Paul E. McKenney [Mon, 30 Aug 2010 16:52:50 +0000 (09:52 -0700)]
rcu: fix _oddness handling of verbose stall warnings
CONFIG_RCU_CPU_STALL_VERBOSE depends on CONFIG_TREE_PREEMPT_RCU, but
rcu_bootup_announce_oddness() complains if CONFIG_RCU_CPU_STALL_VERBOSE
is not set even in the case of CONFIG_TREE_RCU. This commit therefore
fixes rcu_bootup_announce_oddness() to avoid insisting on impossibilities.
Reported-by: Guy Martin <gmsoft@tuxicoman.be> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney [Mon, 23 Aug 2010 23:34:02 +0000 (16:34 -0700)]
rcu: upgrade stallwarn.txt documentation for CPU-bound RT processes
CPU-bound real-time processes can cause RCU CPU stall warnings, and
much other trouble as well. Document the fact that they can cause
RCU CPU stall warnings.
Suggested-by: Darren Hart <dvhltc@us.ibm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Arjan van de Ven [Sat, 21 Aug 2010 20:07:26 +0000 (13:07 -0700)]
workqueue: Add basic tracepoints to track workqueue execution
With the introduction of the new unified work queue thread pools,
we lost one feature: It's no longer possible to know which worker
is causing the CPU to wake out of idle. The result is that PowerTOP
now reports a lot of "kworker/a:b" instead of more readable results.
This patch adds a pair of tracepoints to the new workqueue code,
similar in style to the timer/hrtimer tracepoints.
With this pair of tracepoints, the next PowerTOP can correctly
report which work item caused the wakeup (and how long it took):
Interrupt (43) i915 time 3.51ms wakeups 141
Work ieee80211_iface_work time 0.81ms wakeups 29
Work do_dbs_timer time 0.55ms wakeups 24
Process Xorg time 21.36ms wakeups 4
Timer sched_rt_period_timer time 0.01ms wakeups 1
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Samuel Thibault [Sat, 21 Aug 2010 19:32:41 +0000 (21:32 +0200)]
Replace Configure with Enable in description of MAXSMP
The "Configure" word tends to make user believe they have to say 'yes'
to be able to choose the number of procs/nodes. "Enable" should be
unambiguous enough.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds [Fri, 20 Aug 2010 23:49:40 +0000 (16:49 -0700)]
mm: make stack guard page logic use vm_prev pointer
Like the mlock() change previously, this makes the stack guard check
code use vma->vm_prev to see what the mapping below the current stack
is, rather than have to look it up with find_vma().
Also, accept an abutting stack segment, since that happens naturally if
you split the stack with mlock or mprotect.
Tested-by: Ian Campbell <ijc@hellion.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linus Torvalds [Fri, 20 Aug 2010 23:24:55 +0000 (16:24 -0700)]
mm: make the vma list be doubly linked
It's a really simple list, and several of the users want to go backwards
in it to find the previous vma. So rather than have to look up the
previous entry with 'find_vma_prev()' or something similar, just make it
doubly linked instead.
Tested-by: Ian Campbell <ijc@hellion.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tilman Sauerbeck [Fri, 20 Aug 2010 21:01:47 +0000 (14:01 -0700)]
mtd: nand: Fix probe of Samsung NAND chips
Apparently, the check for a 6-byte ID string introduced by commit 426c457a3216fac74e3d44dd39729b0689f4c7ab ("mtd: nand: extend NAND flash
detection to new MLC chips") is NOT sufficient to determine whether or
not a Samsung chip uses their new MLC detection scheme or the old,
standard scheme. This adds a condition to check cell type.
Signed-off-by: Tilman Sauerbeck <tilman@code-monkey.de> Signed-off-by: Brian Norris <norris@broadcom.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Cc: stable@kernel.org
Stefan Richter [Thu, 19 Aug 2010 21:13:43 +0000 (14:13 -0700)]
Documentation: kernel-locking: mutex_trylock cannot be used in interrupt context
Chapter 6 is right about mutex_trylock, but chapter 10 wasn't. This error
was introduced during semaphore-to-mutex conversion of the Unreliable
guide. :-)
If user context which performs mutex_lock() or mutex_trylock() is
preempted by interrupt context which performs mutex_trylock() on the same
mutex instance, a deadlock occurs. This is because these functions do not
disable local IRQs when they operate on mutex->wait_lock.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Andrew Morton [Thu, 19 Aug 2010 21:13:42 +0000 (14:13 -0700)]
drivers/scsi/qla4xxx: fix build
gcc-4.0.2:
drivers/scsi/qla4xxx/ql4_os.c: In function 'qla4_8xxx_error_recovery':
drivers/scsi/qla4xxx/ql4_glbl.h:135: sorry, unimplemented: inlining failed in call to 'qla4_8xxx_set_drv_active': function body not available
drivers/scsi/qla4xxx/ql4_os.c:2377: sorry, unimplemented: called from here
drivers/scsi/qla4xxx/ql4_glbl.h:135: sorry, unimplemented: inlining failed in call to 'qla4_8xxx_set_drv_active': function body not available
drivers/scsi/qla4xxx/ql4_os.c:2393: sorry, unimplemented: called from here
Cc: Ravi Anand <ravi.anand@qlogic.com> Cc: Vikas Chaudhary <vikas.chaudhary@qlogic.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Miklos Szeredi [Thu, 19 Aug 2010 21:13:40 +0000 (14:13 -0700)]
uml: fix compile error in dma_get_cache_alignment()
Fix uml compile error:
include/linux/dma-mapping.h:145: error: redefinition of 'dma_get_cache_alignment'
arch/um/include/asm/dma-mapping.h:99: note: previous definition of 'dma_get_cache_alignment' was here
Introduced by commit 4565f0170dfc ("dma-mapping: unify
dma_get_cache_alignment implementations")
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: Jeff Dike <jdike@addtoit.com> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
KOSAKI Motohiro [Thu, 19 Aug 2010 21:13:39 +0000 (14:13 -0700)]
oom: __task_cred() need rcu_read_lock()
dump_tasks() needs to hold the RCU read lock around its access of the
target task's UID. To this end it should use task_uid() as it only needs
that one thing from the creds.
The fact that dump_tasks() holds tasklist_lock is insufficient to prevent the
target process replacing its credentials on another CPU.
Then, this patch change to call rcu_read_lock() explicitly.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
KOSAKI Motohiro [Thu, 19 Aug 2010 21:13:39 +0000 (14:13 -0700)]
oom: fix tasklist_lock leak
Commit 0aad4b3124 ("oom: fold __out_of_memory into out_of_memory")
introduced a tasklist_lock leak. Then it caused following obvious
danger warnings and panic.
================================================
[ BUG: lock held when returning to user space! ]
------------------------------------------------
rsyslogd/1422 is leaving the kernel with locks still held!
1 lock held by rsyslogd/1422:
#0: (tasklist_lock){.+.+.+}, at: [<ffffffff810faf64>] out_of_memory+0x164/0x3f0
BUG: scheduling while atomic: rsyslogd/1422/0x00000002
INFO: lockdep is turned off.
This patch fixes it.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Kyungmin Park [Thu, 19 Aug 2010 21:13:37 +0000 (14:13 -0700)]
drivers/mmc/host/sdhci-s3c.c: use the correct mutex and card detect function
There's some merge problem between sdhic core and sdhci-s3c host. After
mutex is changed to spinlock. It needs to use use spin lock functions and
use the correct card detection function.
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Cc: <linux-mmc@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jan Kara [Thu, 19 Aug 2010 21:13:33 +0000 (14:13 -0700)]
lib/radix-tree.c: fix overflow in radix_tree_range_tag_if_tagged()
When radix_tree_maxindex() is ~0UL, it can happen that scanning overflows
index and tree traversal code goes astray reading memory until it hits
unreadable memory. Check for overflow and exit in that case.
Signed-off-by: Jan Kara <jack@suse.cz> Cc: Christoph Hellwig <hch@lst.de> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
: A second review after I've received a data sheet for this device from
: Fintek has turned up a few bugs.
:
: Unfortunately Giel (nor I) have time to fix this in time for the 2.6.36
: cycle. Therefor I would like to see this patch reverted as not having any
: support for the hwmon function of this superio chip is better then having
: unreliable support.
Cc: Giel van Schijndel <me@mortis.eu> Cc: Jean Delvare <khali@linux-fr.org> Cc: Hans de Goede <hdegoede@redhat.com> Cc: Jonathan Cameron <jic23@cam.ac.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Ondrej Zary [Thu, 19 Aug 2010 21:13:25 +0000 (14:13 -0700)]
matroxfb: fix incorrect use of memcpy_toio()
Screen is completely corrupted since 2.6.34. Bisection revealed that it's
caused by commit 6175ddf06b61720 ("x86: Clean up mem*io functions.").
H. Peter Anvin explained that memcpy_toio() does not copy data in 32bit
chunks anymore on x86.
Signed-off-by: Ondrej Zary <linux@rainbow-software.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Petr Vandrovec <vandrove@vc.cvut.cz> Cc: Jean Delvare <khali@linux-fr.org> Cc: <stable@kernel.org> [2.6.34.x, 2.6.35.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Paul E. McKenney [Fri, 20 Aug 2010 04:43:09 +0000 (21:43 -0700)]
rcu: add comment stating that list_empty() applies to RCU-protected lists
Because list_empty() does not dereference any RCU-protected pointers, and
further does not pass such pointers to the caller (so that the caller
does not dereference them either), it is safe to use list_empty() on
RCU-protected lists. There is no need for a list_empty_rcu(). This
commit adds a comment stating this explicitly.
Requested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney [Thu, 19 Aug 2010 23:57:45 +0000 (16:57 -0700)]
rcu: apply TINY_PREEMPT_RCU read-side speedup to TREE_PREEMPT_RCU
Replace one of the ACCESS_ONCE() calls in each of __rcu_read_lock()
and __rcu_read_unlock() with barrier() as suggested by Steve Rostedt in
order to avoid the potential compiler-optimization-induced bug noted by
Mathieu Desnoyers.
Located-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney [Tue, 17 Aug 2010 21:18:46 +0000 (14:18 -0700)]
rcu: combine duplicate code, courtesy of CONFIG_PREEMPT_RCU
The CONFIG_PREEMPT_RCU kernel configuration parameter was recently
re-introduced, but as an indication of the type of RCU (preemptible
vs. non-preemptible) instead of as selecting a given implementation.
This commit uses CONFIG_PREEMPT_RCU to combine duplicate code
from include/linux/rcutiny.h and include/linux/rcutree.h into
include/linux/rcupdate.h. This commit also combines a few other pieces
of duplicate code that have accumulated.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney [Mon, 16 Aug 2010 17:50:54 +0000 (10:50 -0700)]
rcu: Upgrade srcu_read_lock() docbook about SRCU grace periods
It is illegal to wait for an SRCU grace period while within the
corresponding flavor of SRCU read-side critical section. Therefore,
this commit updates the srcu_read_lock() docbook accordingly.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney [Tue, 10 Aug 2010 21:28:53 +0000 (14:28 -0700)]
rcu: permit suppressing current grace period's CPU stall warnings
When using a kernel debugger, a long sojourn in the debugger can get
you lots of RCU CPU stall warnings once you resume. This might not be
helpful, especially if you are using the system console. This patch
therefore allows RCU CPU stall warnings to be suppressed, but only for
the duration of the current set of grace periods.
This differs from Jason's original patch in that it adds support for
tiny RCU and preemptible RCU, and uses a slightly different method for
suppressing the RCU CPU stall warning messages.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Jason Wessel <jason.wessel@windriver.com>
rcu: refer RCU CPU stall-warning victims to stallwarn.txt
There is some documentation on RCU CPU stall warnings contained in
Documentation/RCU/stallwarn.txt, but it will not be apparent to someone
who runs into such a warning while under time pressure. This commit
therefore adds comments preceding the printk()s pointing out the
location of this documentation.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The comment says that blocking is illegal in rcu_read_lock()-style
RCU read-side critical sections, which is no longer entirely true
given preemptible RCU. This commit provides a fix.
Suggested-by: David Miller <davem@davemloft.net> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney [Tue, 29 Jun 2010 23:49:16 +0000 (16:49 -0700)]
rcu: Add a TINY_PREEMPT_RCU
Implement a small-memory-footprint uniprocessor-only implementation of
preemptible RCU. This implementation uses but a single blocked-tasks
list rather than the combinatorial number used per leaf rcu_node by
TREE_PREEMPT_RCU, which reduces memory consumption and greatly simplifies
processing. This version also takes advantage of uniprocessor execution
to accelerate grace periods in the case where there are no readers.
The general design is otherwise broadly similar to that of TREE_PREEMPT_RCU.
This implementation is a step towards having RCU implementation driven
off of the SMP and PREEMPT kernel configuration variables, which can
happen once this implementation has accumulated sufficient experience.
Removed ACCESS_ONCE() from __rcu_read_unlock() and added barrier() as
suggested by Steve Rostedt in order to avoid the compiler-reordering
issue noted by Mathieu Desnoyers (http://lkml.org/lkml/2010/8/16/183).
As can be seen below, CONFIG_TINY_PREEMPT_RCU represents almost 5Kbyte
savings compared to CONFIG_TREE_PREEMPT_RCU. Of course, for non-real-time
workloads, CONFIG_TINY_RCU is even better.
CONFIG_TREE_PREEMPT_RCU
text data bss dec filename
13 0 0 13 kernel/rcupdate.o
6170 825 28 7023 kernel/rcutree.o
----
7026 Total
CONFIG_TINY_PREEMPT_RCU
text data bss dec filename
13 0 0 13 kernel/rcupdate.o
2081 81 8 2170 kernel/rcutiny.o
----
2183 Total
CONFIG_TINY_RCU (non-preemptible)
text data bss dec filename
13 0 0 13 kernel/rcupdate.o
719 25 0 744 kernel/rcutiny.o
---
757 Total
Requested-by: Loïc Minier <loic.minier@canonical.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Commit cf244dc01bf68 added a fourth level to the TREE_RCU hierarchy,
but the RCU_FANOUT help message still said "cube root". This commit
fixes this to "fourth root" and also emphasizes that production
systems are well-served by the default. (Stress-testing RCU itself
uses small RCU_FANOUT values in order to test large-system code paths
on small(er) systems.)
Located-by: John Kacur <jkacur@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney [Wed, 21 Jul 2010 15:05:56 +0000 (08:05 -0700)]
rcu: Allow RCU CPU stall warnings to be off at boot, but manually enablable
Currently, if RCU CPU stall warnings are enabled, they are enabled
immediately upon boot. They can be manually disabled via /sys (and
also re-enabled via /sys), and are automatically disabled upon panic.
However, some users need RCU CPU stalls to be disabled at boot time,
but to be enabled without rebuilding/rebooting. For example, someone
running a real-time application in production might not want the
additional latency of RCU CPU stall detection in normal operation, but
might need to enable it at any point for fault isolation purposes.
This commit therefore provides a new CONFIG_RCU_CPU_STALL_DETECTOR_RUNNABLE
kernel configuration parameter that maintains the current behavior
(enable at boot) by default, but allows a kernel to be configured
with RCU CPU stall detection built into the kernel, but disabled at
boot time.
Requested-by: Clark Williams <williams@redhat.com> Requested-by: John Kacur <jkacur@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Paul E. McKenney [Wed, 21 Jul 2010 13:52:40 +0000 (06:52 -0700)]
rcu: restrict TREE_RCU to SMP builds with !PREEMPT
Because both TINY_RCU and TREE_PREEMPT_RCU have been in mainline for
several releases, it is time to restrict the use of TREE_RCU to SMP
non-preemptible systems. This reduces testing/validation effort. This
commit is a first step towards driving the selection of RCU implementation
directly off of the SMP and PREEMPT configuration parameters.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
rcu: improve kerneldoc for rcu_read_lock(), call_rcu(), and synchronize_rcu()
Make it explicit that new RCU read-side critical sections that start
after call_rcu() and synchronize_rcu() start might still be running
after the end of the relevant grace period.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Paul E. McKenney [Wed, 30 Jun 2010 18:43:52 +0000 (11:43 -0700)]
rcu: add boot parameter to suppress RCU CPU stall warning messages
Although the RCU CPU stall warning messages are a very good way to alert
people to a problem, once alerted, it is sometimes helpful to shut them
off in order to avoid obscuring other messages that might be being used
to track down the problem. Although you can rebuild the kernel with
CONFIG_RCU_CPU_STALL_DETECTOR=n, this is sometimes inconvenient. This
commit therefore adds a boot parameter named "rcu_cpu_stall_suppress"
that shuts these messages off without requiring a rebuild (though a
reboot might be needed for those not brave enough to patch their kernel
while it is running).
This message-suppression was already in place for the panic case, so this
commit need only rename the variable and export it via module_param().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Also set the default to 60 seconds, up from the previous hard-coded timeout
of 10 seconds. This allows people who care to set short timeouts, while
avoiding people with unusual configurations (make randconfig!!!) from being
bothered with spurious CPU stall warnings.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Tetsuo Handa [Fri, 25 Jun 2010 16:08:19 +0000 (01:08 +0900)]
Add RCU check for find_task_by_vpid().
find_task_by_vpid() says "Must be called under rcu_read_lock().". But due to
commit 3120438 "rcu: Disable lockdep checking in RCU list-traversal primitives",
we are currently unable to catch "find_task_by_vpid() with tasklist_lock held
but RCU lock not held" errors due to the RCU-lockdep checks being
suppressed in the RCU variants of the struct list_head traversals.
This commit therefore places an explicit check for being in an RCU
read-side critical section in find_task_by_pid_ns().
Lai Jiangshan [Mon, 28 Jun 2010 08:25:04 +0000 (16:25 +0800)]
rcu: simplify the usage of percpu data
&percpu_data is compatible with allocated percpu data.
And we use it and remove the "->rda[NR_CPUS]" array, saving significant
storage on systems with large numbers of CPUs. This does add an additional
level of indirection and thus an additional cache line referenced, but
because ->rda is not used on the read side, this is OK.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Reviewed-by: Tejun Heo <tj@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Lai Jiangshan [Mon, 21 Jun 2010 08:57:42 +0000 (16:57 +0800)]
rcutorture: add random preemption
Add random preemption to help we to torture the preemptable rcu.
srcu_read_delay() also calls rcu_read_delay() for shorter delays.
Added comment to preempt_schedule() call indicating that no quiescent
states happen if preemption is disabled.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Paul E. McKenney [Wed, 16 Jun 2010 23:48:13 +0000 (16:48 -0700)]
rcu: add shiny new debug assists to Documentation/RCU/checklist.txt
Add a section describing PROVE_RCU, DEBUG_OBJECTS_RCU_HEAD, and
the __rcu sparse checking to the RCU checklist.
Suggested-by: David Miller <davem@davemloft.net> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Arnd Bergmann [Thu, 25 Feb 2010 15:55:13 +0000 (16:55 +0100)]
rculist: avoid __rcu annotations
This avoids warnings from missing __rcu annotations
in the rculist implementation, making it possible to
use the same lists in both RCU and non-RCU cases.
We can add rculist annotations later, together with
lockdep support for rculist, which is missing as well,
but that may involve changing all the users.
Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Paul E. McKenney [Wed, 28 Apr 2010 21:39:09 +0000 (14:39 -0700)]
rcu: define __rcu address space modifier for sparse
This commit provides definitions for the __rcu annotation defined earlier.
This annotation permits sparse to check for correct use of RCU-protected
pointers. If a pointer that is annotated with __rcu is accessed
directly (as opposed to via rcu_dereference(), rcu_assign_pointer(),
or one of their variants), sparse can be made to complain. To enable
such complaints, use the new default-disabled CONFIG_SPARSE_RCU_POINTER
kernel configuration option. Please note that these sparse complaints are
intended to be a debugging aid, -not- a code-style-enforcement mechanism.
There are special rcu_dereference_protected() and rcu_access_pointer()
accessors for use when RCU read-side protection is not required, for
example, when no other CPU has access to the data structure in question
or while the current CPU hold the update-side lock.
This patch also updates a number of docbook comments that were showing
their age.
Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Christopher Li <sparse@chrisli.org> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Paul E. McKenney [Tue, 15 Jun 2010 00:06:21 +0000 (17:06 -0700)]
net: convert to rcu_dereference_index_check()
The task_cls_classid() function applies rcu_dereference() to integers,
which does not work with the shiny new sparse-based checking in
rcu_dereference(). This commit therefore moves to the new RCU API
rcu_dereference_index_check().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Borislav Petkov [Thu, 19 Aug 2010 18:10:29 +0000 (20:10 +0200)]
x86, hotplug: Serialize CPU hotplug to avoid bringup concurrency issues
When testing cpu hotplug code on 32-bit we kept hitting the "CPU%d:
Stuck ??" message due to multiple cores concurrently accessing the
cpu_callin_mask, among others.
Since these codepaths are not protected from concurrent access due to
the fact that there's no sane reason for making an already complex
code unnecessarily more complex - we hit the issue only when insanely
switching cores off- and online - serialize hotplugging cores on the
sysfs level and be done with it.
[ v2.1: fix !HOTPLUG_CPU build ]
Cc: <stable@kernel.org> Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20100819181029.GC17171@aftab> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Brian Norris [Wed, 18 Aug 2010 18:25:04 +0000 (11:25 -0700)]
mtd: nand: Fix regression in BBM detection
Commit c7b28e25cb9beb943aead770ff14551b55fa8c79 ("mtd: nand: refactor BB
marker detection") caused a regression in detection of factory-set bad
block markers, especially for certain small-page NAND. This fix removes
some unneeded constraints on using NAND_SMALL_BADBLOCK_POS, making the
detection code more correct.
This regression can be seen, for example, in Hynix HY27US081G1M and
similar.
Signed-off-by: Brian Norris <norris@broadcom.com> Tested-by: Michael Guntsche <mike@it-loops.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Linus Torvalds [Wed, 18 Aug 2010 22:45:23 +0000 (15:45 -0700)]
Merge branch 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6
* 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6:
NFS: Fix an Oops in the NFSv4 atomic open code
NFS: Fix the selection of security flavours in Kconfig
NFS: fix the return value of nfs_file_fsync()
rpcrdma: Fix SQ size calculation when memreg is FRMR
xprtrdma: Do not truncate iova_start values in frmr registrations.
nfs: Remove redundant NULL check upon kfree()
nfs: Add "lookupcache" to displayed mount options
NFS: allow close-to-open cache semantics to apply to root of NFS filesystem
SUNRPC: fix NFS client over TCP hangs due to packet loss (Bug 16494)
Linus Torvalds [Wed, 18 Aug 2010 22:29:38 +0000 (15:29 -0700)]
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid:
USB HID: Add ID for eGalax Multitouch used in JooJoo tablet
HID: hiddev: fix memory corruption due to invalid intfdata
HID: hiddev: protect against disconnect/NULL-dereference race
HID: picolcd: correct ordering of framebuffer freeing
HID: picolcd: testing the wrong variable
Missed the declaration of sys_execve in the ia64 asm/unistd.h (perhaps
because there is no reason for it to be there ... it might be a left over
from the COMPAT code?). Just delete the conflicting version.
Linus Torvalds [Wed, 18 Aug 2010 16:35:08 +0000 (09:35 -0700)]
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
fs: brlock vfsmount_lock
fs: scale files_lock
lglock: introduce special lglock and brlock spin locks
tty: fix fu_list abuse
fs: cleanup files_lock locking
fs: remove extra lookup in __lookup_hash
fs: fs_struct rwlock to spinlock
apparmor: use task path helpers
fs: dentry allocation consolidation
fs: fix do_lookup false negative
mbcache: Limit the maximum number of cache entries
hostfs ->follow_link() braino
hostfs: dumb (and usually harmless) tpyo - strncpy instead of strlcpy
remove SWRITE* I/O types
kill BH_Ordered flag
vfs: update ctime when changing the file's permission by setfacl
cramfs: only unlock new inodes
fix reiserfs_evict_inode end_writeback second call
Kusanagi Kouichi [Wed, 18 Aug 2010 16:32:37 +0000 (13:32 -0300)]
perf tools: Fix build error on read only source.
Parts of the build process were generating files outside the specified
O= directory, causing the build to fail on systems where the sources are
in a read only file system.
Fix it by using $(OUTPUT) on these locations.
Also check that $(OUTPUT) actually exists, just like the top level
kernel Makefile does. Otherwise the failure message emitted is
completely misleading.
Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20100817140841.0859362C03A@msa106.auone-net.jp> Signed-off-by: Kusanagi Kouichi <slash@ac.auone-net.jp> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linus Torvalds [Wed, 18 Aug 2010 16:32:13 +0000 (09:32 -0700)]
Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf tools: Fix build on POSIX shells
latencytop: Fix kconfig dependency warnings
perf annotate tui: Fix exit and RIGHT keys handling
tracing: Sanitize value returned from write(trace_marker, "...", len)
tracing/events: Convert format output to seq_file
tracing: Extend recordmcount to better support Blackfin mcount
tracing: Fix ring_buffer_read_page reading out of page boundary
tracing: Fix an unallocated memory access in function_graph
Linus Torvalds [Wed, 18 Aug 2010 16:27:10 +0000 (09:27 -0700)]
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu:
m68knommu: include sched.h in ColdFire/SPI driver
m68knommu: formatting of pointers in printk()
m68knommu: arch/m68k/include/asm/ide.h fix for nommu
Linus Torvalds [Wed, 18 Aug 2010 16:26:42 +0000 (09:26 -0700)]
Merge branch 'for-linus' of git://neil.brown.name/md
* 'for-linus' of git://neil.brown.name/md:
md raid-1/10 Fix bio_rw bit manipulations again
md: provide appropriate return value for spare_active functions.
md: Notify sysfs when RAID1/5/10 disk is In_sync.
Update recovery_offset even when external metadata is used.
Linus Torvalds [Wed, 18 Aug 2010 16:26:17 +0000 (09:26 -0700)]
Merge branch 'merge-devicetree' of git://git.secretlab.ca/git/linux-2.6
* 'merge-devicetree' of git://git.secretlab.ca/git/linux-2.6:
spi.h: missing kernel-doc notation, please fix
of: fix missing headers for of_address_to_resource() in MTD and SysACE drivers
of: Fix missing includes
ata: update for of_device to platform_device replacement
microblaze: Fix of: eliminate of_device->node and dev_archdata->{of,prom}_node
microblaze: Fix of/address: Merge all of the bus translation code
booting-without-of: Remove nonexistent chapters from TOC, fix numbering
Joerg Roedel [Mon, 16 Aug 2010 12:38:33 +0000 (14:38 +0200)]
x86-32: Separate 1:1 pagetables from swapper_pg_dir
This patch fixes machine crashes which occur when heavily exercising the
CPU hotplug codepaths on a 32-bit kernel. These crashes are caused by
AMD Erratum 383 and result in a fatal machine check exception. Here's
the scenario:
1. On 32-bit, the swapper_pg_dir page table is used as the initial page
table for booting a secondary CPU.
2. To make this work, swapper_pg_dir needs a direct mapping of physical
memory in it (the low mappings). By adding those low, large page (2M)
mappings (PAE kernel), we create the necessary conditions for Erratum
383 to occur.
3. Other CPUs which do not participate in the off- and onlining game may
use swapper_pg_dir while the low mappings are present (when leave_mm is
called). For all steps below, the CPU referred to is a CPU that is using
swapper_pg_dir, and not the CPU which is being onlined.
4. The presence of the low mappings in swapper_pg_dir can result
in TLB entries for addresses below __PAGE_OFFSET to be established
speculatively. These TLB entries are marked global and large.
5. When the CPU with such TLB entry switches to another page table, this
TLB entry remains because it is global.
6. The process then generates an access to an address covered by the
above TLB entry but there is a permission mismatch - the TLB entry
covers a large global page not accessible to userspace.
7. Due to this permission mismatch a new 4kb, user TLB entry gets
established. Further, Erratum 383 provides for a small window of time
where both TLB entries are present. This results in an uncorrectable
machine check exception signalling a TLB multimatch which panics the
machine.
There are two ways to fix this issue:
1. Always do a global TLB flush when a new cr3 is loaded and the
old page table was swapper_pg_dir. I consider this a hack hard
to understand and with performance implications
2. Do not use swapper_pg_dir to boot secondary CPUs like 64-bit
does.
This patch implements solution 2. It introduces a trampoline_pg_dir
which has the same layout as swapper_pg_dir with low_mappings. This page
table is used as the initial page table of the booting CPU. Later in the
bringup process, it switches to swapper_pg_dir and does a global TLB
flush. This fixes the crashes in our test cases.
-v2: switch to swapper_pg_dir right after entering start_secondary() so
that we are able to access percpu data which might not be mapped in the
trampoline page table.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
LKML-Reference: <20100816123833.GB28147@aftab> Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Hans Rosenfeld [Wed, 18 Aug 2010 14:19:50 +0000 (16:19 +0200)]
x86, cpu: Fix regression in AMD errata checking code
A bug in the family-model-stepping matching code caused the presence of
errata to go undetected when OSVW was not used. This causes hangs on
some K8 systems because the E400 workaround is not enabled.
Signed-off-by: Hans Rosenfeld <hans.rosenfeld@amd.com>
LKML-Reference: <1282141190-930137-1-git-send-email-hans.rosenfeld@amd.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Jaroslav Kysela [Wed, 18 Aug 2010 12:08:17 +0000 (14:08 +0200)]
ALSA: emu10k1 - delay the PCM interrupts (add pcm_irq_delay parameter)
With some hardware combinations, the PCM interrupts are acknowledged
before the period boundary from the emu10k1 chip. The midlevel PCM code
gets confused and the playback stream is interrupted.
It seems that the interrupt processing shift by 2 samples is enough
to fix this issue. This default value does not harm other,
non-affected hardware.
More information: Kernel bugzilla bug#16300
[A copmile warning fixed by tiwai]
Signed-off-by: Jaroslav Kysela <perex@perex.cz> Cc: <stable@kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Nick Piggin [Tue, 17 Aug 2010 18:37:39 +0000 (04:37 +1000)]
fs: brlock vfsmount_lock
fs: brlock vfsmount_lock
Use a brlock for the vfsmount lock. It must be taken for write whenever
modifying the mount hash or associated fields, and may be taken for read when
performing mount hash lookups.
A new lock is added for the mnt-id allocator, so it doesn't need to take
the heavy vfsmount write-lock.
The number of atomics should remain the same for fastpath rlock cases, though
code would be slightly slower due to per-cpu access. Scalability is not not be
much improved in common cases yet, due to other locks (ie. dcache_lock) getting
in the way. However path lookups crossing mountpoints should be one case where
scalability is improved (currently requiring the global lock).
The slowpath is slower due to use of brlock. On a 64 core, 64 socket, 32 node
Altix system (high latency to remote nodes), a simple umount microbenchmark
(mount --bind mnt mnt2 ; umount mnt2 loop 1000 times), before this patch it
took 6.8s, afterwards took 7.1s, about 5% slower.
Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Nick Piggin [Tue, 17 Aug 2010 18:37:38 +0000 (04:37 +1000)]
fs: scale files_lock
fs: scale files_lock
Improve scalability of files_lock by adding per-cpu, per-sb files lists,
protected with an lglock. The lglock provides fast access to the per-cpu lists
to add and remove files. It also provides a snapshot of all the per-cpu lists
(although this is very slow).
One difficulty with this approach is that a file can be removed from the list
by another CPU. We must track which per-cpu list the file is on with a new
variale in the file struct (packed into a hole on 64-bit archs). Scalability
could suffer if files are frequently removed from different cpu's list.
However loads with frequent removal of files imply short interval between
adding and removing the files, and the scheduler attempts to avoid moving
processes too far away. Also, even in the case of cross-CPU removal, the
hardware has much more opportunity to parallelise cacheline transfers with N
cachelines than with 1.
A worst-case test of 1 CPU allocating files subsequently being freed by N CPUs
degenerates to contending on a single lock, which is no worse than before. When
more than one CPU are allocating files, even if they are always freed by
different CPUs, there will be more parallelism than the single-lock case.
Testing results:
On a 2 socket, 8 core opteron, I measure the number of times the lock is taken
to remove the file, the number of times it is removed by the same CPU that
added it, and the number of times it is removed by the same node that added it.
So a file is removed from the same CPU it was added by over 90% of the time.
It remains within the same node 95% of the time.
Tim Chen ran some numbers for a 64 thread Nehalem system performing a compile.
throughput
2.6.34-rc2 24.5
+patch 24.9
us sys idle IO wait (in %)
2.6.34-rc2 51.25 28.25 17.25 3.25
+patch 53.75 18.5 19 8.75
So significantly less CPU time spent in kernel code, higher idle time and
slightly higher throughput.
Single threaded performance difference was within the noise of microbenchmarks.
That is not to say penalty does not exist, the code is larger and more memory
accesses required so it will be slightly slower.
Cc: linux-kernel@vger.kernel.org Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
projects / karo-tx-linux.git / log