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* preparation for generic kernel_thread()Al Viro2012-09-30
| | | | | | | | | Let architectures select GENERIC_KERNEL_THREAD and have their copy_thread() treat NULL regs as "it came from kernel_thread(), sp argument contains the function new thread will be calling and stack_size - the argument for that function". Switching the architectures begins shortly... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Merge branch 'for-3.6-fixes' of ↵Linus Torvalds2012-09-19
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull workqueue / powernow-k8 fix from Tejun Heo: "This is the fix for the bug where cpufreq/powernow-k8 was tripping BUG_ON() in try_to_wake_up_local() by migrating workqueue worker to a different CPU. https://bugzilla.kernel.org/show_bug.cgi?id=47301 As discussed, the fix is now two parts - one to reimplement work_on_cpu() so that it doesn't create a new kthread each time and the actual fix which makes powernow-k8 use work_on_cpu() instead of performing manual migration. While pretty late in the merge cycle, both changes are on the safer side. Jiri and I verified two existing users of work_on_cpu() and Duncan confirmed that the powernow-k8 fix survived about 18 hours of testing." * 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: cpufreq/powernow-k8: workqueue user shouldn't migrate the kworker to another CPU workqueue: reimplement work_on_cpu() using system_wq
| * workqueue: reimplement work_on_cpu() using system_wqTejun Heo2012-09-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The existing work_on_cpu() implementation is hugely inefficient. It creates a new kthread, execute that single function and then let the kthread die on each invocation. Now that system_wq can handle concurrent executions, there's no advantage of doing this. Reimplement work_on_cpu() using system_wq which makes it simpler and way more efficient. stable: While this isn't a fix in itself, it's needed to fix a workqueue related bug in cpufreq/powernow-k8. AFAICS, this shouldn't break other existing users. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Jiri Kosina <jkosina@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Len Brown <lenb@kernel.org> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: stable@vger.kernel.org
* | Merge branch 'for-3.6-fixes' of ↵Linus Torvalds2012-09-17
|\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull another workqueue fix from Tejun Heo: "Unfortunately, yet another late fix. This too is discovered and fixed by Lai. This bug was introduced during this merge window by commit 25511a477657 ("workqueue: reimplement CPU online rebinding to handle idle workers") which started using WORKER_REBIND flag for idle rebind too. The bug is relatively easy to trigger if the CPU rapidly goes through off, on and then off (and stay off). The fix is on the safer side. This hasn't been on linux-next yet but I'm pushing early so that it can get more exposure before v3.6 release." * 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: always clear WORKER_REBIND in busy_worker_rebind_fn()
| * workqueue: always clear WORKER_REBIND in busy_worker_rebind_fn()Lai Jiangshan2012-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | busy_worker_rebind_fn() didn't clear WORKER_REBIND if rebinding failed (CPU is down again). This used to be okay because the flag wasn't used for anything else. However, after 25511a477 "workqueue: reimplement CPU online rebinding to handle idle workers", WORKER_REBIND is also used to command idle workers to rebind. If not cleared, the worker may confuse the next CPU_UP cycle by having REBIND spuriously set or oops / get stuck by prematurely calling idle_worker_rebind(). WARNING: at /work/os/wq/kernel/workqueue.c:1323 worker_thread+0x4cd/0x5 00() Hardware name: Bochs Modules linked in: test_wq(O-) Pid: 33, comm: kworker/1:1 Tainted: G O 3.6.0-rc1-work+ #3 Call Trace: [<ffffffff8109039f>] warn_slowpath_common+0x7f/0xc0 [<ffffffff810903fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff810b3f1d>] worker_thread+0x4cd/0x500 [<ffffffff810bc16e>] kthread+0xbe/0xd0 [<ffffffff81bd2664>] kernel_thread_helper+0x4/0x10 ---[ end trace e977cf20f4661968 ]--- BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff810b3db0>] worker_thread+0x360/0x500 PGD 0 Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC Modules linked in: test_wq(O-) CPU 0 Pid: 33, comm: kworker/1:1 Tainted: G W O 3.6.0-rc1-work+ #3 Bochs Bochs RIP: 0010:[<ffffffff810b3db0>] [<ffffffff810b3db0>] worker_thread+0x360/0x500 RSP: 0018:ffff88001e1c9de0 EFLAGS: 00010086 RAX: 0000000000000000 RBX: ffff88001e633e00 RCX: 0000000000004140 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000009 RBP: ffff88001e1c9ea0 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000002 R11: 0000000000000000 R12: ffff88001fc8d580 R13: ffff88001fc8d590 R14: ffff88001e633e20 R15: ffff88001e1c6900 FS: 0000000000000000(0000) GS:ffff88001fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000000 CR3: 00000000130e8000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kworker/1:1 (pid: 33, threadinfo ffff88001e1c8000, task ffff88001e1c6900) Stack: ffff880000000000 ffff88001e1c9e40 0000000000000001 ffff88001e1c8010 ffff88001e519c78 ffff88001e1c9e58 ffff88001e1c6900 ffff88001e1c6900 ffff88001e1c6900 ffff88001e1c6900 ffff88001fc8d340 ffff88001fc8d340 Call Trace: [<ffffffff810bc16e>] kthread+0xbe/0xd0 [<ffffffff81bd2664>] kernel_thread_helper+0x4/0x10 Code: b1 00 f6 43 48 02 0f 85 91 01 00 00 48 8b 43 38 48 89 df 48 8b 00 48 89 45 90 e8 ac f0 ff ff 3c 01 0f 85 60 01 00 00 48 8b 53 50 <8b> 02 83 e8 01 85 c0 89 02 0f 84 3b 01 00 00 48 8b 43 38 48 8b RIP [<ffffffff810b3db0>] worker_thread+0x360/0x500 RSP <ffff88001e1c9de0> CR2: 0000000000000000 There was no reason to keep WORKER_REBIND on failure in the first place - WORKER_UNBOUND is guaranteed to be set in such cases preventing incorrectly activating concurrency management. Always clear WORKER_REBIND. tj: Updated comment and description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | pid-namespace: limit value of ns_last_pid to (0, max_pid)Andrew Vagin2012-09-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kernel doesn't check the pid for negative values, so if you try to write -2 to /proc/sys/kernel/ns_last_pid, you will get a kernel panic. The crash happens because the next pid is -1, and alloc_pidmap() will try to access to a nonexistent pidmap. map = &pid_ns->pidmap[pid/BITS_PER_PAGE]; Signed-off-by: Andrew Vagin <avagin@openvz.org> Acked-by: Cyrill Gorcunov <gorcunov@openvz.org> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Revert "sched: Improve scalability via 'CPU buddies', which withstand random ↵Linus Torvalds2012-09-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | perturbations" This reverts commit 970e178985cadbca660feb02f4d2ee3a09f7fdda. Nikolay Ulyanitsky reported thatthe 3.6-rc5 kernel has a 15-20% performance drop on PostgreSQL 9.2 on his machine (running "pgbench"). Borislav Petkov was able to reproduce this, and bisected it to this commit 970e178985ca ("sched: Improve scalability via 'CPU buddies' ...") apparently because the new single-idle-buddy model simply doesn't find idle CPU's to reschedule on aggressively enough. Mike Galbraith suspects that it is likely due to the user-mode spinlocks in PostgreSQL not reacting well to preemption, but we don't really know the details - I'll just revert the commit for now. There are hopefully other approaches to improve scheduler scalability without it causing these kinds of downsides. Reported-by: Nikolay Ulyanitsky <lystor@gmail.com> Bisected-by: Borislav Petkov <bp@alien8.de> Acked-by: Mike Galbraith <efault@gmx.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds2012-09-14
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "Smaller fixlets" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Fix kernel-doc warnings in kernel/sched/fair.c sched: Unthrottle rt runqueues in __disable_runtime() sched: Add missing call to calc_load_exit_idle() sched: Fix load avg vs cpu-hotplug
| * | sched: Fix kernel-doc warnings in kernel/sched/fair.cRandy Dunlap2012-09-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix two kernel-doc warnings in kernel/sched/fair.c: Warning(kernel/sched/fair.c:3660): Excess function parameter 'cpus' description in 'update_sg_lb_stats' Warning(kernel/sched/fair.c:3806): Excess function parameter 'cpus' description in 'update_sd_lb_stats' Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/50303714.3090204@xenotime.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Unthrottle rt runqueues in __disable_runtime()Peter Boonstoppel2012-09-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | sched: Add missing call to calc_load_exit_idle()Charles Wang2012-09-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Azat Khuzhin reported high loadavg in Linux v3.6 After checking the upstream scheduler code, I found Peter's commit: 5167e8d5417b sched/nohz: Rewrite and fix load-avg computation -- again not fully applied, missing the call to calc_load_exit_idle(). After that idle exit in sampling window will always be calculated to non-idle, and the load will be higher than normal. This patch adds the missing call to calc_load_exit_idle(). Signed-off-by: Charles Wang <muming.wq@taobao.com> Cc: stable@kernel.org Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1345449754-27130-1-git-send-email-muming.wq@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Fix load avg vs cpu-hotplugPeter Zijlstra2012-09-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rabik and Paul reported two different issues related to the same few lines of code. Rabik's issue is that the nr_uninterruptible migration code is wrong in that he sees artifacts due to this (Rabik please do expand in more detail). Paul's issue is that this code as it stands relies on us using stop_machine() for unplug, we all would like to remove this assumption so that eventually we can remove this stop_machine() usage altogether. The only reason we'd have to migrate nr_uninterruptible is so that we could use for_each_online_cpu() loops in favour of for_each_possible_cpu() loops, however since nr_uninterruptible() is the only such loop and its using possible lets not bother at all. The problem Rabik sees is (probably) caused by the fact that by migrating nr_uninterruptible we screw rq->calc_load_active for both rqs involved. So don't bother with fancy migration schemes (meaning we now have to keep using for_each_possible_cpu()) and instead fold any nr_active delta after we migrate all tasks away to make sure we don't have any skewed nr_active accounting. Reported-by: Rakib Mullick <rakib.mullick@gmail.com> Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1345454817.23018.27.camel@twins Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds2012-09-14
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Ingo Molnar: "This tree includes various fixes" Ingo really needs to improve on the whole "explain git pull" part. "Various fixes" indeed. * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf/hwpb: Invoke __perf_event_disable() if interrupts are already disabled perf/x86: Enable Intel Cedarview Atom suppport perf_event: Switch to internal refcount, fix race with close() oprofile, s390: Fix uninitialized memory access when writing to oprofilefs perf/x86: Fix microcode revision check for SNB-PEBS
| * | | perf/hwpb: Invoke __perf_event_disable() if interrupts are already disabledK.Prasad2012-09-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While debugging a warning message on PowerPC while using hardware breakpoints, it was discovered that when perf_event_disable is invoked through hw_breakpoint_handler function with interrupts disabled, a subsequent IPI in the code path would trigger a WARN_ON_ONCE message in smp_call_function_single function. This patch calls __perf_event_disable() when interrupts are already disabled, instead of perf_event_disable(). Reported-by: Edjunior Barbosa Machado <emachado@linux.vnet.ibm.com> Signed-off-by: K.Prasad <Prasad.Krishnan@gmail.com> [naveen.n.rao@linux.vnet.ibm.com: v3: Check to make sure we target current task] Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20120802081635.5811.17737.stgit@localhost.localdomain [ Fixed build error on MIPS. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | perf_event: Switch to internal refcount, fix race with close()Al Viro2012-09-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Don't mess with file refcounts (or keep a reference to file, for that matter) in perf_event. Use explicit refcount of its own instead. Deal with the race between the final reference to event going away and new children getting created for it by use of atomic_long_inc_not_zero() in inherit_event(); just have the latter free what it had allocated and return NULL, that works out just fine (children of siblings of something doomed are created as singletons, same as if the child of leader had been created and immediately killed). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@kernel.org Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20120820135925.GG23464@ZenIV.linux.org.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | | Merge branch 'for-3.6-fixes' of ↵Linus Torvalds2012-09-11
|\ \ \ \ | |_|/ / |/| | / | | |/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull workqueue fixes from Tejun Heo: "It's later than I'd like but well the timing just didn't work out this time. There are three bug fixes. One from before 3.6-rc1 and two from the new CPU hotplug code. Kudos to Lai for discovering all of them and providing fixes. * Atomicity bug when clearing a flag and setting another. The two operation should have been atomic but wasn't. This bug has existed for a long time but is unlikely to have actually happened. Fix is safe. Marked for -stable. * If CPU hotplug cycles happen back-to-back before workers finish the previous cycle, the states could get out of sync and it could get stuck. Fixed by waiting for workers to complete before finishing hotplug cycle. * While CPU hotplug is in progress, idle workers could be depleted which can then lead to deadlock. I think both happening together is highly unlikely but still better to fix it and the fix isn't too scary. There's another workqueue related regression which reported a few days ago: https://bugzilla.kernel.org/show_bug.cgi?id=47301 It's a bit of head scratcher but there is a semi-reliable reproduce case, so I'm hoping to resolve it soonish." * 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: fix possible idle worker depletion across CPU hotplug workqueue: restore POOL_MANAGING_WORKERS workqueue: fix possible deadlock in idle worker rebinding workqueue: move WORKER_REBIND clearing in rebind_workers() to the end of the function workqueue: UNBOUND -> REBIND morphing in rebind_workers() should be atomic
| * | workqueue: fix possible idle worker depletion across CPU hotplugLai Jiangshan2012-09-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To simplify both normal and CPU hotplug paths, worker management is prevented while CPU hoplug is in progress. This is achieved by CPU hotplug holding the same exclusion mechanism used by workers to ensure there's only one manager per pool. If someone else seems to be performing the manager role, workers proceed to execute work items. CPU hotplug using the same mechanism can lead to idle worker depletion because all workers could proceed to execute work items while CPU hotplug is in progress and CPU hotplug itself wouldn't actually perform the worker management duty - it doesn't guarantee that there's an idle worker left when it releases management. This idle worker depletion, under extreme circumstances, can break forward-progress guarantee and thus lead to deadlock. This patch fixes the bug by using separate mechanisms for manager exclusion among workers and hotplug exclusion. For manager exclusion, POOL_MANAGING_WORKERS which was restored by the previous patch is used. pool->manager_mutex is now only used for exclusion between the elected manager and CPU hotplug. The elected manager won't proceed without holding pool->manager_mutex. This ensures that the worker which won the manager position can't skip managing while CPU hotplug is in progress. It will block on manager_mutex and perform management after CPU hotplug is complete. Note that hotplug may happen while waiting for manager_mutex. A manager isn't either on idle or busy list and thus the hoplug code can't unbind/rebind it. Make the manager handle its own un/rebinding. tj: Updated comment and description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
| * | workqueue: restore POOL_MANAGING_WORKERSLai Jiangshan2012-09-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch restores POOL_MANAGING_WORKERS which was replaced by pool->manager_mutex by 6037315269 "workqueue: use mutex for global_cwq manager exclusion". There's a subtle idle worker depletion bug across CPU hotplug events and we need to distinguish an actual manager and CPU hotplug preventing management. POOL_MANAGING_WORKERS will be used for the former and manager_mutex the later. This patch just lays POOL_MANAGING_WORKERS on top of the existing manager_mutex and doesn't introduce any synchronization changes. The next patch will update it. Note that this patch fixes a non-critical anomaly where too_many_workers() may return %true spuriously while CPU hotplug is in progress. While the issue could schedule idle timer spuriously, it didn't trigger any actual misbehavior. tj: Rewrote patch description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
| * | workqueue: fix possible deadlock in idle worker rebindingTejun Heo2012-09-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, rebind_workers() and idle_worker_rebind() are two-way interlocked. rebind_workers() waits for idle workers to finish rebinding and rebound idle workers wait for rebind_workers() to finish rebinding busy workers before proceeding. Unfortunately, this isn't enough. The second wait from idle workers is implemented as follows. wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND)); rebind_workers() clears WORKER_REBIND, wakes up the idle workers and then returns. If CPU hotplug cycle happens again before one of the idle workers finishes the above wait_event(), rebind_workers() will repeat the first part of the handshake - set WORKER_REBIND again and wait for the idle worker to finish rebinding - and this leads to deadlock because the idle worker would be waiting for WORKER_REBIND to clear. This is fixed by adding another interlocking step at the end - rebind_workers() now waits for all the idle workers to finish the above WORKER_REBIND wait before returning. This ensures that all rebinding steps are complete on all idle workers before the next hotplug cycle can happen. This problem was diagnosed by Lai Jiangshan who also posted a patch to fix the issue, upon which this patch is based. This is the minimal fix and further patches are scheduled for the next merge window to simplify the CPU hotplug path. Signed-off-by: Tejun Heo <tj@kernel.org> Original-patch-by: Lai Jiangshan <laijs@cn.fujitsu.com> LKML-Reference: <1346516916-1991-3-git-send-email-laijs@cn.fujitsu.com>
| * | workqueue: move WORKER_REBIND clearing in rebind_workers() to the end of the ↵Tejun Heo2012-09-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | function This doesn't make any functional difference and is purely to help the next patch to be simpler. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
| * | workqueue: UNBOUND -> REBIND morphing in rebind_workers() should be atomicLai Jiangshan2012-09-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The compiler may compile the following code into TWO write/modify instructions. worker->flags &= ~WORKER_UNBOUND; worker->flags |= WORKER_REBIND; so the other CPU may temporarily see worker->flags which doesn't have either WORKER_UNBOUND or WORKER_REBIND set and perform local wakeup prematurely. Fix it by using single explicit assignment via ACCESS_ONCE(). Because idle workers have another WORKER_NOT_RUNNING flag, this bug doesn't exist for them; however, update it to use the same pattern for consistency. tj: Applied the change to idle workers too and updated comments and patch description a bit. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org
* | | time: Move ktime_t overflow checking into timespec_valid_strictJohn Stultz2012-09-01
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Andreas Bombe reported that the added ktime_t overflow checking added to timespec_valid in commit 4e8b14526ca7 ("time: Improve sanity checking of timekeeping inputs") was causing problems with X.org because it caused timeouts larger then KTIME_T to be invalid. Previously, these large timeouts would be clamped to KTIME_MAX and would never expire, which is valid. This patch splits the ktime_t overflow checking into a new timespec_valid_strict function, and converts the timekeeping codes internal checking to use this more strict function. Reported-and-tested-by: Andreas Bombe <aeb@debian.org> Cc: Zhouping Liu <zliu@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds2012-08-24
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Ingo Molnar: "This tree contains misc fixlets: a perf script python binding fix, a uprobes fix and a syscall tracing fix." * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf tools: Add missing files to build the python binding uprobes: Fix mmap_region()'s mm->mm_rb corruption if uprobe_mmap() fails tracing/syscalls: Fix perf syscall tracing when syscall_nr == -1
| * \ Merge branch 'tip/perf/urgent' of ↵Ingo Molnar2012-08-21
| |\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/urgent Pull syscall tracing fix from Steve Rostedt. Signed-off-by: Ingo Molnar <mingo@kernel.org>
| | * | tracing/syscalls: Fix perf syscall tracing when syscall_nr == -1Will Deacon2012-08-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | syscall_get_nr can return -1 in the case that the task is not executing a system call. This patch fixes perf_syscall_{enter,exit} to check that the syscall number is valid before using it as an index into a bitmap. Link: http://lkml.kernel.org/r/1345137254-7377-1-git-send-email-will.deacon@arm.com Cc: Jason Baron <jbaron@redhat.com> Cc: Wade Farnsworth <wade_farnsworth@mentor.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | uprobes: Fix mmap_region()'s mm->mm_rb corruption if uprobe_mmap() failsOleg Nesterov2012-08-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes: https://bugzilla.redhat.com/show_bug.cgi?id=843640 If mmap_region()->uprobe_mmap() fails, unmap_and_free_vma path does unmap_region() but does not remove the soon-to-be-freed vma from rb tree. Actually there are more problems but this is how William noticed this bug. Perhaps we could do do_munmap() + return in this case, but in fact it is simply wrong to abort if uprobe_mmap() fails. Until at least we move the !UPROBE_COPY_INSN code from install_breakpoint() to uprobe_register(). For example, uprobe_mmap()->install_breakpoint() can fail if the probed insn is not supported (remember, uprobe_register() succeeds if nobody mmaps inode/offset), mmap() should not fail in this case. dup_mmap()->uprobe_mmap() is wrong too by the same reason, fork() can race with uprobe_register() and fail for no reason if it wins the race and does install_breakpoint() first. And, if nothing else, both mmap_region() and dup_mmap() return success if uprobe_mmap() fails. Change them to ignore the error code from uprobe_mmap(). Reported-and-tested-by: William Cohen <wcohen@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> # v3.5 Cc: Anton Arapov <anton@redhat.com> Cc: William Cohen <wcohen@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20120819171042.GB26957@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | | Merge branch 'timers-urgent-for-linus' of ↵Linus Torvalds2012-08-24
|\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer fixes from Thomas Gleixner: "Mostly small fixes for the fallout of the timekeeping overhaul in 3.6 along with stable fixes to address an accumulation problem and missing sanity checks for RTC readouts and user space provided values." * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: time: Avoid making adjustments if we haven't accumulated anything time: Avoid potential shift overflow with large shift values time: Fix casting issue in timekeeping_forward_now time: Ensure we normalize the timekeeper in tk_xtime_add time: Improve sanity checking of timekeeping inputs
| * | | | time: Avoid making adjustments if we haven't accumulated anythingJohn Stultz2012-08-22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If update_wall_time() is called and the current offset isn't large enough to accumulate, avoid re-calling timekeeping_adjust which may change the clock freq and can cause 1ns inconsistencies with CLOCK_REALTIME_COARSE/CLOCK_MONOTONIC_COARSE. Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1345595449-34965-5-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | | time: Avoid potential shift overflow with large shift valuesJohn Stultz2012-08-22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Andreas Schwab noticed that the 1 << tk->shift could overflow if the shift value was greater than 30, since 1 would be a 32bit long on 32bit architectures. This issue was introduced by 1e75fa8be (time: Condense timekeeper.xtime into xtime_sec) Use 1ULL instead to ensure we don't overflow on the shift. Reported-by: Andreas Schwab <schwab@linux-m68k.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/1345595449-34965-4-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | | time: Fix casting issue in timekeeping_forward_nowAndreas Schwab2012-08-22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | arch_gettimeoffset returns a u32 value which when shifted by tk->shift can overflow. This issue was introduced with 1e75fa8be (time: Condense timekeeper.xtime into xtime_sec) Cast it to u64 first. Signed-off-by: Andreas Schwab <schwab@linux-m68k.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/1345595449-34965-3-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | | time: Ensure we normalize the timekeeper in tk_xtime_addJohn Stultz2012-08-22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Andreas noticed problems with resume on specific hardware after commit 1e75fa8b (time: Condense timekeeper.xtime into xtime_sec) combined with commit b44d50dca (time: Fix casting issue in tk_set_xtime and tk_xtime_add) After some digging I realized we aren't normalizing the timekeeper after the add. Add the missing normalize call. Reported-by: Andreas Schwab <schwab@linux-m68k.org> Tested-by: Andreas Schwab <schwab@linux-m68k.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/1345595449-34965-2-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | | time: Improve sanity checking of timekeeping inputsJohn Stultz2012-08-15
| | |/ / | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Unexpected behavior could occur if the time is set to a value large enough to overflow a 64bit ktime_t (which is something larger then the year 2262). Also unexpected behavior could occur if large negative offsets are injected via adjtimex. So this patch improves the sanity check timekeeping inputs by improving the timespec_valid() check, and then makes better use of timespec_valid() to make sure we don't set the time to an invalid negative value or one that overflows ktime_t. Note: This does not protect from setting the time close to overflowing ktime_t and then letting natural accumulation cause the overflow. Reported-by: CAI Qian <caiqian@redhat.com> Reported-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Zhouping Liu <zliu@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1344454580-17031-1-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | | | Merge branch 'audit-fixes' of ↵Linus Torvalds2012-08-21
|\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs Pull audit-tree fixes from Miklos Szeredi: "The audit subsystem maintainers (Al and Eric) are not responding to repeated resends. Eric did ack them a while ago, but no response since then. So I'm sending these directly to you." * 'audit-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: audit: clean up refcounting in audit-tree audit: fix refcounting in audit-tree audit: don't free_chunk() after fsnotify_add_mark()
| * | | | audit: clean up refcounting in audit-treeMiklos Szeredi2012-08-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Drop the initial reference by fsnotify_init_mark early instead of audit_tree_freeing_mark() at destroy time. In the cases we destroy the mark before we drop the initial reference we need to get rid of the get_mark that balances the put_mark in audit_tree_freeing_mark(). Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
| * | | | audit: fix refcounting in audit-treeMiklos Szeredi2012-08-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Refcounting of fsnotify_mark in audit tree is broken. E.g: refcount create_chunk alloc_chunk 1 fsnotify_add_mark 2 untag_chunk fsnotify_get_mark 3 fsnotify_destroy_mark audit_tree_freeing_mark 2 fsnotify_put_mark 1 fsnotify_put_mark 0 via destroy_list fsnotify_mark_destroy -1 This was reported by various people as triggering Oops when stopping auditd. We could just remove the put_mark from audit_tree_freeing_mark() but that would break freeing via inode destruction. So this patch simply omits a put_mark after calling destroy_mark or adds a get_mark before. The additional get_mark is necessary where there's no other put_mark after fsnotify_destroy_mark() since it assumes that the caller is holding a reference (or the inode is keeping the mark pinned, not the case here AFAICS). Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Reported-by: Valentin Avram <aval13@gmail.com> Reported-by: Peter Moody <pmoody@google.com> Acked-by: Eric Paris <eparis@redhat.com> CC: stable@vger.kernel.org
| * | | | audit: don't free_chunk() after fsnotify_add_mark()Miklos Szeredi2012-08-15
| |/ / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Don't do free_chunk() after fsnotify_add_mark(). That one does a delayed unref via the destroy list and this results in use-after-free. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Acked-by: Eric Paris <eparis@redhat.com> CC: stable@vger.kernel.org
* | / / task_work: add a scheduling point in task_work_run()Eric Dumazet2012-08-21
| |/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It seems commit 4a9d4b024a31 ("switch fput to task_work_add") re- introduced the problem addressed in 944be0b22472 ("close_files(): add scheduling point") If a server process with a lot of files (say 2 million tcp sockets) is killed, we can spend a lot of time in task_work_run() and trigger a soft lockup. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds2012-08-20
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar. * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Fix migration thread runtime bogosity sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttled sched,cgroup: Fix up task_groups list sched: fix divide by zero at {thread_group,task}_times sched, cgroup: Reduce rq->lock hold times for large cgroup hierarchies
| * | | sched: Fix migration thread runtime bogosityMike Galbraith2012-08-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make stop scheduler class do the same accounting as other classes, Migration threads can be caught in the act while doing exec balancing, leading to the below due to use of unmaintained ->se.exec_start. The load that triggered this particular instance was an apparently out of control heavily threaded application that does system monitoring in what equated to an exec bomb, with one of the VERY frequently migrated tasks being ps. %CPU PID USER CMD 99.3 45 root [migration/10] 97.7 53 root [migration/12] 97.0 57 root [migration/13] 90.1 49 root [migration/11] 89.6 65 root [migration/15] 88.7 17 root [migration/3] 80.4 37 root [migration/8] 78.1 41 root [migration/9] 44.2 13 root [migration/2] Signed-off-by: Mike Galbraith <mgalbraith@suse.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1344051854.6739.19.camel@marge.simpson.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttledMike Galbraith2012-08-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | | sched,cgroup: Fix up task_groups listMike Galbraith2012-08-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With multiple instances of task_groups, for_each_rt_rq() is a noop, no task groups having been added to the rt.c list instance. This renders __enable/disable_runtime() and print_rt_stats() noop, the user (non) visible effect being that rt task groups are missing in /proc/sched_debug. Signed-off-by: Mike Galbraith <efault@gmx.de> Cc: stable@kernel.org # v3.3+ Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1344308413.6846.7.camel@marge.simpson.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | sched: fix divide by zero at {thread_group,task}_timesStanislaw Gruszka2012-08-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On architectures where cputime_t is 64 bit type, is possible to trigger divide by zero on do_div(temp, (__force u32) total) line, if total is a non zero number but has lower 32 bit's zeroed. Removing casting is not a good solution since some do_div() implementations do cast to u32 internally. This problem can be triggered in practice on very long lived processes: PID: 2331 TASK: ffff880472814b00 CPU: 2 COMMAND: "oraagent.bin" #0 [ffff880472a51b70] machine_kexec at ffffffff8103214b #1 [ffff880472a51bd0] crash_kexec at ffffffff810b91c2 #2 [ffff880472a51ca0] oops_end at ffffffff814f0b00 #3 [ffff880472a51cd0] die at ffffffff8100f26b #4 [ffff880472a51d00] do_trap at ffffffff814f03f4 #5 [ffff880472a51d60] do_divide_error at ffffffff8100cfff #6 [ffff880472a51e00] divide_error at ffffffff8100be7b [exception RIP: thread_group_times+0x56] RIP: ffffffff81056a16 RSP: ffff880472a51eb8 RFLAGS: 00010046 RAX: bc3572c9fe12d194 RBX: ffff880874150800 RCX: 0000000110266fad RDX: 0000000000000000 RSI: ffff880472a51eb8 RDI: 001038ae7d9633dc RBP: ffff880472a51ef8 R8: 00000000b10a3a64 R9: ffff880874150800 R10: 00007fcba27ab680 R11: 0000000000000202 R12: ffff880472a51f08 R13: ffff880472a51f10 R14: 0000000000000000 R15: 0000000000000007 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #7 [ffff880472a51f00] do_sys_times at ffffffff8108845d #8 [ffff880472a51f40] sys_times at ffffffff81088524 #9 [ffff880472a51f80] system_call_fastpath at ffffffff8100b0f2 RIP: 0000003808caac3a RSP: 00007fcba27ab6d8 RFLAGS: 00000202 RAX: 0000000000000064 RBX: ffffffff8100b0f2 RCX: 0000000000000000 RDX: 00007fcba27ab6e0 RSI: 000000000076d58e RDI: 00007fcba27ab6e0 RBP: 00007fcba27ab700 R8: 0000000000000020 R9: 000000000000091b R10: 00007fcba27ab680 R11: 0000000000000202 R12: 00007fff9ca41940 R13: 0000000000000000 R14: 00007fcba27ac9c0 R15: 00007fff9ca41940 ORIG_RAX: 0000000000000064 CS: 0033 SS: 002b Cc: stable@vger.kernel.org Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20120808092714.GA3580@redhat.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | | sched, cgroup: Reduce rq->lock hold times for large cgroup hierarchiesPeter Zijlstra2012-08-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Peter Portante reported that for large cgroup hierarchies (and or on large CPU counts) we get immense lock contention on rq->lock and stuff stops working properly. His workload was a ton of processes, each in their own cgroup, everybody idling except for a sporadic wakeup once every so often. It was found that: schedule() idle_balance() load_balance() local_irq_save() double_rq_lock() update_h_load() walk_tg_tree(tg_load_down) tg_load_down() Results in an entire cgroup hierarchy walk under rq->lock for every new-idle balance and since new-idle balance isn't throttled this results in a lot of work while holding the rq->lock. This patch does two things, it removes the work from under rq->lock based on the good principle of race and pray which is widely employed in the load-balancer as a whole. And secondly it throttles the update_h_load() calculation to max once per jiffy. I considered excluding update_h_load() for new-idle balance all-together, but purely relying on regular balance passes to update this data might not work out under some rare circumstances where the new-idle busiest isn't the regular busiest for a while (unlikely, but a nightmare to debug if someone hits it and suffers). Cc: pjt@google.com Cc: Larry Woodman <lwoodman@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Reported-by: Peter Portante <pportant@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-aaarrzfpnaam7pqrekofu8a6@git.kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | | | Merge branch 'alpha' (alpha architecture patches)Linus Torvalds2012-08-19
|\ \ \ \ | |_|/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge alpha architecture update from Michael Cree: "The Alpha Maintainer, Matt Turner, is currently unavailable, so I have collected up patches that have been posted to the linux-alpha mailing list over the last couple of months, and are forwarding them to you in the hope that you are prepared to accept them via me. The patches by Al Viro and myself I have been running against kernels for two months now so have had quite a bit of testing. All except one patch were intended for the 3.5 kernel but because of Matt's unavailability never got forwarded to you." * emailed patches from Michael Cree <mcree@orcon.net.nz>: (9 commits) alpha: Fix fall-out from disintegrating asm/system.h Redefine ATOMIC_INIT and ATOMIC64_INIT to drop the casts alpha: fix fpu.h usage in userspace alpha/mm/fault.c: Port OOM changes to do_page_fault alpha: take kernel_execve() out of entry.S alpha: take a bunch of syscalls into osf_sys.c alpha: Use new generic strncpy_from_user() and strnlen_user() alpha: Wire up cross memory attach syscalls alpha: Don't export SOCK_NONBLOCK to user space.
| * | | alpha: take a bunch of syscalls into osf_sys.cAl Viro2012-08-19
| | |/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | New helper: current_thread_info(). Allows to do a bunch of odd syscalls in C. While we are at it, there had never been a reason to do osf_getpriority() in assembler. We also get "namespace"-aware (read: consistent with getuid(2), etc.) behaviour from getx?id() syscalls now. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Michael Cree <mcree@orcon.net.nz> Acked-by: Matt Turner <mattst88@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | Merge tag 'pm-for-3.6-rc2' of ↵Linus Torvalds2012-08-12
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull power management fixes from Rafael J. Wysocki: - Fix for two recent regressions in the generic PM domains framework. - Revert of a commit that introduced a resume regression and is conceptually incorrect in my opinion. - Fix for a return value in pcc-cpufreq.c from Julia Lawall. - RTC wakeup signaling fix from Neil Brown. - Suppression of compiler warnings for CONFIG_PM_SLEEP unset in ACPI, platform/x86 and TPM drivers. * tag 'pm-for-3.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: tpm_tis / PM: Fix unused function warning for CONFIG_PM_SLEEP platform / x86 / PM: Fix unused function warnings for CONFIG_PM_SLEEP ACPI / PM: Fix unused function warnings for CONFIG_PM_SLEEP Revert "NMI watchdog: fix for lockup detector breakage on resume" PM: Make dev_pm_get_subsys_data() always return 0 on success drivers/cpufreq/pcc-cpufreq.c: fix error return code RTC: Avoid races between RTC alarm wakeup and suspend.
| * | | Revert "NMI watchdog: fix for lockup detector breakage on resume"Rafael J. Wysocki2012-08-08
| |/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Revert commit 45226e9 (NMI watchdog: fix for lockup detector breakage on resume) which breaks resume from system suspend on my SH7372 Mackerel board (by causing a NULL pointer dereference to happen) and is generally wrong, because it abuses the CPU hotplug functionality in a shamelessly blatant way. The original issue should be addressed through appropriate syscore resume callback instead. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
* | | printk: Fix calculation of length used to discard recordsJeff Mahoney2012-08-12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While tracking down a weird buffer overflow issue in a program that looked to be sane, I started double checking the length returned by syslog(SYSLOG_ACTION_READ_ALL, ...) to make sure it wasn't overflowing the buffer. Sure enough, it was. I saw this in strace: 11339 syslog(SYSLOG_ACTION_READ_ALL, "<5>[244017.708129] REISERFS (dev"..., 8192) = 8279 It turns out that the loops that calculate how much space the entries will take when they're copied don't include the newlines and prefixes that will be included in the final output since prev flags is passed as zero. This patch properly accounts for it and fixes the overflow. CC: stable@kernel.org Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | time: Fix adjustment cleanup bug in timekeeping_adjust()Ingo Molnar2012-08-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Tetsuo Handa reported that sporadically the system clock starts counting up too quickly which is enough to confuse the hangcheck timer to print a bogus stall warning. Commit 2a8c0883 "time: Move xtime_nsec adjustment underflow handling timekeeping_adjust" overlooked this exit path: } else return; which should really be a proper exit sequence, fixing the bug as a side effect. Also make the flow more readable by properly balancing curly braces. Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote: Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote: Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: john.stultz@linaro.org Cc: a.p.zijlstra@chello.nl Cc: richardcochran@gmail.com Cc: prarit@redhat.com Link: http://lkml.kernel.org/r/20120804192114.GA28347@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | Merge branch 'core-urgent-for-linus' of ↵Linus Torvalds2012-08-03
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull futex fixes from Ingo Molnar: "A couple of futex fixes from Darren Hart: two bugs reported by Dave Jones (found with his trinity test) and Dan Carpenter through static analysis. The third found while debugging the first two." * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: futex: Forbid uaddr == uaddr2 in futex_wait_requeue_pi() futex: Fix bug in WARN_ON for NULL q.pi_state futex: Test for pi_mutex on fault in futex_wait_requeue_pi()
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