linux/kernel, branch v3.0-rc4

Merge branches 'perf-urgent-for-linus', 'sched-urgent-for-linus', 'timers-urgent-for-linus' and 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2011-06-19T16:00:18Z

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: tools/perf: Fix static build of perf tool tracing: Fix regression in printk_formats file * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: generic-ipi: Fix kexec boot crash by initializing call_single_queue before enabling interrupts * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: clocksource: Make watchdog robust vs. interruption timerfd: Fix wakeup of processes when timer is cancelled on clock change * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, MAINTAINERS: Add x86 MCE people x86, efi: Do not reserve boot services regions within reserved areas

Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2011-06-19T15:56:56Z

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: rcu: Move RCU_BOOST #ifdefs to header file rcu: use softirq instead of kthreads except when RCU_BOOST=y rcu: Use softirq to address performance regression rcu: Simplify curing of load woes

KEYS/DNS: Fix ____call_usermodehelper() to not lose the session keyring

2011-06-17T16:40:48Z

____call_usermodehelper() now erases any credentials set by the subprocess_inf::init() function. The problem is that commit 17f60a7da150 ("capabilites: allow the application of capability limits to usermode helpers") creates and commits new credentials with prepare_kernel_cred() after the call to the init() function. This wipes all keyrings after umh_keys_init() is called. The best way to deal with this is to put the init() call just prior to the commit_creds() call, and pass the cred pointer to init(). That means that umh_keys_init() and suchlike can modify the credentials _before_ they are published and potentially in use by the rest of the system. This prevents request_key() from working as it is prevented from passing the session keyring it set up with the authorisation token to /sbin/request-key, and so the latter can't assume the authority to instantiate the key. This causes the in-kernel DNS resolver to fail with ENOKEY unconditionally. Signed-off-by: David Howells Acked-by: Eric Paris Tested-by: Jeff Layton Signed-off-by: Linus Torvalds

generic-ipi: Fix kexec boot crash by initializing call_single_queue before enabling interrupts

2011-06-17T08:17:12Z

There is a problem that kdump(2nd kernel) sometimes hangs up due to a pending IPI from 1st kernel. Kernel panic occurs because IPI comes before call_single_queue is initialized. To fix the crash, rename init_call_single_data() to call_function_init() and call it in start_kernel() so that call_single_queue can be initialized before enabling interrupts. The details of the crash are: (1) 2nd kernel boots up (2) A pending IPI from 1st kernel comes when irqs are first enabled in start_kernel(). (3) Kernel tries to handle the interrupt, but call_single_queue is not initialized yet at this point. As a result, in the generic_smp_call_function_single_interrupt(), NULL pointer dereference occurs when list_replace_init() tries to access &q->list.next. Therefore this patch changes the name of init_call_single_data() to call_function_init() and calls it before local_irq_enable() in start_kernel(). Signed-off-by: Takao Indoh Reviewed-by: WANG Cong Acked-by: Neil Horman Acked-by: Vivek Goyal Acked-by: Peter Zijlstra Cc: Milton Miller Cc: Jens Axboe Cc: Paul E. McKenney Cc: kexec@lists.infradead.org Link: http://lkml.kernel.org/r/D6CBEE2F420741indou.takao@jp.fujitsu.com Signed-off-by: Ingo Molnar

rcu: Move RCU_BOOST #ifdefs to header file

2011-06-16T23:12:05Z

The commit "use softirq instead of kthreads except when RCU_BOOST=y" just applied #ifdef in place. This commit is a cleanup that moves the newly #ifdef'ed code to the header file kernel/rcutree_plugin.h. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney

clocksource: Make watchdog robust vs. interruption

2011-06-16T17:30:53Z

The clocksource watchdog code is interruptible and it has been observed that this can trigger false positives which disable the TSC. The reason is that an interrupt storm or a long running interrupt handler between the read of the watchdog source and the read of the TSC brings the two far enough apart that the delta is larger than the unstable treshold. Move both reads into a short interrupt disabled region to avoid that. Reported-and-tested-by: Vernon Mauery Signed-off-by: Thomas Gleixner Cc: stable@kernel.org

rcu: use softirq instead of kthreads except when RCU_BOOST=y

2011-06-16T06:07:21Z

This patch #ifdefs RCU kthreads out of the kernel unless RCU_BOOST=y, thus eliminating context-switch overhead if RCU priority boosting has not been configured. Signed-off-by: Paul E. McKenney

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2011-06-16T04:45:18Z

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Check if lowest_mask is initialized in find_lowest_rq() sched: Fix need_resched() when checking peempt

gcov: disable CONFIG_CONSTRUCTORS when not needed by CONFIG_GCOV_KERNEL

2011-06-16T03:04:01Z

CONFIG_CONSTRUCTORS controls support for running constructor functions at kernel init time. According to commit b99b87f70c7785ab ("kernel: constructor support"), gcov (CONFIG_GCOV_KERNEL) needs this. However, CONFIG_CONSTRUCTORS currently defaults to y, with no option to disable it, and CONFIG_GCOV_KERNEL depends on it. Instead, default it to n and have CONFIG_GCOV_KERNEL select it, so that the normal case of CONFIG_GCOV_KERNEL=n will result in CONFIG_CONSTRUCTORS=n. Observed in the short list of =y values in a minimal kernel configuration. Signed-off-by: Josh Triplett Acked-by: WANG Cong Acked-by: Peter Oberparleiter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

memcg: clear mm->owner when last possible owner leaves

2011-06-16T03:04:01Z

The following crash was reported: > Call Trace: > [] mem_cgroup_from_task+0x15/0x17 > [] __mem_cgroup_try_charge+0x148/0x4b4 > [] ? need_resched+0x23/0x2d > [] ? preempt_schedule+0x46/0x4f > [] mem_cgroup_charge_common+0x9a/0xce > [] mem_cgroup_newpage_charge+0x5d/0x5f > [] khugepaged+0x5da/0xfaf > [] ? __init_waitqueue_head+0x4b/0x4b > [] ? add_mm_counter.constprop.5+0x13/0x13 > [] kthread+0xa8/0xb0 > [] ? sub_preempt_count+0xa1/0xb4 > [] kernel_thread_helper+0x4/0x10 > [] ? retint_restore_args+0x13/0x13 > [] ? __init_kthread_worker+0x5a/0x5a What happens is that khugepaged tries to charge a huge page against an mm whose last possible owner has already exited, and the memory controller crashes when the stale mm->owner is used to look up the cgroup to charge. mm->owner has never been set to NULL with the last owner going away, but nobody cared until khugepaged came along. Even then it wasn't a problem because the final mmput() on an mm was forced to acquire and release mmap_sem in write-mode, preventing an exiting owner to go away while the mmap_sem was held, and until "692e0b3 mm: thp: optimize memcg charge in khugepaged", the memory cgroup charge was protected by mmap_sem in read-mode. Instead of going back to relying on the mmap_sem to enforce lifetime of a task, this patch ensures that mm->owner is properly set to NULL when the last possible owner is exiting, which the memory controller can handle just fine. [akpm@linux-foundation.org: tweak comments] Signed-off-by: Hugh Dickins Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Johannes Weiner Reported-by: Hugh Dickins Reported-by: Dave Jones Reviewed-by: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds