Jack Ren and Eric Miao tracked down the following long standing
problem in the NOHZ code:
scheduler switch to idle task
enable interrupts
Window starts here
----> interrupt happens (does not set NEED_RESCHED)
irq_exit() stops the tick
----> interrupt happens (does set NEED_RESCHED)
return from schedule()
cpu_idle(): preempt_disable();
Window ends here
The interrupts can happen at any point inside the race window. The
first interrupt stops the tick, the second one causes the scheduler to
rerun and switch away from idle again and we end up with the tick
disabled.
The fact that it needs two interrupts where the first one does not set
NEED_RESCHED and the second one does made the bug obscure and extremly
hard to reproduce and analyse. Kudos to Jack and Eric.
Solution: Limit the NOHZ functionality to the idle loop to make sure
that we can not run into such a situation ever again.
cpu_idle()
{
preempt_disable();
while(1) {
tick_nohz_stop_sched_tick(1); <- tell NOHZ code that we
are in the idle loop
while (!need_resched())
halt();
tick_nohz_restart_sched_tick(); <- disables NOHZ mode
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
In hindsight we should have done this forever, but ...
/me grabs a large brown paperbag.
Debugged-by: Jack Ren <jack.ren@marvell.com>,
Debugged-by: eric miao <eric.y.miao@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This avoids calling kobject_uevent() with cache_kobject that has
already been deallocated in an error path.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
re-enable OPTIMIZE_INLINING more widely. Jeff Dike fixed the remaining
outstanding issue in this commit:
| commit 4f81c5350b
| Author: Jeff Dike <jdike@addtoit.com>
| Date: Mon Jul 7 13:36:56 2008 -0400
|
| [UML] fix gcc ICEs and unresolved externs
[...]
| This patch reintroduces unit-at-a-time for gcc >= 4.0, bringing back the
| possibility of Uli's crash. If that happens, we'll debug it.
it's still default-off and thus opt-in.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
i386 has show_trace_log_lvl and show_stack_log_lvl, allowing
traces to be emitted with log-level annotations. This patch
introduces them to x86_64, but log_lvl is only ever set to
an empty string. Output of traces is unchanged.
i386-chunk is whitespace-only.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Make the diff between the traps_32.c and traps_64.c a bit smaller.
Change traps_32.c to look more like traps_64.c:
- move lock information to file scope
- split out oops_begin() and oops_end() from die()
- increment nest counter in oops_begin
Only whitespace change in traps_64.c
No functional changes intended.
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fixes this type of problem:
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
caused by "stacktrace: export save_stack_trace[_tsk]"
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Real-time code needs to know the number of cycles per second
on SGI UV. The information is provided via a run time BIOS
call. This patch provides the linux side of that interface.
This is the first of several run time BIOS calls to be defined
in uv/bios.h and bios_uv.c.
Note that BIOS_CALL() is just a stub for now. The bios
side is being worked on.
Signed-off-by: Russ Anderson <rja@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Following recent (and less so) issues with the 8254 timer when routed
through the I/O or local APIC, always report which configurations have
been tried and which one has been set up eventually. This is so that logs
posted by people for some other reason can be used as a cross-reference
when investigating any possible future problems.
The change unifies messages printed on 32-bit and 64-bit platforms and
adds trailing newlines (removes leading ones), so that proper log level
annotation can be used and any possible interspersed output will not cause
a mess.
I have chosen to use apic_printk(APIC_QUIET, ...) rather than printk(...)
so that the distinction of these messages is maintained making possible
future decisions about changes in this area easier. A change posted
separately making apic_verbosity unsigned removes any extra code that
would otherwise be generated as a result of this design decision.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
As a microoptimisation, make apic_verbosity unsigned. This will make
apic_printk(APIC_QUIET, ...) expand into just printk(...) with the
surrounding condition and a reference to apic_verbosity removed.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Include <asm/i8259.h> for i8259A_lock used in print_PIC() -- #if-0-ed out
by default. The 32-bit version gets it right already.
The plan is to enable this code with "apic=debug" eventually. This will
aid with debugging strange problems without the need to ask people to
apply patches.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Introduce calibrate_APIC_clock so it could help in further 32/64bit
apic code merging.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: macro@linux-mips.org
Cc: yhlu.kernel@gmail.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
it's separate functionality that deserves its own file.
This also prepares 32-bit memtest support.
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Make and use macro FIX_EFLAGS, instead of immediate value 0x40DD5 in
ia32_restore_sigcontext().
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Various versions of the hypervisor have differences in what ABIs and
features they support. Print some details into the boot log to help
with remote debugging.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use alternatives to select the workaround for the 11AP Pentium erratum
for the affected steppings on the fly rather than build time. Remove the
X86_GOOD_APIC configuration option and replace all the calls to
apic_write_around() with plain apic_write(), protecting accesses to the
ESR as appropriate due to the 3AP Pentium erratum. Remove
apic_read_around() and all its invocations altogether as not needed.
Remove apic_write_atomic() and all its implementing backends. The use of
ASM_OUTPUT2() is not strictly needed for input constraints, but I have
used it for readability's sake.
I had the feeling no one else was brave enough to do it, so I went ahead
and here it is. Verified by checking the generated assembly and tested
with both a 32-bit and a 64-bit configuration, also with the 11AP
"feature" forced on and verified with gdb on /proc/kcore to work as
expected (as an 11AP machines are quite hard to get hands on these days).
Some script complained about the use of "volatile", but apic_write() needs
it for the same reason and is effectively a replacement for writel(), so I
have disregarded it.
I am not sure what the policy wrt defconfig files is, they are generated
and there is risk of a conflict resulting from an unrelated change, so I
have left changes to them out. The option will get removed from them at
the next run.
Some testing with machines other than mine will be needed to avoid some
stupid mistake, but despite its volume, the change is not really that
intrusive, so I am fairly confident that because it works for me, it will
everywhere.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch does a few small cleanups around the atmel mci platform code
and in the atmel-mci driver. The platform changes simply removes an
unused variable, uses the fact that by the end we always have some form
of platform data and notes that GPIO_PIN_NONE != 0. This last point
could cause the incorrect attempt to twice reserve pin PA0.
While we've got the hood up, add linux/err.h to the atmel-mci.c include
list. It needs it and generally pulls it by voodoo but I did once
stumble across a config which don't build.
This is against Linus' latest git.
Signed-off-by: Ben Nizette <bn@niasdigital.com>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Adrian Bunk reported that enabling 4MB page size breaks the build.
The problem is that MAX_ORDER combined with the page shift exceeds the
SECTION_SIZE_BITS we use in asm-sparc64/sparsemem.h
There are several ways I suppose we could work around this. For one
we could define a CONFIG_FORCE_MAX_ZONEORDER to decrease MAX_ORDER in
these higher page size cases.
But I also know that these page size cases are broken wrt. TLB miss
handling especially on pre-hypervisor systems, and there isn't an easy
way to fix that.
These options were meant to be fun experimental hacks anyways, and
only 8K and 64K make any sense to support.
So remove 512K and 4M base page size support. Of course, we still
support these page sizes for huge pages.
Signed-off-by: David S. Miller <davem@davemloft.net>
kernel bugzilla #11059:
sparc64 config menu is missing "Processor type and features",
so add that and move General Setup before Processor menu.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This changes arch/sparc/kernel/apc.c to use unlocked_ioctl
Signed-off-by: Stoyan Gaydarov <stoyboyker@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
sparc64 exports openprom.h to userspace so let sparc follow
the example.
As openprom.h pulled in another not-for-export vaddrs.h header
file it required a few changes to fix the build.
The definition af VMALLOC_* were moved to pgtable as this is
where sparc64 has them.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
David Miller noticed that the build of vmlinux.lds
failed to use the -m64 specifier.
This caused the build to break with a bi-arch gcc with
unified headers.
Add the -m64 option to CPPFLAGS_vmlinux.lds so we
have the correct defines available when building
vmliux.lds.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Yinghai Lu noticed that arch/x86/kernel/smpcommon_32.c got
renamed to arch/x86/kernel/smpcommon.c but the old almost-empty
file stayed around. Zap it.
Reported-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Linus observed:
> The real bug is that we shouldn't have "double negatives", and
> certainly not negative config options. Making that "promiscuous
> /dev/mem" option a negated thing as a config option was bad.
right ... lets rename this option. There should never be a negation
in config options.
[ that reminds me of CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER, but that
is for another commit ;-) ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch removes the experimental status of kdump on IA64. kdump is on IA64
now since more than one year and it has proven to be stable.
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Merge the GDT_ENTRY() macro between arch/x86/boot/pm.c and
arch/x86/kernel/acpi/sleep.c and put the new one in
<asm-x86/segment.h>.
While we're at it, correct the bitmasks for the limit and flags. The
new version relies on using ULL constants in order to cause type
promotion rather than explicit casts; this avoids having to include
<linux/types.h> in <asm-x86/segments.h>.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
acpi_map_lsapic tries to stuff a long into ia64_cpu_to_sapicid[],
which can only hold ints, so let's fix that.
We need to update the signature of acpi_map_cpu2node() too.
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
module_free() refers the first parameter before checking.
But it is called like below(in kernel/kprobes). The first parameter is always NULL.
This happens when many probe points(>1024) are set by kprobes.
I encountered this with using SystemTap. It can set many probes easily.
static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
{
...
if (kip->nused == 0) {
hlist_del(&kip->hlist);
if (hlist_empty(&kprobe_insn_pages)) {
...
} else {
module_free(NULL, kip->insns); //<<< 1st param always NULL
kfree(kip);
}
return 1;
}
return 0;
}
Signed-off-by: Akiyama, Nobuyuki <akiyama.nobuyuk@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
When dprintk is enabled the following warnings are generated:
arch/ia64/kernel/cpufreq/acpi-cpufreq.c: In function 'processor_set_pstate':
arch/ia64/kernel/cpufreq/acpi-cpufreq.c:54: warning: format '%x' expects type 'unsigned int', but argumen
t 3 has type 's64'
arch/ia64/kernel/cpufreq/acpi-cpufreq.c: In function 'processor_get_pstate':
arch/ia64/kernel/cpufreq/acpi-cpufreq.c:76: warning: format '%x' expects type 'unsigned int', but argumen
t 2 has type 's64'
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: fix asm/e820.h for userspace inclusion
x86: fix numaq_tsc_disable
x86: fix kernel_physical_mapping_init() for large x86 systems
