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2013-04-29Merge branch 'core-locking-for-linus' of ↵Linus Torvalds5-72/+165
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking changes from Ingo Molnar: "The most noticeable change are mutex speedups from Waiman Long, for higher loads. These scalability changes should be most noticeable on larger server systems. There are also cleanups, fixes and debuggability improvements." * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: lockdep: Consolidate bug messages into a single print_lockdep_off() function lockdep: Print out additional debugging advice when we hit lockdep BUGs mutex: Back out architecture specific check for negative mutex count mutex: Queue mutex spinners with MCS lock to reduce cacheline contention mutex: Make more scalable by doing less atomic operations mutex: Move mutex spinning code from sched/core.c back to mutex.c locking/rtmutex/tester: Set correct permissions on sysfs files lockdep: Remove unnecessary 'hlock_next' variable
2013-04-27Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds1-0/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fix from Ingo Molnar: "This fix adds missing RCU read protection" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: events: Protect access via task_subsys_state_check()
2013-04-26lockdep: Consolidate bug messages into a single print_lockdep_off() functionDave Jones1-15/+13
Also add some missing printk levels. Signed-off-by: Dave Jones <davej@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20130425174002.GA26769@redhat.com [ Tweaked the messages a bit. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-26lockdep: Print out additional debugging advice when we hit lockdep BUGsDave Jones1-0/+5
We occasionally get reports of these BUGs being hit, and the stack trace doesn't necessarily always tell us what we need to know about why we are hitting those limits. If users start attaching /proc/lock_stats to reports we may have more of a clue what's going on. Signed-off-by: Dave Jones <davej@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20130423163403.GA12839@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-22kernel/hz.bc: ignore.Rusty Russell1-0/+1
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-21Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Ingo Molnar: "Misc fixes" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf/x86: Fix offcore_rsp valid mask for SNB/IVB perf: Treat attr.config as u64 in perf_swevent_init()
2013-04-21events: Protect access via task_subsys_state_check()Paul E. McKenney1-0/+2
The following RCU splat indicates lack of RCU protection: [ 953.267649] =============================== [ 953.267652] [ INFO: suspicious RCU usage. ] [ 953.267657] 3.9.0-0.rc6.git2.4.fc19.ppc64p7 #1 Not tainted [ 953.267661] ------------------------------- [ 953.267664] include/linux/cgroup.h:534 suspicious rcu_dereference_check() usage! [ 953.267669] [ 953.267669] other info that might help us debug this: [ 953.267669] [ 953.267675] [ 953.267675] rcu_scheduler_active = 1, debug_locks = 0 [ 953.267680] 1 lock held by glxgears/1289: [ 953.267683] #0: (&sig->cred_guard_mutex){+.+.+.}, at: [<c00000000027f884>] .prepare_bprm_creds+0x34/0xa0 [ 953.267700] [ 953.267700] stack backtrace: [ 953.267704] Call Trace: [ 953.267709] [c0000001f0d1b6e0] [c000000000016e30] .show_stack+0x130/0x200 (unreliable) [ 953.267717] [c0000001f0d1b7b0] [c0000000001267f8] .lockdep_rcu_suspicious+0x138/0x180 [ 953.267724] [c0000001f0d1b840] [c0000000001d43a4] .perf_event_comm+0x4c4/0x690 [ 953.267731] [c0000001f0d1b950] [c00000000027f6e4] .set_task_comm+0x84/0x1f0 [ 953.267737] [c0000001f0d1b9f0] [c000000000280414] .setup_new_exec+0x94/0x220 [ 953.267744] [c0000001f0d1ba70] [c0000000002f665c] .load_elf_binary+0x58c/0x19b0 ... This commit therefore adds the required RCU read-side critical section to perf_event_comm(). Reported-by: Adam Jackson <ajax@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: a.p.zijlstra@chello.nl Cc: paulus@samba.org Cc: acme@ghostprotocols.net Link: http://lkml.kernel.org/r/20130419190124.GA8638@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Gustavo Luiz Duarte <gusld@br.ibm.com>
2013-04-20Merge branch 'x86-kdump-for-linus' of ↵Linus Torvalds1-13/+105
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull kdump fixes from Peter Anvin: "The kexec/kdump people have found several problems with the support for loading over 4 GiB that was introduced in this merge cycle. This is partly due to a number of design problems inherent in the way the various pieces of kdump fit together (it is pretty horrifically manual in many places.) After a *lot* of iterations this is the patchset that was agreed upon, but of course it is now very late in the cycle. However, because it changes both the syntax and semantics of the crashkernel option, it would be desirable to avoid a stable release with the broken interfaces." I'm not happy with the timing, since originally the plan was to release the final 3.9 tomorrow. But apparently I'm doing an -rc8 instead... * 'x86-kdump-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: kexec: use Crash kernel for Crash kernel low x86, kdump: Change crashkernel_high/low= to crashkernel=,high/low x86, kdump: Retore crashkernel= to allocate under 896M x86, kdump: Set crashkernel_low automatically
2013-04-19mutex: Back out architecture specific check for negative mutex countWaiman Long1-7/+2
Linus suggested that probably all the supported architectures can allow a negative mutex count without incorrect behavior, so we can then back out the architecture specific change and allow the mutex count to go to any negative number. That should further reduce contention for non-x86 architecture. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Waiman Long <Waiman.Long@hp.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Chandramouleeswaran Aswin <aswin@hp.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Norton Scott J <scott.norton@hp.com> Cc: Rik van Riel <riel@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: David Howells <dhowells@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1366226594-5506-5-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-19mutex: Queue mutex spinners with MCS lock to reduce cacheline contentionWaiman Long1-1/+90
The current mutex spinning code (with MUTEX_SPIN_ON_OWNER option turned on) allow multiple tasks to spin on a single mutex concurrently. A potential problem with the current approach is that when the mutex becomes available, all the spinning tasks will try to acquire the mutex more or less simultaneously. As a result, there will be a lot of cacheline bouncing especially on systems with a large number of CPUs. This patch tries to reduce this kind of contention by putting the mutex spinners into a queue so that only the first one in the queue will try to acquire the mutex. This will reduce contention and allow all the tasks to move forward faster. The queuing of mutex spinners is done using an MCS lock based implementation which will further reduce contention on the mutex cacheline than a similar ticket spinlock based implementation. This patch will add a new field into the mutex data structure for holding the MCS lock. This expands the mutex size by 8 bytes for 64-bit system and 4 bytes for 32-bit system. This overhead will be avoid if the MUTEX_SPIN_ON_OWNER option is turned off. The following table shows the jobs per minute (JPM) scalability data on an 8-node 80-core Westmere box with a 3.7.10 kernel. The numactl command is used to restrict the running of the fserver workloads to 1/2/4/8 nodes with hyperthreading off. +-----------------+-----------+-----------+-------------+----------+ | Configuration | Mean JPM | Mean JPM | Mean JPM | % Change | | | w/o patch | patch 1 | patches 1&2 | 1->1&2 | +-----------------+------------------------------------------------+ | | User Range 1100 - 2000 | +-----------------+------------------------------------------------+ | 8 nodes, HT off | 227972 | 227237 | 305043 | +34.2% | | 4 nodes, HT off | 393503 | 381558 | 394650 | +3.4% | | 2 nodes, HT off | 334957 | 325240 | 338853 | +4.2% | | 1 node , HT off | 198141 | 197972 | 198075 | +0.1% | +-----------------+------------------------------------------------+ | | User Range 200 - 1000 | +-----------------+------------------------------------------------+ | 8 nodes, HT off | 282325 | 312870 | 332185 | +6.2% | | 4 nodes, HT off | 390698 | 378279 | 393419 | +4.0% | | 2 nodes, HT off | 336986 | 326543 | 340260 | +4.2% | | 1 node , HT off | 197588 | 197622 | 197582 | 0.0% | +-----------------+-----------+-----------+-------------+----------+ At low user range 10-100, the JPM differences were within +/-1%. So they are not that interesting. The fserver workload uses mutex spinning extensively. With just the mutex change in the first patch, there is no noticeable change in performance. Rather, there is a slight drop in performance. This mutex spinning patch more than recovers the lost performance and show a significant increase of +30% at high user load with the full 8 nodes. Similar improvements were also seen in a 3.8 kernel. The table below shows the %time spent by different kernel functions as reported by perf when running the fserver workload at 1500 users with all 8 nodes. +-----------------------+-----------+---------+-------------+ | Function | % time | % time | % time | | | w/o patch | patch 1 | patches 1&2 | +-----------------------+-----------+---------+-------------+ | __read_lock_failed | 34.96% | 34.91% | 29.14% | | __write_lock_failed | 10.14% | 10.68% | 7.51% | | mutex_spin_on_owner | 3.62% | 3.42% | 2.33% | | mspin_lock | N/A | N/A | 9.90% | | __mutex_lock_slowpath | 1.46% | 0.81% | 0.14% | | _raw_spin_lock | 2.25% | 2.50% | 1.10% | +-----------------------+-----------+---------+-------------+ The fserver workload for an 8-node system is dominated by the contention in the read/write lock. Mutex contention also plays a role. With the first patch only, mutex contention is down (as shown by the __mutex_lock_slowpath figure) which help a little bit. We saw only a few percents improvement with that. By applying patch 2 as well, the single mutex_spin_on_owner figure is now split out into an additional mspin_lock figure. The time increases from 3.42% to 11.23%. It shows a great reduction in contention among the spinners leading to a 30% improvement. The time ratio 9.9/2.33=4.3 indicates that there are on average 4+ spinners waiting in the spin_lock loop for each spinner in the mutex_spin_on_owner loop. Contention in other locking functions also go down by quite a lot. The table below shows the performance change of both patches 1 & 2 over patch 1 alone in other AIM7 workloads (at 8 nodes, hyperthreading off). +--------------+---------------+----------------+-----------------+ | Workload | mean % change | mean % change | mean % change | | | 10-100 users | 200-1000 users | 1100-2000 users | +--------------+---------------+----------------+-----------------+ | alltests | 0.0% | -0.8% | +0.6% | | five_sec | -0.3% | +0.8% | +0.8% | | high_systime | +0.4% | +2.4% | +2.1% | | new_fserver | +0.1% | +14.1% | +34.2% | | shared | -0.5% | -0.3% | -0.4% | | short | -1.7% | -9.8% | -8.3% | +--------------+---------------+----------------+-----------------+ The short workload is the only one that shows a decline in performance probably due to the spinner locking and queuing overhead. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Reviewed-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Chandramouleeswaran Aswin <aswin@hp.com> Cc: Norton Scott J <scott.norton@hp.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: David Howells <dhowells@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1366226594-5506-4-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-19mutex: Make more scalable by doing less atomic operationsWaiman Long1-3/+16
In the __mutex_lock_common() function, an initial entry into the lock slow path will cause two atomic_xchg instructions to be issued. Together with the atomic decrement in the fast path, a total of three atomic read-modify-write instructions will be issued in rapid succession. This can cause a lot of cache bouncing when many tasks are trying to acquire the mutex at the same time. This patch will reduce the number of atomic_xchg instructions used by checking the counter value first before issuing the instruction. The atomic_read() function is just a simple memory read. The atomic_xchg() function, on the other hand, can be up to 2 order of magnitude or even more in cost when compared with atomic_read(). By using atomic_read() to check the value first before calling atomic_xchg(), we can avoid a lot of unnecessary cache coherency traffic. The only downside with this change is that a task on the slow path will have a tiny bit less chance of getting the mutex when competing with another task in the fast path. The same is true for the atomic_cmpxchg() function in the mutex-spin-on-owner loop. So an atomic_read() is also performed before calling atomic_cmpxchg(). The mutex locking and unlocking code for the x86 architecture can allow any negative number to be used in the mutex count to indicate that some tasks are waiting for the mutex. I am not so sure if that is the case for the other architectures. So the default is to avoid atomic_xchg() if the count has already been set to -1. For x86, the check is modified to include all negative numbers to cover a larger case. The following table shows the jobs per minutes (JPM) scalability data on an 8-node 80-core Westmere box with a 3.7.10 kernel. The numactl command is used to restrict the running of the high_systime workloads to 1/2/4/8 nodes with hyperthreading on and off. +-----------------+-----------+------------+----------+ | Configuration | Mean JPM | Mean JPM | % Change | | | w/o patch | with patch | | +-----------------+-----------------------------------+ | | User Range 1100 - 2000 | +-----------------+-----------------------------------+ | 8 nodes, HT on | 36980 | 148590 | +301.8% | | 8 nodes, HT off | 42799 | 145011 | +238.8% | | 4 nodes, HT on | 61318 | 118445 | +51.1% | | 4 nodes, HT off | 158481 | 158592 | +0.1% | | 2 nodes, HT on | 180602 | 173967 | -3.7% | | 2 nodes, HT off | 198409 | 198073 | -0.2% | | 1 node , HT on | 149042 | 147671 | -0.9% | | 1 node , HT off | 126036 | 126533 | +0.4% | +-----------------+-----------------------------------+ | | User Range 200 - 1000 | +-----------------+-----------------------------------+ | 8 nodes, HT on | 41525 | 122349 | +194.6% | | 8 nodes, HT off | 49866 | 124032 | +148.7% | | 4 nodes, HT on | 66409 | 106984 | +61.1% | | 4 nodes, HT off | 119880 | 130508 | +8.9% | | 2 nodes, HT on | 138003 | 133948 | -2.9% | | 2 nodes, HT off | 132792 | 131997 | -0.6% | | 1 node , HT on | 116593 | 115859 | -0.6% | | 1 node , HT off | 104499 | 104597 | +0.1% | +-----------------+------------+-----------+----------+ At low user range 10-100, the JPM differences were within +/-1%. So they are not that interesting. AIM7 benchmark run has a pretty large run-to-run variance due to random nature of the subtests executed. So a difference of less than +-5% may not be really significant. This patch improves high_systime workload performance at 4 nodes and up by maintaining transaction rates without significant drop-off at high node count. The patch has practically no impact on 1 and 2 nodes system. The table below shows the percentage time (as reported by perf record -a -s -g) spent on the __mutex_lock_slowpath() function by the high_systime workload at 1500 users for 2/4/8-node configurations with hyperthreading off. +---------------+-----------------+------------------+---------+ | Configuration | %Time w/o patch | %Time with patch | %Change | +---------------+-----------------+------------------+---------+ | 8 nodes | 65.34% | 0.69% | -99% | | 4 nodes | 8.70% | 1.02% | -88% | | 2 nodes | 0.41% | 0.32% | -22% | +---------------+-----------------+------------------+---------+ It is obvious that the dramatic performance improvement at 8 nodes was due to the drastic cut in the time spent within the __mutex_lock_slowpath() function. The table below show the improvements in other AIM7 workloads (at 8 nodes, hyperthreading off). +--------------+---------------+----------------+-----------------+ | Workload | mean % change | mean % change | mean % change | | | 10-100 users | 200-1000 users | 1100-2000 users | +--------------+---------------+----------------+-----------------+ | alltests | +0.6% | +104.2% | +185.9% | | five_sec | +1.9% | +0.9% | +0.9% | | fserver | +1.4% | -7.7% | +5.1% | | new_fserver | -0.5% | +3.2% | +3.1% | | shared | +13.1% | +146.1% | +181.5% | | short | +7.4% | +5.0% | +4.2% | +--------------+---------------+----------------+-----------------+ Signed-off-by: Waiman Long <Waiman.Long@hp.com> Reviewed-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Chandramouleeswaran Aswin <aswin@hp.com> Cc: Norton: Scott J <scott.norton@hp.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: David Howells <dhowells@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1366226594-5506-3-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-19mutex: Move mutex spinning code from sched/core.c back to mutex.cWaiman Long3-52/+46
As mentioned by Ingo, the SCHED_FEAT_OWNER_SPIN scheduler feature bit was really just an early hack to make with/without mutex-spinning testable. So it is no longer necessary. This patch removes the SCHED_FEAT_OWNER_SPIN feature bit and move the mutex spinning code from kernel/sched/core.c back to kernel/mutex.c which is where they should belong. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Chandramouleeswaran Aswin <aswin@hp.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Norton Scott J <scott.norton@hp.com> Cc: Rik van Riel <riel@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: David Howells <dhowells@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1366226594-5506-2-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-18Merge branch 'userns-fixes' of ↵Linus Torvalds1-9/+13
git://git.kernel.org/pub/scm/linux/kernel/git/luto/linux Pull user-namespace fixes from Andy Lutomirski. * 'userns-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/luto/linux: userns: Changing any namespace id mappings should require privileges userns: Check uid_map's opener's fsuid, not the current fsuid userns: Don't let unprivileged users trick privileged users into setting the id_map
2013-04-18Revert "block: add missing block_bio_complete() tracepoint"Linus Torvalds1-23/+3
This reverts commit 3a366e614d0837d9fc23f78cdb1a1186ebc3387f. Wanlong Gao reports that it causes a kernel panic on his machine several minutes after boot. Reverting it removes the panic. Jens says: "It's not quite clear why that is yet, so I think we should just revert the commit for 3.9 final (which I'm assuming is pretty close). The wifi is crap at the LSF hotel, so sending this email instead of queueing up a revert and pull request." Reported-by: Wanlong Gao <gaowanlong@cn.fujitsu.com> Requested-by: Jens Axboe <axboe@kernel.dk> Cc: Tejun Heo <tj@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-18kprobes: Fix a double lock bug of kprobe_mutexMasami Hiramatsu1-6/+13
Fix a double locking bug caused when debug.kprobe-optimization=0. While the proc_kprobes_optimization_handler locks kprobe_mutex, wait_for_kprobe_optimizer locks it again and that causes a double lock. To fix the bug, this introduces different mutex for protecting sysctl parameter and locks it in proc_kprobes_optimization_handler. Of course, since we need to lock kprobe_mutex when touching kprobes resources, that is done in *optimize_all_kprobes(). This bug was introduced by commit ad72b3bea744 ("kprobes: fix wait_for_kprobe_optimizer()") Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-17kernel/signal.c: stop info leak via the tkill and the tgkill syscallsEmese Revfy1-1/+1
This fixes a kernel memory contents leak via the tkill and tgkill syscalls for compat processes. This is visible in the siginfo_t->_sifields._rt.si_sigval.sival_ptr field when handling signals delivered from tkill. The place of the infoleak: int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from) { ... put_user_ex(ptr_to_compat(from->si_ptr), &to->si_ptr); ... } Signed-off-by: Emese Revfy <re.emese@gmail.com> Reviewed-by: PaX Team <pageexec@freemail.hu> Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Serge Hallyn <serge.hallyn@canonical.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-17kexec: use Crash kernel for Crash kernel lowYinghai Lu1-1/+1
We can extend kexec-tools to support multiple "Crash kernel" in /proc/iomem instead. So we can use "Crash kernel" instead of "Crash kernel low" in /proc/iomem. Suggested-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Yinghai Lu <yinghai@kernel.org> Link: http://lkml.kernel.org/r/1366089828-19692-3-git-send-email-yinghai@kernel.org Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2013-04-17x86, kdump: Change crashkernel_high/low= to crashkernel=,high/lowYinghai Lu1-13/+96
Per hpa, use crashkernel=X,high crashkernel=Y,low instead of crashkernel_hign=X crashkernel_low=Y. As that could be extensible. -v2: according to Vivek, change delimiter to ; -v3: let hign and low only handle simple form and it conforms to description in kernel-parameters.txt still keep crashkernel=X override any crashkernel=X,high crashkernel=Y,low -v4: update get_last_crashkernel returning and add more strict checking in parse_crashkernel_simple() found by HATAYAMA. -v5: Change delimiter back to , according to HPA. also separate parse_suffix from parse_simper according to vivek. so we can avoid @pos in that path. -v6: Tight the checking about crashkernel=X,highblahblah,high found by HTYAYAMA. Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> Signed-off-by: Yinghai Lu <yinghai@kernel.org> Link: http://lkml.kernel.org/r/1366089828-19692-5-git-send-email-yinghai@kernel.org Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2013-04-17x86, kdump: Retore crashkernel= to allocate under 896MYinghai Lu1-0/+9
Vivek found old kexec-tools does not work new kernel anymore. So change back crashkernel= back to old behavoir, and add crashkernel_high= to let user decide if buffer could be above 4G, and also new kexec-tools will be needed. -v2: let crashkernel=X override crashkernel_high= update description about _high will be ignored by crashkernel=X -v3: update description about kernel-parameters.txt according to Vivek. Signed-off-by: Yinghai Lu <yinghai@kernel.org> Link: http://lkml.kernel.org/r/1366089828-19692-4-git-send-email-yinghai@kernel.org Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2013-04-15Merge branches 'timers-urgent-for-linus', 'irq-urgent-for-linus' and ↵Linus Torvalds3-28/+41
'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull {timer,irq,core} fixes from Thomas Gleixner: - timer: bug fix for a cpu hotplug race. - irq: single bugfix for a wrong return value, which prevents the calling function to invoke the software fallback. - core: bugfix which plugs two race confitions which can cause hotplug per cpu threads to end up on the wrong cpu. * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: hrtimer: Don't reinitialize a cpu_base lock on CPU_UP * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: irqchip: gic: fix irq_trigger return * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: kthread: Prevent unpark race which puts threads on the wrong cpu
2013-04-15perf: Treat attr.config as u64 in perf_swevent_init()Tommi Rantala1-1/+1
Trinity discovered that we fail to check all 64 bits of attr.config passed by user space, resulting to out-of-bounds access of the perf_swevent_enabled array in sw_perf_event_destroy(). Introduced in commit b0a873ebb ("perf: Register PMU implementations"). Signed-off-by: Tommi Rantala <tt.rantala@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: davej@redhat.com Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Link: http://lkml.kernel.org/r/1365882554-30259-1-git-send-email-tt.rantala@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-14userns: Changing any namespace id mappings should require privilegesAndy Lutomirski1-3/+3
Changing uid/gid/projid mappings doesn't change your id within the namespace; it reconfigures the namespace. Unprivileged programs should *not* be able to write these files. (We're also checking the privileges on the wrong task.) Given the write-once nature of these files and the other security checks, this is likely impossible to usefully exploit. Signed-off-by: Andy Lutomirski <luto@amacapital.net>
2013-04-14userns: Check uid_map's opener's fsuid, not the current fsuidAndy Lutomirski1-2/+2
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
2013-04-14userns: Don't let unprivileged users trick privileged users into setting the ↵Eric W. Biederman1-4/+8
id_map When we require privilege for setting /proc/<pid>/uid_map or /proc/<pid>/gid_map no longer allow an unprivileged user to open the file and pass it to a privileged program to write to the file. Instead when privilege is required require both the opener and the writer to have the necessary capabilities. I have tested this code and verified that setting /proc/<pid>/uid_map fails when an unprivileged user opens the file and a privielged user attempts to set the mapping, that unprivileged users can still map their own id, and that a privileged users can still setup an arbitrary mapping. Reported-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andy Lutomirski <luto@amacapital.net>
2013-04-14Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds3-4/+32
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "Misc fixlets" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/cputime: Fix accounting on multi-threaded processes sched/debug: Fix sd->*_idx limit range avoiding overflow sched_clock: Prevent 64bit inatomicity on 32bit systems sched: Convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()s
2013-04-14Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds5-10/+26
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Ingo Molnar: "Misc fixlets" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf: Fix error return code ftrace: Fix strncpy() use, use strlcpy() instead of strncpy() perf: Fix strncpy() use, use strlcpy() instead of strncpy() perf: Fix strncpy() use, always make sure it's NUL terminated perf: Fix ring_buffer perf_output_space() boundary calculation perf/x86: Fix uninitialized pt_regs in intel_pmu_drain_bts_buffer()
2013-04-14Merge tag 'trace-fixes-v3.9-rc-v3' of ↵Linus Torvalds2-19/+19
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull ftrace fixes from Steven Rostedt: "Namhyung Kim found and fixed a bug that can crash the kernel by simply doing: echo 1234 | tee -a /sys/kernel/debug/tracing/set_ftrace_pid Luckily, this can only be done by root, but still is a nasty bug." * tag 'trace-fixes-v3.9-rc-v3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ftrace: Move ftrace_filter_lseek out of CONFIG_DYNAMIC_FTRACE section tracing: Fix possible NULL pointer dereferences
2013-04-14Add file_ns_capable() helper function for open-time capability checkingLinus Torvalds1-0/+24
Nothing is using it yet, but this will allow us to delay the open-time checks to use time, without breaking the normal UNIX permission semantics where permissions are determined by the opener (and the file descriptor can then be passed to a different process, or the process can drop capabilities). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-12ftrace: Move ftrace_filter_lseek out of CONFIG_DYNAMIC_FTRACE sectionSteven Rostedt (Red Hat)1-14/+14
As ftrace_filter_lseek is now used with ftrace_pid_fops, it needs to be moved out of the #ifdef CONFIG_DYNAMIC_FTRACE section as the ftrace_pid_fops is defined when DYNAMIC_FTRACE is not. Cc: stable@vger.kernel.org Cc: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-04-12tracing: Fix possible NULL pointer dereferencesNamhyung Kim2-6/+6
Currently set_ftrace_pid and set_graph_function files use seq_lseek for their fops. However seq_open() is called only for FMODE_READ in the fops->open() so that if an user tries to seek one of those file when she open it for writing, it sees NULL seq_file and then panic. It can be easily reproduced with following command: $ cd /sys/kernel/debug/tracing $ echo 1234 | sudo tee -a set_ftrace_pid In this example, GNU coreutils' tee opens the file with fopen(, "a") and then the fopen() internally calls lseek(). Link: http://lkml.kernel.org/r/1365663302-2170-1-git-send-email-namhyung@kernel.org Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: stable@vger.kernel.org Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-04-12kthread: Prevent unpark race which puts threads on the wrong cpuThomas Gleixner2-26/+40
The smpboot threads rely on the park/unpark mechanism which binds per cpu threads on a particular core. Though the functionality is racy: CPU0 CPU1 CPU2 unpark(T) wake_up_process(T) clear(SHOULD_PARK) T runs leave parkme() due to !SHOULD_PARK bind_to(CPU2) BUG_ON(wrong CPU) We cannot let the tasks move themself to the target CPU as one of those tasks is actually the migration thread itself, which requires that it starts running on the target cpu right away. The solution to this problem is to prevent wakeups in park mode which are not from unpark(). That way we can guarantee that the association of the task to the target cpu is working correctly. Add a new task state (TASK_PARKED) which prevents other wakeups and use this state explicitly for the unpark wakeup. Peter noticed: Also, since the task state is visible to userspace and all the parked tasks are still in the PID space, its a good hint in ps and friends that these tasks aren't really there for the moment. The migration thread has another related issue. CPU0 CPU1 Bring up CPU2 create_thread(T) park(T) wait_for_completion() parkme() complete() sched_set_stop_task() schedule(TASK_PARKED) The sched_set_stop_task() call is issued while the task is on the runqueue of CPU1 and that confuses the hell out of the stop_task class on that cpu. So we need the same synchronizaion before sched_set_stop_task(). Reported-by: Dave Jones <davej@redhat.com> Reported-and-tested-by: Dave Hansen <dave@sr71.net> Reported-and-tested-by: Borislav Petkov <bp@alien8.de> Acked-by: Peter Ziljstra <peterz@infradead.org> Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Cc: dhillf@gmail.com Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1304091635430.21884@ionos Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-04-12perf: Fix error return codeWei Yongjun1-0/+1
Fix to return -ENOMEM in the allocation error case instead of 0 (if pmu_bus_running == 1), as done elsewhere in this function. Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Cc: a.p.zijlstra@chello.nl Cc: paulus@samba.org Cc: acme@ghostprotocols.net Link: http://lkml.kernel.org/r/CAPgLHd8j_fWcgqe%3DKLWjpBj%2B%3Do0Pw6Z-SEq%3DNTPU08c2w1tngQ@mail.gmail.com [ Tweaked the error code setting placement and the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-11Merge tag 'pm-3.9-rc7' of ↵Linus Torvalds1-1/+2
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull power management fixes from Rafael Wysocki: - System reboot/halt fix related to CPU offline ordering from Huacai Chen. - intel_pstate driver fix for a delay time computation error occasionally crashing systems using it from Dirk Brandewie. * tag 'pm-3.9-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: PM / reboot: call syscore_shutdown() after disable_nonboot_cpus() cpufreq / intel_pstate: Set timer timeout correctly
2013-04-10Merge tag 'trace-fixes-3.9-rc-v2' of ↵Linus Torvalds1-1/+0
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fix from Steven Rostedt: "Namhyung Kim fixed a long standing bug that can cause a kernel panic. If the function profiler fails to allocate memory for everything, it will do a double free on the same pointer which can cause a panic" * tag 'trace-fixes-3.9-rc-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Fix double free when function profile init failed
2013-04-10locking/rtmutex/tester: Set correct permissions on sysfs filesSasha Levin1-2/+3
sysfs started complaining about cases where permissions don't match what's in the sysfs ops structure (such as allowing read without a "show" callback). Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: williams@redhat.com Link: http://lkml.kernel.org/r/1363795105-5884-1-git-send-email-sasha.levin@oracle.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-09tracing: Fix double free when function profile init failedNamhyung Kim1-1/+0
On the failure path, stat->start and stat->pages will refer same page. So it'll attempt to free the same page again and get kernel panic. Link: http://lkml.kernel.org/r/1364820385-32027-1-git-send-email-namhyung@kernel.org Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: stable@vger.kernel.org Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-04-08Merge tag 'trace-fixes-3.9-rc6' of ↵Linus Torvalds2-9/+9
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fixes from Steven Rostedt: "This includes three fixes. Two fix features added in 3.9 and one fixes a long time minor bug. The first patch fixes a race that can happen if the user switches from the irqsoff tracer to another tracer. If a irqs off latency is detected, it will try to use the snapshot buffer, but the new tracer wont have it allocated. There's a nasty warning that gets printed and the trace is ignored. Nothing crashes, just a nasty WARN_ON is shown. The second patch fixes an issue where if the sysctl is used to disable and enable function tracing, it can put the function tracing into an unstable state. The third patch fixes an issue with perf using the function tracer. An update was done, where the stub function could be called during the perf function tracing, and that stub function wont have the "control" flag set and cause a nasty warning when running perf." * tag 'trace-fixes-3.9-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ftrace: Do not call stub functions in control loop ftrace: Consistently restore trace function on sysctl enabling tracing: Fix race with update_max_tr_single and changing tracers
2013-04-08PM / reboot: call syscore_shutdown() after disable_nonboot_cpus()Huacai Chen1-1/+2
As commit 40dc166c (PM / Core: Introduce struct syscore_ops for core subsystems PM) say, syscore_ops operations should be carried with one CPU on-line and interrupts disabled. However, after commit f96972f2d (kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()), syscore_shutdown() is called before disable_nonboot_cpus(), so break the rules. We have a MIPS machine with a 8259A PIC, and there is an external timer (HPET) linked at 8259A. Since 8259A has been shutdown too early (by syscore_shutdown()), disable_nonboot_cpus() runs without timer interrupt, so it hangs and reboot fails. This patch call syscore_shutdown() a little later (after disable_nonboot_cpus()) to avoid reboot failure, this is the same way as poweroff does. For consistency, add disable_nonboot_cpus() to kernel_halt(). Signed-off-by: Huacai Chen <chenhc@lemote.com> Cc: <stable@vger.kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-04-08ftrace: Do not call stub functions in control loopSteven Rostedt (Red Hat)1-2/+3
The function tracing control loop used by perf spits out a warning if the called function is not a control function. This is because the control function references a per cpu allocated data structure on struct ftrace_ops that is not allocated for other types of functions. commit 0a016409e42 "ftrace: Optimize the function tracer list loop" Had an optimization done to all function tracing loops to optimize for a single registered ops. Unfortunately, this allows for a slight race when tracing starts or ends, where the stub function might be called after the current registered ops is removed. In this case we get the following dump: root# perf stat -e ftrace:function sleep 1 [ 74.339105] WARNING: at include/linux/ftrace.h:209 ftrace_ops_control_func+0xde/0xf0() [ 74.349522] Hardware name: PRIMERGY RX200 S6 [ 74.357149] Modules linked in: sg igb iTCO_wdt ptp pps_core iTCO_vendor_support i7core_edac dca lpc_ich i2c_i801 coretemp edac_core crc32c_intel mfd_core ghash_clmulni_intel dm_multipath acpi_power_meter pcspk r microcode vhost_net tun macvtap macvlan nfsd kvm_intel kvm auth_rpcgss nfs_acl lockd sunrpc uinput xfs libcrc32c sd_mod crc_t10dif sr_mod cdrom mgag200 i2c_algo_bit drm_kms_helper ttm qla2xxx mptsas ahci drm li bahci scsi_transport_sas mptscsih libata scsi_transport_fc i2c_core mptbase scsi_tgt dm_mirror dm_region_hash dm_log dm_mod [ 74.446233] Pid: 1377, comm: perf Tainted: G W 3.9.0-rc1 #1 [ 74.453458] Call Trace: [ 74.456233] [<ffffffff81062e3f>] warn_slowpath_common+0x7f/0xc0 [ 74.462997] [<ffffffff810fbc60>] ? rcu_note_context_switch+0xa0/0xa0 [ 74.470272] [<ffffffff811041a2>] ? __unregister_ftrace_function+0xa2/0x1a0 [ 74.478117] [<ffffffff81062e9a>] warn_slowpath_null+0x1a/0x20 [ 74.484681] [<ffffffff81102ede>] ftrace_ops_control_func+0xde/0xf0 [ 74.491760] [<ffffffff8162f400>] ftrace_call+0x5/0x2f [ 74.497511] [<ffffffff8162f400>] ? ftrace_call+0x5/0x2f [ 74.503486] [<ffffffff8162f400>] ? ftrace_call+0x5/0x2f [ 74.509500] [<ffffffff810fbc65>] ? synchronize_sched+0x5/0x50 [ 74.516088] [<ffffffff816254d5>] ? _cond_resched+0x5/0x40 [ 74.522268] [<ffffffff810fbc65>] ? synchronize_sched+0x5/0x50 [ 74.528837] [<ffffffff811041a2>] ? __unregister_ftrace_function+0xa2/0x1a0 [ 74.536696] [<ffffffff816254d5>] ? _cond_resched+0x5/0x40 [ 74.542878] [<ffffffff8162402d>] ? mutex_lock+0x1d/0x50 [ 74.548869] [<ffffffff81105c67>] unregister_ftrace_function+0x27/0x50 [ 74.556243] [<ffffffff8111eadf>] perf_ftrace_event_register+0x9f/0x140 [ 74.563709] [<ffffffff816254d5>] ? _cond_resched+0x5/0x40 [ 74.569887] [<ffffffff8162402d>] ? mutex_lock+0x1d/0x50 [ 74.575898] [<ffffffff8111e94e>] perf_trace_destroy+0x2e/0x50 [ 74.582505] [<ffffffff81127ba9>] tp_perf_event_destroy+0x9/0x10 [ 74.589298] [<ffffffff811295d0>] free_event+0x70/0x1a0 [ 74.595208] [<ffffffff8112a579>] perf_event_release_kernel+0x69/0xa0 [ 74.602460] [<ffffffff816254d5>] ? _cond_resched+0x5/0x40 [ 74.608667] [<ffffffff8112a640>] put_event+0x90/0xc0 [ 74.614373] [<ffffffff8112a740>] perf_release+0x10/0x20 [ 74.620367] [<ffffffff811a3044>] __fput+0xf4/0x280 [ 74.625894] [<ffffffff811a31de>] ____fput+0xe/0x10 [ 74.631387] [<ffffffff81083697>] task_work_run+0xa7/0xe0 [ 74.637452] [<ffffffff81014981>] do_notify_resume+0x71/0xb0 [ 74.643843] [<ffffffff8162fa92>] int_signal+0x12/0x17 To fix this a new ftrace_ops flag is added that denotes the ftrace_list_end ftrace_ops stub as just that, a stub. This flag is now checked in the control loop and the function is not called if the flag is set. Thanks to Jovi for not just reporting the bug, but also pointing out where the bug was in the code. Link: http://lkml.kernel.org/r/514A8855.7090402@redhat.com Link: http://lkml.kernel.org/r/1364377499-1900-15-git-send-email-jovi.zhangwei@huawei.com Tested-by: WANG Chao <chaowang@redhat.com> Reported-by: WANG Chao <chaowang@redhat.com> Reported-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-04-08ftrace: Consistently restore trace function on sysctl enablingJan Kiszka1-6/+2
If we reenable ftrace via syctl, we currently set ftrace_trace_function based on the previous simplistic algorithm. This is inconsistent with what update_ftrace_function does. So better call that helper instead. Link: http://lkml.kernel.org/r/5151D26F.1070702@siemens.com Cc: stable@vger.kernel.org Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-04-08tracing: Fix race with update_max_tr_single and changing tracersSteven Rostedt (Red Hat)1-1/+4
The commit 34600f0e9 "tracing: Fix race with max_tr and changing tracers" fixed the updating of the main buffers with the race of changing tracers, but left out the fix to the updating of just a per cpu buffer. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-04-08sched/cputime: Fix accounting on multi-threaded processesStanislaw Gruszka1-1/+1
Recent commit 6fac4829 ("cputime: Use accessors to read task cputime stats") introduced a bug, where we account many times the cputime of the first thread, instead of cputimes of all the different threads. Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20130404085740.GA2495@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-08lockdep: Remove unnecessary 'hlock_next' variableHong Zhiguo1-4/+2
Signed-off-by: Hong Zhiguo <honkiko@gmail.com> Cc: peterz@infradead.org Link: http://lkml.kernel.org/r/1365058881-4044-1-git-send-email-honkiko@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-08ftrace: Fix strncpy() use, use strlcpy() instead of strncpy()Chen Gang1-2/+2
For NUL terminated string we always need to set '\0' at the end. Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: rostedt@goodmis.org Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/516243B7.9020405@asianux.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-08perf: Fix strncpy() use, use strlcpy() instead of strncpy()Chen Gang1-2/+2
For NUL terminated string we always need to set '\0' at the end. Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: rostedt@goodmis.org Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/51624254.30301@asianux.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-08perf: Fix strncpy() use, always make sure it's NUL terminatedChen Gang1-1/+2
For NUL terminated string, always make sure that there's '\0' at the end. In our case we need a return value, so still use strncpy() and fix up the tail explicitly. (strlcpy() returns the size, not the pointer) Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: a.p.zijlstra@chello.nl <a.p.zijlstra@chello.nl> Cc: paulus@samba.org <paulus@samba.org> Cc: acme@ghostprotocols.net <acme@ghostprotocols.net> Link: http://lkml.kernel.org/r/51623E0B.7070101@asianux.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-08sched/debug: Fix sd->*_idx limit range avoiding overflowlibin1-1/+1
Commit 201c373e8e ("sched/debug: Limit sd->*_idx range on sysctl") was an incomplete bug fix. This patch fixes sd->*_idx limit range to [0 ~ CPU_LOAD_IDX_MAX-1] avoiding array overflow caused by setting sd->*_idx to CPU_LOAD_IDX_MAX on sysctl. Signed-off-by: Libin <huawei.libin@huawei.com> Cc: <jiang.liu@huawei.com> Cc: <guohanjun@huawei.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/51626610.2040607@huawei.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-04-08sched_clock: Prevent 64bit inatomicity on 32bit systemsThomas Gleixner1-0/+26
The sched_clock_remote() implementation has the following inatomicity problem on 32bit systems when accessing the remote scd->clock, which is a 64bit value. CPU0 CPU1 sched_clock_local() sched_clock_remote(CPU0) ... remote_clock = scd[CPU0]->clock read_low32bit(scd[CPU0]->clock) cmpxchg64(scd->clock,...) read_high32bit(scd[CPU0]->clock) While the update of scd->clock is using an atomic64 mechanism, the readout on the remote cpu is not, which can cause completely bogus readouts. It is a quite rare problem, because it requires the update to hit the narrow race window between the low/high readout and the update must go across the 32bit boundary. The resulting misbehaviour is, that CPU1 will see the sched_clock on CPU1 ~4 seconds ahead of it's own and update CPU1s sched_clock value to this bogus timestamp. This stays that way due to the clamping implementation for about 4 seconds until the synchronization with CLOCK_MONOTONIC undoes the problem. The issue is hard to observe, because it might only result in a less accurate SCHED_OTHER timeslicing behaviour. To create observable damage on realtime scheduling classes, it is necessary that the bogus update of CPU1 sched_clock happens in the context of an realtime thread, which then gets charged 4 seconds of RT runtime, which results in the RT throttler mechanism to trigger and prevent scheduling of RT tasks for a little less than 4 seconds. So this is quite unlikely as well. The issue was quite hard to decode as the reproduction time is between 2 days and 3 weeks and intrusive tracing makes it less likely, but the following trace recorded with trace_clock=global, which uses sched_clock_local(), gave the final hint: <idle>-0 0d..30 400269.477150: hrtimer_cancel: hrtimer=0xf7061e80 <idle>-0 0d..30 400269.477151: hrtimer_start: hrtimer=0xf7061e80 ... irq/20-S-587 1d..32 400273.772118: sched_wakeup: comm= ... target_cpu=0 <idle>-0 0dN.30 400273.772118: hrtimer_cancel: hrtimer=0xf7061e80 What happens is that CPU0 goes idle and invokes sched_clock_idle_sleep_event() which invokes sched_clock_local() and CPU1 runs a remote wakeup for CPU0 at the same time, which invokes sched_remote_clock(). The time jump gets propagated to CPU0 via sched_remote_clock() and stays stale on both cores for ~4 seconds. There are only two other possibilities, which could cause a stale sched clock: 1) ktime_get() which reads out CLOCK_MONOTONIC returns a sporadic wrong value. 2) sched_clock() which reads the TSC returns a sporadic wrong value. #1 can be excluded because sched_clock would continue to increase for one jiffy and then go stale. #2 can be excluded because it would not make the clock jump forward. It would just result in a stale sched_clock for one jiffy. After quite some brain twisting and finding the same pattern on other traces, sched_clock_remote() remained the only place which could cause such a problem and as explained above it's indeed racy on 32bit systems. So while on 64bit systems the readout is atomic, we need to verify the remote readout on 32bit machines. We need to protect the local->clock readout in sched_clock_remote() on 32bit as well because an NMI could hit between the low and the high readout, call sched_clock_local() and modify local->clock. Thanks to Siegfried Wulsch for bearing with my debug requests and going through the tedious tasks of running a bunch of reproducer systems to generate the debug information which let me decode the issue. Reported-by: Siegfried Wulsch <Siegfried.Wulsch@rovema.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1304051544160.21884@ionos Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org
2013-03-31Revert "lockdep: check that no locks held at freeze time"Paul Walmsley2-9/+10
This reverts commit 6aa9707099c4b25700940eb3d016f16c4434360d. Commit 6aa9707099c4 ("lockdep: check that no locks held at freeze time") causes problems with NFS root filesystems. The failures were noticed on OMAP2 and 3 boards during kernel init: [ BUG: swapper/0/1 still has locks held! ] 3.9.0-rc3-00344-ga937536 #1 Not tainted ------------------------------------- 1 lock held by swapper/0/1: #0: (&type->s_umount_key#13/1){+.+.+.}, at: [<c011e84c>] sget+0x248/0x574 stack backtrace: rpc_wait_bit_killable __wait_on_bit out_of_line_wait_on_bit __rpc_execute rpc_run_task rpc_call_sync nfs_proc_get_root nfs_get_root nfs_fs_mount_common nfs_try_mount nfs_fs_mount mount_fs vfs_kern_mount do_mount sys_mount do_mount_root mount_root prepare_namespace kernel_init_freeable kernel_init Although the rootfs mounts, the system is unstable. Here's a transcript from a PM test: http://www.pwsan.com/omap/testlogs/test_v3.9-rc3/20130317194234/pm/37xxevm/37xxevm_log.txt Here's what the test log should look like: http://www.pwsan.com/omap/testlogs/test_v3.8/20130218214403/pm/37xxevm/37xxevm_log.txt Mailing list discussion is here: http://lkml.org/lkml/2013/3/4/221 Deal with this for v3.9 by reverting the problem commit, until folks can figure out the right long-term course of action. Signed-off-by: Paul Walmsley <paul@pwsan.com> Cc: Mandeep Singh Baines <msb@chromium.org> Cc: Jeff Layton <jlayton@redhat.com> Cc: Shawn Guo <shawn.guo@linaro.org> Cc: <maciej.rutecki@gmail.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ben Chan <benchan@chromium.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-03-28Merge branch 'for-linus' of ↵Linus Torvalds3-1/+15
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull userns fixes from Eric W Biederman: "The bulk of the changes are fixing the worst consequences of the user namespace design oversight in not considering what happens when one namespace starts off as a clone of another namespace, as happens with the mount namespace. The rest of the changes are just plain bug fixes. Many thanks to Andy Lutomirski for pointing out many of these issues." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: userns: Restrict when proc and sysfs can be mounted ipc: Restrict mounting the mqueue filesystem vfs: Carefully propogate mounts across user namespaces vfs: Add a mount flag to lock read only bind mounts userns: Don't allow creation if the user is chrooted yama: Better permission check for ptraceme pid: Handle the exit of a multi-threaded init. scm: Require CAP_SYS_ADMIN over the current pidns to spoof pids.
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