (61) r3 = *(u32 *)(r1 +80)
2: (61) r7 = *(u32 *)(r1 +8)
3: (b7) r8 = 1
4: (bf) r0 = r2
5: (07) r0 += 14
6: (25) if r7 > 0x1 goto pc+4
R0=pkt(id=0,off=14,r=0) R1=ctx R2=pkt(id=0,off=0,r=0)
R3=pkt_end R7=inv,min_value=0,max_value=1
R8=imm1,min_value=1,max_value=1,min_align=1 R10=fp
7: (2d) if r0 > r3 goto pc+1
R0=pkt(id=0,off=14,r=14) R1=ctx R2=pkt(id=0,off=0,r=14)
R3=pkt_end R7=inv,min_value=0,max_value=1
R8=imm1,min_value=1,max_value=1,min_align=1 R10=fp
8: (63) *(u32 *)(r0 -4) = r0
9: (b7) r0 = 0
10: (95) exit
from 7 to 9:
R0=pkt(id=0,off=14,r=0) R1=ctx R2=pkt(id=0,off=0,r=0)
R3=pkt_end R7=inv,min_value=0,max_value=1
R8=imm1,min_value=1,max_value=1,min_align=1 R10=fp
9: (b7) r0 = 0
10: (95) exit
from 6 to 11:
R0=pkt(id=0,off=14,r=0) R1=ctx R2=pkt(id=0,off=0,r=0)
R3=pkt_end R7=inv,min_value=2
R8=imm1,min_value=1,max_value=1,min_align=1 R10=fp
11: (07) r0 += 1
12: (b7) r8 = 0
13: (05) goto pc-7 <----- mismatch due to r8
7: (2d) if r0 > r3 goto pc+1
R0=pkt(id=0,off=15,r=15) R1=ctx R2=pkt(id=0,off=0,r=15)
R3=pkt_end R7=inv,min_value=2
R8=imm0,min_value=0,max_value=0,min_align=2147483648 R10=fp
8: (63) *(u32 *)(r0 -4) = r0
misaligned packet access off 2+15+-4 size 4
The reason why we fail to see it in states_equal() is that the
third test in compare_ptrs_to_packet() ...
if (old->off <= cur->off &&
old->off >= old->range && cur->off >= cur->range)
return true;
... will let the above pass. The situation we run into is that
old->off <= cur->off (14 <= 15), meaning that prior walked paths
went with smaller offset, which was later used in the packet
access after successful packet range check and found to be safe
already.
For example: Given is R0=pkt(id=0,off=0,r=0). Adding offset 14
as in above program to it, results in R0=pkt(id=0,off=14,r=0)
before the packet range test. Now, testing this against R3=pkt_end
with 'if r0 > r3 goto out' will transform R0 into R0=pkt(id=0,off=14,r=14)
for the case when we're within bounds. A write into the packet
at offset *(u32 *)(r0 -4), that is, 2 + 14 -4, is valid and
aligned (2 is for NET_IP_ALIGN). After processing this with
all fall-through paths, we later on check paths from branches.
When the above skb->mark test is true, then we jump near the
end of the program, perform r0 += 1, and jump back to the
'if r0 > r3 goto out' test we've visited earlier already. This
time, R0 is of type R0=pkt(id=0,off=15,r=0), and we'll prune
that part because this time we'll have a larger safe packet
range, and we already found that with off=14 all further insn
were already safe, so it's safe as well with a larger off.
However, the problem is that the subsequent write into the packet
with 2 + 15 -4 is then unaligned, and not caught by the alignment
tracking. Note that min_align, aux_off, and aux_off_align were
all 0 in this example.
Since we cannot tell at this time what kind of packet access was
performed in the prior walk and what minimal requirements it has
(we might do so in the future, but that requires more complexity),
fix it to disable this pruning case for strict alignment for now,
and let the verifier do check such paths instead. With that applied,
the test cases pass and reject the program due to misalignment.
Fixes: d117441674 ("bpf: Track alignment of register values in the verifier.")
Reference: http://patchwork.ozlabs.org/patch/761909/
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch makes it possible to pass additional arguments in addition
to uevent action name when writing /sys/.../uevent attribute. These
additional arguments are then inserted into generated synthetic uevent
as additional environment variables.
Before, we were not able to pass any additional uevent environment
variables for synthetic uevents. This made it hard to identify such uevents
properly in userspace to make proper distinction between genuine uevents
originating from kernel and synthetic uevents triggered from userspace.
Also, it was not possible to pass any additional information which would
make it possible to optimize and change the way the synthetic uevents are
processed back in userspace based on the originating environment of the
triggering action in userspace. With the extra additional variables, we are
able to pass through this extra information needed and also it makes it
possible to synchronize with such synthetic uevents as they can be clearly
identified back in userspace.
The format for writing the uevent attribute is following:
ACTION [UUID [KEY=VALUE ...]
There's no change in how "ACTION" is recognized - it stays the same
("add", "change", "remove"). The "ACTION" is the only argument required
to generate synthetic uevent, the rest of arguments, that this patch
adds support for, are optional.
The "UUID" is considered as transaction identifier so it's possible to
use the same UUID value for one or more synthetic uevents in which case
we logically group these uevents together for any userspace listeners.
The "UUID" is expected to be in "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
format where "x" is a hex digit. The value appears in uevent as
"SYNTH_UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" environment variable.
The "KEY=VALUE" pairs can contain alphanumeric characters only. It's
possible to define zero or more more pairs - each pair is then delimited
by a space character " ". Each pair appears in synthetic uevents as
"SYNTH_ARG_KEY=VALUE" environment variable. That means the KEY name gains
"SYNTH_ARG_" prefix to avoid possible collisions with existing variables.
To pass the "KEY=VALUE" pairs, it's also required to pass in the "UUID"
part for the synthetic uevent first.
If "UUID" is not passed in, the generated synthetic uevent gains
"SYNTH_UUID=0" environment variable automatically so it's possible to
identify this situation in userspace when reading generated uevent and so
we can still make a difference between genuine and synthetic uevents.
Signed-off-by: Peter Rajnoha <prajnoha@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In most cases, a cgroup controller don't care about the liftimes of
cgroups. For the controller, a css becomes online when ->css_online()
is called on it and offline when ->css_offline() is called.
However, cpuset is special in that the user interface it exposes cares
whether certain cgroups exist or not. Combined with the RCU delay
between cgroup removal and css offlining, this can lead to user
visible behavior oddities where operations which should succeed after
cgroup removals fail for some time period. The effects of cgroup
removals are delayed when seen from userland.
This patch adds css_is_dying() which tests whether offline is pending
and updates is_cpuset_online() so that the function returns false also
while offline is pending. This gets rid of the userland visible
delays.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Link: http://lkml.kernel.org/r/327ca1f5-7957-fbb9-9e5f-9ba149d40ba2@oracle.com
Cc: stable@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull ptrace fix from Eric Biederman:
"This fixes a brown paper bag bug. When I fixed the ptrace interaction
with user namespaces I added a new field ptracer_cred in struct_task
and I failed to properly initialize it on fork.
This dangling pointer wound up breaking runing setuid applications run
from the enlightenment window manager.
As this is the worst sort of bug. A regression breaking user space for
no good reason let's get this fixed"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
ptrace: Properly initialize ptracer_cred on fork
The more strict early boot preemption warnings found that
__set_sched_clock_stable() was incorrectly assuming we'd still be
running on a single CPU:
BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
caller is debug_smp_processor_id+0x1c/0x1e
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.12.0-rc2-00108-g1c3c5ea #1
Call Trace:
dump_stack+0x110/0x192
check_preemption_disabled+0x10c/0x128
? set_debug_rodata+0x25/0x25
debug_smp_processor_id+0x1c/0x1e
sched_clock_init_late+0x27/0x87
[...]
Fix it by disabling IRQs.
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: lkp@01.org
Cc: tipbuild@zytor.com
Link: http://lkml.kernel.org/r/20170524065202.v25vyu7pvba5mhpd@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A recent commit added extra printks for CPU/RT limits. This can result in
excessive spam in dmesg.
Make the printks conditional on print_fatal_signals.
Fixes: e7ea7c9806 ("rlimits: Print more information when CPU/RT limits are exceeded")
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arun Raghavan <arun@arunraghavan.net>
The cap_* fields swing in and out of PATH records.
If no capabilities are set, the cap_* fields are completely missing and when
one of the cap_fi or cap_fp values is empty, that field is omitted.
Original:
type=PATH msg=audit(04/20/2017 12:17:11.222:193) : item=1 name=/lib64/ld-linux-x86-64.so.2 inode=787694 dev=08:03 mode=file,755 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:ld_so_t:s0 nametype=NORMAL
type=PATH msg=audit(04/20/2017 12:17:11.222:193) : item=0 name=/home/sleep inode=1319469 dev=08:03 mode=file,suid,755 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:bin_t:s0 nametype=NORMAL cap_fp=sys_admin cap_fe=1 cap_fver=2
Normalize the PATH record by always printing all 4 cap_* fields.
Fixed:
type=PATH msg=audit(04/20/2017 13:01:31.679:201) : item=1 name=/lib64/ld-linux-x86-64.so.2 inode=787694 dev=08:03 mode=file,755 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:ld_so_t:s0 nametype=NORMAL cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
type=PATH msg=audit(04/20/2017 13:01:31.679:201) : item=0 name=/home/sleep inode=1319469 dev=08:03 mode=file,suid,755 ouid=root ogid=root rdev=00:00 obj=system_u:object_r:bin_t:s0 nametype=NORMAL cap_fp=sys_admin cap_fi=none cap_fe=1 cap_fver=2
See: https://github.com/linux-audit/audit-kernel/issues/42
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
When I introduced ptracer_cred I failed to consider the weirdness of
fork where the task_struct copies the old value by default. This
winds up leaving ptracer_cred set even when a process forks and
the child process does not wind up being ptraced.
Because ptracer_cred is not set on non-ptraced processes whose
parents were ptraced this has broken the ability of the enlightenment
window manager to start setuid children.
Fix this by properly initializing ptracer_cred in ptrace_init_task
This must be done with a little bit of care to preserve the current value
of ptracer_cred when ptrace carries through fork. Re-reading the
ptracer_cred from the ptracing process at this point is inconsistent
with how PT_PTRACE_CAP has been maintained all of these years.
Tested-by: Takashi Iwai <tiwai@suse.de>
Fixes: 64b875f7ac ("ptrace: Capture the ptracer's creds not PT_PTRACE_CAP")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
might_sleep() and smp_processor_id() checks are enabled after the boot
process is done. That hides bugs in the SMP bringup and driver
initialization code.
Enable it right when the scheduler starts working, i.e. when init task and
kthreadd have been created and right before the idle task enables
preemption.
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170516184736.272225698@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
To enable smp_processor_id() and might_sleep() debug checks earlier, it's
required to add system states between SYSTEM_BOOTING and SYSTEM_RUNNING.
Adjust the system_state check in boot_delay_msec() to handle the extra
states.
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170516184736.027534895@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
To enable smp_processor_id() and might_sleep() debug checks earlier, it's
required to add system states between SYSTEM_BOOTING and SYSTEM_RUNNING.
Adjust the system_state check in core_kernel_text() to handle the extra
states, i.e. to cover init text up to the point where the system switches
to state RUNNING.
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170516184735.949992741@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
To enable smp_processor_id() and might_sleep() debug checks earlier, it's
required to add system states between SYSTEM_BOOTING and SYSTEM_RUNNING.
Adjust the system_state check in async_run_entry_fn() and
async_synchronize_cookie_domain() to handle the extra states.
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170516184735.865155020@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A customer has reported a soft-lockup when running an intensive
memory stress test, where the trace on multiple CPU's looks like this:
RIP: 0010:[<ffffffff810c53fe>]
[<ffffffff810c53fe>] native_queued_spin_lock_slowpath+0x10e/0x190
...
Call Trace:
[<ffffffff81182d07>] queued_spin_lock_slowpath+0x7/0xa
[<ffffffff811bc331>] change_protection_range+0x3b1/0x930
[<ffffffff811d4be8>] change_prot_numa+0x18/0x30
[<ffffffff810adefe>] task_numa_work+0x1fe/0x310
[<ffffffff81098322>] task_work_run+0x72/0x90
Further investigation showed that the lock contention here is pmd_lock().
The task_numa_work() function makes sure that only one thread is let to perform
the work in a single scan period (via cmpxchg), but if there's a thread with
mmap_sem locked for writing for several periods, multiple threads in
task_numa_work() can build up a convoy waiting for mmap_sem for read and then
all get unblocked at once.
This patch changes the down_read() to the trylock version, which prevents the
build up. For a workload experiencing mmap_sem contention, it's probably better
to postpone the NUMA balancing work anyway. This seems to have fixed the soft
lockups involving pmd_lock(), which is in line with the convoy theory.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170515131316.21909-1-vbabka@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With CONFIG_RT_GROUP_SCHED=y, do_sched_rt_period_timer() sequentially
takes each CPU's rq->lock. On a large, busy system, the cumulative time it
takes to acquire each lock can be excessive, even triggering a watchdog
timeout.
If rt_rq->rt_time and rt_rq->rt_nr_running are both zero, this function does
nothing while holding the lock, so don't bother taking it at all.
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a767637b-df85-912f-ba69-c90ee00a3fb6@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When priority inheritance was added back in 2.6.18 to sched_setscheduler(), it
added a path to taking an rt-mutex wait_lock, which is not IRQ safe. As PI
is not a common occurrence, lockdep will likely never trigger if
sched_setscheduler was called from interrupt context. A BUG_ON() was added
to trigger if __sched_setscheduler() was ever called from interrupt context
because there was a possibility to take the wait_lock.
Today the wait_lock is irq safe, but the path to taking it in
sched_setscheduler() is the same as the path to taking it from normal
context. The wait_lock is taken with raw_spin_lock_irq() and released with
raw_spin_unlock_irq() which will indiscriminately enable interrupts,
which would be bad in interrupt context.
The problem is that normalize_rt_tasks, which is called by triggering the
sysrq nice-all-RT-tasks was changed to call __sched_setscheduler(), and this
is done from interrupt context!
Now __sched_setscheduler() takes a "pi" parameter that is used to know if
the priority inheritance should be called or not. As the BUG_ON() only cares
about calling the PI code, it should only bug if called from interrupt
context with the "pi" parameter set to true.
Reported-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Tested-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: dbc7f069b9 ("sched: Use replace normalize_task() with __sched_setscheduler()")
Link: http://lkml.kernel.org/r/20170308124654.10e598f2@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
pick_next_pushable_dl_task(rq) has BUG_ON(rq->cpu != task_cpu(task))
when it returns a task other than NULL, which means that task_cpu(task)
must be rq->cpu. So if task == next_task, then task_cpu(next_task) must
be rq->cpu as well. Remove the redundant condition and make the code simpler.
This way one unnecessary branch and two LOAD operations can be avoided.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: <kernel-team@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1494551159-22367-1-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
pick_next_pushable_task(rq) has BUG_ON(rq_cpu != task_cpu(task)) when
it returns a task other than NULL, which means that task_cpu(task) must
be rq->cpu. So if task == next_task, then task_cpu(next_task) must be
rq->cpu as well. Remove the redundant condition and make the code simpler.
This way one unnecessary branch and two LOAD operations can be avoided.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: <kernel-team@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1494551143-22219-1-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that we've added llist_for_each_entry_safe(), use it to simplify
an open coded version of it in sched_ttwu_pending().
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <kernel-team@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1494549584-11730-1-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The cpumasks in smp_call_function_many() are private and not subject
to concurrency, atomic bitops are pointless and expensive.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Inter-Processor-Interrupt(IPI) is needed when a page is unmapped and the
process' mm_cpumask() shows the process has ever run on other CPUs. page
migration, page reclaim all need IPIs. The number of IPI needed to send
to different CPUs is especially large for multi-threaded workload since
mm_cpumask() is per process.
For smp_call_function_many(), whenever a CPU queues a CSD to a target
CPU, it will send an IPI to let the target CPU to handle the work.
This isn't necessary - we need only send IPI when queueing a CSD
to an empty call_single_queue.
The reason:
flush_smp_call_function_queue() that is called upon a CPU receiving an
IPI will empty the queue and then handle all of the CSDs there. So if
the target CPU's call_single_queue is not empty, we know that:
i. An IPI for the target CPU has already been sent by 'previous queuers';
ii. flush_smp_call_function_queue() hasn't emptied that CPU's queue yet.
Thus, it's safe for us to just queue our CSD there without sending an
addtional IPI. And for the 'previous queuers', we can limit it to the
first queuer.
To demonstrate the effect of this patch, a multi-thread workload that
spawns 80 threads to equally consume 100G memory is used. This is tested
on a 2 node broadwell-EP which has 44cores/88threads and 32G memory. So
after 32G memory is used up, page reclaiming starts to happen a lot.
With this patch, IPI number dropped 88% and throughput increased about
15% for the above workload.
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Link: http://lkml.kernel.org/r/20170519075331.GE2084@aaronlu.sh.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We don't set an error code here which means that perf_event_alloc()
returns ERR_PTR(0) (in other words NULL). The callers are not expecting
that and would Oops.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Fixes: 375637bc52 ("perf/core: Introduce address range filtering")
Link: http://lkml.kernel.org/r/20170522090418.hvs6icgpdo53wkn5@mwanda
Signed-off-by: Ingo Molnar <mingo@kernel.org>
perf_init_event() can't return NULL. If it did, the error handling is
incomplete and we would crash. I have removed this confusing dead code.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20170522090348.5g7yyld5en3yeky4@mwanda
Signed-off-by: Ingo Molnar <mingo@kernel.org>
- Fix RTC wakeup from suspend-to-idle broken by the recent rework
of ACPI wakeup handling (Rafael Wysocki).
- Update intel_pstate driver documentation to reflect the current
code and explain how it works in more detail (Rafael Wysocki).
- Fix an issue related to CPU idleness detection on systems with
shared cpufreq policies in the schedutil governor (Juri Lelli).
- Fix a possible build issue in the dbx500 cpufreq driver (Arnd
Bergmann).
- Fix a function in the power capping framework core to return
an error code instead of 0 when there's an error (Dan Carpenter).
- Clean up variable definition in the hibernation core (Pushkar
Jambhlekar).
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Merge tag 'pm-4.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fixes from Rafael Wysocki:
"These fix RTC wakeup from suspend-to-idle broken recently, fix CPU
idleness detection condition in the schedutil cpufreq governor, fix a
cpufreq driver build failure, fix an error code path in the power
capping framework, clean up the hibernate core and update the
intel_pstate documentation.
Specifics:
- Fix RTC wakeup from suspend-to-idle broken by the recent rework of
ACPI wakeup handling (Rafael Wysocki).
- Update intel_pstate driver documentation to reflect the current
code and explain how it works in more detail (Rafael Wysocki).
- Fix an issue related to CPU idleness detection on systems with
shared cpufreq policies in the schedutil governor (Juri Lelli).
- Fix a possible build issue in the dbx500 cpufreq driver (Arnd
Bergmann).
- Fix a function in the power capping framework core to return an
error code instead of 0 when there's an error (Dan Carpenter).
- Clean up variable definition in the hibernation core (Pushkar
Jambhlekar)"
* tag 'pm-4.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpufreq: dbx500: add a Kconfig symbol
PM / hibernate: Declare variables as static
PowerCap: Fix an error code in powercap_register_zone()
RTC: rtc-cmos: Fix wakeup from suspend-to-idle
PM / wakeup: Fix up wakeup_source_report_event()
cpufreq: intel_pstate: Document the current behavior and user interface
cpufreq: schedutil: use now as reference when aggregating shared policy requests
In order to ease debug, let's populate the domain name upfront, before any
MSI gets requested. This allows the domain to appear in the
irq_domain_mapping, and the user to easily find the expected data.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/20170512115538.10767-4-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
If the system is using ACPI, there is no of_node to display. But ACPI can
use a struct irqchip_fwid as a domain identifier, and it can be used to
display the name contained in that structure.
The output on such a system will look like this:
pMSI 0 0 0 irqchip@00000000e1180000
MSI 37 0 0 irqchip@00000000e1180000
GICv2m 37 0 0 irqchip@00000000e1180000
GICv2 448 448 0 irqchip@ffff000008003000
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/20170512115538.10767-3-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Hierarchical domains seem to be hard to grasp, and a number of
aspiring kernel hackers find them utterly discombobulating.
In order to ease their pain, let's make them appear in
/sys/kernel/debug/irq_domain_mapping, such as the following:
96 0x81808 MSI 0x (null) RADIX MSI
96+ 0x00063 GICv2m 0xffff8003ee116980 RADIX GICv2m
96+ 0x00063 GICv2 0xffff00000916bfd8 LINEAR GICv2
[output compressed to fit in a commit log]
This shows that IRQ96 is implemented by a stack of three domains,
the + sign indicating the stacking.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/20170512115538.10767-2-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
If a kthread forks (e.g. usermodehelper since commit 1da5c46fa9) but
fails in copy_process() between calling dup_task_struct() and setting
p->set_child_tid, then the value of p->set_child_tid will be inherited
from the parent and get prematurely freed by free_kthread_struct().
kthread()
- worker_thread()
- process_one_work()
| - call_usermodehelper_exec_work()
| - kernel_thread()
| - _do_fork()
| - copy_process()
| - dup_task_struct()
| - arch_dup_task_struct()
| - tsk->set_child_tid = current->set_child_tid // implied
| - ...
| - goto bad_fork_*
| - ...
| - free_task(tsk)
| - free_kthread_struct(tsk)
| - kfree(tsk->set_child_tid)
- ...
- schedule()
- __schedule()
- wq_worker_sleeping()
- kthread_data(task)->flags // UAF
The problem started showing up with commit 1da5c46fa9 since it reused
->set_child_tid for the kthread worker data.
A better long-term solution might be to get rid of the ->set_child_tid
abuse. The comment in set_kthread_struct() also looks slightly wrong.
Debugged-by: Jamie Iles <jamie.iles@oracle.com>
Fixes: 1da5c46fa9 ("kthread: Make struct kthread kmalloc'ed")
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jamie Iles <jamie.iles@oracle.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170509073959.17858-1-vegard.nossum@oracle.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
min_vecs is the minimum amount of vectors needed to operate in MSI-X mode
which may just include the vectors that don't need affinity.
Disabling affinity settings causes the qla2xxx driver scsi_add_host() to fail
when blk_mq is enabled as the blk_mq_pci_map_queues() expects affinity masks
on each vector.
Fixes: dfef358bd1 ("PCI/MSI: Don't apply affinity if there aren't enough vectors left")
Signed-off-by: Michael Hernandez <michael.hernandez@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org # v4.10+
Markus reported that the glibc/nptl/tst-robustpi8 test was failing after
commit:
cfafcd117d ("futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()")
The following trace shows the problem:
ld-linux-x86-64-2161 [019] .... 410.760971: SyS_futex: 00007ffbeb76b028: 80000875 op=FUTEX_LOCK_PI
ld-linux-x86-64-2161 [019] ...1 410.760972: lock_pi_update_atomic: 00007ffbeb76b028: curval=80000875 uval=80000875 newval=80000875 ret=0
ld-linux-x86-64-2165 [011] .... 410.760978: SyS_futex: 00007ffbeb76b028: 80000875 op=FUTEX_UNLOCK_PI
ld-linux-x86-64-2165 [011] d..1 410.760979: do_futex: 00007ffbeb76b028: curval=80000875 uval=80000875 newval=80000871 ret=0
ld-linux-x86-64-2165 [011] .... 410.760980: SyS_futex: 00007ffbeb76b028: 80000871 ret=0000
ld-linux-x86-64-2161 [019] .... 410.760980: SyS_futex: 00007ffbeb76b028: 80000871 ret=ETIMEDOUT
Task 2165 does an UNLOCK_PI, assigning the lock to the waiter task 2161
which then returns with -ETIMEDOUT. That wrecks the lock state, because now
the owner isn't aware it acquired the lock and removes the pending robust
list entry.
If 2161 is killed, the robust list will not clear out this futex and the
subsequent acquire on this futex will then (correctly) result in -ESRCH
which is unexpected by glibc, triggers an internal assertion and dies.
Task 2161 Task 2165
rt_mutex_wait_proxy_lock()
timeout();
/* T2161 is still queued in the waiter list */
return -ETIMEDOUT;
futex_unlock_pi()
spin_lock(hb->lock);
rtmutex_unlock()
remove_rtmutex_waiter(T2161);
mark_lock_available();
/* Make the next waiter owner of the user space side */
futex_uval = 2161;
spin_unlock(hb->lock);
spin_lock(hb->lock);
rt_mutex_cleanup_proxy_lock()
if (rtmutex_owner() !== current)
...
return FAIL;
....
return -ETIMEOUT;
This means that rt_mutex_cleanup_proxy_lock() needs to call
try_to_take_rt_mutex() so it can take over the rtmutex correctly which was
assigned by the waker. If the rtmutex is owned by some other task then this
call is harmless and just confirmes that the waiter is not able to acquire
it.
While there, fix what looks like a merge error which resulted in
rt_mutex_cleanup_proxy_lock() having two calls to
fixup_rt_mutex_waiters() and rt_mutex_wait_proxy_lock() not having any.
Both should have one, since both potentially touch the waiter list.
Fixes: 38d589f2fd ("futex,rt_mutex: Restructure rt_mutex_finish_proxy_lock()")
Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Bug-Spotted-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Link: http://lkml.kernel.org/r/20170519154850.mlomgdsd26drq5j6@hirez.programming.kicks-ass.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull networking fixes from David Miller:
"Mostly netfilter bug fixes in here, but we have some bits elsewhere as
well.
1) Don't do SNAT replies for non-NATed connections in IPVS, from
Julian Anastasov.
2) Don't delete conntrack helpers while they are still in use, from
Liping Zhang.
3) Fix zero padding in xtables's xt_data_to_user(), from Willem de
Bruijn.
4) Add proper RCU protection to nf_tables_dump_set() because we
cannot guarantee that we hold the NFNL_SUBSYS_NFTABLES lock. From
Liping Zhang.
5) Initialize rcv_mss in tcp_disconnect(), from Wei Wang.
6) smsc95xx devices can't handle IPV6 checksums fully, so don't
advertise support for offloading them. From Nisar Sayed.
7) Fix out-of-bounds access in __ip6_append_data(), from Eric
Dumazet.
8) Make atl2_probe() propagate the error code properly on failures,
from Alexey Khoroshilov.
9) arp_target[] in bond_check_params() is used uninitialized. This
got changes from a global static to a local variable, which is how
this mistake happened. Fix from Jarod Wilson.
10) Fix fallout from unnecessary NULL check removal in cls_matchall,
from Jiri Pirko. This is definitely brown paper bag territory..."
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (26 commits)
net: sched: cls_matchall: fix null pointer dereference
vsock: use new wait API for vsock_stream_sendmsg()
bonding: fix randomly populated arp target array
net: Make IP alignment calulations clearer.
bonding: fix accounting of active ports in 3ad
net: atheros: atl2: don't return zero on failure path in atl2_probe()
ipv6: fix out of bound writes in __ip6_append_data()
bridge: start hello_timer when enabling KERNEL_STP in br_stp_start
smsc95xx: Support only IPv4 TCP/UDP csum offload
arp: always override existing neigh entries with gratuitous ARP
arp: postpone addr_type calculation to as late as possible
arp: decompose is_garp logic into a separate function
arp: fixed error in a comment
tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0
netfilter: xtables: fix build failure from COMPAT_XT_ALIGN outside CONFIG_COMPAT
ebtables: arpreply: Add the standard target sanity check
netfilter: nf_tables: revisit chain/object refcounting from elements
netfilter: nf_tables: missing sanitization in data from userspace
netfilter: nf_tables: can't assume lock is acquired when dumping set elems
netfilter: synproxy: fix conntrackd interaction
...
* intel_pstate:
cpufreq: intel_pstate: Document the current behavior and user interface
* pm-cpufreq:
cpufreq: dbx500: add a Kconfig symbol
* pm-cpufreq-sched:
cpufreq: schedutil: use now as reference when aggregating shared policy requests
The assignmnet:
ip_align = strict ? 2 : NET_IP_ALIGN;
in compare_pkt_ptr_alignment() trips up Coverity because we can only
get to this code when strict is true, therefore ip_align will always
be 2 regardless of NET_IP_ALIGN's value.
So just assign directly to '2' and explain the situation in the
comment above.
Reported-by: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull scheduler fix from Thomas Gleixner:
"A single scheduler fix:
Prevent idle task from ever being preempted. That makes sure that
synchronize_rcu_tasks() which is ignoring idle task does not pretend
that no task is stuck in preempted state. If that happens and idle was
preempted on a ftrace trampoline the machine crashes due to
inconsistent state"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/core: Call __schedule() from do_idle() without enabling preemption
Pull irq fixes from Thomas Gleixner:
"A set of small fixes for the irq subsystem:
- Cure a data ordering problem with chained interrupts
- Three small fixlets for the mbigen irq chip"
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
genirq: Fix chained interrupt data ordering
irqchip/mbigen: Fix the clear register offset calculation
irqchip/mbigen: Fix potential NULL dereferencing
irqchip/mbigen: Fix memory mapping code
have kernel_waitid() collect the information needed for siginfo into
a small structure (waitid_info) passed to it; deal with copyout in
sys_waitid()/compat_sys_waitid().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
New helpers: kernel_waitid() and kernel_wait4(). sys_waitid(),
sys_wait4() and their compat variants switched to those. Copying
struct rusage to userland is left to syscall itself. For
compat_sys_wait4() that eliminates the use of set_fs() completely.
For compat_sys_waitid() it's still needed (for siginfo handling);
that will change shortly.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
