Now that it is safe to use get_online_cpus() we can revert
[S390] cpu topology: Fix possible deadlock.
commit: fd781fa25c
and call arch_reinit_sched_domains() directly from topology_work_fn().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Max Krasnyansky <maxk@qualcomm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently list of kretprobe instances are stored in kretprobe object (as
used_instances,free_instances) and in kretprobe hash table. We have one
global kretprobe lock to serialise the access to these lists. This causes
only one kretprobe handler to execute at a time. Hence affects system
performance, particularly on SMP systems and when return probe is set on
lot of functions (like on all systemcalls).
Solution proposed here gives fine-grain locks that performs better on SMP
system compared to present kretprobe implementation.
Solution:
1) Instead of having one global lock to protect kretprobe instances
present in kretprobe object and kretprobe hash table. We will have
two locks, one lock for protecting kretprobe hash table and another
lock for kretporbe object.
2) We hold lock present in kretprobe object while we modify kretprobe
instance in kretprobe object and we hold per-hash-list lock while
modifying kretprobe instances present in that hash list. To prevent
deadlock, we never grab a per-hash-list lock while holding a kretprobe
lock.
3) We can remove used_instances from struct kretprobe, as we can
track used instances of kretprobe instances using kretprobe hash
table.
Time duration for kernel compilation ("make -j 8") on a 8-way ppc64 system
with return probes set on all systemcalls looks like this.
cacheline non-cacheline Un-patched kernel
aligned patch aligned patch
===============================================================================
real 9m46.784s 9m54.412s 10m2.450s
user 40m5.715s 40m7.142s 40m4.273s
sys 2m57.754s 2m58.583s 3m17.430s
===========================================================
Time duration for kernel compilation ("make -j 8) on the same system, when
kernel is not probed.
=========================
real 9m26.389s
user 40m8.775s
sys 2m7.283s
=========================
Signed-off-by: Srinivasa DS <srinivasa@in.ibm.com>
Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch enables virtio_console as the default console on kvm for
s390. We currently use the same notify hack as lguest for early
console output. I will try to address this for lguest and s390 later.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
nohz: adjust tick_nohz_stop_sched_tick() call of s390 as well
nohz: prevent tick stop outside of the idle loop
This allow to dynamically generate attributes and share show/store
functions between attributes. Right now most attributes are generated
by special macros and lots of duplicated code. With the attribute
passed it's instead possible to attach some data to the attribute
and then use that in shared low level functions to do different things.
I need this for the dynamically generated bank attributes in the x86
machine check code, but it'll allow some further cleanups.
I converted all users in tree to the new show/store prototype. It's a single
huge patch to avoid unbisectable sections.
Runtime tested: x86-32, x86-64
Compiled only: ia64, powerpc
Not compile tested/only grep converted: sh, arm, avr32
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Add missing module.h include to fix this:
CC arch/s390/kernel/stacktrace.o
arch/s390/kernel/stacktrace.c:84: warning: data definition has no type or storage class
arch/s390/kernel/stacktrace.c:84: warning: type defaults to 'int' in declaration of 'EXPORT_SYMBOL_GPL'
arch/s390/kernel/stacktrace.c:84: warning: parameter names (without types) in function declaration
arch/s390/kernel/stacktrace.c:97: warning: data definition has no type or storage class
arch/s390/kernel/stacktrace.c:97: warning: type defaults to 'int' in declaration of 'EXPORT_SYMBOL_GPL'
arch/s390/kernel/stacktrace.c:97: warning: parameter names (without types) in function declaration
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Most likely it is broken anyway because of the changes in memory
detection. Since we can't test it and there are probably better ways
that using a P390 card, remove support for it.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Move memory detection code to own file and also simplify it.
Also add an interface which can be called at any time to get the
current memory layout. This interface is needed by our kernel
internal system dumper.
Cc: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Cc: Michael Holzheu <holzheu@de.ibm.com>
Cc: Frank Munzert <munzert@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
As noted by Akinobu Mita in patch b1fceac2b9,
alloc_bootmem and related functions never return NULL and always return a
zeroed region of memory. Thus a NULL test or memset after calls to these
functions is unnecessary.
arch/s390/kernel/topology.c | 2 --
1 file changed, 2 deletions(-)
This was fixed using the following semantic patch.
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@@
expression E;
statement S;
@@
E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
... when != E
(
- BUG_ON (E == NULL);
|
- if (E == NULL) S
)
@@
expression E,E1;
@@
E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
... when != E
- memset(E,0,E1);
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Now it is possible to specify additional kernel parameters on the IPL
command line using the IPL PARM option.
If the Linux system is already running, the new reipl sysfs attribute
'parm' can be used to change kernel parameters for the next reboot.
Examples:
IPL C PARM dasd=1234 root=/dev/dasda1
IPL 1234 PARM savesys=mylnxnss
echo "init=/bin/bash" > /sys/firmware/reipl/ccw/parm
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
The idle notifier chain consists of at most one element. So there's
no point in having a notifier chain. Remove it and directly call the
function.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add support for clock synchronization with the server time protocol.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
In case the initrd is located within the bss section it will be
overwritten when the section is cleared. To prevent this just move
the initrd right behind the bss section if it starts within the
section.
The current code already moves the initrd if the bootmem allocator
bitmap would overwrite it. With this patch we should be safe against
initrd corruptions.
Cc: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add the user_regset definitions for normal and compat processes, replace
the dump_regs core dump cruft with the generic CORE_DUMP_USER_REGSET and
replace binfmt_elf32.c with the generic compat_binfmt_elf.c implementation.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Using the ipldelay kernel parameter leads to a crash at IPL time.
Since this is broken since a long time it looks like nobody is using
it anymore. So remove it instead of fixing it.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Andrew Morton reported this against linux-next:
ERROR: ".save_stack_trace" [tests/backtracetest.ko] undefined!
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It's not even passed on to smp_call_function() anymore, since that
was removed. So kill it.
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
It's never used and the comments refer to nonatomic and retry
interchangably. So get rid of it.
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
The first argument to __ctl_store() should be the array to store
stuff in, not just the first element of that array. With the
current code in __cpu_up(), mainline GCC dies with an internal
compiler error. I didn't diagnose that further, but just fixed
the kernel bug.
Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
The correct instruction format of idte is "idte r1,r3,r2" with
r1 at bit 24, r3 at bit 16 and r2 at bit 28.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This fixes the last remaining section mismatch warnings in s390
architecture code. It reveals also a real bug introduced by... me
with git commit 2069e978d5
("[S390] sparsemem vmemmap: initialize memmap.")
Calling the generic vmemmap_alloc_block() function to get initialized
memory is a nice idea, however that function is __meminit annotated
and therefore the function might be gone if we try to call it later.
This can happen if a DCSS segment gets added.
So basically revert the patch and clear the memmap explicitly to fix
the original bug.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Surround all the code withing show_interrupts() with
get/put_online_cpus() to prevent strange results wrt cpu hotplug.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Both smp_call_function() and __smp_call_function_map() access
cpu_online_map. Both functions run with preemption disabled which
protects for cpus going offline. However new cpus can be added and
therefore the cpu_online_map can change unexpectedly.
So use the call_lock to protect against changes to the cpu_online_map
in start_secondary() and all smp_call_* functions.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
We should use const char * for passing the name of the debug feature
around since it will not be changed.
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This removes redundant arch code for generic ptrace requests
already handled by ptrace_request and compat_ptrace_request.
It simplifies things to just have the standard entry points,
and use the generic compat_sys_ptrace.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
This patch fixes a bug with cpu bound guest on kvm-s390. Sometimes it
was impossible to deliver a signal to a spinning guest. We used
preemption as a circumvention. The preemption notifiers called
vcpu_load, which checked for pending signals and triggered a host
intercept. But even with preemption, a sigkill was not delivered
immediately.
This patch changes the low level host interrupt handler to check for the
SIE instruction, if TIF_WORK is set. In that case we change the
instruction pointer of the return PSW to rerun the vcpu_run loop. The kvm
code sees an intercept reason 0 if that happens. This patch adds accounting
for these types of intercept as well.
The advantages:
- works with and without preemption
- signals are delivered immediately
- much better host latencies without preemption
Acked-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
On return from syscall or interrupt, we have to check if we return to
userspace (likely) and if there is work todo (less likely) to decide
if we handle the work. We can optimize this check: we first check for
the less likely work case and then check for userspace.
This patch is also a preparation for an additional patch, that fixes a bug
in KVM dealing with cpu bound guests.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This replaces the duplicated arch-specific versions of "sys_pipe()" with
one unified implementation. This removes almost 250 lines of duplicated
code.
It's marked __weak, so that *if* an architecture wants to override the
default implementation it can do so by simply having its own replacement
version, since many architectures use alternate calling conventions for
the 'pipe()' system call for legacy reasons (ie traditional UNIX
implementations often return the two file descriptors in registers)
I still haven't changed the cris version even though Linus says the BKL
isn't needed. The arch maintainer can easily do it if there are really
no obstacles.
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
TIF_RESTORE_SIGMASK no longer needs to be in the _TIF_WORK_* masks. Those low
bits are scarce, and are all used up now. Renumber TIF_RESTORE_SIGMASK to
free one up.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After the PT_IEEE_IP hack has been removed s390 can now use
the common code sys_ptrace function.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The self referential PT_IEEE_IP ptrace peek & poke calls have been
broken for that last 6 years. For peek the code always returns 0
instead of the last ieee fault and for poke the code does nothing.
Since nobody noticed the code seems to be superfluous. So lets
remove it.
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This adds hugetlbfs support on System z, using both hardware large page
support if available and software large page emulation on older hardware.
Shared (large) page tables are implemented in software emulation mode,
by using page->index of the first tail page from a compound large page
to store page table information.
Signed-off-by: Gerald Schaefer <geraldsc@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
From: Heiko Carstens <heiko.carstens@de.ibm.com>
From: Carsten Otte <cotte@de.ibm.com>
This lets us use defines for the magic bits in machine flags instead
of using plain numbers all over the place.
In addition on newer machines features/facilities are indicated by the
result of the stfl instruction. So we use these bits instead of trying
to execute new instructions and check wether we get an exception or
not.
Also the mvpg instruction is always available when in zArch mode,
whereas the idte instruction is only available in zArch mode. This
results in some minor optimizations.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
When we get a notification that cpu topology changed, we schedule a
work struct which just calls arch_reinit_sched_domains. This function
in turn calls get_online_cpus() which results int the lockdep warning
below.
After all it turnded out that it's not legal to call get_online_cpus()
from the context of a multi-threaded work queue.
It could deadlock this way:
process 0 (events/cpu-x):
-> run_workqueue
-> removes my work_struct from the work queue
-> calls work_struct->fn
-> get_online_cpus()
-> locks on cpu_hotplug.lock since process 1 below is doing cpu hotplug
process 1:
-> cpu_down (for cpu-x)
-> cpu_hotplug_begin (holds cpu_hotplug.lock now)
-> cpu-x dead
-> notifier_call_chain with CPU_DEAD
-> cleanup_workqueue_thread
-> flush_cpu_workqueue (succeeds)
-> kthread_stop for events/cpu-x
-> now kthread_stop waits for my work_struct to complete from within
process 0. -> dead.
A single threaded workqueue wouldn't have such problems, however there is
no such common queue available and it's not worth to create one for the
very rare calls to arch_reinit_sched_domains.
So we just create a kernel thread from our work struct which calls
arch_reinit_sched_domains and are done with it.
Thanks to Oleg Nesterov and Peter Zijlstra for helping me figuring out
that this isn't a false positive lockdep warning:
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.25-03562-g3dc5063-dirty #12
-------------------------------------------------------
events/3/14 is trying to acquire lock:
(&cpu_hotplug.lock){--..}, at: [<0000000000076094>] get_online_cpus+0x50/0x78
but task is already holding lock:
(topology_work){--..}, at: [<0000000000059cde>] run_workqueue+0x106/0x278
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (topology_work){--..}:
[<000000000006fc74>] __lock_acquire+0x1010/0x111c
[<000000000006fe40>] lock_acquire+0xc0/0xf8
[<0000000000059d48>] run_workqueue+0x170/0x278
[<0000000000059edc>] worker_thread+0x8c/0xf0
[<000000000005f5bc>] kthread+0x68/0xa0
[<000000000001a33e>] kernel_thread_starter+0x6/0xc
[<000000000001a338>] kernel_thread_starter+0x0/0xc
-> #1 (events){--..}:
[<000000000006fc74>] __lock_acquire+0x1010/0x111c
[<000000000006fe40>] lock_acquire+0xc0/0xf8
[<000000000005a23c>] cleanup_workqueue_thread+0x60/0xa8
[<00000000003b2ab8>] workqueue_cpu_callback+0xbc/0x170
[<00000000003bba80>] notifier_call_chain+0x5c/0xa4
[<00000000000655a2>] __raw_notifier_call_chain+0x26/0x38
[<00000000000655e2>] raw_notifier_call_chain+0x2e/0x40
[<0000000000075e00>] cpu_down+0x228/0x31c
[<00000000003b1dd8>] store_online+0x64/0xb8
[<00000000001e7128>] sysdev_store+0x48/0x58
[<0000000000121cd2>] sysfs_write_file+0x126/0x1c0
[<00000000000c1944>] vfs_write+0xb0/0x15c
[<00000000000c20e6>] sys_write+0x56/0x88
[<0000000000027a68>] sys32_write+0x34/0x4c
[<0000000000023f70>] sysc_noemu+0x10/0x16
[<0000000077f3f186>] 0x77f3f186
-> #0 (&cpu_hotplug.lock){--..}:
[<000000000006fa84>] __lock_acquire+0xe20/0x111c
[<000000000006fe40>] lock_acquire+0xc0/0xf8
[<00000000003b701c>] mutex_lock_nested+0xd0/0x364
[<0000000000076094>] get_online_cpus+0x50/0x78
[<000000000003a03e>] arch_reinit_sched_domains+0x26/0x58
[<000000000002700e>] topology_work_fn+0x26/0x34
[<0000000000059d4e>] run_workqueue+0x176/0x278
[<0000000000059edc>] worker_thread+0x8c/0xf0
[<000000000005f5bc>] kthread+0x68/0xa0
[<000000000001a33e>] kernel_thread_starter+0x6/0xc
[<000000000001a338>] kernel_thread_starter+0x0/0xc
other info that might help us debug this:
2 locks held by events/3/14:
#0: (events){--..}, at: [<0000000000059cde>] run_workqueue+0x106/0x278
#1: (topology_work){--..}, at: [<0000000000059cde>] run_workqueue+0x106/0x278
stack backtrace:
CPU: 3 Not tainted 2.6.25-03562-g3dc5063-dirty #12
Process events/3 (pid: 14, task: 000000002fb04038, ksp: 000000002fb0bd70)
0400000000000000 000000002fb0ba40 0000000000000002 0000000000000000
000000002fb0bae0 000000002fb0ba58 000000002fb0ba58 0000000000016488
0000000000000000 000000002fb0bd70 0000000000000000 0000000000000000
000000002fb0ba40 000000000000000c 000000002fb0ba40 000000002fb0bab0
00000000003c99e0 0000000000016488 000000002fb0ba40 000000002fb0ba90
Call Trace:
([<00000000000163fc>] show_trace+0x138/0x158)
[<00000000000164e2>] show_stack+0xc6/0xf8
[<0000000000016624>] dump_stack+0xb0/0xc0
[<000000000006cd36>] print_circular_bug_tail+0xa2/0xb4
[<000000000006fa84>] __lock_acquire+0xe20/0x111c
[<000000000006fe40>] lock_acquire+0xc0/0xf8
[<00000000003b701c>] mutex_lock_nested+0xd0/0x364
[<0000000000076094>] get_online_cpus+0x50/0x78
[<000000000003a03e>] arch_reinit_sched_domains+0x26/0x58
[<000000000002700e>] topology_work_fn+0x26/0x34
[<0000000000059d4e>] run_workqueue+0x176/0x278
[<0000000000059edc>] worker_thread+0x8c/0xf0
[<000000000005f5bc>] kthread+0x68/0xa0
[<000000000001a33e>] kernel_thread_starter+0x6/0xc
[<000000000001a338>] kernel_thread_starter+0x0/0xc
INFO: lockdep is turned off.
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
