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On architectures where cputime_t is 64 bit type, is possible to trigger
divide by zero on do_div(temp, (__force u32) total) line, if total is a
non zero number but has lower 32 bit's zeroed. Removing casting is not
a good solution since some do_div() implementations do cast to u32
internally.
This problem can be triggered in practice on very long lived processes:
PID: 2331 TASK: ffff880472814b00 CPU: 2 COMMAND: "oraagent.bin"
#0 [ffff880472a51b70] machine_kexec at ffffffff8103214b
#1 [ffff880472a51bd0] crash_kexec at ffffffff810b91c2
#2 [ffff880472a51ca0] oops_end at ffffffff814f0b00
#3 [ffff880472a51cd0] die at ffffffff8100f26b
#4 [ffff880472a51d00] do_trap at ffffffff814f03f4
#5 [ffff880472a51d60] do_divide_error at ffffffff8100cfff
#6 [ffff880472a51e00] divide_error at ffffffff8100be7b
[exception RIP: thread_group_times+0x56]
RIP: ffffffff81056a16 RSP: ffff880472a51eb8 RFLAGS: 00010046
RAX: bc3572c9fe12d194 RBX: ffff880874150800 RCX: 0000000110266fad
RDX: 0000000000000000 RSI: ffff880472a51eb8 RDI: 001038ae7d9633dc
RBP: ffff880472a51ef8 R8: 00000000b10a3a64 R9: ffff880874150800
R10: 00007fcba27ab680 R11: 0000000000000202 R12: ffff880472a51f08
R13: ffff880472a51f10 R14: 0000000000000000 R15: 0000000000000007
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#7 [ffff880472a51f00] do_sys_times at ffffffff8108845d
#8 [ffff880472a51f40] sys_times at ffffffff81088524
#9 [ffff880472a51f80] system_call_fastpath at ffffffff8100b0f2
RIP: 0000003808caac3a RSP: 00007fcba27ab6d8 RFLAGS: 00000202
RAX: 0000000000000064 RBX: ffffffff8100b0f2 RCX: 0000000000000000
RDX: 00007fcba27ab6e0 RSI: 000000000076d58e RDI: 00007fcba27ab6e0
RBP: 00007fcba27ab700 R8: 0000000000000020 R9: 000000000000091b
R10: 00007fcba27ab680 R11: 0000000000000202 R12: 00007fff9ca41940
R13: 0000000000000000 R14: 00007fcba27ac9c0 R15: 00007fff9ca41940
ORIG_RAX: 0000000000000064 CS: 0033 SS: 002b
Cc: stable@vger.kernel.org
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120808092714.GA3580@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Peter Portante reported that for large cgroup hierarchies (and or on
large CPU counts) we get immense lock contention on rq->lock and stuff
stops working properly.
His workload was a ton of processes, each in their own cgroup,
everybody idling except for a sporadic wakeup once every so often.
It was found that:
schedule()
idle_balance()
load_balance()
local_irq_save()
double_rq_lock()
update_h_load()
walk_tg_tree(tg_load_down)
tg_load_down()
Results in an entire cgroup hierarchy walk under rq->lock for every
new-idle balance and since new-idle balance isn't throttled this
results in a lot of work while holding the rq->lock.
This patch does two things, it removes the work from under rq->lock
based on the good principle of race and pray which is widely employed
in the load-balancer as a whole. And secondly it throttles the
update_h_load() calculation to max once per jiffy.
I considered excluding update_h_load() for new-idle balance
all-together, but purely relying on regular balance passes to update
this data might not work out under some rare circumstances where the
new-idle busiest isn't the regular busiest for a while (unlikely, but
a nightmare to debug if someone hits it and suffers).
Cc: pjt@google.com
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Reported-by: Peter Portante <pportant@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-aaarrzfpnaam7pqrekofu8a6@git.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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With this patch struct ld_env will have a pointer of the load balancing
cpumask and we don't need to pass a cpumask around anymore.
Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4FFE8665.3080705@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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PREEMPT_ACTIVE flag is bit 27, not 28. Fix the comment.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: paulmck@linux.vnet.ibm.com
Cc: josh@joshtriplett.org
Cc: rostedt@goodmis.org
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120720192459.6149.14821.stgit@srivatsabhat.in.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Delete redudant spaces between type name and data name or operators.
Signed-off-by: Ying Xue <ying.xue0@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1342076622-6606-1-git-send-email-ying.xue0@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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It seems there's no specific reason to open-code it. I guess
commit 0122ec5b02f76 ("sched: Add p->pi_lock to task_rq_lock()")
simply missed it. Let's be consistent with others.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1341647342-6742-1-git-send-email-namhyung@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Commit 8e7fbcbc22c ("sched: Remove stale power aware scheduling remnants
and dysfunctional knobs") removed SD_PERFER_SIBLING from the CPU domain.
On NUMA machines this causes that load_balance() doesn't perfer LCPU in
same physical CPU package.
It causes some actual performance regressions on our NUMA machines from
Core2 to NHM and SNB.
Adding this domain flag again recovers the performance drop.
This change doesn't have any bad impact on any of my benchmarks:
specjbb, kbuild, fio, hackbench .. etc, on all my machines.
Signed-off-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1342765190-21540-1-git-send-email-alex.shi@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Stefan reported a crash on a kernel before a3e5d1091c1 ("sched:
Don't call task_group() too many times in set_task_rq()"), he
found the reason to be that the multiple task_group()
invocations in set_task_rq() returned different values.
Looking at all that I found a lack of serialization and plain
wrong comments.
The below tries to fix it using an extra pointer which is
updated under the appropriate scheduler locks. Its not pretty,
but I can't really see another way given how all the cgroup
stuff works.
Reported-and-tested-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1340364965.18025.71.camel@twins
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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of (pinned) task
Current load balance scheme requires only one cpu in a
sched_group (balance_cpu) to look at other peer sched_groups for
imbalance and pull tasks towards itself from a busy cpu. Tasks
thus pulled by balance_cpu could later get picked up by cpus
that are in the same sched_group as that of balance_cpu.
This scheme however fails to pull tasks that are not allowed to
run on balance_cpu (but are allowed to run on other cpus in its
sched_group). That can affect fairness and in some worst case
scenarios cause starvation.
Consider a two core (2 threads/core) system running tasks as
below:
Core0 Core1
/ \ / \
C0 C1 C2 C3
| | | |
v v v v
F0 T1 F1 [idle]
T2
F0 = SCHED_FIFO task (pinned to C0)
F1 = SCHED_FIFO task (pinned to C2)
T1 = SCHED_OTHER task (pinned to C1)
T2 = SCHED_OTHER task (pinned to C1 and C2)
F1 could become a cpu hog, which will starve T2 unless C1 pulls
it. Between C0 and C1 however, C0 is required to look for
imbalance between cores, which will fail to pull T2 towards
Core0. T2 will starve eternally in this case. The same scenario
can arise in presence of non-rt tasks as well (say we replace F1
with high irq load).
We tackle this problem by having balance_cpu move pinned tasks
to one of its sibling cpus (where they can run). We first check
if load balance goal can be met by ignoring pinned tasks,
failing which we retry move_tasks() with a new env->dst_cpu.
This patch modifies load balance semantics on who can move load
towards a given cpu in a given sched_domain.
Before this patch, a given_cpu or a ilb_cpu acting on behalf of
an idle given_cpu is responsible for moving load to given_cpu.
With this patch applied, balance_cpu can in addition decide on
moving some load to a given_cpu.
There is a remote possibility that excess load could get moved
as a result of this (balance_cpu and given_cpu/ilb_cpu deciding
*independently* and at *same* time to move some load to a
given_cpu). However we should see less of such conflicting
decisions in practice and moreover subsequent load balance
cycles should correct the excess load moved to given_cpu.
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4FE06CDB.2060605@linux.vnet.ibm.com
[ minor edits ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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balance
While load balancing, if all tasks on the source runqueue are pinned,
we retry after excluding the corresponding source cpu. However, loop counters
env.loop and env.loop_break are not reset before retrying, which can lead
to failure in moving the tasks. In this patch we reset env.loop and
env.loop_break to their inital values before we retry.
Signed-off-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4FE06EEF.2090709@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Members of 'struct lb_env' are not in appropriate order to reuse compiler
added padding on 64bit architectures. In this patch we reorder those struct
members and help reduce the size of the structure from 96 bytes to 80
bytes on 64 bit architectures.
Suggested-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4FE06DDE.7000403@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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perturbations
Traversing an entire package is not only expensive, it also leads to tasks
bouncing all over a partially idle and possible quite large package. Fix
that up by assigning a 'buddy' CPU to try to motivate. Each buddy may try
to motivate that one other CPU, if it's busy, tough, it may then try its
SMT sibling, but that's all this optimization is allowed to cost.
Sibling cache buddies are cross-wired to prevent bouncing.
4 socket 40 core + SMT Westmere box, single 30 sec tbench runs, higher is better:
clients 1 2 4 8 16 32 64 128
..........................................................................
pre 30 41 118 645 3769 6214 12233 14312
post 299 603 1211 2418 4697 6847 11606 14557
A nice increase in performance.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1339471112.7352.32.camel@marge.simpson.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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cpuset_track_online_cpus() is no longer present. So remove the
outdated comment and replace it with reference to cpuset_update_active_cpus()
which is its equivalent.
Also, we don't lack memory hot-unplug anymore. And David Rientjes pointed
out how it is dealt with. So update that comment as well.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20120524141700.3692.98192.stgit@srivatsabhat.in.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Separate out the cpuset related handling for CPU/Memory online/offline.
This also helps us exploit the most obvious and basic level of optimization
that any notification mechanism (CPU/Mem online/offline) has to offer us:
"We *know* why we have been invoked. So stop pretending that we are lost,
and do only the necessary amount of processing!".
And while at it, rename scan_for_empty_cpusets() to
scan_cpusets_upon_hotplug(), which is more appropriate considering how
it is restructured.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20120524141650.3692.48637.stgit@srivatsabhat.in.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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At present, the functions that deal with cpusets during CPU/Mem hotplug
are quite messy, since a lot of the functionality is mixed up without clear
separation. And this takes a toll on optimization as well. For example,
the function cpuset_update_active_cpus() is called on both CPU offline and CPU
online events; and it invokes scan_for_empty_cpusets(), which makes sense
only for CPU offline events. And hence, the current code ends up unnecessarily
traversing the cpuset tree during CPU online also.
As a first step towards cleaning up those functions, encapsulate the cpuset
tree traversal in a helper function, so as to facilitate upcoming changes.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20120524141635.3692.893.stgit@srivatsabhat.in.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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In the event of CPU hotplug, the kernel modifies the cpusets' cpus_allowed
masks as and when necessary to ensure that the tasks belonging to the cpusets
have some place (online CPUs) to run on. And regular CPU hotplug is
destructive in the sense that the kernel doesn't remember the original cpuset
configurations set by the user, across hotplug operations.
However, suspend/resume (which uses CPU hotplug) is a special case in which
the kernel has the responsibility to restore the system (during resume), to
exactly the same state it was in before suspend.
In order to achieve that, do the following:
1. Don't modify cpusets during suspend/resume. At all.
In particular, don't move the tasks from one cpuset to another, and
don't modify any cpuset's cpus_allowed mask. So, simply ignore cpusets
during the CPU hotplug operations that are carried out in the
suspend/resume path.
2. However, cpusets and sched domains are related. We just want to avoid
altering cpusets alone. So, to keep the sched domains updated, build
a single sched domain (containing all active cpus) during each of the
CPU hotplug operations carried out in s/r path, effectively ignoring
the cpusets' cpus_allowed masks.
(Since userspace is frozen while doing all this, it will go unnoticed.)
3. During the last CPU online operation during resume, build the sched
domains by looking up the (unaltered) cpusets' cpus_allowed masks.
That will bring back the system to the same original state as it was in
before suspend.
Ultimately, this will not only solve the cpuset problem related to suspend
resume (ie., restores the cpusets to exactly what it was before suspend, by
not touching it at all) but also speeds up suspend/resume because we avoid
running cpuset update code for every CPU being offlined/onlined.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20120524141611.3692.20155.stgit@srivatsabhat.in.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The x86 sched power implementation has been broken forever and gets in
the way of other stuff, remove it.
[ For archaeological interest, fixing this code would require dealing
with the cross-cpu calling of these functions and more importantly, we
need to filter idle time out of the a/m-perf stuff because the ratio
will go down to 0 when idle, giving a 0 capacity which is not what
we'd want. ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Link: http://lkml.kernel.org/r/1339594110.8980.38.camel@twins
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The SYSTEM_SUSPEND_DISK system state is never used, so drop it.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge emailed kgdb dmesg fixups patches from Anton Vorontsov:
"The dmesg command appears to be broken after the printk rework. The
old logic in the kdb code makes no sense in terms of current
printk/logging storage format, and KDB simply hangs forever upon
entering 'dmesg' command.
The first patch revives the command by switching to kmsg_dumper
iterator. As a side-effect, the code is now much more simpler.
A few changes were needed in the printk.c: we needed unlocked variant
of the kmsg_dumper iterator, but these can surely wait for 3.6.
It's probably too late even for the first patch to go to 3.5, but I'll
try to convince otherwise. :-) Here we go:
- The current code is broken for sure, and has no hope to work at
all. It is a regression
- The new code works for me, and probably works for everyone else;
- If it compiles (and I urge everyone to compile-test it on your
setup), it hardly can make things worse."
* Merge emailed patches from Anton Vorontsov: (4 commits)
kdb: Switch to nolock variants of kmsg_dump functions
printk: Implement some unlocked kmsg_dump functions
printk: Remove kdb_syslog_data
kdb: Revive dmesg command
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The locked variants are prone to deadlocks (suppose we got to the
debugger w/ the logbuf lock held), so let's switch to nolock variants.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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If used from KDB, the locked variants are prone to deadlocks (suppose we
got to the debugger w/ the logbuf lock held).
So, we have to implement a few routines that grab no logbuf lock.
Yet we don't need these functions in modules, so we don't export them.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The function is no longer needed, so remove it.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The kgdb dmesg command is broken after the printk rework. The old logic
in kdb code makes no sense in terms of current printk/logging storage
format, and KDB simply hangs forever.
This patch revives the command by switching to kmsg_dumper iterator.
The code is now much more simpler and shorter.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pull late MIPS fixes from Ralf Baechle:
"This fixes a number of lose ends in the MIPS code and various bug
fixes.
Aside of dropping some patch that should not be in this pull request
everything has sat in -next for quite a while and there are no known
issues.
The biggest patch in this patch set moves the allocation of an array
that is aliased to a function (for runtime generated code) to
assembler code. This avoids an issue with certain toolchains when
building for microMIPS."
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (35 commits)
MIPS: PCI: Move fixups from __init to __devinit.
MIPS: Fix bug.h MIPS build regression
MIPS: sync-r4k: remove redundant irq operation
MIPS: smp: Warn on too early irq enable
MIPS: call set_cpu_online() on cpu being brought up with irq disabled
MIPS: call ->smp_finish() a little late
MIPS: Yosemite: delay irq enable to ->smp_finish()
MIPS: SMTC: delay irq enable to ->smp_finish()
MIPS: BMIPS: delay irq enable to ->smp_finish()
MIPS: Octeon: delay enable irq to ->smp_finish()
MIPS: Oprofile: Fix build as a module.
MIPS: BCM63XX: Fix BCM6368 IPSec clock bit
MIPS: perf: Fix build error caused by unused counters_per_cpu_to_total()
MIPS: Fix Magic SysRq L kernel crash.
MIPS: BMIPS: Fix duplicate header inclusion.
mips: mark const init data with __initconst instead of __initdata
MIPS: cmpxchg.h: Add missing include
MIPS: Malta may also be equipped with MIPS64 R2 processors.
MIPS: Fix typo multipy -> multiply
MIPS: Cavium: Fix duplicate ARCH_SPARSEMEM_ENABLE in kconfig.
...
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git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm
Pull device-mapper discard fixes from Alasdair G Kergon:
- avoid a crash in dm-raid1 when discards coincide with mirror
recovery;
- avoid discarding shared data that's still needed in dm-thin;
- don't guarantee that discarded blocks will be wiped in dm-raid1.
* tag 'dm-3.5-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm:
dm raid1: set discard_zeroes_data_unsupported
dm thin: do not send discards to shared blocks
dm raid1: fix crash with mirror recovery and discard
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Pull pnfs/ore fixes from Boaz Harrosh:
"These are catastrophic fixes to the pnfs objects-layout that were just
discovered. They are also destined for @stable.
I have found these and worked on them at around RC1 time but
unfortunately went to the hospital for kidney stones and had a very
slow recovery. I refrained from sending them as is, before proper
testing, and surly I have found a bug just yesterday.
So now they are all well tested, and have my sign-off. Other then
fixing the problem at hand, and assuming there are no bugs at the new
code, there is low risk to any surrounding code. And in anyway they
affect only these paths that are now broken. That is RAID5 in pnfs
objects-layout code. It does also affect exofs (which was not broken)
but I have tested exofs and it is lower priority then objects-layout
because no one is using exofs, but objects-layout has lots of users."
* 'for-linus' of git://git.open-osd.org/linux-open-osd:
pnfs-obj: Fix __r4w_get_page when offset is beyond i_size
pnfs-obj: don't leak objio_state if ore_write/read fails
ore: Unlock r4w pages in exact reverse order of locking
ore: Remove support of partial IO request (NFS crash)
ore: Fix NFS crash by supporting any unaligned RAID IO
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Pull UBIFS free space fix-up bugfix from Artem Bityutskiy:
"It's been reported already twice recently:
http://lists.infradead.org/pipermail/linux-mtd/2012-May/041408.html
http://lists.infradead.org/pipermail/linux-mtd/2012-June/042422.html
and we finally have the fix. I am quite confident the fix is correct
because I could reproduce the problem with nandsim and verify the fix.
It was also verified by Iwo (the reporter).
I am also confident that this is OK to merge the fix so late because
this patch affects only the fixup functionality, which is not used by
most users."
* tag 'upstream-3.5-rc8' of git://git.infradead.org/linux-ubifs:
UBIFS: fix a bug in empty space fix-up
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We can't guarantee that REQ_DISCARD on dm-mirror zeroes the data even if
the underlying disks support zero on discard. So this patch sets
ti->discard_zeroes_data_unsupported.
For example, if the mirror is in the process of resynchronizing, it may
happen that kcopyd reads a piece of data, then discard is sent on the
same area and then kcopyd writes the piece of data to another leg.
Consequently, the data is not zeroed.
The flag was made available by commit 983c7db347db8ce2d8453fd1d89b7a4bb6920d56
(dm crypt: always disable discard_zeroes_data).
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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When process_discard receives a partial discard that doesn't cover a
full block, it sends this discard down to that block. Unfortunately, the
block can be shared and the discard would corrupt the other snapshots
sharing this block.
This patch detects block sharing and ends the discard with success when
sending it to the shared block.
The above change means that if the device supports discard it can't be
guaranteed that a discard request zeroes data. Therefore, we set
ti->discard_zeroes_data_unsupported.
Thin target discard support with this bug arrived in commit
104655fd4dcebd50068ef30253a001da72e3a081 (dm thin: support discards).
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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This patch fixes a crash when a discard request is sent during mirror
recovery.
Firstly, some background. Generally, the following sequence happens during
mirror synchronization:
- function do_recovery is called
- do_recovery calls dm_rh_recovery_prepare
- dm_rh_recovery_prepare uses a semaphore to limit the number
simultaneously recovered regions (by default the semaphore value is 1,
so only one region at a time is recovered)
- dm_rh_recovery_prepare calls __rh_recovery_prepare,
__rh_recovery_prepare asks the log driver for the next region to
recover. Then, it sets the region state to DM_RH_RECOVERING. If there
are no pending I/Os on this region, the region is added to
quiesced_regions list. If there are pending I/Os, the region is not
added to any list. It is added to the quiesced_regions list later (by
dm_rh_dec function) when all I/Os finish.
- when the region is on quiesced_regions list, there are no I/Os in
flight on this region. The region is popped from the list in
dm_rh_recovery_start function. Then, a kcopyd job is started in the
recover function.
- when the kcopyd job finishes, recovery_complete is called. It calls
dm_rh_recovery_end. dm_rh_recovery_end adds the region to
recovered_regions or failed_recovered_regions list (depending on
whether the copy operation was successful or not).
The above mechanism assumes that if the region is in DM_RH_RECOVERING
state, no new I/Os are started on this region. When I/O is started,
dm_rh_inc_pending is called, which increases reg->pending count. When
I/O is finished, dm_rh_dec is called. It decreases reg->pending count.
If the count is zero and the region was in DM_RH_RECOVERING state,
dm_rh_dec adds it to the quiesced_regions list.
Consequently, if we call dm_rh_inc_pending/dm_rh_dec while the region is
in DM_RH_RECOVERING state, it could be added to quiesced_regions list
multiple times or it could be added to this list when kcopyd is copying
data (it is assumed that the region is not on any list while kcopyd does
its jobs). This results in memory corruption and crash.
There already exist bypasses for REQ_FLUSH requests: REQ_FLUSH requests
do not belong to any region, so they are always added to the sync list
in do_writes. dm_rh_inc_pending does not increase count for REQ_FLUSH
requests. In mirror_end_io, dm_rh_dec is never called for REQ_FLUSH
requests. These bypasses avoid the crash possibility described above.
These bypasses were improperly implemented for REQ_DISCARD when
the mirror target gained discard support in commit
5fc2ffeabb9ee0fc0e71ff16b49f34f0ed3d05b4 (dm raid1: support discard).
In do_writes, REQ_DISCARD requests is always added to the sync queue and
immediately dispatched (even if the region is in DM_RH_RECOVERING). However,
dm_rh_inc and dm_rh_dec is called for REQ_DISCARD resusts. So it violates the
rule that no I/Os are started on DM_RH_RECOVERING regions, and causes the list
corruption described above.
This patch changes it so that REQ_DISCARD requests follow the same path
as REQ_FLUSH. This avoids the crash.
Reference: https://bugzilla.redhat.com/837607
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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It is very common for the end of the file to be unaligned on
stripe size. But since we know it's beyond file's end then
the XOR should be preformed with all zeros.
Old code used to just read zeros out of the OSD devices, which is a great
waist. But what scares me more about this situation is that, we now have
pages attached to the file's mapping that are beyond i_size. I don't
like the kind of bugs this calls for.
Fix both birds, by returning a global zero_page, if offset is beyond
i_size.
TODO:
Change the API to ->__r4w_get_page() so a NULL can be
returned without being considered as error, since XOR API
treats NULL entries as zero_pages.
[Bug since 3.2. Should apply the same way to all Kernels since]
CC: Stable Tree <stable@kernel.org>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
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[Bug since 3.2 Kernel]
CC: Stable Tree <stable@kernel.org>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
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The read-4-write pages are locked in address ascending order.
But where unlocked in a way easiest for coding. Fix that,
locks should be released in opposite order of locking, .i.e
descending address order.
I have not hit this dead-lock. It was found by inspecting the
dbug print-outs. I suspect there is an higher lock at caller that
protects us, but fix it regardless.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
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Do to OOM situations the ore might fail to allocate all resources
needed for IO of the full request. If some progress was possible
it would proceed with a partial/short request, for the sake of
forward progress.
Since this crashes NFS-core and exofs is just fine without it just
remove this contraption, and fail.
TODO:
Support real forward progress with some reserved allocations
of resources, such as mem pools and/or bio_sets
[Bug since 3.2 Kernel]
CC: Stable Tree <stable@kernel.org>
CC: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
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In RAID_5/6 We used to not permit an IO that it's end
byte is not stripe_size aligned and spans more than one stripe.
.i.e the caller must check if after submission the actual
transferred bytes is shorter, and would need to resubmit
a new IO with the remainder.
Exofs supports this, and NFS was supposed to support this
as well with it's short write mechanism. But late testing has
exposed a CRASH when this is used with none-RPC layout-drivers.
The change at NFS is deep and risky, in it's place the fix
at ORE to lift the limitation is actually clean and simple.
So here it is below.
The principal here is that in the case of unaligned IO on
both ends, beginning and end, we will send two read requests
one like old code, before the calculation of the first stripe,
and also a new site, before the calculation of the last stripe.
If any "boundary" is aligned or the complete IO is within a single
stripe. we do a single read like before.
The code is clean and simple by splitting the old _read_4_write
into 3 even parts:
1._read_4_write_first_stripe
2. _read_4_write_last_stripe
3. _read_4_write_execute
And calling 1+3 at the same place as before. 2+3 before last
stripe, and in the case of all in a single stripe then 1+2+3
is preformed additively.
Why did I not think of it before. Well I had a strike of
genius because I have stared at this code for 2 years, and did
not find this simple solution, til today. Not that I did not try.
This solution is much better for NFS than the previous supposedly
solution because the short write was dealt with out-of-band after
IO_done, which would cause for a seeky IO pattern where as in here
we execute in order. At both solutions we do 2 separate reads, only
here we do it within a single IO request. (And actually combine two
writes into a single submission)
NFS/exofs code need not change since the ORE API communicates the new
shorter length on return, what will happen is that this case would not
occur anymore.
hurray!!
[Stable this is an NFS bug since 3.2 Kernel should apply cleanly]
CC: Stable Tree <stable@kernel.org>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
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UBIFS has a feature called "empty space fix-up" which is a quirk to work-around
limitations of dumb flasher programs. Namely, of those flashers that are unable
to skip NAND pages full of 0xFFs while flashing, resulting in empty space at
the end of half-filled eraseblocks to be unusable for UBIFS. This feature is
relatively new (introduced in v3.0).
The fix-up routine (fixup_free_space()) is executed only once at the very first
mount if the superblock has the 'space_fixup' flag set (can be done with -F
option of mkfs.ubifs). It basically reads all the UBIFS data and metadata and
writes it back to the same LEB. The routine assumes the image is pristine and
does not have anything in the journal.
There was a bug in 'fixup_free_space()' where it fixed up the log incorrectly.
All but one LEB of the log of a pristine file-system are empty. And one
contains just a commit start node. And 'fixup_free_space()' just unmapped this
LEB, which resulted in wiping the commit start node. As a result, some users
were unable to mount the file-system next time with the following symptom:
UBIFS error (pid 1): replay_log_leb: first log node at LEB 3:0 is not CS node
UBIFS error (pid 1): replay_log_leb: log error detected while replaying the log at LEB 3:0
The root-cause of this bug was that 'fixup_free_space()' wrongly assumed
that the beginning of empty space in the log head (c->lhead_offs) was known
on mount. However, it is not the case - it was always 0. UBIFS does not store
in it the master node and finds out by scanning the log on every mount.
The fix is simple - just pass commit start node size instead of 0 to
'fixup_leb()'.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>
Cc: stable@vger.kernel.org [v3.0+]
Reported-by: Iwo Mergler <Iwo.Mergler@netcommwireless.com>
Tested-by: Iwo Mergler <Iwo.Mergler@netcommwireless.com>
Reported-by: James Nute <newten82@gmail.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
Pull last minute Ceph fixes from Sage Weil:
"The important one fixes a bug in the socket failure handling behavior
that was turned up in some recent failure injection testing. The
other two are minor bug fixes."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
rbd: endian bug in rbd_req_cb()
rbd: Fix ceph_snap_context size calculation
libceph: fix messenger retry
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Pull three md bugfixes from NeilBrown:
"One of the bugs was introduced in 3.5-rc1. Others have been there for
longer."
* tag 'md-3.5-fixes' of git://neil.brown.name/md:
md/raid1: close some possible races on write errors during resync
md: avoid crash when stopping md array races with closing other open fds.
md: fix bug in handling of new_data_offset
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Pull networking changes from David Miller:
"Ok, we should be good to go now"
1) We have to statically initialize the init_net device list head rather
than do so in an initcall, otherwise netprio_cgroup crashes if it's
built statically rather than modular (Mark D. Rustad)
2) Fix SKB null oopser in CIPSO ipv4 option processing (Paul Moore)
3) Qlogic maintainers update (Anirban Chakraborty)
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
net: Statically initialize init_net.dev_base_head
MAINTAINERS: Changes in qlcnic and qlge maintainers list
cipso: don't follow a NULL pointer when setsockopt() is called
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git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid
Pull HID update from Jiri Kosina:
"A final round of changes for HID for 3.5: just device ID additions."
* 'upstream-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid:
HID: hid-multitouch: add support for Zytronic panels
HID: add Sennheiser BTD500USB device support
HID: add battery quirk for Apple Wireless ANSI
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The strcpy was being used to set the name of the board. Since the
destination char* was read-only and the name is set statically at
compile time; this was both wrong and redundant.
The type of char* is changed to const char* to prevent future errors.
Reported-by: Radek Masin <radek@masin.eu>
Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com>
[ Taking directly due to vacations - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Fixups are executed once the pci-device is found which is during boot
process so __init seems fine as long as the platform does not support
hotplug.
However it is possible to remove the PCI bus at run time and have it
rediscovered again via "echo 1 > /sys/bus/pci/rescan" and this will call
the fixups again.
[ralf@linux-mips.org: Made piixirqmap[] in malta_piix_func0_fixup()
__initdata.]
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: linux-mips@linux-mips.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Commit: 3777808873b0c49c5cf27e44c948dfb02675d578 [bug.h: need linux/kernel.h
for TAINT_WARN.] breaks all MIPS builds.
CC arch/mips/kernel/machine_kexec.o
In file included from include/linux/kernel.h:20:0,
from include/asm-generic/bug.h:35,
from /home/yuasa/src/linux/kernel/git/linux-2.6/arch/mips/include/asm/bug.h:41,
from /home/yuasa/src/linux/kernel/git/linux-2.6/arch/mips/include/asm/bitops.h:20,
from include/linux/bitops.h:22,
from include/linux/signal.h:38,
from include/linux/elfcore.h:5,
from include/linux/kexec.h:60,
from arch/mips/kernel/machine_kexec.c:9:
include/linux/log2.h: In function '__ilog2_u32':
include/linux/log2.h:34:2: error: implicit declaration of function 'fls' [-Werror=implicit-function-declaration]
include/linux/log2.h: In function '__ilog2_u64':
include/linux/log2.h:42:2: error: implicit declaration of function 'fls64' [-Werror=implicit-function-declaration]
include/linux/log2.h: In function '__roundup_pow_of_two':
include/linux/log2.h:63:2: error: implicit declaration of function 'fls_long' [-Werror=implicit-function-declaration]
In file included from include/linux/bitops.h:22:0,
from include/linux/signal.h:38,
from include/linux/elfcore.h:5,
from include/linux/kexec.h:60,
from arch/mips/kernel/machine_kexec.c:9:
/home/yuasa/src/linux/kernel/git/linux-2.6/arch/mips/include/asm/bitops.h: At top level:
/home/yuasa/src/linux/kernel/git/linux-2.6/arch/mips/include/asm/bitops.h:615:19: error: static declaration of 'fls' follows non-static declaration
include/linux/log2.h:34:9: note: previous implicit declaration of 'fls' was here
In file included from /home/yuasa/src/linux/kernel/git/linux-2.6/arch/mips/include/asm/bitops.h:651:0,
from include/linux/bitops.h:22,
from include/linux/signal.h:38,
from include/linux/elfcore.h:5,
from include/linux/kexec.h:60,
from arch/mips/kernel/machine_kexec.c:9:
include/asm-generic/bitops/fls64.h:18:28: error: static declaration of 'fls64' follows non-static declaration
include/linux/log2.h:42:9: note: previous implicit declaration of 'fls64' was here
In file included from include/linux/signal.h:38:0,
from include/linux/elfcore.h:5,
from include/linux/kexec.h:60,
from arch/mips/kernel/machine_kexec.c:9:
include/linux/bitops.h:160:24: error: conflicting types for 'fls_long'
include/linux/log2.h:63:16: note: previous implicit declaration of 'fls_long' was here
cc1: all warnings being treated as errors
make[2]: *** [arch/mips/kernel/machine_kexec.o] Error 1
Signed-off-by: Yoichi Yuasa <yuasa@linux-mips.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: yuasa@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: Linuxppc-dev <linuxppc-dev@ozlabs.org>
Cc: Linux MIPS Mailing List <linux-mips@linux-mips.org>
Cc: Linux-sh list <linux-sh@vger.kernel.org>
Cc: Chris Zankel <chris@zankel.net>
Patchwork: https://patchwork.linux-mips.org/patch/4000/
Tested-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Since we have delayed irq enabling to ->smp_finish()
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Cc: David Daney <david.daney@cavium.com>
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Just to catch a potential issue.
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Cc: David Daney <david.daney@cavium.com>
Acked-by: David Daney <david.daney@cavium.com>
Patchwork: https://patchwork.linux-mips.org/patch/3852/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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To prevent a problem as commit 5fbd036b [sched: Cleanup cpu_active madness]
and commit 2baab4e9 [sched: Fix select_fallback_rq() vs cpu_active/cpu_online]
try to resolve, move set_cpu_online() to the brought up CPU and with irq
disabled.
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Cc: David Daney <david.daney@cavium.com>
Acked-by: David Daney <david.daney@cavium.com>
Patchwork: https://patchwork.linux-mips.org/patch/3851/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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We have move irq enable to ->smp_finish. Place ->smp_finish() a little
late to prepare for move set_cpu_online() into start_secondary.
And it's not necessary to call cpu_set(cpu, cpu_callin_map) and
synchronise_count_slave() with irq enabled.
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Cc: David Daney <david.daney@cavium.com>
Acked-by: David Daney <david.daney@cavium.com>
Patchwork: https://patchwork.linux-mips.org/patch/3850/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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To prepare for smoothing set_cpu_[active|online]() mess up
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Cc: David Daney <david.daney@cavium.com>
Acked-by: David Daney <david.daney@cavium.com>
Patchwork: https://patchwork.linux-mips.org/patch/3848/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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