Make sure we always return, as all syscalls should. Also move the common
prototype to <linux/syscalls.h>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Make the pid argument a long as on every other arcihtecture. Despite pid_t
beeing a 32bit type even on 64bit parisc this is not an ABI change due to
the parisc calling conventions. And even if it did it wouldn't matter too
much because 64bit userspace on parisc is in an embrionic stage.
Acked-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
task_struct is an internal structure to the kernel with a lot of good
information, that is probably interesting in core dumps. However there is
no way for user space to know what format that information is in making it
useless.
I grepped the GDB 6.3 source code and NT_TASKSTRUCT while defined is not
used anywhere else. So I would be surprised if anyone notices it is
missing.
In addition exporting kernel pointers to all the interesting kernel data
structures sounds like the very definition of an information leak. I
haven't a clue what someone with evil intentions could do with that
information, but in any attack against the kernel it looks like this is the
perfect tool for aiming that attack.
So since NT_TASKSTRUCT is useless as currently defined and is potentially
dangerous, let's just not export it.
(akpm: Daniel Jacobowitz <dan@debian.org> "would be amazed" if anything was
using NT_TASKSTRUCT).
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove timer_list.magic and associated debugging code.
I originally added this when a spinlock was added to timer_list - this meant
that an all-zeroes timer became illegal and init_timer() was required.
That spinlock isn't even there any more, although timer.base must now be
initialised.
I'll keep this debugging code in -mm.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Removed some more references to check_region().
I checked these changes into the 'checkreg' branch of
rsync://rsync.kernel.org/pub/scm/linux/kernel/git/jgarzik/misc-2.6.git
The only valid references remaining are in:
drivers/scsi/advansys.c
drivers/scsi/BusLogic.c
drivers/cdrom/sbpcd.c
sound/oss/pss.c
Remove last vestiges of ide_check_region()
drivers/char/specialix: trim trailing whitespace
drivers/char/specialix: eliminate use of check_region()
Remove outdated and unused references to check_region()
[sound oss] remove check_region() usage from cs4232, wavfront
[netdrvr eepro] trim trailing whitespace
[netdrvr eepro] remove check_region() usage
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
TIOCSTART and TIOCSTOP are defined in asm/ioctls.h and asm/termios.h by
various architectures but not actually implemented anywhere but in the IRIX
compatibility layer, so remove their COMPATIBLE_IOCTL from parisc, ppc64
and sparc64.
Move the TIOCSLTC COMPATIBLE_IOCTL to common code, guided by an ifdef to
only show up on architectures that support it (same as the code handling it
in tty_ioctl.c), aswell as it's brother TIOCGLTC that wasn't handled so
far.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Every user of init_timer() also needs to initialize ->function and ->data
fields. This patch adds a simple setup_timer() helper for that.
The schedule_timeout() is patched as an example of usage.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Martin Schwidefsky <schwidefsky@de.ibm.com>
Fix fullscreen view of the 3270 device driver.
Signed-off-by: Richard Hitt <rbh00@utsglobal.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
I just noted that -mtune is used, which is only supported on recent GCCs; by
reading http://gcc.gnu.org/gcc-3.4/changes.html, you see "-mcpu has been
renamed to -mtune.", so for GCC < 3.4 we're not using any specific tuning in
the appropriate cases. However -mcpu is deprecated, so use -mtune when
possible.
This was introduced by commit e9d4dce954a60dc23dd1d967766ca2347b780e54 of the
old tree (between 2.6.10-rc3 and 2.6.10) by Linus Torvalds, to remove the use
of -march, since that could trigger gcc using SSE on its own. But no
attention was used about using -mcpu vs. -mtune.
And btw, the old 2.6.4 code (for instance) was:
cflags-$(CONFIG_MPENTIUMII) += $(call check_gcc,-march=pentium2,-march=i686)
cflags-$(CONFIG_MPENTIUMIII) += $(call check_gcc,-march=pentium3,-march=i686)
cflags-$(CONFIG_MPENTIUMM) += $(call check_gcc,-march=pentium3,-march=i686)
cflags-$(CONFIG_MPENTIUM4) += $(call check_gcc,-march=pentium4,-march=i686)
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This was used in the old dark age of 2.4, ARCH_CFLAGS doesn't work any more
since some time, and UM_FASTCALL was never used in 2.6.
Instead, reintroduce the thing more properly now, directly in
include/asm-um/linkage.h.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove RWSEM_GENERIC_SPINLOCK, it's now defined (only if needed) by the
underlying arch/i386/Kconfig.cpu. Leave it only for x86_64. Even there, it's
totally wrong, as they even have the code to support XCHG_ADD.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Make UML share the underlying cpu-specific tuning done on i386.
Actually, for now many config options aren't used a lot - but that can be done
later. Also, UML relies on GCC optimization for things like memcpy and such
more than i386, so specifying the correct -march and -mtune should be enough.
Later, we may want to correct some other stuff.
For instance, since FPU context switching, for us, is done (at least
partially, i.e. between our kernelspace and userspace) by the host, we may
allow usage of FPU operations by GCC. This doesn't hold for kernelspace vs.
kernelspace, but we don't support preemption.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Update SMC91x driver for m32r.
- Remove needless NONCACHE_OFFSET adjustment.
> [PATCH 2.6.14-rc4] m32r: NONCACHE_OFFSET in _port2addr
> Change _port2addr() not to add NONCACHE_OFFSET.
> Adding NONCACHE_OFFSET requires needless address adjusting by a driver
> using ioremap() like a SMC91x driver.
- Fix lots of warnings as following:
/usr/src/ctest/git/kernel/drivers/net/smc91x.c: In function `smc_reset':
/usr/src/ctest/git/kernel/drivers/net/smc91x.c:324: warning: passing arg 2 of `_outw' makes integer from pointer without a cast
/usr/src/ctest/git/kernel/drivers/net/smc91x.c:325: warning: passing arg 2 of `_outw' makes integer from pointer without a cast
/usr/src/ctest/git/kernel/drivers/net/smc91x.c:341: warning: passing arg 2 of `_outw' makes integer from pointer without a cast
/usr/src/ctest/git/kernel/drivers/net/smc91x.c:342: warning: passing arg 2 of `_outw' makes integer from pointer without a cast
:
/usr/src/ctest/git/kernel/drivers/net/smc91x.c:1915: warning: passing arg 1 of `_inw' makes integer from pointer without a cast
/usr/src/ctest/git/kernel/drivers/net/smc91x.c:1915: warning: passing arg 1 of `_inw' makes integer from pointer without a cast
Signed-off-by: Hayato Fujiwara <fujiwara@linux-m32r.org>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Change _port2addr() not to add NONCACHE_OFFSET. Adding NONCACHE_OFFSET
requires needless address adjusting by a driver using ioremap() like a
SMC91x driver.
Signed-off-by: Hayato Fujiwara <fujiwara@linux-m32r.org>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The following patch makes swsusp use the PG_nosave and PG_nosave_free flags to
mark pages that should be freed in case of an error during resume.
This allows us to simplify the code and to use swsusp_free() in all of the
swsusp's resume error paths, which makes them actually work.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
cpu cache entries should be populated only when cpu is online and removed
when they are logically offlined.
Without which entries are not removed when cpu is offlined, or dont appear
when we boot with maxcpus=1 and then kick the rest of the cpus via echo 1
to the sysfs online file.
- Changed __devinit to __cpuinit for consistency.
- Changed sysfs_driver_register to register_cpu_notifier.
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Zwane Mwaikambo <zwane@holomorphy.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch adds a check for the return value of acpi_find_root_pointer().
Without this patch systems without ACPI support such as QEMU crashes when
booting a NUMA kernel with CONFIG_ACPI_SRAT=y.
Signed-off-by: Magnus Damm <magnus@valinux.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
After staring at mpparse.c for a little longer I noticed that when we hit
our limit of num_processors we are filtering out information about other
processors that we can still store.
This patch just reorders the code so we store everything we can.
This should avoid the incorrect warning about our boot CPU not being listed
by the BIOS that we are now getting in the kexec on panic case, and it
should allow us to detect all apicid conflicts even when our physical
number of cpus exceeds maxcpus.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
o Removes the unnecessary call to local_irq_disable().
o Kdump was failing while second kernel was coming up. Check for presence
of boot cpu apic id was failing in (apic_id_registered), hence hitting
BUG().
o This should not have failed because before calling setup_local_APIC(), it is
ensured that even if BIOS has not reported boot cpu, then hard set the
prence of it. Problem happens because of usage of hard_smp_processor_id()
which is hardcoded to zero in case of non SMP kernel. In kdump case second
kernel can boot on a cpu whose boot cpu id is not zero.
o Using boot_cpu_physical_apicid instead to hard set the presence of boot cpu.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Handle 32-bit mtrr ioctls in the mtrr driver instead of the ia32
compatability layer.
Signed-off-by: Brian Gerst <bgerst@didntduck.org>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
If VMX feature is available in the CPU, this patch will make it visible in
the /proc/cpuinfo with the cpuid detection.
Signed-Off-By: Nitin A Kamble <nitin.a.kamble@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
It is dangerous to shutdown the apics in machine_crash_shutdown.
With my previous patch to initialize apics in init_IRQ we should be able to
boot a kernel without this. As long as we reinitialize the APICs we don't
care what state they were in during bootup.
This should make machine_crash_shutdown noticeably more reliable.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
All kinds of ugliness exists because we don't initialize
the apics during init_IRQs.
- We calibrate jiffies in non apic mode even when we are using apics.
- We have to have special code to initialize the apics when non-smp.
- The legacy i8259 must exist and be setup correctly, even
when we won't use it past initialization.
- The kexec on panic code must restore the state of the io_apics.
- init/main.c needs a special case for !smp smp_init on x86
In addition to pure code movement I needed a couple
of non-obvious changes:
- Move setup_boot_APIC_clock into APIC_late_time_init for
simplicity.
- Use cpu_khz to generate a better approximation of loops_per_jiffies
so I can verify the timer interrupt is working.
- Call setup_apic_nmi_watchdog again after cpu_khz is initialized on
the boot cpu.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The per cpu nmi watchdog timer is based on an event counter. idle cpus
don't generate events so the NMI watchdog doesn't fire and the test to see
if the watchdog is working fails.
- Add nmi_cpu_busy so idle cpus don't mess up the test.
- kmalloc prev_nmi_count to keep kernel stack usage bounded.
- Improve the error message on failure so there is enough
information to debug problems.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Currently we attempt to restore virtual wire mode on reboot, which only
works if we can figure out where the i8259 is connected. This is very
useful when we kexec another kernel and likely helpful when dealing with a
BIOS that make assumptions about how the system is setup.
Since the acpi MADT table does not provide the location where the i8259 is
connected we have to look at the hardware to figure it out.
Most systems have the i8259 connected the local apic of the cpu so won't be
affected but people running Opteron and some serverworks chipsets should be
able to use kexec now.
In addition this patch removes the hard coded assumption that the io_apic
that delivers isa interrups is always known to the kernel as io_apic 0. As
there does not appear to be anything to guarantee that assumption is true.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This is platform code update for ES7000: disables IRQ overrides for the
recent ES7000 (Rascal/Zorro), cleans up the compile warning. The patch
only affects the ES7000 subarch.
Signed-off-by: <Natalie.Protasevich@unisys.com>
Acked-by: Zwane Mwaikambo <zwane@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The code that prints the cache size assumes that L3 always lives in chipset
and is shared across CPUs. Which is not really true.
I think all the cachesizes reported by cpuid are in the processor itself.
The attached patch changes the code to reflect that.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This was reported because someone was getting oopses reading /proc/iomem.
It was tracked down to a zero-sized 'struct resource' entry which was
located right at 4GB.
You need two conditions to hit this bug: a BIOS E820_RAM area starting at
exactly the boundary where you specify mem= (to get a zero-sized entry),
and for the legacy_init_iomem_resources() loop to skip that resource (which
only happens at exactly 4G).
I think the killing zero-sized e820 entry is the easiest way to fix this.
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Make P6 MCA initialization code complaint with guidelines in IA-32 SDM
Vol3. Bank 0 control register should not be set by OS and clear status
registers on all banks on reset.
This will prevent false MCE alarms on the systems that has some non-MCE
information left-over in MC0_STATUS on reboot.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add an accessor function for getting the per-CPU gdt. Callee must already
have the CPU.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The per-CPU initialization code is copying in bogus data into
thread->tls_array. Note that it copies &per_cpu(cpu_gdt_table, cpu), not
&per_cpu(cpu_gdt_table, cpu)[GDT_ENTRY_TLS_MIN). That is totally broken
and unnecessary. Make the initialization explicitly NULL.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The patch allows physical bring-up of new processors (not initially present
in the configuration) from facilities such as driver/utility implemented on
a platform. The actual method of making processors available is up to the
platform implementation.
Signed-off-by: Natalie Protasevich <Natalie.Protasevich@unisys.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Zwane Mwaikambo <zwane@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial internal version of Venki's cpuid(4) deterministic cache parameter
identification patch used static arrays of size MAX_CACHE_LEAVES. Final patch
which made to the base used dynamic array allocation, with this
MAX_CACHE_LEAVES limit hunk still in place.
cpuid(4) already has a mechanism to find out the number of cache levels
implemented and there is no need for this hardcoded MAX_CACHE_LEAVES limit.
So remove the MAX_CACHE_LEAVES limit from the routine which calculates the
number of cache levels using cpuid(4)
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There exists a field io_bitmap_owner in the TSS that is only checked, but
never set to anything else but NULL.
Signed-off-by: Bart Oldeman <bartoldeman@users.sourceforge.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
mxcsr_feature_mask_init isn't needed in suspend/resume time (we can use
boot time mask). And actually it's harmful, as it clear task's saved
fxsave in resume. This bug is widely seen by users using zsh.
(akpm: my eyes. Fixed some surrounding whitespace mess)
Signed-off-by: Shaohua Li<shaohua.li@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This adjusts i386's cmpxchg patterns so that
- for word and long cmpxchg-es the compiler can utilize all possible
registers
- cmpxchg8b gets disabled when the minimum specified hardware architectur
doesn't support it (like was already happening for the byte, word, and
long ones).
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
I just found out that some precision is unnecessarily lost in the
arch/i386/kernel/timers/timer_tsc.c:set_cyc2ns_scale function. It uses a
cpu_mhz parameter when it could use a cpu_khz. In the specific case of an
Intel P4 running at 3001.171 Mhz, the truncation to 3001 Mhz leads to an
imprecision of 19 microseconds per second : this is very sad for a timer with
nearly nanosecond accuracy.
Fix the x86_64 architecture too.
Cc: george anzinger <george@mvista.com>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add CONFIG_X86_32 for i386. This allows selecting options that only apply
to 32-bit systems.
(X86 && !X86_64) becomes X86_32
(X86 || X86_64) becomes X86
Signed-off-by: Brian Gerst <bgerst@didntduck.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Here is a set of ppc64 specific patches that at least allow
compilation/booting with the following configurations:
FLATMEM
SPARSEMEN
SPARSEMEM + MEMORY_HOTPLUG
Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Adds the necessary for non-NUMA hot-add of highmem to an existing zone on
i386.
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
pgdat->node_size_lock is basically only neeeded in one place in the normal
code: show_mem(), which is the arch-specific sysrq-m printing function.
Strictly speaking, the architectures not doing memory hotplug do no need this
locking in show_mem(). However, they are all included for completeness. This
should also make any future consolidation of all of the implementations a
little more straightforward.
This lock is also held in the sparsemem code during a memory removal, as
sections are invalidated. This is the place there pfn_valid() is made false
for a memory area that's being removed. The lock is only required when doing
pfn_valid() operations on memory which the user does not already have a
reference on the page, such as in show_mem().
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
In worrying over the various pte operations in different architectures, I came
across some unused functions in UML: remove mprotect_kernel_vm,
protect_vm_page and addr_pte.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There's usually a good reason when a pte is examined without the lock; but it
makes me nervous when the pointer is dereferenced more than once.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The cris v32 switch_mm guards get_mmu_context with next->page_table_lock: good
it's not really SMP yet, since get_mmu_context messes with global variables
affecting other mms. Replace by global mmu_context_lock.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
There's a worrying function translation_exists in parisc cacheflush.h,
unaffected by split ptlock since flush_dcache_page is using it on some other
mm, without any relevant lock. Oh well, make it a slightly more robust by
factoring the pfn check within it. And it looked liable to confuse a
camouflaged swap or file entry with a good pte: fix that too.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
