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2014-05-18tracepoint: Do not waste memory on mods with no tracepointsSteven Rostedt (Red Hat)
commit 7dec935a3aa04412cba2cebe1524ae0d34a30c24 upstream. No reason to allocate tp_module structures for modules that have no tracepoints. This just wastes memory. Fixes: b75ef8b44b1c "Tracepoint: Dissociate from module mutex" Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-18blktrace: fix accounting of partially completed requestsRoman Pen
commit af5040da01ef980670b3741b3e10733ee3e33566 upstream. trace_block_rq_complete does not take into account that request can be partially completed, so we can get the following incorrect output of blkparser: C R 232 + 240 [0] C R 240 + 232 [0] C R 248 + 224 [0] C R 256 + 216 [0] but should be: C R 232 + 8 [0] C R 240 + 8 [0] C R 248 + 8 [0] C R 256 + 8 [0] Also, the whole output summary statistics of completed requests and final throughput will be incorrect. This patch takes into account real completion size of the request and fixes wrong completion accounting. Signed-off-by: Roman Pen <r.peniaev@gmail.com> CC: Steven Rostedt <rostedt@goodmis.org> CC: Frederic Weisbecker <fweisbec@gmail.com> CC: Ingo Molnar <mingo@redhat.com> CC: linux-kernel@vger.kernel.org Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-06hung_task: check the value of "sysctl_hung_task_timeout_sec"Liu Hua
commit 80df28476505ed4e6701c3448c63c9229a50c655 upstream. As sysctl_hung_task_timeout_sec is unsigned long, when this value is larger then LONG_MAX/HZ, the function schedule_timeout_interruptible in watchdog will return immediately without sleep and with print : schedule_timeout: wrong timeout value ffffffffffffff83 and then the funtion watchdog will call schedule_timeout_interruptible again and again. The screen will be filled with "schedule_timeout: wrong timeout value ffffffffffffff83" This patch does some check and correction in sysctl, to let the function schedule_timeout_interruptible allways get the valid parameter. Signed-off-by: Liu Hua <sdu.liu@huawei.com> Tested-by: Satoru Takeuchi <satoru.takeuchi@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-26wait: fix reparent_leader() vs EXIT_DEAD->EXIT_ZOMBIE raceOleg Nesterov
commit dfccbb5e49a621c1b21a62527d61fc4305617aca upstream. wait_task_zombie() first does EXIT_ZOMBIE->EXIT_DEAD transition and drops tasklist_lock. If this task is not the natural child and it is traced, we change its state back to EXIT_ZOMBIE for ->real_parent. The last transition is racy, this is even documented in 50b8d257486a "ptrace: partially fix the do_wait(WEXITED) vs EXIT_DEAD->EXIT_ZOMBIE race". wait_consider_task() tries to detect this transition and clear ->notask_error but we can't rely on ptrace_reparented(), debugger can exit and do ptrace_unlink() before its sub-thread sets EXIT_ZOMBIE. And there is another problem which were missed before: this transition can also race with reparent_leader() which doesn't reset >exit_signal if EXIT_DEAD, assuming that this task must be reaped by someone else. So the tracee can be re-parented with ->exit_signal != SIGCHLD, and if /sbin/init doesn't use __WALL it becomes unreapable. Change reparent_leader() to update ->exit_signal even if EXIT_DEAD. Note: this is the simple temporary hack for -stable, it doesn't try to solve all problems, it will be reverted by the next changes. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Jan Kratochvil <jan.kratochvil@redhat.com> Reported-by: Michal Schmidt <mschmidt@redhat.com> Tested-by: Michal Schmidt <mschmidt@redhat.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Lennart Poettering <lpoetter@redhat.com> Cc: Roland McGrath <roland@hack.frob.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-14workqueue: cond_resched() after processing each work itemTejun Heo
commit b22ce2785d97423846206cceec4efee0c4afd980 upstream. If !PREEMPT, a kworker running work items back to back can hog CPU. This becomes dangerous when a self-requeueing work item which is waiting for something to happen races against stop_machine. Such self-requeueing work item would requeue itself indefinitely hogging the kworker and CPU it's running on while stop_machine would wait for that CPU to enter stop_machine while preventing anything else from happening on all other CPUs. The two would deadlock. Jamie Liu reports that this deadlock scenario exists around scsi_requeue_run_queue() and libata port multiplier support, where one port may exclude command processing from other ports. With the right timing, scsi_requeue_run_queue() can end up requeueing itself trying to execute an IO which is asked to be retried while another device has an exclusive access, which in turn can't make forward progress due to stop_machine. Fix it by invoking cond_resched() after executing each work item. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jamie Liu <jamieliu@google.com> References: http://thread.gmane.org/gmane.linux.kernel/1552567 [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Qiang Huang <h.huangqiang@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Jianguo Wu <wujianguo@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-14printk: Fix rq->lock vs logbuf_lock unlock lock inversionBu, Yitian
commit dbda92d16f8655044e082930e4e9d244b87fde77 upstream. commit 07354eb1a74d1 ("locking printk: Annotate logbuf_lock as raw") reintroduced a lock inversion problem which was fixed in commit 0b5e1c5255 ("printk: Release console_sem after logbuf_lock"). This happened probably when fixing up patch rejects. Restore the ordering and unlock logbuf_lock before releasing console_sem. Signed-off-by: ybu <ybu@qti.qualcomm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/E807E903FE6CBE4D95E420FBFCC273B827413C@nasanexd01h.na.qualcomm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Qiang Huang <h.huangqiang@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Jianguo Wu <wujianguo@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-04-14audit: wait_for_auditd() should use TASK_UNINTERRUPTIBLEOleg Nesterov
commit f000cfdde5de4fc15dead5ccf524359c07eadf2b upstream. audit_log_start() does wait_for_auditd() in a loop until audit_backlog_wait_time passes or audit_skb_queue has a room. If signal_pending() is true this becomes a busy-wait loop, schedule() in TASK_INTERRUPTIBLE won't block. Thanks to Guy for fully investigating and explaining the problem. (akpm: that'll cause the system to lock up on a non-preemptible uniprocessor kernel) (Guy: "Our customer was in fact running a uniprocessor machine, and they reported a system hang.") Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Guy Streeter <streeter@redhat.com> Cc: Eric Paris <eparis@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.2: adjust context, indentation] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Qiang Huang <h.huangqiang@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Jianguo Wu <wujianguo@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-23tracing: Do not add event files for modules that fail tracepointsSteven Rostedt (Red Hat)
commit 45ab2813d40d88fc575e753c38478de242d03f88 upstream. If a module fails to add its tracepoints due to module tainting, do not create the module event infrastructure in the debugfs directory. As the events will not work and worse yet, they will silently fail, making the user wonder why the events they enable do not display anything. Having a warning on module load and the events not visible to the users will make the cause of the problem much clearer. Link: http://lkml.kernel.org/r/20140227154923.265882695@goodmis.org Fixes: 6d723736e472 "tracing/events: add support for modules to TRACE_EVENT" Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-23cpuset: fix a race condition in __cpuset_node_allowed_softwall()Li Zefan
commit 99afb0fd5f05aac467ffa85c36778fec4396209b upstream. It's not safe to access task's cpuset after releasing task_lock(). Holding callback_mutex won't help. Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-23genirq: Remove racy waitqueue_active checkChuansheng Liu
commit c685689fd24d310343ac33942e9a54a974ae9c43 upstream. We hit one rare case below: T1 calling disable_irq(), but hanging at synchronize_irq() always; The corresponding irq thread is in sleeping state; And all CPUs are in idle state; After analysis, we found there is one possible scenerio which causes T1 is waiting there forever: CPU0 CPU1 synchronize_irq() wait_event() spin_lock() atomic_dec_and_test(&threads_active) insert the __wait into queue spin_unlock() if(waitqueue_active) atomic_read(&threads_active) wake_up() Here after inserted the __wait into queue on CPU0, and before test if queue is empty on CPU1, there is no barrier, it maybe cause it is not visible for CPU1 immediately, although CPU0 has updated the queue list. It is similar for CPU0 atomic_read() threads_active also. So we'd need one smp_mb() before waitqueue_active.that, but removing the waitqueue_active() check solves it as wel l and it makes things simple and clear. Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com> Cc: Xiaoming Wang <xiaoming.wang@intel.com> Link: http://lkml.kernel.org/r/1393212590-32543-1-git-send-email-chuansheng.liu@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-23sched: Fix double normalization of vruntimeGeorge McCollister
commit 791c9e0292671a3bfa95286bb5c08129d8605618 upstream. dequeue_entity() is called when p->on_rq and sets se->on_rq = 0 which appears to guarentee that the !se->on_rq condition is met. If the task has done set_current_state(TASK_INTERRUPTIBLE) without schedule() the second condition will be met and vruntime will be incorrectly adjusted twice. In certain cases this can result in the task's vruntime never increasing past the vruntime of other tasks on the CFS' run queue, starving them of CPU time. This patch changes switched_from_fair() to use !p->on_rq instead of !se->on_rq. I'm able to cause a task with a priority of 120 to starve all other tasks with the same priority on an ARM platform running 3.2.51-rt72 PREEMPT RT by writing one character at time to a serial tty (16550 UART) in a tight loop. I'm also able to verify making this change corrects the problem on that platform and kernel version. Signed-off-by: George McCollister <george.mccollister@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1392767811-28916-1-git-send-email-george.mccollister@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-11cgroup: cgroup_subsys->fork() should be called after the task is added to ↵Tejun Heo
css_set commit 5edee61edeaaebafe584f8fb7074c1ef4658596b upstream. cgroup core has a bug which violates a basic rule about event notifications - when a new entity needs to be added, you add that to the notification list first and then make the new entity conform to the current state. If done in the reverse order, an event happening inbetween will be lost. cgroup_subsys->fork() is invoked way before the new task is added to the css_set. Currently, cgroup_freezer is the only user of ->fork() and uses it to make new tasks conform to the current state of the freezer. If FROZEN state is requested while fork is in progress between cgroup_fork_callbacks() and cgroup_post_fork(), the child could escape freezing - the cgroup isn't frozen when ->fork() is called and the freezer couldn't see the new task on the css_set. This patch moves cgroup_subsys->fork() invocation to cgroup_post_fork() after the new task is added to the css_set. cgroup_fork_callbacks() is removed. Because now a task may be migrated during cgroup_subsys->fork(), freezer_fork() is updated so that it adheres to the usual RCU locking and the rather pointless comment on why locking can be different there is removed (if it doesn't make anything simpler, why even bother?). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Rafael J. Wysocki <rjw@sisk.pl> [hq: Backported to 3.4: - Adjust context - Iterate over first CGROUP_BUILTIN_SUBSYS_COUNT elements of subsys] Signed-off-by: Qiang Huang <h.huangqiang@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-11perf: Fix hotplug splatPeter Zijlstra
commit e3703f8cdfcf39c25c4338c3ad8e68891cca3731 upstream. Drew Richardson reported that he could make the kernel go *boom* when hotplugging while having perf events active. It turned out that when you have a group event, the code in __perf_event_exit_context() fails to remove the group siblings from the context. We then proceed with destroying and freeing the event, and when you re-plug the CPU and try and add another event to that CPU, things go *boom* because you've still got dead entries there. Reported-by: Drew Richardson <drew.richardson@arm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Link: http://lkml.kernel.org/n/tip-k6v5wundvusvcseqj1si0oz0@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-03-11workqueue: ensure @task is valid across kthread_stop()Lai Jiangshan
commit 5bdfff96c69a4d5ab9c49e60abf9e070ecd2acbb upstream. When a kworker should die, the kworkre is notified through WORKER_DIE flag instead of kthread_should_stop(). This, IIRC, is primarily to keep the test synchronized inside worker_pool lock. WORKER_DIE is first set while holding pool->lock, the lock is dropped and kthread_stop() is called. Unfortunately, this means that there's a slight chance that the target kworker may see WORKER_DIE before kthread_stop() finishes and exits and frees the target task before or during kthread_stop(). Fix it by pinning the target task before setting WORKER_DIE and putting it after kthread_stop() is done. tj: Improved patch description and comment. Moved pinning above WORKER_DIE for better signify what it's protecting. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-22genirq: Add missing irq_to_desc export for CONFIG_SPARSE_IRQ=nPaul Gortmaker
commit 2c45aada341121438affc4cb8d5b4cfaa2813d3d upstream. In allmodconfig builds for sparc and any other arch which does not set CONFIG_SPARSE_IRQ, the following will be seen at modpost: CC [M] lib/cpu-notifier-error-inject.o CC [M] lib/pm-notifier-error-inject.o ERROR: "irq_to_desc" [drivers/gpio/gpio-mcp23s08.ko] undefined! make[2]: *** [__modpost] Error 1 This happens because commit 3911ff30f5 ("genirq: export handle_edge_irq() and irq_to_desc()") added one export for it, but there were actually two instances of it, in an if/else clause for CONFIG_SPARSE_IRQ. Add the second one. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Jiri Kosina <jkosina@suse.cz> Link: http://lkml.kernel.org/r/1392057610-11514-1-git-send-email-paul.gortmaker@windriver.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-22ring-buffer: Fix first commit on sub-buffer having non-zero deltaSteven Rostedt (Red Hat)
commit d651aa1d68a2f0a7ee65697b04c6a92f8c0a12f2 upstream. Each sub-buffer (buffer page) has a full 64 bit timestamp. The events on that page use a 27 bit delta against that timestamp in order to save on bits written to the ring buffer. If the time between events is larger than what the 27 bits can hold, a "time extend" event is added to hold the entire 64 bit timestamp again and the events after that hold a delta from that timestamp. As a "time extend" is always paired with an event, it is logical to just allocate the event with the time extend, to make things a bit more efficient. Unfortunately, when the pairing code was written, it removed the "delta = 0" from the first commit on a page, causing the events on the page to be slightly skewed. Fixes: 69d1b839f7ee "ring-buffer: Bind time extend and data events together" Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-22time: Fix overflow when HZ is smaller than 60Mikulas Patocka
commit 80d767d770fd9c697e434fd080c2db7b5c60c6dd upstream. When compiling for the IA-64 ski emulator, HZ is set to 32 because the emulation is slow and we don't want to waste too many cycles processing timers. Alpha also has an option to set HZ to 32. This causes integer underflow in kernel/time/jiffies.c: kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow] .mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */ ^ This patch reduces the JIFFIES_SHIFT value to avoid the overflow. Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1401241639100.23871@file01.intranet.prod.int.rdu2.redhat.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-20PM / Hibernate: Hibernate/thaw fixes/improvementsBojan Smojver
commit 5a21d489fd9541a4a66b9a500659abaca1b19a51 upstream. 1. Do not allocate memory for buffers from emergency pools, unless absolutely required. Do not warn about and do not retry non-essential failed allocations. 2. Do not check the amount of free pages left on every single page write, but wait until one map is completely populated and then check. 3. Set maximum number of pages for read buffering consistently, instead of inadvertently depending on the size of the sector type. 4. Fix copyright line, which I missed when I submitted the hibernation threading patch. 5. Dispense with bit shifting arithmetic to improve readability. 6. Really recalculate the number of pages required to be free after all allocations have been done. 7. Fix calculation of pages required for read buffering. Only count in pages that do not belong to high memory. Signed-off-by: Bojan Smojver <bojan@rexursive.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Li Zefan <lizefan@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-20sched/nohz: Fix rq->cpu_load calculations some morePeter Zijlstra
commit 5aaa0b7a2ed5b12692c9ffb5222182bd558d3146 upstream. Follow up on commit 556061b00 ("sched/nohz: Fix rq->cpu_load[] calculations") since while that fixed the busy case it regressed the mostly idle case. Add a callback from the nohz exit to also age the rq->cpu_load[] array. This closes the hole where either there was no nohz load balance pass during the nohz, or there was a 'significant' amount of idle time between the last nohz balance and the nohz exit. So we'll update unconditionally from the tick to not insert any accidental 0 load periods while busy, and we try and catch up from nohz idle balance and nohz exit. Both these are still prone to missing a jiffy, but that has always been the case. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: pjt@google.com Cc: Venkatesh Pallipadi <venki@google.com> Link: http://lkml.kernel.org/n/tip-kt0trz0apodbf84ucjfdbr1a@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-20sched/nohz: Fix rq->cpu_load[] calculationsPeter Zijlstra
commit 556061b00c9f2fd6a5524b6bde823ef12f299ecf upstream. While investigating why the load-balancer did funny I found that the rq->cpu_load[] tables were completely screwy.. a bit more digging revealed that the updates that got through were missing ticks followed by a catchup of 2 ticks. The catchup assumes the cpu was idle during that time (since only nohz can cause missed ticks and the machine is idle etc..) this means that esp. the higher indices were significantly lower than they ought to be. The reason for this is that its not correct to compare against jiffies on every jiffy on any other cpu than the cpu that updates jiffies. This patch cludges around it by only doing the catch-up stuff from nohz_idle_balance() and doing the regular stuff unconditionally from the tick. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: pjt@google.com Cc: Venkatesh Pallipadi <venki@google.com> Link: http://lkml.kernel.org/n/tip-tp4kj18xdd5aj4vvj0qg55s2@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-20ftrace: Have function graph only trace based on global_ops filtersSteven Rostedt
commit 23a8e8441a0a74dd612edf81dc89d1600bc0a3d1 upstream. Doing some different tests, I discovered that function graph tracing, when filtered via the set_ftrace_filter and set_ftrace_notrace files, does not always keep with them if another function ftrace_ops is registered to trace functions. The reason is that function graph just happens to trace all functions that the function tracer enables. When there was only one user of function tracing, the function graph tracer did not need to worry about being called by functions that it did not want to trace. But now that there are other users, this becomes a problem. For example, one just needs to do the following: # cd /sys/kernel/debug/tracing # echo schedule > set_ftrace_filter # echo function_graph > current_tracer # cat trace [..] 0) | schedule() { ------------------------------------------ 0) <idle>-0 => rcu_pre-7 ------------------------------------------ 0) ! 2980.314 us | } 0) | schedule() { ------------------------------------------ 0) rcu_pre-7 => <idle>-0 ------------------------------------------ 0) + 20.701 us | } # echo 1 > /proc/sys/kernel/stack_tracer_enabled # cat trace [..] 1) + 20.825 us | } 1) + 21.651 us | } 1) + 30.924 us | } /* SyS_ioctl */ 1) | do_page_fault() { 1) | __do_page_fault() { 1) 0.274 us | down_read_trylock(); 1) 0.098 us | find_vma(); 1) | handle_mm_fault() { 1) | _raw_spin_lock() { 1) 0.102 us | preempt_count_add(); 1) 0.097 us | do_raw_spin_lock(); 1) 2.173 us | } 1) | do_wp_page() { 1) 0.079 us | vm_normal_page(); 1) 0.086 us | reuse_swap_page(); 1) 0.076 us | page_move_anon_rmap(); 1) | unlock_page() { 1) 0.082 us | page_waitqueue(); 1) 0.086 us | __wake_up_bit(); 1) 1.801 us | } 1) 0.075 us | ptep_set_access_flags(); 1) | _raw_spin_unlock() { 1) 0.098 us | do_raw_spin_unlock(); 1) 0.105 us | preempt_count_sub(); 1) 1.884 us | } 1) 9.149 us | } 1) + 13.083 us | } 1) 0.146 us | up_read(); When the stack tracer was enabled, it enabled all functions to be traced, which now the function graph tracer also traces. This is a side effect that should not occur. To fix this a test is added when the function tracing is changed, as well as when the graph tracer is enabled, to see if anything other than the ftrace global_ops function tracer is enabled. If so, then the graph tracer calls a test trampoline that will look at the function that is being traced and compare it with the filters defined by the global_ops. As an optimization, if there's no other function tracers registered, or if the only registered function tracers also use the global ops, the function graph infrastructure will call the registered function graph callback directly and not go through the test trampoline. Fixes: d2d45c7a03a2 "tracing: Have stack_tracer use a separate list of functions" Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-20ftrace: Fix synchronization location disabling and freeing ftrace_opsSteven Rostedt
commit a4c35ed241129dd142be4cadb1e5a474a56d5464 upstream. The synchronization needed after ftrace_ops are unregistered must happen after the callback is disabled from becing called by functions. The current location happens after the function is being removed from the internal lists, but not after the function callbacks were disabled, leaving the functions susceptible of being called after their callbacks are freed. This affects perf and any externel users of function tracing (LTTng and SystemTap). Fixes: cdbe61bfe704 "ftrace: Allow dynamically allocated function tracers" Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-20ftrace: Synchronize setting function_trace_op with ftrace_trace_functionSteven Rostedt
commit 405e1d834807e51b2ebd3dea81cb51e53fb61504 upstream. [ Partial commit backported to 3.4. The ftrace_sync() code by this is required for other fixes that 3.4 needs. ] ftrace_trace_function is a variable that holds what function will be called directly by the assembly code (mcount). If just a single function is registered and it handles recursion itself, then the assembly will call that function directly without any helper function. It also passes in the ftrace_op that was registered with the callback. The ftrace_op to send is stored in the function_trace_op variable. The ftrace_trace_function and function_trace_op needs to be coordinated such that the called callback wont be called with the wrong ftrace_op, otherwise bad things can happen if it expected a different op. Luckily, there's no callback that doesn't use the helper functions that requires this. But there soon will be and this needs to be fixed. Use a set_function_trace_op to store the ftrace_op to set the function_trace_op to when it is safe to do so (during the update function within the breakpoint or stop machine calls). Or if dynamic ftrace is not being used (static tracing) then we have to do a bit more synchronization when the ftrace_trace_function is set as that takes affect immediately (as oppose to dynamic ftrace doing it with the modification of the trampoline). Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-20printk: Fix scheduling-while-atomic problem in console_cpu_notify()Paul E. McKenney
commit 85eae82a0855d49852b87deac8653e4ebc8b291f upstream. The console_cpu_notify() function runs with interrupts disabled in the CPU_DYING case. It therefore cannot block, for example, as will happen when it calls console_lock(). Therefore, remove the CPU_DYING leg of the switch statement to avoid this problem. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Guillaume Morin <guillaume@morinfr.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-133.4.y: timekeeping: fix 32-bit overflow in get_monotonic_boottimeColin Cross
fixed upstream in v3.6 by ec145babe754f9ea1079034a108104b6001e001c get_monotonic_boottime adds three nanonsecond values stored in longs, followed by an s64. If the long values are all close to 1e9 the first three additions can overflow and become negative when added to the s64. Cast the first value to s64 so that all additions are 64 bit. Signed-off-by: Colin Cross <ccross@android.com> [jstultz: Fished this out of the AOSP commong.git tree. This was fixed upstream in v3.6 by ec145babe754f9ea1079034a108104b6001e001c] Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-13timekeeping: Avoid possible deadlock from clock_was_set_delayedJohn Stultz
commit 6fdda9a9c5db367130cf32df5d6618d08b89f46a upstream. As part of normal operaions, the hrtimer subsystem frequently calls into the timekeeping code, creating a locking order of hrtimer locks -> timekeeping locks clock_was_set_delayed() was suppoed to allow us to avoid deadlocks between the timekeeping the hrtimer subsystem, so that we could notify the hrtimer subsytem the time had changed while holding the timekeeping locks. This was done by scheduling delayed work that would run later once we were out of the timekeeing code. But unfortunately the lock chains are complex enoguh that in scheduling delayed work, we end up eventually trying to grab an hrtimer lock. Sasha Levin noticed this in testing when the new seqlock lockdep enablement triggered the following (somewhat abrieviated) message: [ 251.100221] ====================================================== [ 251.100221] [ INFO: possible circular locking dependency detected ] [ 251.100221] 3.13.0-rc2-next-20131206-sasha-00005-g8be2375-dirty #4053 Not tainted [ 251.101967] ------------------------------------------------------- [ 251.101967] kworker/10:1/4506 is trying to acquire lock: [ 251.101967] (timekeeper_seq){----..}, at: [<ffffffff81160e96>] retrigger_next_event+0x56/0x70 [ 251.101967] [ 251.101967] but task is already holding lock: [ 251.101967] (hrtimer_bases.lock#11){-.-...}, at: [<ffffffff81160e7c>] retrigger_next_event+0x3c/0x70 [ 251.101967] [ 251.101967] which lock already depends on the new lock. [ 251.101967] [ 251.101967] [ 251.101967] the existing dependency chain (in reverse order) is: [ 251.101967] -> #5 (hrtimer_bases.lock#11){-.-...}: [snipped] -> #4 (&rt_b->rt_runtime_lock){-.-...}: [snipped] -> #3 (&rq->lock){-.-.-.}: [snipped] -> #2 (&p->pi_lock){-.-.-.}: [snipped] -> #1 (&(&pool->lock)->rlock){-.-...}: [ 251.101967] [<ffffffff81194803>] validate_chain+0x6c3/0x7b0 [ 251.101967] [<ffffffff81194d9d>] __lock_acquire+0x4ad/0x580 [ 251.101967] [<ffffffff81194ff2>] lock_acquire+0x182/0x1d0 [ 251.101967] [<ffffffff84398500>] _raw_spin_lock+0x40/0x80 [ 251.101967] [<ffffffff81153e69>] __queue_work+0x1a9/0x3f0 [ 251.101967] [<ffffffff81154168>] queue_work_on+0x98/0x120 [ 251.101967] [<ffffffff81161351>] clock_was_set_delayed+0x21/0x30 [ 251.101967] [<ffffffff811c4bd1>] do_adjtimex+0x111/0x160 [ 251.101967] [<ffffffff811e2711>] compat_sys_adjtimex+0x41/0x70 [ 251.101967] [<ffffffff843a4b49>] ia32_sysret+0x0/0x5 [ 251.101967] -> #0 (timekeeper_seq){----..}: [snipped] [ 251.101967] other info that might help us debug this: [ 251.101967] [ 251.101967] Chain exists of: timekeeper_seq --> &rt_b->rt_runtime_lock --> hrtimer_bases.lock#11 [ 251.101967] Possible unsafe locking scenario: [ 251.101967] [ 251.101967] CPU0 CPU1 [ 251.101967] ---- ---- [ 251.101967] lock(hrtimer_bases.lock#11); [ 251.101967] lock(&rt_b->rt_runtime_lock); [ 251.101967] lock(hrtimer_bases.lock#11); [ 251.101967] lock(timekeeper_seq); [ 251.101967] [ 251.101967] *** DEADLOCK *** [ 251.101967] [ 251.101967] 3 locks held by kworker/10:1/4506: [ 251.101967] #0: (events){.+.+.+}, at: [<ffffffff81154960>] process_one_work+0x200/0x530 [ 251.101967] #1: (hrtimer_work){+.+...}, at: [<ffffffff81154960>] process_one_work+0x200/0x530 [ 251.101967] #2: (hrtimer_bases.lock#11){-.-...}, at: [<ffffffff81160e7c>] retrigger_next_event+0x3c/0x70 [ 251.101967] [ 251.101967] stack backtrace: [ 251.101967] CPU: 10 PID: 4506 Comm: kworker/10:1 Not tainted 3.13.0-rc2-next-20131206-sasha-00005-g8be2375-dirty #4053 [ 251.101967] Workqueue: events clock_was_set_work So the best solution is to avoid calling clock_was_set_delayed() while holding the timekeeping lock, and instead using a flag variable to decide if we should call clock_was_set() once we've released the locks. This works for the case here, where the do_adjtimex() was the deadlock trigger point. Unfortuantely, in update_wall_time() we still hold the jiffies lock, which would deadlock with the ipi triggered by clock_was_set(), preventing us from calling it even after we drop the timekeeping lock. So instead call clock_was_set_delayed() at that point. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Sasha Levin <sasha.levin@oracle.com> Reported-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-13sched/rt: Avoid updating RT entry timeout twice within one tick periodYing Xue
commit 57d2aa00dcec67afa52478730f2b524521af14fb upstream. The issue below was found in 2.6.34-rt rather than mainline rt kernel, but the issue still exists upstream as well. So please let me describe how it was noticed on 2.6.34-rt: On this version, each softirq has its own thread, it means there is at least one RT FIFO task per cpu. The priority of these tasks is set to 49 by default. If user launches an RT FIFO task with priority lower than 49 of softirq RT tasks, it's possible there are two RT FIFO tasks enqueued one cpu runqueue at one moment. By current strategy of balancing RT tasks, when it comes to RT tasks, we really need to put them off to a CPU that they can run on as soon as possible. Even if it means a bit of cache line flushing, we want RT tasks to be run with the least latency. When the user RT FIFO task which just launched before is running, the sched timer tick of the current cpu happens. In this tick period, the timeout value of the user RT task will be updated once. Subsequently, we try to wake up one softirq RT task on its local cpu. As the priority of current user RT task is lower than the softirq RT task, the current task will be preempted by the higher priority softirq RT task. Before preemption, we check to see if current can readily move to a different cpu. If so, we will reschedule to allow the RT push logic to try to move current somewhere else. Whenever the woken softirq RT task runs, it first tries to migrate the user FIFO RT task over to a cpu that is running a task of lesser priority. If migration is done, it will send a reschedule request to the found cpu by IPI interrupt. Once the target cpu responds the IPI interrupt, it will pick the migrated user RT task to preempt its current task. When the user RT task is running on the new cpu, the sched timer tick of the cpu fires. So it will tick the user RT task again. This also means the RT task timeout value will be updated again. As the migration may be done in one tick period, it means the user RT task timeout value will be updated twice within one tick. If we set a limit on the amount of cpu time for the user RT task by setrlimit(RLIMIT_RTTIME), the SIGXCPU signal should be posted upon reaching the soft limit. But exactly when the SIGXCPU signal should be sent depends on the RT task timeout value. In fact the timeout mechanism of sending the SIGXCPU signal assumes the RT task timeout is increased once every tick. However, currently the timeout value may be added twice per tick. So it results in the SIGXCPU signal being sent earlier than expected. To solve this issue, we prevent the timeout value from increasing twice within one tick time by remembering the jiffies value of last updating the timeout. As long as the RT task's jiffies is different with the global jiffies value, we allow its timeout to be updated. Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Fan Du <fan.du@windriver.com> Reviewed-by: Yong Zhang <yong.zhang0@gmail.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: <peterz@infradead.org> Link: http://lkml.kernel.org/r/1342508623-2887-1-git-send-email-ying.xue@windriver.com Signed-off-by: Ingo Molnar <mingo@kernel.org> [ lizf: backported to 3.4: adjust context ] Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-13sched: Unthrottle rt runqueues in __disable_runtime()Peter Boonstoppel
commit a4c96ae319b8047f62dedbe1eac79e321c185749 upstream. migrate_tasks() uses _pick_next_task_rt() to get tasks from the real-time runqueues to be migrated. When rt_rq is throttled _pick_next_task_rt() won't return anything, in which case migrate_tasks() can't move all threads over and gets stuck in an infinite loop. Instead unthrottle rt runqueues before migrating tasks. Additionally: move unthrottle_offline_cfs_rqs() to rq_offline_fair() Signed-off-by: Peter Boonstoppel <pboonstoppel@nvidia.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Turner <pjt@google.com> Link: http://lkml.kernel.org/r/5FBF8E85CA34454794F0F7ECBA79798F379D3648B7@HQMAIL04.nvidia.com Signed-off-by: Ingo Molnar <mingo@kernel.org> [ lizf: backported to 3.4: adjust context ] Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-13sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttledMike Galbraith
commit e221d028bb08b47e624c5f0a31732c642db9d19a upstream. Root task group bandwidth replenishment must service all CPUs, regardless of where the timer was last started, and regardless of the isolation mechanism, lest 'Quoth the Raven, "Nevermore"' become rt scheduling policy. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1344326558.6968.25.camel@marge.simpson.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Li Zefan <lizefan@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-02-13sched/rt: Fix SCHED_RR across cgroupsColin Cross
commit 454c79999f7eaedcdf4c15c449e43902980cbdf5 upstream. task_tick_rt() has an optimization to only reschedule SCHED_RR tasks if they were the only element on their rq. However, with cgroups a SCHED_RR task could be the only element on its per-cgroup rq but still be competing with other SCHED_RR tasks in its parent's cgroup. In this case, the SCHED_RR task in the child cgroup would never yield at the end of its timeslice. If the child cgroup rt_runtime_us was the same as the parent cgroup rt_runtime_us, the task in the parent cgroup would starve completely. Modify task_tick_rt() to check that the task is the only task on its rq, and that the each of the scheduling entities of its ancestors is also the only entity on its rq. Signed-off-by: Colin Cross <ccross@android.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1337229266-15798-1-git-send-email-ccross@android.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-15sched: Guarantee new group-entities always have weightPaul Turner
commit 0ac9b1c21874d2490331233b3242085f8151e166 upstream. Currently, group entity load-weights are initialized to zero. This admits some races with respect to the first time they are re-weighted in earlty use. ( Let g[x] denote the se for "g" on cpu "x". ) Suppose that we have root->a and that a enters a throttled state, immediately followed by a[0]->t1 (the only task running on cpu[0]) blocking: put_prev_task(group_cfs_rq(a[0]), t1) put_prev_entity(..., t1) check_cfs_rq_runtime(group_cfs_rq(a[0])) throttle_cfs_rq(group_cfs_rq(a[0])) Then, before unthrottling occurs, let a[0]->b[0]->t2 wake for the first time: enqueue_task_fair(rq[0], t2) enqueue_entity(group_cfs_rq(b[0]), t2) enqueue_entity_load_avg(group_cfs_rq(b[0]), t2) account_entity_enqueue(group_cfs_ra(b[0]), t2) update_cfs_shares(group_cfs_rq(b[0])) < skipped because b is part of a throttled hierarchy > enqueue_entity(group_cfs_rq(a[0]), b[0]) ... We now have b[0] enqueued, yet group_cfs_rq(a[0])->load.weight == 0 which violates invariants in several code-paths. Eliminate the possibility of this by initializing group entity weight. Signed-off-by: Paul Turner <pjt@google.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20131016181627.22647.47543.stgit@sword-of-the-dawn.mtv.corp.google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Chris J Arges <chris.j.arges@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-15sched: Fix hrtimer_cancel()/rq->lock deadlockBen Segall
commit 927b54fccbf04207ec92f669dce6806848cbec7d upstream. __start_cfs_bandwidth calls hrtimer_cancel while holding rq->lock, waiting for the hrtimer to finish. However, if sched_cfs_period_timer runs for another loop iteration, the hrtimer can attempt to take rq->lock, resulting in deadlock. Fix this by ensuring that cfs_b->timer_active is cleared only if the _latest_ call to do_sched_cfs_period_timer is returning as idle. Then __start_cfs_bandwidth can just call hrtimer_try_to_cancel and wait for that to succeed or timer_active == 1. Signed-off-by: Ben Segall <bsegall@google.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: pjt@google.com Link: http://lkml.kernel.org/r/20131016181622.22647.16643.stgit@sword-of-the-dawn.mtv.corp.google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Chris J Arges <chris.j.arges@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-15sched: Fix cfs_bandwidth misuse of hrtimer_expires_remainingBen Segall
commit db06e78cc13d70f10877e0557becc88ab3ad2be8 upstream. hrtimer_expires_remaining does not take internal hrtimer locks and thus must be guarded against concurrent __hrtimer_start_range_ns (but returning HRTIMER_RESTART is safe). Use cfs_b->lock to make it safe. Signed-off-by: Ben Segall <bsegall@google.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: pjt@google.com Link: http://lkml.kernel.org/r/20131016181617.22647.73829.stgit@sword-of-the-dawn.mtv.corp.google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Chris J Arges <chris.j.arges@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-15sched: Fix race on toggling cfs_bandwidth_usedBen Segall
commit 1ee14e6c8cddeeb8a490d7b54cd9016e4bb900b4 upstream. When we transition cfs_bandwidth_used to false, any currently throttled groups will incorrectly return false from cfs_rq_throttled. While tg_set_cfs_bandwidth will unthrottle them eventually, currently running code (including at least dequeue_task_fair and distribute_cfs_runtime) will cause errors. Fix this by turning off cfs_bandwidth_used only after unthrottling all cfs_rqs. Tested: toggle bandwidth back and forth on a loaded cgroup. Caused crashes in minutes without the patch, hasn't crashed with it. Signed-off-by: Ben Segall <bsegall@google.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: pjt@google.com Link: http://lkml.kernel.org/r/20131016181611.22647.80365.stgit@sword-of-the-dawn.mtv.corp.google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Chris J Arges <chris.j.arges@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-08sched: Avoid throttle_cfs_rq() racing with period_timer stoppingBen Segall
commit f9f9ffc237dd924f048204e8799da74f9ecf40cf upstream. throttle_cfs_rq() doesn't check to make sure that period_timer is running, and while update_curr/assign_cfs_runtime does, a concurrently running period_timer on another cpu could cancel itself between this cpu's update_curr and throttle_cfs_rq(). If there are no other cfs_rqs running in the tg to restart the timer, this causes the cfs_rq to be stranded forever. Fix this by calling __start_cfs_bandwidth() in throttle if the timer is inactive. (Also add some sched_debug lines for cfs_bandwidth.) Tested: make a run/sleep task in a cgroup, loop switching the cgroup between 1ms/100ms quota and unlimited, checking for timer_active=0 and throttled=1 as a failure. With the throttle_cfs_rq() change commented out this fails, with the full patch it passes. Signed-off-by: Ben Segall <bsegall@google.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: pjt@google.com Link: http://lkml.kernel.org/r/20131016181632.22647.84174.stgit@sword-of-the-dawn.mtv.corp.google.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Chris J Arges <chris.j.arges@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-08sched/rt: Fix rq's cpupri leak while enqueue/dequeue child RT entitiesKirill Tkhai
commit 757dfcaa41844595964f1220f1d33182dae49976 upstream. This patch touches the RT group scheduling case. Functions inc_rt_prio_smp() and dec_rt_prio_smp() change (global) rq's priority, while rt_rq passed to them may be not the top-level rt_rq. This is wrong, because changing of priority on a child level does not guarantee that the priority is the highest all over the rq. So, this leak makes RT balancing unusable. The short example: the task having the highest priority among all rq's RT tasks (no one other task has the same priority) are waking on a throttle rt_rq. The rq's cpupri is set to the task's priority equivalent, but real rq->rt.highest_prio.curr is less. The patch below fixes the problem. Signed-off-by: Kirill Tkhai <tkhai@yandex.ru> Signed-off-by: Peter Zijlstra <peterz@infradead.org> CC: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/49231385567953@web4m.yandex.ru Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-08ftrace: Initialize the ftrace profiler for each possible cpuMiao Xie
commit c4602c1c818bd6626178d6d3fcc152d9f2f48ac0 upstream. Ftrace currently initializes only the online CPUs. This implementation has two problems: - If we online a CPU after we enable the function profile, and then run the test, we will lose the trace information on that CPU. Steps to reproduce: # echo 0 > /sys/devices/system/cpu/cpu1/online # cd <debugfs>/tracing/ # echo <some function name> >> set_ftrace_filter # echo 1 > function_profile_enabled # echo 1 > /sys/devices/system/cpu/cpu1/online # run test - If we offline a CPU before we enable the function profile, we will not clear the trace information when we enable the function profile. It will trouble the users. Steps to reproduce: # cd <debugfs>/tracing/ # echo <some function name> >> set_ftrace_filter # echo 1 > function_profile_enabled # run test # cat trace_stat/function* # echo 0 > /sys/devices/system/cpu/cpu1/online # echo 0 > function_profile_enabled # echo 1 > function_profile_enabled # cat trace_stat/function* # run test # cat trace_stat/function* So it is better that we initialize the ftrace profiler for each possible cpu every time we enable the function profile instead of just the online ones. Link: http://lkml.kernel.org/r/1387178401-10619-1-git-send-email-miaox@cn.fujitsu.com Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-20futex: fix handling of read-only-mapped hugepagesLinus Torvalds
commit f12d5bfceb7e1f9051563381ec047f7f13956c3c upstream. The hugepage code had the exact same bug that regular pages had in commit 7485d0d3758e ("futexes: Remove rw parameter from get_futex_key()"). The regular page case was fixed by commit 9ea71503a8ed ("futex: Fix regression with read only mappings"), but the transparent hugepage case (added in a5b338f2b0b1: "thp: update futex compound knowledge") case remained broken. Found by Dave Jones and his trinity tool. Reported-and-tested-by: Dave Jones <davej@fedoraproject.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Darren Hart <dvhart@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-11irq: Enable all irqs unconditionally in irq_resumeLaxman Dewangan
commit ac01810c9d2814238f08a227062e66a35a0e1ea2 upstream. When the system enters suspend, it disables all interrupts in suspend_device_irqs(), including the interrupts marked EARLY_RESUME. On the resume side things are different. The EARLY_RESUME interrupts are reenabled in sys_core_ops->resume and the non EARLY_RESUME interrupts are reenabled in the normal system resume path. When suspend_noirq() failed or suspend is aborted for any other reason, we might omit the resume side call to sys_core_ops->resume() and therefor the interrupts marked EARLY_RESUME are not reenabled and stay disabled forever. To solve this, enable all irqs unconditionally in irq_resume() regardless whether interrupts marked EARLY_RESUMEhave been already enabled or not. This might try to reenable already enabled interrupts in the non failure case, but the only affected platform is XEN and it has been confirmed that it does not cause any side effects. [ tglx: Massaged changelog. ] Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com> Acked-by-and-tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: Heiko Stuebner <heiko@sntech.de> Reviewed-by: Pavel Machek <pavel@ucw.cz> Cc: <ian.campbell@citrix.com> Cc: <rjw@rjwysocki.net> Cc: <len.brown@intel.com> Cc: <gregkh@linuxfoundation.org> Link: http://lkml.kernel.org/r/1385388587-16442-1-git-send-email-ldewangan@nvidia.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-04ftrace: Fix function graph with loading of modulesSteven Rostedt (Red Hat)
commit 8a56d7761d2d041ae5e8215d20b4167d8aa93f51 upstream. Commit 8c4f3c3fa9681 "ftrace: Check module functions being traced on reload" fixed module loading and unloading with respect to function tracing, but it missed the function graph tracer. If you perform the following # cd /sys/kernel/debug/tracing # echo function_graph > current_tracer # modprobe nfsd # echo nop > current_tracer You'll get the following oops message: ------------[ cut here ]------------ WARNING: CPU: 2 PID: 2910 at /linux.git/kernel/trace/ftrace.c:1640 __ftrace_hash_rec_update.part.35+0x168/0x1b9() Modules linked in: nfsd exportfs nfs_acl lockd ipt_MASQUERADE sunrpc ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables uinput snd_hda_codec_idt CPU: 2 PID: 2910 Comm: bash Not tainted 3.13.0-rc1-test #7 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007 0000000000000668 ffff8800787efcf8 ffffffff814fe193 ffff88007d500000 0000000000000000 ffff8800787efd38 ffffffff8103b80a 0000000000000668 ffffffff810b2b9a ffffffff81a48370 0000000000000001 ffff880037aea000 Call Trace: [<ffffffff814fe193>] dump_stack+0x4f/0x7c [<ffffffff8103b80a>] warn_slowpath_common+0x81/0x9b [<ffffffff810b2b9a>] ? __ftrace_hash_rec_update.part.35+0x168/0x1b9 [<ffffffff8103b83e>] warn_slowpath_null+0x1a/0x1c [<ffffffff810b2b9a>] __ftrace_hash_rec_update.part.35+0x168/0x1b9 [<ffffffff81502f89>] ? __mutex_lock_slowpath+0x364/0x364 [<ffffffff810b2cc2>] ftrace_shutdown+0xd7/0x12b [<ffffffff810b47f0>] unregister_ftrace_graph+0x49/0x78 [<ffffffff810c4b30>] graph_trace_reset+0xe/0x10 [<ffffffff810bf393>] tracing_set_tracer+0xa7/0x26a [<ffffffff810bf5e1>] tracing_set_trace_write+0x8b/0xbd [<ffffffff810c501c>] ? ftrace_return_to_handler+0xb2/0xde [<ffffffff811240a8>] ? __sb_end_write+0x5e/0x5e [<ffffffff81122aed>] vfs_write+0xab/0xf6 [<ffffffff8150a185>] ftrace_graph_caller+0x85/0x85 [<ffffffff81122dbd>] SyS_write+0x59/0x82 [<ffffffff8150a185>] ftrace_graph_caller+0x85/0x85 [<ffffffff8150a2d2>] system_call_fastpath+0x16/0x1b ---[ end trace 940358030751eafb ]--- The above mentioned commit didn't go far enough. Well, it covered the function tracer by adding checks in __register_ftrace_function(). The problem is that the function graph tracer circumvents that (for a slight efficiency gain when function graph trace is running with a function tracer. The gain was not worth this). The problem came with ftrace_startup() which should always be called after __register_ftrace_function(), if you want this bug to be completely fixed. Anyway, this solution moves __register_ftrace_function() inside of ftrace_startup() and removes the need to call them both. Reported-by: Dave Wysochanski <dwysocha@redhat.com> Fixes: ed926f9b35cd ("ftrace: Use counters to enable functions to trace") Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-04cpuset: Fix memory allocator deadlockPeter Zijlstra
commit 0fc0287c9ed1ffd3706f8b4d9b314aa102ef1245 upstream. Juri hit the below lockdep report: [ 4.303391] ====================================================== [ 4.303392] [ INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected ] [ 4.303394] 3.12.0-dl-peterz+ #144 Not tainted [ 4.303395] ------------------------------------------------------ [ 4.303397] kworker/u4:3/689 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: [ 4.303399] (&p->mems_allowed_seq){+.+...}, at: [<ffffffff8114e63c>] new_slab+0x6c/0x290 [ 4.303417] [ 4.303417] and this task is already holding: [ 4.303418] (&(&q->__queue_lock)->rlock){..-...}, at: [<ffffffff812d2dfb>] blk_execute_rq_nowait+0x5b/0x100 [ 4.303431] which would create a new lock dependency: [ 4.303432] (&(&q->__queue_lock)->rlock){..-...} -> (&p->mems_allowed_seq){+.+...} [ 4.303436] [ 4.303898] the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock: [ 4.303918] -> (&p->mems_allowed_seq){+.+...} ops: 2762 { [ 4.303922] HARDIRQ-ON-W at: [ 4.303923] [<ffffffff8108ab9a>] __lock_acquire+0x65a/0x1ff0 [ 4.303926] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303929] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303931] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303933] SOFTIRQ-ON-W at: [ 4.303933] [<ffffffff8108abcc>] __lock_acquire+0x68c/0x1ff0 [ 4.303935] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303940] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303955] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303959] INITIAL USE at: [ 4.303960] [<ffffffff8108a884>] __lock_acquire+0x344/0x1ff0 [ 4.303963] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140 [ 4.303966] [<ffffffff81063dd6>] kthreadd+0x86/0x180 [ 4.303969] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0 [ 4.303972] } Which reports that we take mems_allowed_seq with interrupts enabled. A little digging found that this can only be from cpuset_change_task_nodemask(). This is an actual deadlock because an interrupt doing an allocation will hit get_mems_allowed()->...->__read_seqcount_begin(), which will spin forever waiting for the write side to complete. Cc: John Stultz <john.stultz@linaro.org> Cc: Mel Gorman <mgorman@suse.de> Reported-by: Juri Lelli <juri.lelli@gmail.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Tested-by: Juri Lelli <juri.lelli@gmail.com> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-04audit: fix info leak in AUDIT_GET requestsMathias Krause
commit 64fbff9ae0a0a843365d922e0057fc785f23f0e3 upstream. We leak 4 bytes of kernel stack in response to an AUDIT_GET request as we miss to initialize the mask member of status_set. Fix that. Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Eric Paris <eparis@redhat.com> Signed-off-by: Mathias Krause <minipli@googlemail.com> Signed-off-by: Richard Guy Briggs <rgb@redhat.com> Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-04audit: use nlmsg_len() to get message payload lengthMathias Krause
commit 4d8fe7376a12bf4524783dd95cbc00f1fece6232 upstream. Using the nlmsg_len member of the netlink header to test if the message is valid is wrong as it includes the size of the netlink header itself. Thereby allowing to send short netlink messages that pass those checks. Use nlmsg_len() instead to test for the right message length. The result of nlmsg_len() is guaranteed to be non-negative as the netlink message already passed the checks of nlmsg_ok(). Also switch to min_t() to please checkpatch.pl. Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Eric Paris <eparis@redhat.com> Signed-off-by: Mathias Krause <minipli@googlemail.com> Signed-off-by: Richard Guy Briggs <rgb@redhat.com> Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-04audit: printk USER_AVC messages when audit isn't enabledTyler Hicks
commit 0868a5e150bc4c47e7a003367cd755811eb41e0b upstream. When the audit=1 kernel parameter is absent and auditd is not running, AUDIT_USER_AVC messages are being silently discarded. AUDIT_USER_AVC messages should be sent to userspace using printk(), as mentioned in the commit message of 4a4cd633 ("AUDIT: Optimise the audit-disabled case for discarding user messages"). When audit_enabled is 0, audit_receive_msg() discards all user messages except for AUDIT_USER_AVC messages. However, audit_log_common_recv_msg() refuses to allocate an audit_buffer if audit_enabled is 0. The fix is to special case AUDIT_USER_AVC messages in both functions. It looks like commit 50397bd1 ("[AUDIT] clean up audit_receive_msg()") introduced this bug. Signed-off-by: Tyler Hicks <tyhicks@canonical.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Eric Paris <eparis@redhat.com> Cc: linux-audit@redhat.com Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Richard Guy Briggs <rgb@redhat.com> Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-04PM / hibernate: Avoid overflow in hibernate_preallocate_memory()Aaron Lu
commit fd432b9f8c7c88428a4635b9f5a9c6e174df6e36 upstream. When system has a lot of highmem (e.g. 16GiB using a 32 bits kernel), the code to calculate how much memory we need to preallocate in normal zone may cause overflow. As Leon has analysed: It looks that during computing 'alloc' variable there is overflow: alloc = (3943404 - 1970542) - 1978280 = -5418 (signed) And this function goes to err_out. Fix this by avoiding that overflow. References: https://bugzilla.kernel.org/show_bug.cgi?id=60817 Reported-and-tested-by: Leon Drugi <eyak@wp.pl> Signed-off-by: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-12-04alarmtimer: return EINVAL instead of ENOTSUPP if rtcdev doesn't existKOSAKI Motohiro
commit 98d6f4dd84a134d942827584a3c5f67ffd8ec35f upstream. Fedora Ruby maintainer reported latest Ruby doesn't work on Fedora Rawhide on ARM. (http://bugs.ruby-lang.org/issues/9008) Because of, commit 1c6b39ad3f (alarmtimers: Return -ENOTSUPP if no RTC device is present) intruduced to return ENOTSUPP when clock_get{time,res} can't find a RTC device. However this is incorrect. First, ENOTSUPP isn't exported to userland (ENOTSUP or EOPNOTSUP are the closest userland equivlents). Second, Posix and Linux man pages agree that clock_gettime and clock_getres should return EINVAL if clk_id argument is invalid. While the arugment that the clockid is valid, but just not supported on this hardware could be made, this is just a technicality that doesn't help userspace applicaitons, and only complicates error handling. Thus, this patch changes the code to use EINVAL. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Reported-by: Vit Ondruch <v.ondruch@tiscali.cz> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> [jstultz: Tweaks to commit message to include full rational] Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29exec/ptrace: fix get_dumpable() incorrect testsKees Cook
commit d049f74f2dbe71354d43d393ac3a188947811348 upstream. The get_dumpable() return value is not boolean. Most users of the function actually want to be testing for non-SUID_DUMP_USER(1) rather than SUID_DUMP_DISABLE(0). The SUID_DUMP_ROOT(2) is also considered a protected state. Almost all places did this correctly, excepting the two places fixed in this patch. Wrong logic: if (dumpable == SUID_DUMP_DISABLE) { /* be protective */ } or if (dumpable == 0) { /* be protective */ } or if (!dumpable) { /* be protective */ } Correct logic: if (dumpable != SUID_DUMP_USER) { /* be protective */ } or if (dumpable != 1) { /* be protective */ } Without this patch, if the system had set the sysctl fs/suid_dumpable=2, a user was able to ptrace attach to processes that had dropped privileges to that user. (This may have been partially mitigated if Yama was enabled.) The macros have been moved into the file that declares get/set_dumpable(), which means things like the ia64 code can see them too. CVE-2013-2929 Reported-by: Vasily Kulikov <segoon@openwall.com> Signed-off-by: Kees Cook <keescook@chromium.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-29perf/ftrace: Fix paranoid level for enabling function tracerSteven Rostedt
commit 12ae030d54ef250706da5642fc7697cc60ad0df7 upstream. The current default perf paranoid level is "1" which has "perf_paranoid_kernel()" return false, and giving any operations that use it, access to normal users. Unfortunately, this includes function tracing and normal users should not be allowed to enable function tracing by default. The proper level is defined at "-1" (full perf access), which "perf_paranoid_tracepoint_raw()" will only give access to. Use that check instead for enabling function tracing. Reported-by: Dave Jones <davej@redhat.com> Reported-by: Vince Weaver <vincent.weaver@maine.edu> Tested-by: Vince Weaver <vincent.weaver@maine.edu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> CVE: CVE-2013-2930 Fixes: ced39002f5ea ("ftrace, perf: Add support to use function tracepoint in perf") Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-20tracing: Fix potential out-of-bounds in trace_get_user()Steven Rostedt
commit 057db8488b53d5e4faa0cedb2f39d4ae75dfbdbb upstream. Andrey reported the following report: ERROR: AddressSanitizer: heap-buffer-overflow on address ffff8800359c99f3 ffff8800359c99f3 is located 0 bytes to the right of 243-byte region [ffff8800359c9900, ffff8800359c99f3) Accessed by thread T13003: #0 ffffffff810dd2da (asan_report_error+0x32a/0x440) #1 ffffffff810dc6b0 (asan_check_region+0x30/0x40) #2 ffffffff810dd4d3 (__tsan_write1+0x13/0x20) #3 ffffffff811cd19e (ftrace_regex_release+0x1be/0x260) #4 ffffffff812a1065 (__fput+0x155/0x360) #5 ffffffff812a12de (____fput+0x1e/0x30) #6 ffffffff8111708d (task_work_run+0x10d/0x140) #7 ffffffff810ea043 (do_exit+0x433/0x11f0) #8 ffffffff810eaee4 (do_group_exit+0x84/0x130) #9 ffffffff810eafb1 (SyS_exit_group+0x21/0x30) #10 ffffffff81928782 (system_call_fastpath+0x16/0x1b) Allocated by thread T5167: #0 ffffffff810dc778 (asan_slab_alloc+0x48/0xc0) #1 ffffffff8128337c (__kmalloc+0xbc/0x500) #2 ffffffff811d9d54 (trace_parser_get_init+0x34/0x90) #3 ffffffff811cd7b3 (ftrace_regex_open+0x83/0x2e0) #4 ffffffff811cda7d (ftrace_filter_open+0x2d/0x40) #5 ffffffff8129b4ff (do_dentry_open+0x32f/0x430) #6 ffffffff8129b668 (finish_open+0x68/0xa0) #7 ffffffff812b66ac (do_last+0xb8c/0x1710) #8 ffffffff812b7350 (path_openat+0x120/0xb50) #9 ffffffff812b8884 (do_filp_open+0x54/0xb0) #10 ffffffff8129d36c (do_sys_open+0x1ac/0x2c0) #11 ffffffff8129d4b7 (SyS_open+0x37/0x50) #12 ffffffff81928782 (system_call_fastpath+0x16/0x1b) Shadow bytes around the buggy address: ffff8800359c9700: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd ffff8800359c9780: fd fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa ffff8800359c9800: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa ffff8800359c9880: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa ffff8800359c9900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 =>ffff8800359c9980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00[03]fb ffff8800359c9a00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa ffff8800359c9a80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa ffff8800359c9b00: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00 ffff8800359c9b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8800359c9c00: 00 00 00 00 00 00 00 00 fa fa fa fa fa fa fa fa Shadow byte legend (one shadow byte represents 8 application bytes): Addressable: 00 Partially addressable: 01 02 03 04 05 06 07 Heap redzone: fa Heap kmalloc redzone: fb Freed heap region: fd Shadow gap: fe The out-of-bounds access happens on 'parser->buffer[parser->idx] = 0;' Although the crash happened in ftrace_regex_open() the real bug occurred in trace_get_user() where there's an incrementation to parser->idx without a check against the size. The way it is triggered is if userspace sends in 128 characters (EVENT_BUF_SIZE + 1), the loop that reads the last character stores it and then breaks out because there is no more characters. Then the last character is read to determine what to do next, and the index is incremented without checking size. Then the caller of trace_get_user() usually nulls out the last character with a zero, but since the index is equal to the size, it writes a nul character after the allocated space, which can corrupt memory. Luckily, only root user has write access to this file. Link: http://lkml.kernel.org/r/20131009222323.04fd1a0d@gandalf.local.home Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-13clockevents: Sanitize ticks to nsec conversionThomas Gleixner
commit 97b9410643475d6557d2517c2aff9fd2221141a9 upstream. Marc Kleine-Budde pointed out, that commit 77cc982 "clocksource: use clockevents_config_and_register() where possible" caused a regression for some of the converted subarchs. The reason is, that the clockevents core code converts the minimal hardware tick delta to a nanosecond value for core internal usage. This conversion is affected by integer math rounding loss, so the backwards conversion to hardware ticks will likely result in a value which is less than the configured hardware limitation. The affected subarchs used their own workaround (SIGH!) which got lost in the conversion. The solution for the issue at hand is simple: adding evt->mult - 1 to the shifted value before the integer divison in the core conversion function takes care of it. But this only works for the case where for the scaled math mult/shift pair "mult <= 1 << shift" is true. For the case where "mult > 1 << shift" we can apply the rounding add only for the minimum delta value to make sure that the backward conversion is not less than the given hardware limit. For the upper bound we need to omit the rounding add, because the backwards conversion is always larger than the original latch value. That would violate the upper bound of the hardware device. Though looking closer at the details of that function reveals another bogosity: The upper bounds check is broken as well. Checking for a resulting "clc" value greater than KTIME_MAX after the conversion is pointless. The conversion does: u64 clc = (latch << evt->shift) / evt->mult; So there is no sanity check for (latch << evt->shift) exceeding the 64bit boundary. The latch argument is "unsigned long", so on a 64bit arch the handed in argument could easily lead to an unnoticed shift overflow. With the above rounding fix applied the calculation before the divison is: u64 clc = (latch << evt->shift) + evt->mult - 1; So we need to make sure, that neither the shift nor the rounding add is overflowing the u64 boundary. [ukl: move assignment to rnd after eventually changing mult, fix build issue and correct comment with the right math] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Russell King - ARM Linux <linux@arm.linux.org.uk> Cc: Marc Kleine-Budde <mkl@pengutronix.de> Cc: nicolas.ferre@atmel.com Cc: Marc Pignat <marc.pignat@hevs.ch> Cc: john.stultz@linaro.org Cc: kernel@pengutronix.de Cc: Ronald Wahl <ronald.wahl@raritan.com> Cc: LAK <linux-arm-kernel@lists.infradead.org> Cc: Ludovic Desroches <ludovic.desroches@atmel.com> Link: http://lkml.kernel.org/r/1380052223-24139-1-git-send-email-u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>