linux.git/kernel/time, branch v4.16 Linux kernel source tree posix-timers: Protect posix clock array access against speculation 2018-03-22T11:29:27+00:00 Thomas Gleixner tglx@linutronix.de 2018-02-15T16:21:55+00:00 19b558db12f9f4e45a22012bae7b4783e62224da The clockid argument of clockid_to_kclock() comes straight from user space via various syscalls and is used as index into the posix_clocks array. Protect it against spectre v1 array out of bounds speculation. Remove the redundant check for !posix_clock[id] as this is another source for speculation and does not provide any advantage over the return posix_clock[id] path which returns NULL in that case anyway. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Dan Williams <dan.j.williams@intel.com> Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: stable@vger.kernel.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: David Woodhouse <dwmw@amazon.co.uk> Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1802151718320.1296@nanos.tec.linutronix.de 
The clockid argument of clockid_to_kclock() comes straight from user space
via various syscalls and is used as index into the posix_clocks array.

Protect it against spectre v1 array out of bounds speculation. Remove the
redundant check for !posix_clock[id] as this is another source for
speculation and does not provide any advantage over the return
posix_clock[id] path which returns NULL in that case anyway.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1802151718320.1296@nanos.tec.linutronix.de
timers: Forward timer base before migrating timers 2018-02-28T22:34:33+00:00 Lingutla Chandrasekhar clingutla@codeaurora.org 2018-01-18T11:50:22+00:00 c52232a49e203a65a6e1a670cd5262f59e9364a0 On CPU hotunplug the enqueued timers of the unplugged CPU are migrated to a live CPU. This happens from the control thread which initiated the unplug. If the CPU on which the control thread runs came out from a longer idle period then the base clock of that CPU might be stale because the control thread runs prior to any event which forwards the clock. In such a case the timers from the unplugged CPU are queued on the live CPU based on the stale clock which can cause large delays due to increased granularity of the outer timer wheels which are far away from base:;clock. But there is a worse problem than that. The following sequence of events illustrates it: - CPU0 timer1 is queued expires = 59969 and base->clk = 59131. The timer is queued at wheel level 2, with resulting expiry time = 60032 (due to level granularity). - CPU1 enters idle @60007, with next timer expiry @60020. - CPU0 is hotplugged at @60009 - CPU1 exits idle and runs the control thread which migrates the timers from CPU0 timer1 is now queued in level 0 for immediate handling in the next softirq because the requested expiry time 59969 is before CPU1 base->clk 60007 - CPU1 runs code which forwards the base clock which succeeds because the next expiring timer. which was collected at idle entry time is still set to 60020. So it forwards beyond 60007 and therefore misses to expire the migrated timer1. That timer gets expired when the wheel wraps around again, which takes between 63 and 630ms depending on the HZ setting. Address both problems by invoking forward_timer_base() for the control CPUs timer base. All other places, which might run into a similar problem (mod_timer()/add_timer_on()) already invoke forward_timer_base() to avoid that. [ tglx: Massaged comment and changelog ] Fixes: a683f390b93f ("timers: Forward the wheel clock whenever possible") Co-developed-by: Neeraj Upadhyay <neeraju@codeaurora.org> Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org> Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: linux-arm-msm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180118115022.6368-1-clingutla@codeaurora.org 
On CPU hotunplug the enqueued timers of the unplugged CPU are migrated to a
live CPU. This happens from the control thread which initiated the unplug.

If the CPU on which the control thread runs came out from a longer idle
period then the base clock of that CPU might be stale because the control
thread runs prior to any event which forwards the clock.

In such a case the timers from the unplugged CPU are queued on the live CPU
based on the stale clock which can cause large delays due to increased
granularity of the outer timer wheels which are far away from base:;clock.

But there is a worse problem than that. The following sequence of events
illustrates it:

 - CPU0 timer1 is queued expires = 59969 and base->clk = 59131.

   The timer is queued at wheel level 2, with resulting expiry time = 60032
   (due to level granularity).

 - CPU1 enters idle @60007, with next timer expiry @60020.

 - CPU0 is hotplugged at @60009

 - CPU1 exits idle and runs the control thread which migrates the
   timers from CPU0

   timer1 is now queued in level 0 for immediate handling in the next
   softirq because the requested expiry time 59969 is before CPU1 base->clk
   60007

 - CPU1 runs code which forwards the base clock which succeeds because the
   next expiring timer. which was collected at idle entry time is still set
   to 60020.

   So it forwards beyond 60007 and therefore misses to expire the migrated
   timer1. That timer gets expired when the wheel wraps around again, which
   takes between 63 and 630ms depending on the HZ setting.

Address both problems by invoking forward_timer_base() for the control CPUs
timer base. All other places, which might run into a similar problem
(mod_timer()/add_timer_on()) already invoke forward_timer_base() to avoid
that.

[ tglx: Massaged comment and changelog ]

Fixes: a683f390b93f ("timers: Forward the wheel clock whenever possible")
Co-developed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: linux-arm-msm@vger.kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180118115022.6368-1-clingutla@codeaurora.org
vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11T22:34:03+00:00 Linus Torvalds torvalds@linux-foundation.org 2018-02-11T22:34:03+00:00 a9a08845e9acbd224e4ee466f5c1275ed50054e8 This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script: for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done done with de-mangling cleanups yet to come. NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al. The next patch from Al will sort out the final differences, and we should be all done. Scripted-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:

    for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
        L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
        for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
    done

with de-mangling cleanups yet to come.

NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do.  But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.

The next patch from Al will sort out the final differences, and we
should be all done.

Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hrtimer: remove unneeded kallsyms include 2018-02-07T02:32:47+00:00 Sergey Senozhatsky sergey.senozhatsky.work@gmail.com 2018-02-06T23:41:10+00:00 64fce87b6271043092a664d798bc4b791e5c0952 hrtimer does not seem to use any of kallsyms functions/defines. Link: http://lkml.kernel.org/r/20171208025616.16267-9-sergey.senozhatsky@gmail.com Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
hrtimer does not seem to use any of kallsyms functions/defines.

Link: http://lkml.kernel.org/r/20171208025616.16267-9-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-31T01:58:07+00:00 Linus Torvalds torvalds@linux-foundation.org 2018-01-31T01:58:07+00:00 168fe32a072a4b8dc81a3aebf0e5e588d38e2955 Pull poll annotations from Al Viro: "This introduces a __bitwise type for POLL### bitmap, and propagates the annotations through the tree. Most of that stuff is as simple as 'make ->poll() instances return __poll_t and do the same to local variables used to hold the future return value'. Some of the obvious brainos found in process are fixed (e.g. POLLIN misspelled as POLL_IN). At that point the amount of sparse warnings is low and most of them are for genuine bugs - e.g. ->poll() instance deciding to return -EINVAL instead of a bitmap. I hadn't touched those in this series - it's large enough as it is. Another problem it has caught was eventpoll() ABI mess; select.c and eventpoll.c assumed that corresponding POLL### and EPOLL### were equal. That's true for some, but not all of them - EPOLL### are arch-independent, but POLL### are not. The last commit in this series separates userland POLL### values from the (now arch-independent) kernel-side ones, converting between them in the few places where they are copied to/from userland. AFAICS, this is the least disruptive fix preserving poll(2) ABI and making epoll() work on all architectures. As it is, it's simply broken on sparc - try to give it EPOLLWRNORM and it will trigger only on what would've triggered EPOLLWRBAND on other architectures. EPOLLWRBAND and EPOLLRDHUP, OTOH, are never triggered at all on sparc. With this patch they should work consistently on all architectures" * 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (37 commits) make kernel-side POLL... arch-independent eventpoll: no need to mask the result of epi_item_poll() again eventpoll: constify struct epoll_event pointers debugging printk in sg_poll() uses %x to print POLL... bitmap annotate poll(2) guts 9p: untangle ->poll() mess ->si_band gets POLL... bitmap stored into a user-visible long field ring_buffer_poll_wait() return value used as return value of ->poll() the rest of drivers/*: annotate ->poll() instances media: annotate ->poll() instances fs: annotate ->poll() instances ipc, kernel, mm: annotate ->poll() instances net: annotate ->poll() instances apparmor: annotate ->poll() instances tomoyo: annotate ->poll() instances sound: annotate ->poll() instances acpi: annotate ->poll() instances crypto: annotate ->poll() instances block: annotate ->poll() instances x86: annotate ->poll() instances ... 
Pull poll annotations from Al Viro:
 "This introduces a __bitwise type for POLL### bitmap, and propagates
  the annotations through the tree. Most of that stuff is as simple as
  'make ->poll() instances return __poll_t and do the same to local
  variables used to hold the future return value'.

  Some of the obvious brainos found in process are fixed (e.g. POLLIN
  misspelled as POLL_IN). At that point the amount of sparse warnings is
  low and most of them are for genuine bugs - e.g. ->poll() instance
  deciding to return -EINVAL instead of a bitmap. I hadn't touched those
  in this series - it's large enough as it is.

  Another problem it has caught was eventpoll() ABI mess; select.c and
  eventpoll.c assumed that corresponding POLL### and EPOLL### were
  equal. That's true for some, but not all of them - EPOLL### are
  arch-independent, but POLL### are not.

  The last commit in this series separates userland POLL### values from
  the (now arch-independent) kernel-side ones, converting between them
  in the few places where they are copied to/from userland. AFAICS, this
  is the least disruptive fix preserving poll(2) ABI and making epoll()
  work on all architectures.

  As it is, it's simply broken on sparc - try to give it EPOLLWRNORM and
  it will trigger only on what would've triggered EPOLLWRBAND on other
  architectures. EPOLLWRBAND and EPOLLRDHUP, OTOH, are never triggered
  at all on sparc. With this patch they should work consistently on all
  architectures"

* 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (37 commits)
  make kernel-side POLL... arch-independent
  eventpoll: no need to mask the result of epi_item_poll() again
  eventpoll: constify struct epoll_event pointers
  debugging printk in sg_poll() uses %x to print POLL... bitmap
  annotate poll(2) guts
  9p: untangle ->poll() mess
  ->si_band gets POLL... bitmap stored into a user-visible long field
  ring_buffer_poll_wait() return value used as return value of ->poll()
  the rest of drivers/*: annotate ->poll() instances
  media: annotate ->poll() instances
  fs: annotate ->poll() instances
  ipc, kernel, mm: annotate ->poll() instances
  net: annotate ->poll() instances
  apparmor: annotate ->poll() instances
  tomoyo: annotate ->poll() instances
  sound: annotate ->poll() instances
  acpi: annotate ->poll() instances
  crypto: annotate ->poll() instances
  block: annotate ->poll() instances
  x86: annotate ->poll() instances
  ...
Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-01-30T22:18:52+00:00 Linus Torvalds torvalds@linux-foundation.org 2018-01-30T22:18:52+00:00 d4173023e63cb85ec02eda02d1789bf078719f00 Pull siginfo cleanups from Eric Biederman: "Long ago when 2.4 was just a testing release copy_siginfo_to_user was made to copy individual fields to userspace, possibly for efficiency and to ensure initialized values were not copied to userspace. Unfortunately the design was complex, it's assumptions unstated, and humans are fallible and so while it worked much of the time that design failed to ensure unitialized memory is not copied to userspace. This set of changes is part of a new design to clean up siginfo and simplify things, and hopefully make the siginfo handling robust enough that a simple inspection of the code can be made to ensure we don't copy any unitializied fields to userspace. The design is to unify struct siginfo and struct compat_siginfo into a single definition that is shared between all architectures so that anyone adding to the set of information shared with struct siginfo can see the whole picture. Hopefully ensuring all future si_code assignments are arch independent. The design is to unify copy_siginfo_to_user32 and copy_siginfo_from_user32 so that those function are complete and cope with all of the different cases documented in signinfo_layout. I don't think there was a single implementation of either of those functions that was complete and correct before my changes unified them. The design is to introduce a series of helpers including force_siginfo_fault that take the values that are needed in struct siginfo and build the siginfo structure for their callers. Ensuring struct siginfo is built correctly. The remaining work for 4.17 (unless someone thinks it is post -rc1 material) is to push usage of those helpers down into the architectures so that architecture specific code will not need to deal with the fiddly work of intializing struct siginfo, and then when struct siginfo is guaranteed to be fully initialized change copy siginfo_to_user into a simple wrapper around copy_to_user. Further there is work in progress on the issues that have been documented requires arch specific knowledge to sort out. The changes below fix or at least document all of the issues that have been found with siginfo generation. Then proceed to unify struct siginfo the 32 bit helpers that copy siginfo to and from userspace, and generally clean up anything that is not arch specific with regards to siginfo generation. It is a lot but with the unification you can of siginfo you can already see the code reduction in the kernel" * 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (45 commits) signal/memory-failure: Use force_sig_mceerr and send_sig_mceerr mm/memory_failure: Remove unused trapno from memory_failure signal/ptrace: Add force_sig_ptrace_errno_trap and use it where needed signal/powerpc: Remove unnecessary signal_code parameter of do_send_trap signal: Helpers for faults with specialized siginfo layouts signal: Add send_sig_fault and force_sig_fault signal: Replace memset(info,...) with clear_siginfo for clarity signal: Don't use structure initializers for struct siginfo signal/arm64: Better isolate the COMPAT_TASK portion of ptrace_hbptriggered ptrace: Use copy_siginfo in setsiginfo and getsiginfo signal: Unify and correct copy_siginfo_to_user32 signal: Remove the code to clear siginfo before calling copy_siginfo_from_user32 signal: Unify and correct copy_siginfo_from_user32 signal/blackfin: Remove pointless UID16_SIGINFO_COMPAT_NEEDED signal/blackfin: Move the blackfin specific si_codes to asm-generic/siginfo.h signal/tile: Move the tile specific si_codes to asm-generic/siginfo.h signal/frv: Move the frv specific si_codes to asm-generic/siginfo.h signal/ia64: Move the ia64 specific si_codes to asm-generic/siginfo.h signal/powerpc: Remove redefinition of NSIGTRAP on powerpc signal: Move addr_lsb into the _sigfault union for clarity ... 
Pull siginfo cleanups from Eric Biederman:
 "Long ago when 2.4 was just a testing release copy_siginfo_to_user was
  made to copy individual fields to userspace, possibly for efficiency
  and to ensure initialized values were not copied to userspace.

  Unfortunately the design was complex, it's assumptions unstated, and
  humans are fallible and so while it worked much of the time that
  design failed to ensure unitialized memory is not copied to userspace.

  This set of changes is part of a new design to clean up siginfo and
  simplify things, and hopefully make the siginfo handling robust enough
  that a simple inspection of the code can be made to ensure we don't
  copy any unitializied fields to userspace.

  The design is to unify struct siginfo and struct compat_siginfo into a
  single definition that is shared between all architectures so that
  anyone adding to the set of information shared with struct siginfo can
  see the whole picture. Hopefully ensuring all future si_code
  assignments are arch independent.

  The design is to unify copy_siginfo_to_user32 and
  copy_siginfo_from_user32 so that those function are complete and cope
  with all of the different cases documented in signinfo_layout. I don't
  think there was a single implementation of either of those functions
  that was complete and correct before my changes unified them.

  The design is to introduce a series of helpers including
  force_siginfo_fault that take the values that are needed in struct
  siginfo and build the siginfo structure for their callers. Ensuring
  struct siginfo is built correctly.

  The remaining work for 4.17 (unless someone thinks it is post -rc1
  material) is to push usage of those helpers down into the
  architectures so that architecture specific code will not need to deal
  with the fiddly work of intializing struct siginfo, and then when
  struct siginfo is guaranteed to be fully initialized change copy
  siginfo_to_user into a simple wrapper around copy_to_user.

  Further there is work in progress on the issues that have been
  documented requires arch specific knowledge to sort out.

  The changes below fix or at least document all of the issues that have
  been found with siginfo generation. Then proceed to unify struct
  siginfo the 32 bit helpers that copy siginfo to and from userspace,
  and generally clean up anything that is not arch specific with regards
  to siginfo generation.

  It is a lot but with the unification you can of siginfo you can
  already see the code reduction in the kernel"

* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (45 commits)
  signal/memory-failure: Use force_sig_mceerr and send_sig_mceerr
  mm/memory_failure: Remove unused trapno from memory_failure
  signal/ptrace: Add force_sig_ptrace_errno_trap and use it where needed
  signal/powerpc: Remove unnecessary signal_code parameter of do_send_trap
  signal: Helpers for faults with specialized siginfo layouts
  signal: Add send_sig_fault and force_sig_fault
  signal: Replace memset(info,...) with clear_siginfo for clarity
  signal: Don't use structure initializers for struct siginfo
  signal/arm64: Better isolate the COMPAT_TASK portion of ptrace_hbptriggered
  ptrace: Use copy_siginfo in setsiginfo and getsiginfo
  signal: Unify and correct copy_siginfo_to_user32
  signal: Remove the code to clear siginfo before calling copy_siginfo_from_user32
  signal: Unify and correct copy_siginfo_from_user32
  signal/blackfin: Remove pointless UID16_SIGINFO_COMPAT_NEEDED
  signal/blackfin: Move the blackfin specific si_codes to asm-generic/siginfo.h
  signal/tile: Move the tile specific si_codes to asm-generic/siginfo.h
  signal/frv: Move the frv specific si_codes to asm-generic/siginfo.h
  signal/ia64: Move the ia64 specific si_codes to asm-generic/siginfo.h
  signal/powerpc: Remove redefinition of NSIGTRAP on powerpc
  signal: Move addr_lsb into the _sigfault union for clarity
  ...
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-30T19:55:56+00:00 Linus Torvalds torvalds@linux-foundation.org 2018-01-30T19:55:56+00:00 af8c5e2d6071c71d228788d1ebb0b9676829001a Pull scheduler updates from Ingo Molnar: "The main changes in this cycle were: - Implement frequency/CPU invariance and OPP selection for SCHED_DEADLINE (Juri Lelli) - Tweak the task migration logic for better multi-tasking workload scalability (Mel Gorman) - Misc cleanups, fixes and improvements" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/deadline: Make bandwidth enforcement scale-invariant sched/cpufreq: Move arch_scale_{freq,cpu}_capacity() outside of #ifdef CONFIG_SMP sched/cpufreq: Remove arch_scale_freq_capacity()'s 'sd' parameter sched/cpufreq: Always consider all CPUs when deciding next freq sched/cpufreq: Split utilization signals sched/cpufreq: Change the worker kthread to SCHED_DEADLINE sched/deadline: Move CPU frequency selection triggering points sched/cpufreq: Use the DEADLINE utilization signal sched/deadline: Implement "runtime overrun signal" support sched/fair: Only immediately migrate tasks due to interrupts if prev and target CPUs share cache sched/fair: Correct obsolete comment about cpufreq_update_util() sched/fair: Remove impossible condition from find_idlest_group_cpu() sched/cpufreq: Don't pass flags to sugov_set_iowait_boost() sched/cpufreq: Initialize sg_cpu->flags to 0 sched/fair: Consider RT/IRQ pressure in capacity_spare_wake() sched/fair: Use 'unsigned long' for utilization, consistently sched/core: Rework and clarify prepare_lock_switch() sched/fair: Remove unused 'curr' parameter from wakeup_gran sched/headers: Constify object_is_on_stack() 
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Implement frequency/CPU invariance and OPP selection for
     SCHED_DEADLINE (Juri Lelli)

   - Tweak the task migration logic for better multi-tasking
     workload scalability (Mel Gorman)

   - Misc cleanups, fixes and improvements"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/deadline: Make bandwidth enforcement scale-invariant
  sched/cpufreq: Move arch_scale_{freq,cpu}_capacity() outside of #ifdef CONFIG_SMP
  sched/cpufreq: Remove arch_scale_freq_capacity()'s 'sd' parameter
  sched/cpufreq: Always consider all CPUs when deciding next freq
  sched/cpufreq: Split utilization signals
  sched/cpufreq: Change the worker kthread to SCHED_DEADLINE
  sched/deadline: Move CPU frequency selection triggering points
  sched/cpufreq: Use the DEADLINE utilization signal
  sched/deadline: Implement "runtime overrun signal" support
  sched/fair: Only immediately migrate tasks due to interrupts if prev and target CPUs share cache
  sched/fair: Correct obsolete comment about cpufreq_update_util()
  sched/fair: Remove impossible condition from find_idlest_group_cpu()
  sched/cpufreq: Don't pass flags to sugov_set_iowait_boost()
  sched/cpufreq: Initialize sg_cpu->flags to 0
  sched/fair: Consider RT/IRQ pressure in capacity_spare_wake()
  sched/fair: Use 'unsigned long' for utilization, consistently
  sched/core: Rework and clarify prepare_lock_switch()
  sched/fair: Remove unused 'curr' parameter from wakeup_gran
  sched/headers: Constify object_is_on_stack()
Merge branch 'timers/urgent' into timers/core 2018-01-27T14:35:29+00:00 Thomas Gleixner tglx@linutronix.de 2018-01-27T14:35:29+00:00 303c146df1c4574db3495d9acc5c440dd46c6b0f Pick up urgent bug fix and resolve the conflict. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
Pick up urgent bug fix and resolve the conflict.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
hrtimer: Reset hrtimer cpu base proper on CPU hotplug 2018-01-27T14:12:22+00:00 Thomas Gleixner tglx@linutronix.de 2018-01-26T13:54:32+00:00 d5421ea43d30701e03cadc56a38854c36a8b4433 The hrtimer interrupt code contains a hang detection and mitigation mechanism, which prevents that a long delayed hrtimer interrupt causes a continous retriggering of interrupts which prevent the system from making progress. If a hang is detected then the timer hardware is programmed with a certain delay into the future and a flag is set in the hrtimer cpu base which prevents newly enqueued timers from reprogramming the timer hardware prior to the chosen delay. The subsequent hrtimer interrupt after the delay clears the flag and resumes normal operation. If such a hang happens in the last hrtimer interrupt before a CPU is unplugged then the hang_detected flag is set and stays that way when the CPU is plugged in again. At that point the timer hardware is not armed and it cannot be armed because the hang_detected flag is still active, so nothing clears that flag. As a consequence the CPU does not receive hrtimer interrupts and no timers expire on that CPU which results in RCU stalls and other malfunctions. Clear the flag along with some other less critical members of the hrtimer cpu base to ensure starting from a clean state when a CPU is plugged in. Thanks to Paul, Sebastian and Anna-Maria for their help to get down to the root cause of that hard to reproduce heisenbug. Once understood it's trivial and certainly justifies a brown paperbag. Fixes: 41d2e4949377 ("hrtimer: Tune hrtimer_interrupt hang logic") Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Sewior <bigeasy@linutronix.de> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801261447590.2067@nanos 
The hrtimer interrupt code contains a hang detection and mitigation
mechanism, which prevents that a long delayed hrtimer interrupt causes a
continous retriggering of interrupts which prevent the system from making
progress. If a hang is detected then the timer hardware is programmed with
a certain delay into the future and a flag is set in the hrtimer cpu base
which prevents newly enqueued timers from reprogramming the timer hardware
prior to the chosen delay. The subsequent hrtimer interrupt after the delay
clears the flag and resumes normal operation.

If such a hang happens in the last hrtimer interrupt before a CPU is
unplugged then the hang_detected flag is set and stays that way when the
CPU is plugged in again. At that point the timer hardware is not armed and
it cannot be armed because the hang_detected flag is still active, so
nothing clears that flag. As a consequence the CPU does not receive hrtimer
interrupts and no timers expire on that CPU which results in RCU stalls and
other malfunctions.

Clear the flag along with some other less critical members of the hrtimer
cpu base to ensure starting from a clean state when a CPU is plugged in.

Thanks to Paul, Sebastian and Anna-Maria for their help to get down to the
root cause of that hard to reproduce heisenbug. Once understood it's
trivial and certainly justifies a brown paperbag.

Fixes: 41d2e4949377 ("hrtimer: Tune hrtimer_interrupt hang logic")
Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Sewior <bigeasy@linutronix.de>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801261447590.2067@nanos
signal: Replace memset(info,...) with clear_siginfo for clarity 2018-01-23T01:07:08+00:00 Eric W. Biederman ebiederm@xmission.com 2017-08-19T00:56:27+00:00 3b10db2b06e2f6191aabb14babe28dcaa657a947 The function clear_siginfo is just a nice wrapper around memset so this results in no functional change. This change makes mistakes a little more difficult and it makes it clearer what is going on. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> 
The function clear_siginfo is just a nice wrapper around memset so
this results in no functional change.  This change makes mistakes
a little more difficult and it makes it clearer what is going on.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>