linux/kernel, branch v3.6

Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-09-21T21:25:46Z

Pull timer fix from Ingo Molnar: "One more timekeeping fix for v3.6" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: time: Fix timeekeping_get_ns overflow on 32bit systems

Merge branch 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2012-09-19T18:00:07Z

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_wq

2012-09-19T17:13:12Z

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 Acked-by: Jiri Kosina Cc: Linus Torvalds Cc: Bjorn Helgaas Cc: Len Brown Cc: Rafael J. Wysocki Cc: stable@vger.kernel.org

Merge branch 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2012-09-17T23:05:23Z

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()

2012-09-17T22:42:31Z

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: [] warn_slowpath_common+0x7f/0xc0 [] warn_slowpath_null+0x1a/0x20 [] worker_thread+0x4cd/0x500 [] kthread+0xbe/0xd0 [] kernel_thread_helper+0x4/0x10 ---[ end trace e977cf20f4661968 ]--- BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] 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:[] [] 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: [] kthread+0xbe/0xd0 [] 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 [] worker_thread+0x360/0x500 RSP 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 Signed-off-by: Tejun Heo

pid-namespace: limit value of ns_last_pid to (0, max_pid)

2012-09-17T22:00:38Z

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 Acked-by: Cyrill Gorcunov Acked-by: Oleg Nesterov Cc: Eric W. Biederman Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Revert "sched: Improve scalability via 'CPU buddies', which withstand random perturbations"

2012-09-16T19:29:43Z

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 Bisected-by: Borislav Petkov Acked-by: Mike Galbraith Cc: Andrew Morton Cc: Thomas Gleixner Cc: Ingo Molnar Signed-off-by: Linus Torvalds

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-09-15T00:44:52Z

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

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-09-15T00:43:45Z

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

time: Fix timeekeping_get_ns overflow on 32bit systems

2012-09-13T15:39:14Z

Daniel Lezcano reported seeing multi-second stalls from keyboard input on his T61 laptop when NOHZ and CPU_IDLE were enabled on a 32bit kernel. He bisected the problem down to commit 1e75fa8be9fb6 ("time: Condense timekeeper.xtime into xtime_sec"). After reproducing this issue, I narrowed the problem down to the fact that timekeeping_get_ns() returns a 64bit nsec value that hasn't been accumulated. In some cases this value was being then stored in timespec.tv_nsec (which is a long). On 32bit systems, with idle times larger then 4 seconds (or less, depending on the value of xtime_nsec), the returned nsec value would overflow 32bits. This limited kept time from increasing, causing timers to not expire. The fix is to make sure we don't directly store the result of timekeeping_get_ns() into a tv_nsec field, instead using a 64bit nsec value which can then be added into the timespec via timespec_add_ns(). Reported-and-bisected-by: Daniel Lezcano Tested-by: Daniel Lezcano Signed-off-by: John Stultz Acked-by: Prarit Bhargava Cc: Richard Cochran Link: http://lkml.kernel.org/r/1347405963-35715-1-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar