Convert the irq chips to the new functions and use proper flow
handlers. handle_level_irq is appropriate.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Convert the irq chips to the new functions and use proper flow
handlers. handle_level_irq is appropriate.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Paul Mundt <lethal@linux-sh.org>
The irq descriptors are already initialized by the generic
code. Remove the redundant init code and set the irq chip with the
proper accessor function.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Use the generic irq Kconfig. Select GENERIC_HARDIRQS_NO_DEPRECATED as
we have converted all irq_chip functions. Fix the fallout in
show_interrupts().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mikael Starvik <starvik@axis.com>
Convert the irq chip functions and install handle_simple_irq for each
interrupt to get rid of __do_IRQ()
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mikael Starvik <starvik@axis.com>
Convert the irq_chip functions and install handle_simple_irq for each
interrupt. This converts V10 to the flow handling and lets us remove
__do_IRQ().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mikael Starvik <starvik@axis.com>
Use the wrapper around __do_IRQ() so we can convert V10 and V32
seperately.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mikael Starvik <starvik@axis.com>
Switch to the generic irq Kconfig. h8300 has all irq chips converted
to the new functions, so select the GENERIC_HARDIRQS_NO_DEPRECATED
switch as well. Fixup the resulting fallout in show_interrupts().
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Paul Mundt <lethal@linux-sh.org>
__do_IRQ is deprecated so h8300 needs to be converted to proper flow
handling. The irq chip is simple and does not required any
mask/ack/eoi functions, so we can use handle_simple_irq.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Paul Mundt <lethal@linux-sh.org>
No functional change, just straight forward conversion.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Paul Mundt <lethal@linux-sh.org>
Don't say that enable timed out when it was disable, and
show which IRQ had the problem.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Upcoming servers will include a Broadcom NIC, add to the defconfig to
increase testing coverage and make sure mainline builds come up with
networking.
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
- Enable 64kB pages so it gets some regular testing.
- The largest POWER7 has 1024 threads so bump NR_CPUS it to match.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
IRQSOFF_TRACER and STACK_TRACER force the kernel to be built with -pg
which is a substantial overhead.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The dts-installed variable is initialised using a wildcard path that
will be expanded relative to the build directory. Use the existing
variable dtstree to generate an absolute wildcard path that will work
when building in a separate directory.
Reported-by: Gerhard Pircher <gerhard_pircher@gmx.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Tested-by: Gerhard Pircher <gerhard_pircher@gmx.net> [against 2.6.32]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Decoding machine checks is CPU specific and so machine_check_generic doesn't
do the right thing on 64bit chips. Luckily we never call into this code
because we call ppc_md.machine_check_exception instead if available.
Since we check cur_cpu_spec->machine_check before calling it, we may as
well remove machine_check_generic from 64bit archs.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The spec suggests we should first check the extended log flag before checking
the length field.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The FWNMI code uses a global buffer without any locks to read the RTAS error
information. If two CPUs take a machine check at once then we will corrupt
this buffer.
Since most FWNMI rtas messages are not of the extended type, we can create a
64bit percpu buffer and use it where possible. If we do receive an extended
RTAS log then we fall back to the old behaviour of using the global buffer.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Rework pseries machine check handler:
- If MSR_RI isn't set, we cannot recover even if the machine check was fully
recovered
- Rename nonfatal to recovered
- Handle RTAS_DISP_LIMITED_RECOVERY
- Use BUS_MCEERR_AR instead of BUS_ADRERR
- Don't check all the RTAS error log fields when receiving a synchronous
machine check. Recent versions of the pseries firmware do not fill them
in during a machine check and instead send a follow up error log with
the detailed information. If we see a synchronous machine check, and we
came from userspace then kill the task.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
If a machine check comes from userspace we send a SIGBUS to the task and
fail to printk anything.
If we are taking machine checks due to bad hardware we want to know about
it right away. Furthermore if we don't complain loudly then it will look
a lot like a bug in the userspace application, potentially causing a lot
of confusion.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We are calling debugger_fault_handler twice in machine_check_exception.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Newer versions of the System p firwmare send a partial RTAS error log in the
machine check handler with a more detailed response appearing sometime later
via check event.
This means at machine check time we do not have enough information to
ascertain exactly what went on. Furthermore, I have found the RTAS error
logs in the machine check handler contain no useful information, so halting on
them makes little sense. If we want to halt it would make more sense to do
it following the error log received sometime later via check event.
In light of this, never halt the error log in the pseries machine
check handler.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We should never force MSR_RI on. If we take a machine check with MSR_RI off
then we have no chance of recovering safely.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We were printing 64 bits of DSISR in show_regs even though it is 32 bit.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We should disable ftrace during kexec, some of the tracers are very invasive
and we do not want them going off while doing the low level work of swapping
one kernel out for another. This mirrors what we do on x86.
Even though we cannot return from a kexec on powerpc (since we do not implement
CONFIG_KEXEC_JUMP), add the restore code in case we do one day.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Use the crash handler hooks to run the SPU stop code, just like we do for
ehea and cell RAS code.
While I'm here I noticed "CPUSs reliabally"
so fix the spelling MISTAKESs reliabally.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We check for a valid handler before calling ppc_md.machine_kexec_prepare
so we can just remove these empty handlers.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
There's no need to initialise ppc_md.machine_kexec and
ppc_md.machine_kexec_prepare to the default handlers.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
No one uses ppc_md.machine_crash_shutdown, so remove it.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
No one uses ppc_md.machine_kexec, so remove it.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
No one uses ppc_md.machine_kexec_cleanup, so remove it.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Move all the kexec handlers together.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
With cmwq, there's no reason to use a separate workqueue in
cpufreq_spudemand. Use system_wq instead. The work items are already
sync canceled on stop, so it's already guaranteed that no work is
running when spu_gov_exit() is entered.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Dave Jones <davej@redhat.com>
Cc: cpufreq@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Fix error test in fan_{read,write}_reg()
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Simplify read file operation for /proc/powerpc/rtas/* interface
by using simple_read_from_buffer.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Simplify several write fileoperations for spufs by using
simple_write_to_buffer().
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
32-bit variant of the previous patch for 64-bit:
<<
When an interrupt occurs in userspace, we can call trace_hardirqs_on/off()
With one level stack. But if we have irqsoff tracing enabled,
it checks both CALLER_ADDR0 and CALLER_ADDR1. The second call
goes two stack frames up. If this is from user space, then there may
not exist a second stack....
>>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
When an interrupt occurs in userspace, we can call trace_hardirqs_on/off()
With one level stack. But if we have irqsoff tracing enabled,
it checks both CALLER_ADDR0 and CALLER_ADDR1. The second call
goes two stack frames up. If this is from user space, then there may
not exist a second stack.
Add a second stack when calling trace_hardirqs_on/off() otherwise
the following oops might occur:
Oops: Kernel access of bad area, sig: 11 [#1]
PREEMPT SMP NR_CPUS=2 PA Semi PWRficient
last sysfs file: /sys/block/sda/size
Modules linked in: ohci_hcd ehci_hcd usbcore
NIP: c0000000000e1c00 LR: c0000000000034d4 CTR: 000000011012c440
REGS: c00000003e2f3af0 TRAP: 0300 Not tainted (2.6.37-rc6+)
MSR: 9000000000001032 <ME,IR,DR> CR: 48044444 XER: 20000000
DAR: 00000001ffb9db50, DSISR: 0000000040000000
TASK = c00000003e1a00a0[2088] 'emacs' THREAD: c00000003e2f0000 CPU: 1
GPR00: 0000000000000001 c00000003e2f3d70 c00000000084e0d0 c0000000008816e8
GPR04: 000000001034c678 000000001032e8f9 0000000010336540 0000000040020000
GPR08: 0000000040020000 00000001ffb9db40 c00000003e2f3e30 0000000060000000
GPR12: 100000000000f032 c00000000fff0280 000000001032e8c9 0000000000000008
GPR16: 00000000105be9c0 00000000105be950 00000000105be9b0 00000000105be950
GPR20: 00000000ffb9dc50 00000000ffb9dbf0 00000000102f0000 00000000102f0000
GPR24: 00000000102e0000 00000000102f0000 0000000010336540 c0000000009ded38
GPR28: 00000000102e0000 c0000000000034d4 c0000000007ccb10 c00000003e2f3d70
NIP [c0000000000e1c00] .trace_hardirqs_off+0xb0/0x1d0
LR [c0000000000034d4] decrementer_common+0xd4/0x100
Call Trace:
[c00000003e2f3d70] [c00000003e2f3e30] 0xc00000003e2f3e30 (unreliable)
[c00000003e2f3e30] [c0000000000034d4] decrementer_common+0xd4/0x100
Instruction dump:
81690000 7f8b0000 419e0018 f84a0028 60000000 60000000 60000000 e95f0000
80030000 e92a0000 eb6301f8 2f800000 <eb890010> 41fe00dc a06d000a eb1e8050
---[ end trace 4ec7fd2be9240928 ]---
Reported-by: Joerg Sommer <joerg@alea.gnuu.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
When we create an alternative feature section, the else case must be the
same size or smaller than the body. This is because when we patch the
else case in we just overwrite the body, so there must be room.
Up to now we just did this by inspection, but it's quite easy to enforce
it in the assembler, so we should.
The only change is to add the ifgt block, but that effects the alignment
of the tabs and so the whole macro is modified.
Also add a test, but #if 0 it because we don't want to break the build.
Anyone who's modifying the feature macros should enable the test.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
smp: Allow on_each_cpu() to be called while early_boot_irqs_disabled status to init/main.c
lockdep: Move early boot local IRQ enable/disable status to init/main.c
It turns out that some device drivers map pages from the ACPI NVS region
during resume using ioremap(), which conflicts with ioremap_cache() used
for mapping those pages by the NVS save/restore code in nvs.c.
Make the NVS pages mapped by the code in nvs.c be unmapped before device
drivers' resume routines run.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit ca9b600be3 ("ACPI / PM: Make suspend_nvs_save() use
acpi_os_map_memory()") attempted to prevent the code in osl.c and nvs.c
from using different ioremap() variants by making the latter use
acpi_os_map_memory() for mapping the NVS pages. However, that also
requires acpi_os_unmap_memory() to be used for unmapping them, which
causes synchronize_rcu() to be executed many times in a row
unnecessarily and introduces substantial delays during resume on some
systems.
Instead of using acpi_os_map_memory() for mapping the NVS pages in nvs.c
introduce acpi_os_ioremap() calling ioremap_cache() and make the code in
both osl.c and nvs.c use it.
Reported-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make sure that CIFSSMBEcho can handle unaligned fields. Also fix a minor
bug that causes this warning:
fs/cifs/cifssmb.c: In function 'CIFSSMBEcho':
fs/cifs/cifssmb.c:740: warning: large integer implicitly truncated to unsigned type
...WordCount is u8, not __le16, so no need to convert it.
This patch should apply cleanly on top of the rest of the patchset to
clean up unaligned access.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
* akpm:
kernel/smp.c: consolidate writes in smp_call_function_interrupt()
kernel/smp.c: fix smp_call_function_many() SMP race
memcg: correctly order reading PCG_USED and pc->mem_cgroup
backlight: fix 88pm860x_bl macro collision
drivers/leds/ledtrig-gpio.c: make output match input, tighten input checking
MAINTAINERS: update Atmel AT91 entry
mm: fix truncate_setsize() comment
memcg: fix rmdir, force_empty with THP
memcg: fix LRU accounting with THP
memcg: fix USED bit handling at uncharge in THP
memcg: modify accounting function for supporting THP better
fs/direct-io.c: don't try to allocate more than BIO_MAX_PAGES in a bio
mm: compaction: prevent division-by-zero during user-requested compaction
mm/vmscan.c: remove duplicate include of compaction.h
memblock: fix memblock_is_region_memory()
thp: keep highpte mapped until it is no longer needed
kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT
We have to test the cpu mask in the interrupt handler before checking the
refs, otherwise we can start to follow an entry before its deleted and
find it partially initailzed for the next trip. Presently we also clear
the cpumask bit before executing the called function, which implies
getting write access to the line. After the function is called we then
decrement refs, and if they go to zero we then unlock the structure.
However, this implies getting write access to the call function data
before and after another the function is called. If we can assert that no
smp_call_function execution function is allowed to enable interrupts, then
we can move both writes to after the function is called, hopfully allowing
both writes with one cache line bounce.
On a 256 thread system with a kernel compiled for 1024 threads, the time
to execute testcase in the "smp_call_function_many race" changelog was
reduced by about 30-40ms out of about 545 ms.
I decided to keep this as WARN because its now a buggy function, even
though the stack trace is of no value -- a simple printk would give us the
information needed.
Raw data:
Without patch:
ipi_test startup took 1219366ns complete 539819014ns total 541038380ns
ipi_test startup took 1695754ns complete 543439872ns total 545135626ns
ipi_test startup took 7513568ns complete 539606362ns total 547119930ns
ipi_test startup took 13304064ns complete 533898562ns total 547202626ns
ipi_test startup took 8668192ns complete 544264074ns total 552932266ns
ipi_test startup took 4977626ns complete 548862684ns total 553840310ns
ipi_test startup took 2144486ns complete 541292318ns total 543436804ns
ipi_test startup took 21245824ns complete 530280180ns total 551526004ns
With patch:
ipi_test startup took 5961748ns complete 500859628ns total 506821376ns
ipi_test startup took 8975996ns complete 495098924ns total 504074920ns
ipi_test startup took 19797750ns complete 492204740ns total 512002490ns
ipi_test startup took 14824796ns complete 487495878ns total 502320674ns
ipi_test startup took 11514882ns complete 494439372ns total 505954254ns
ipi_test startup took 8288084ns complete 502570774ns total 510858858ns
ipi_test startup took 6789954ns complete 493388112ns total 500178066ns
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h> /* sched clock */
#define ITERATIONS 100
static void do_nothing_ipi(void *dummy)
{
}
static void do_ipis(struct work_struct *dummy)
{
int i;
for (i = 0; i < ITERATIONS; i++)
smp_call_function(do_nothing_ipi, NULL, 1);
printk(KERN_DEBUG "cpu %d finished\n", smp_processor_id());
}
static struct work_struct work[NR_CPUS];
static int __init testcase_init(void)
{
int cpu;
u64 start, started, done;
start = local_clock();
for_each_online_cpu(cpu) {
INIT_WORK(&work[cpu], do_ipis);
schedule_work_on(cpu, &work[cpu]);
}
started = local_clock();
for_each_online_cpu(cpu)
flush_work(&work[cpu]);
done = local_clock();
pr_info("ipi_test startup took %lldns complete %lldns total %lldns\n",
started-start, done-started, done-start);
return 0;
}
static void __exit testcase_exit(void)
{
}
module_init(testcase_init)
module_exit(testcase_exit)
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Anton Blanchard");
Signed-off-by: Milton Miller <miltonm@bga.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I noticed a failure where we hit the following WARN_ON in
generic_smp_call_function_interrupt:
if (!cpumask_test_and_clear_cpu(cpu, data->cpumask))
continue;
data->csd.func(data->csd.info);
refs = atomic_dec_return(&data->refs);
WARN_ON(refs < 0); <-------------------------
We atomically tested and cleared our bit in the cpumask, and yet the
number of cpus left (ie refs) was 0. How can this be?
It turns out commit 54fdade1c3
("generic-ipi: make struct call_function_data lockless") is at fault. It
removes locking from smp_call_function_many and in doing so creates a
rather complicated race.
The problem comes about because:
- The smp_call_function_many interrupt handler walks call_function.queue
without any locking.
- We reuse a percpu data structure in smp_call_function_many.
- We do not wait for any RCU grace period before starting the next
smp_call_function_many.
Imagine a scenario where CPU A does two smp_call_functions back to back,
and CPU B does an smp_call_function in between. We concentrate on how CPU
C handles the calls:
CPU A CPU B CPU C CPU D
smp_call_function
smp_call_function_interrupt
walks
call_function.queue sees
data from CPU A on list
smp_call_function
smp_call_function_interrupt
walks
call_function.queue sees
(stale) CPU A on list
smp_call_function int
clears last ref on A
list_del_rcu, unlock
smp_call_function reuses
percpu *data A
data->cpumask sees and
clears bit in cpumask
might be using old or new fn!
decrements refs below 0
set data->refs (too late!)
The important thing to note is since the interrupt handler walks a
potentially stale call_function.queue without any locking, then another
cpu can view the percpu *data structure at any time, even when the owner
is in the process of initialising it.
The following test case hits the WARN_ON 100% of the time on my PowerPC
box (having 128 threads does help :)
#include <linux/module.h>
#include <linux/init.h>
#define ITERATIONS 100
static void do_nothing_ipi(void *dummy)
{
}
static void do_ipis(struct work_struct *dummy)
{
int i;
for (i = 0; i < ITERATIONS; i++)
smp_call_function(do_nothing_ipi, NULL, 1);
printk(KERN_DEBUG "cpu %d finished\n", smp_processor_id());
}
static struct work_struct work[NR_CPUS];
static int __init testcase_init(void)
{
int cpu;
for_each_online_cpu(cpu) {
INIT_WORK(&work[cpu], do_ipis);
schedule_work_on(cpu, &work[cpu]);
}
return 0;
}
static void __exit testcase_exit(void)
{
}
module_init(testcase_init)
module_exit(testcase_exit)
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Anton Blanchard");
I tried to fix it by ordering the read and the write of ->cpumask and
->refs. In doing so I missed a critical case but Paul McKenney was able
to spot my bug thankfully :) To ensure we arent viewing previous
iterations the interrupt handler needs to read ->refs then ->cpumask then
->refs _again_.
Thanks to Milton Miller and Paul McKenney for helping to debug this issue.
[miltonm@bga.com: add WARN_ON and BUG_ON, remove extra read of refs before initial read of mask that doesn't help (also noted by Peter Zijlstra), adjust comments, hopefully clarify scenario ]
[miltonm@bga.com: remove excess tests]
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Milton Miller <miltonm@bga.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: <stable@kernel.org> [2.6.32+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The placement of the read-side barrier is confused: the writer first
sets pc->mem_cgroup, then PCG_USED. The read-side barrier has to be
between testing PCG_USED and reading pc->mem_cgroup.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Thomas Gleixner