1. 14 Jan, 2017 1 commit
    • Peter Zijlstra's avatar
      sched/clock: Delay switching sched_clock to stable · 9881b024
      Peter Zijlstra authored
      Currently we switch to the stable sched_clock if we guess the TSC is
      usable, and then switch back to the unstable path if it turns out TSC
      isn't stable during SMP bringup after all.
      
      Delay switching to the stable path until after SMP bringup is
      complete. This way we'll avoid switching during the time we detect the
      worst of the TSC offences.
      Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Mike Galbraith <efault@gmx.de>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      9881b024
  2. 25 Dec, 2016 1 commit
    • Nicholas Piggin's avatar
      mm: add PageWaiters indicating tasks are waiting for a page bit · 62906027
      Nicholas Piggin authored
      Add a new page flag, PageWaiters, to indicate the page waitqueue has
      tasks waiting. This can be tested rather than testing waitqueue_active
      which requires another cacheline load.
      
      This bit is always set when the page has tasks on page_waitqueue(page),
      and is set and cleared under the waitqueue lock. It may be set when
      there are no tasks on the waitqueue, which will cause a harmless extra
      wakeup check that will clears the bit.
      
      The generic bit-waitqueue infrastructure is no longer used for pages.
      Instead, waitqueues are used directly with a custom key type. The
      generic code was not flexible enough to have PageWaiters manipulation
      under the waitqueue lock (which simplifies concurrency).
      
      This improves the performance of page lock intensive microbenchmarks by
      2-3%.
      
      Putting two bits in the same word opens the opportunity to remove the
      memory barrier between clearing the lock bit and testing the waiters
      bit, after some work on the arch primitives (e.g., ensuring memory
      operand widths match and cover both bits).
      Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Bob Peterson <rpeterso@redhat.com>
      Cc: Steven Whitehouse <swhiteho@redhat.com>
      Cc: Andrew Lutomirski <luto@kernel.org>
      Cc: Andreas Gruenbacher <agruenba@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Mel Gorman <mgorman@techsingularity.net>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      62906027
  3. 09 Dec, 2016 1 commit
    • Thomas Gleixner's avatar
      x86/amd: Check for the C1E bug post ACPI subsystem init · e7ff3a47
      Thomas Gleixner authored
      AMD CPUs affected by the E400 erratum suffer from the issue that the
      local APIC timer stops when the CPU goes into C1E. Unfortunately there
      is no way to detect the affected CPUs on early boot. It's only possible
      to determine the range of possibly affected CPUs from the family/model
      range.
      
      The actual decision whether to enter C1E and thus cause the bug is done
      by the firmware and we need to detect that case late, after ACPI has
      been initialized.
      
      The current solution is to check in the idle routine whether the CPU is
      affected by reading the MSR_K8_INT_PENDING_MSG MSR and checking for the
      K8_INTP_C1E_ACTIVE_MASK bits. If one of the bits is set then the CPU is
      affected and the system is switched into forced broadcast mode.
      
      This is ineffective and on non-affected CPUs every entry to idle does
      the extra RDMSR.
      
      After doing some research it turns out that the bits are visible on the
      boot CPU right after the ACPI subsystem is initialized in the early
      boot process. So instead of polling for the bits in the idle loop, add
      a detection function after acpi_subsystem_init() and check for the MSR
      bits. If set, then the X86_BUG_AMD_APIC_C1E is set on the boot CPU and
      the TSC is marked unstable when X86_FEATURE_NONSTOP_TSC is not set as it
      will stop in C1E state as well.
      
      The switch to broadcast mode cannot be done at this point because the
      boot CPU still uses HPET as a clockevent device and the local APIC timer
      is not yet calibrated and installed. The switch to broadcast mode on the
      affected CPUs needs to be done when the local APIC timer is actually set
      up.
      
      This allows to cleanup the amd_e400_idle() function in the next step.
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Jiri Olsa <jolsa@redhat.com>
      Link: http://lkml.kernel.org/r/20161209182912.2726-4-bp@alien8.deSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      e7ff3a47
  4. 28 Nov, 2016 2 commits
  5. 24 Oct, 2016 1 commit
  6. 10 Oct, 2016 1 commit
    • Emese Revfy's avatar
      gcc-plugins: Add latent_entropy plugin · 38addce8
      Emese Revfy authored
      This adds a new gcc plugin named "latent_entropy". It is designed to
      extract as much possible uncertainty from a running system at boot time as
      possible, hoping to capitalize on any possible variation in CPU operation
      (due to runtime data differences, hardware differences, SMP ordering,
      thermal timing variation, cache behavior, etc).
      
      At the very least, this plugin is a much more comprehensive example for
      how to manipulate kernel code using the gcc plugin internals.
      
      The need for very-early boot entropy tends to be very architecture or
      system design specific, so this plugin is more suited for those sorts
      of special cases. The existing kernel RNG already attempts to extract
      entropy from reliable runtime variation, but this plugin takes the idea to
      a logical extreme by permuting a global variable based on any variation
      in code execution (e.g. a different value (and permutation function)
      is used to permute the global based on loop count, case statement,
      if/then/else branching, etc).
      
      To do this, the plugin starts by inserting a local variable in every
      marked function. The plugin then adds logic so that the value of this
      variable is modified by randomly chosen operations (add, xor and rol) and
      random values (gcc generates separate static values for each location at
      compile time and also injects the stack pointer at runtime). The resulting
      value depends on the control flow path (e.g., loops and branches taken).
      
      Before the function returns, the plugin mixes this local variable into
      the latent_entropy global variable. The value of this global variable
      is added to the kernel entropy pool in do_one_initcall() and _do_fork(),
      though it does not credit any bytes of entropy to the pool; the contents
      of the global are just used to mix the pool.
      
      Additionally, the plugin can pre-initialize arrays with build-time
      random contents, so that two different kernel builds running on identical
      hardware will not have the same starting values.
      Signed-off-by: default avatarEmese Revfy <re.emese@gmail.com>
      [kees: expanded commit message and code comments]
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      38addce8
  7. 17 Sep, 2016 1 commit
    • Tejun Heo's avatar
      workqueue: make workqueue available early during boot · 3347fa09
      Tejun Heo authored
      Workqueue is currently initialized in an early init call; however,
      there are cases where early boot code has to be split and reordered to
      come after workqueue initialization or the same code path which makes
      use of workqueues is used both before workqueue initailization and
      after.  The latter cases have to gate workqueue usages with
      keventd_up() tests, which is nasty and easy to get wrong.
      
      Workqueue usages have become widespread and it'd be a lot more
      convenient if it can be used very early from boot.  This patch splits
      workqueue initialization into two steps.  workqueue_init_early() which
      sets up the basic data structures so that workqueues can be created
      and work items queued, and workqueue_init() which actually brings up
      workqueues online and starts executing queued work items.  The former
      step can be done very early during boot once memory allocation,
      cpumasks and idr are initialized.  The latter right after kthreads
      become available.
      
      This allows work item queueing and canceling from very early boot
      which is what most of these use cases want.
      
      * As systemd_wq being initialized doesn't indicate that workqueue is
        fully online anymore, update keventd_up() to test wq_online instead.
        The follow-up patches will get rid of all its usages and the
        function itself.
      
      * Flushing doesn't make sense before workqueue is fully initialized.
        The flush functions trigger WARN and return immediately before fully
        online.
      
      * Work items are never in-flight before fully online.  Canceling can
        always succeed by skipping the flush step.
      
      * Some code paths can no longer assume to be called with irq enabled
        as irq is disabled during early boot.  Use irqsave/restore
        operations instead.
      
      v2: Watchdog init, which requires timer to be running, moved from
          workqueue_init_early() to workqueue_init().
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Link: http://lkml.kernel.org/r/CA+55aFx0vPuMuxn00rBSM192n-Du5uxy+4AvKa0SBSOVJeuCGg@mail.gmail.com
      3347fa09
  8. 02 Aug, 2016 2 commits
  9. 25 Jun, 2016 1 commit
  10. 24 Jun, 2016 1 commit
    • Linus Torvalds's avatar
      Clarify naming of thread info/stack allocators · b235beea
      Linus Torvalds authored
      We've had the thread info allocated together with the thread stack for
      most architectures for a long time (since the thread_info was split off
      from the task struct), but that is about to change.
      
      But the patches that move the thread info to be off-stack (and a part of
      the task struct instead) made it clear how confused the allocator and
      freeing functions are.
      
      Because the common case was that we share an allocation with the thread
      stack and the thread_info, the two pointers were identical.  That
      identity then meant that we would have things like
      
      	ti = alloc_thread_info_node(tsk, node);
      	...
      	tsk->stack = ti;
      
      which certainly _worked_ (since stack and thread_info have the same
      value), but is rather confusing: why are we assigning a thread_info to
      the stack? And if we move the thread_info away, the "confusing" code
      just gets to be entirely bogus.
      
      So remove all this confusion, and make it clear that we are doing the
      stack allocation by renaming and clarifying the function names to be
      about the stack.  The fact that the thread_info then shares the
      allocation is an implementation detail, and not really about the
      allocation itself.
      
      This is a pure renaming and type fix: we pass in the same pointer, it's
      just that we clarify what the pointer means.
      
      The ia64 code that actually only has one single allocation (for all of
      task_struct, thread_info and kernel thread stack) now looks a bit odd,
      but since "tsk->stack" is actually not even used there, that oddity
      doesn't matter.  It would be a separate thing to clean that up, I
      intentionally left the ia64 changes as a pure brute-force renaming and
      type change.
      Acked-by: default avatarAndy Lutomirski <luto@amacapital.net>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b235beea
  11. 27 May, 2016 1 commit
  12. 21 May, 2016 3 commits
    • Rasmus Villemoes's avatar
      init/main.c: simplify initcall_blacklisted() · c8cdd2be
      Rasmus Villemoes authored
      Using kasprintf to get the function name makes us look up the name
      twice, along with all the vsnprintf overhead of parsing the format
      string etc.  It also means there is an allocation failure case to deal
      with.  Since symbol_string in vsprintf.c would anyway allocate an array
      of size KSYM_SYMBOL_LEN on the stack, that might as well be done up
      here.
      
      Moreover, since this is a debug feature and the blacklisted_initcalls
      list is usually empty, we might as well test that and thus avoid looking
      up the symbol name even once in the common case.
      Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
      Acked-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      Acked-by: default avatarPrarit Bhargava <prarit@redhat.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c8cdd2be
    • Petr Mladek's avatar
      printk/nmi: generic solution for safe printk in NMI · 42a0bb3f
      Petr Mladek authored
      printk() takes some locks and could not be used a safe way in NMI
      context.
      
      The chance of a deadlock is real especially when printing stacks from
      all CPUs.  This particular problem has been addressed on x86 by the
      commit a9edc880 ("x86/nmi: Perform a safe NMI stack trace on all
      CPUs").
      
      The patchset brings two big advantages.  First, it makes the NMI
      backtraces safe on all architectures for free.  Second, it makes all NMI
      messages almost safe on all architectures (the temporary buffer is
      limited.  We still should keep the number of messages in NMI context at
      minimum).
      
      Note that there already are several messages printed in NMI context:
      WARN_ON(in_nmi()), BUG_ON(in_nmi()), anything being printed out from MCE
      handlers.  These are not easy to avoid.
      
      This patch reuses most of the code and makes it generic.  It is useful
      for all messages and architectures that support NMI.
      
      The alternative printk_func is set when entering and is reseted when
      leaving NMI context.  It queues IRQ work to copy the messages into the
      main ring buffer in a safe context.
      
      __printk_nmi_flush() copies all available messages and reset the buffer.
      Then we could use a simple cmpxchg operations to get synchronized with
      writers.  There is also used a spinlock to get synchronized with other
      flushers.
      
      We do not longer use seq_buf because it depends on external lock.  It
      would be hard to make all supported operations safe for a lockless use.
      It would be confusing and error prone to make only some operations safe.
      
      The code is put into separate printk/nmi.c as suggested by Steven
      Rostedt.  It needs a per-CPU buffer and is compiled only on
      architectures that call nmi_enter().  This is achieved by the new
      HAVE_NMI Kconfig flag.
      
      The are MN10300 and Xtensa architectures.  We need to clean up NMI
      handling there first.  Let's do it separately.
      
      The patch is heavily based on the draft from Peter Zijlstra, see
      
        https://lkml.org/lkml/2015/6/10/327
      
      [arnd@arndb.de: printk-nmi: use %zu format string for size_t]
      [akpm@linux-foundation.org: min_t->min - all types are size_t here]
      Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
      Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
      Suggested-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Cc: Jan Kara <jack@suse.cz>
      Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>	[arm part]
      Cc: Daniel Thompson <daniel.thompson@linaro.org>
      Cc: Jiri Kosina <jkosina@suse.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: David Miller <davem@davemloft.net>
      Cc: Daniel Thompson <daniel.thompson@linaro.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      42a0bb3f
    • Yang Shi's avatar
      mm: call page_ext_init() after all struct pages are initialized · b8f1a75d
      Yang Shi authored
      When DEFERRED_STRUCT_PAGE_INIT is enabled, just a subset of memmap at
      boot are initialized, then the rest are initialized in parallel by
      starting one-off "pgdatinitX" kernel thread for each node X.
      
      If page_ext_init is called before it, some pages will not have valid
      extension, this may lead the below kernel oops when booting up kernel:
      
        BUG: unable to handle kernel NULL pointer dereference at           (null)
        IP: [<ffffffff8118d982>] free_pcppages_bulk+0x2d2/0x8d0
        PGD 0
        Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
        Modules linked in:
        CPU: 11 PID: 106 Comm: pgdatinit1 Not tainted 4.6.0-rc5-next-20160427 #26
        Hardware name: Intel Corporation S5520HC/S5520HC, BIOS S5500.86B.01.10.0025.030220091519 03/02/2009
        task: ffff88017c080040 ti: ffff88017c084000 task.ti: ffff88017c084000
        RIP: 0010:[<ffffffff8118d982>]  [<ffffffff8118d982>] free_pcppages_bulk+0x2d2/0x8d0
        RSP: 0000:ffff88017c087c48  EFLAGS: 00010046
        RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000001
        RDX: 0000000000000980 RSI: 0000000000000080 RDI: 0000000000660401
        RBP: ffff88017c087cd0 R08: 0000000000000401 R09: 0000000000000009
        R10: ffff88017c080040 R11: 000000000000000a R12: 0000000000000400
        R13: ffffea0019810000 R14: ffffea0019810040 R15: ffff88066cfe6080
        FS:  0000000000000000(0000) GS:ffff88066cd40000(0000) knlGS:0000000000000000
        CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
        CR2: 0000000000000000 CR3: 0000000002406000 CR4: 00000000000006e0
        Call Trace:
          free_hot_cold_page+0x192/0x1d0
          __free_pages+0x5c/0x90
          __free_pages_boot_core+0x11a/0x14e
          deferred_free_range+0x50/0x62
          deferred_init_memmap+0x220/0x3c3
          kthread+0xf8/0x110
          ret_from_fork+0x22/0x40
        Code: 49 89 d4 48 c1 e0 06 49 01 c5 e9 de fe ff ff 4c 89 f7 44 89 4d b8 4c 89 45 c0 44 89 5d c8 48 89 4d d0 e8 62 c7 07 00 48 8b 4d d0 <48> 8b 00 44 8b 5d c8 4c 8b 45 c0 44 8b 4d b8 a8 02 0f 84 05 ff
        RIP  [<ffffffff8118d982>] free_pcppages_bulk+0x2d2/0x8d0
         RSP <ffff88017c087c48>
        CR2: 0000000000000000
      
      Move page_ext_init() after page_alloc_init_late() to make sure page extension
      is setup for all pages.
      
      Link: http://lkml.kernel.org/r/1463696006-31360-1-git-send-email-yang.shi@linaro.orgSigned-off-by: default avatarYang Shi <yang.shi@linaro.org>
      Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b8f1a75d
  13. 15 Mar, 2016 1 commit
  14. 01 Mar, 2016 2 commits
    • Thomas Gleixner's avatar
      cpu/hotplug: Unpark smpboot threads from the state machine · 931ef163
      Thomas Gleixner authored
      Handle the smpboot threads in the state machine.
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: linux-arch@vger.kernel.org
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
      Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Arjan van de Ven <arjan@linux.intel.com>
      Cc: Sebastian Siewior <bigeasy@linutronix.de>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Turner <pjt@google.com>
      Link: http://lkml.kernel.org/r/20160226182341.295777684@linutronix.deSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      931ef163
    • Thomas Gleixner's avatar
      cpu/hotplug: Convert to a state machine for the control processor · cff7d378
      Thomas Gleixner authored
      Move the split out steps into a callback array and let the cpu_up/down
      code iterate through the array functions. For now most of the
      callbacks are asymmetric to resemble the current hotplug maze.
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: linux-arch@vger.kernel.org
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
      Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Arjan van de Ven <arjan@linux.intel.com>
      Cc: Sebastian Siewior <bigeasy@linutronix.de>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul Turner <pjt@google.com>
      Link: http://lkml.kernel.org/r/20160226182340.671816690@linutronix.deSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      cff7d378
  15. 22 Feb, 2016 1 commit
    • Kees Cook's avatar
      mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings · d2aa1aca
      Kees Cook authored
      It may be useful to debug writes to the readonly sections of memory,
      so provide a cmdline "rodata=off" to allow for this. This can be
      expanded in the future to support "log" and "write" modes, but that
      will need to be architecture-specific.
      
      This also makes KDB software breakpoints more usable, as read-only
      mappings can now be disabled on any kernel.
      Suggested-by: default avatarH. Peter Anvin <hpa@zytor.com>
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: David Brown <david.brown@linaro.org>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Emese Revfy <re.emese@gmail.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Mathias Krause <minipli@googlemail.com>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Cc: PaX Team <pageexec@freemail.hu>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: kernel-hardening@lists.openwall.com
      Cc: linux-arch <linux-arch@vger.kernel.org>
      Link: http://lkml.kernel.org/r/1455748879-21872-3-git-send-email-keescook@chromium.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      d2aa1aca
  16. 09 Feb, 2016 1 commit
  17. 21 Jan, 2016 1 commit
  18. 04 Dec, 2015 1 commit
  19. 10 Sep, 2015 1 commit
    • Frederic Weisbecker's avatar
      kmod: use system_unbound_wq instead of khelper · 90f02303
      Frederic Weisbecker authored
      We need to launch the usermodehelper kernel threads with the widest
      affinity and this is partly why we use khelper.  This workqueue has
      unbound properties and thus a wide affinity inherited by all its children.
      
      Now khelper also has special properties that we aren't much interested in:
      ordered and singlethread.  There is really no need about ordering as all
      we do is creating kernel threads.  This can be done concurrently.  And
      singlethread is a useless limitation as well.
      
      The workqueue engine already proposes generic unbound workqueues that
      don't share these useless properties and handle well parallel jobs.
      
      The only worrysome specific is their affinity to the node of the current
      CPU.  It's fine for creating the usermodehelper kernel threads but those
      inherit this affinity for longer jobs such as requesting modules.
      
      This patch proposes to use these node affine unbound workqueues assuming
      that a node is sufficient to handle several parallel usermodehelper
      requests.
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
      Cc: Rik van Riel <riel@redhat.com>
      Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
      Cc: Christoph Lameter <cl@linux.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      90f02303
  20. 07 Aug, 2015 1 commit
    • Mel Gorman's avatar
      fs, file table: reinit files_stat.max_files after deferred memory initialisation · 4248b0da
      Mel Gorman authored
      Dave Hansen reported the following;
      
      	My laptop has been behaving strangely with 4.2-rc2.  Once I log
      	in to my X session, I start getting all kinds of strange errors
      	from applications and see this in my dmesg:
      
              	VFS: file-max limit 8192 reached
      
      The problem is that the file-max is calculated before memory is fully
      initialised and miscalculates how much memory the kernel is using.  This
      patch recalculates file-max after deferred memory initialisation.  Note
      that using memory hotplug infrastructure would not have avoided this
      problem as the value is not recalculated after memory hot-add.
      
      4.1:             files_stat.max_files = 6582781
      4.2-rc2:         files_stat.max_files = 8192
      4.2-rc2 patched: files_stat.max_files = 6562467
      
      Small differences with the patch applied and 4.1 but not enough to matter.
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Reported-by: default avatarDave Hansen <dave.hansen@intel.com>
      Cc: Nicolai Stange <nicstange@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Alex Ng <alexng@microsoft.com>
      Cc: Fengguang Wu <fengguang.wu@intel.com>
      Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      4248b0da
  21. 01 Jul, 2015 1 commit
    • Mel Gorman's avatar
      mm: meminit: finish initialisation of struct pages before basic setup · 0e1cc95b
      Mel Gorman authored
      Waiman Long reported that 24TB machines hit OOM during basic setup when
      struct page initialisation was deferred.  One approach is to initialise
      memory on demand but it interferes with page allocator paths.  This patch
      creates dedicated threads to initialise memory before basic setup.  It
      then blocks on a rw_semaphore until completion as a wait_queue and counter
      is overkill.  This may be slower to boot but it's simplier overall and
      also gets rid of a section mangling which existed so kswapd could do the
      initialisation.
      
      [akpm@linux-foundation.org: include rwsem.h, use DECLARE_RWSEM, fix comment, remove unneeded cast]
      Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Waiman Long <waiman.long@hp.com
      Cc: Nathan Zimmer <nzimmer@sgi.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Scott Norton <scott.norton@hp.com>
      Tested-by: default avatarDaniel J Blueman <daniel@numascale.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0e1cc95b
  22. 10 Jun, 2015 1 commit
    • Rafael J. Wysocki's avatar
      ACPI / init: Switch over platform to the ACPI mode later · b064a8fa
      Rafael J. Wysocki authored
      Commit 73f7d1ca "ACPI / init: Run acpi_early_init() before
      timekeeping_init()" moved the ACPI subsystem initialization,
      including the ACPI mode enabling, to an earlier point in the
      initialization sequence, to allow the timekeeping subsystem
      use ACPI early.  Unfortunately, that resulted in boot regressions
      on some systems and the early ACPI initialization was moved toward
      its original position in the kernel initialization code by commit
      c4e1acbb "ACPI / init: Invoke early ACPI initialization later".
      
      However, that turns out to be insufficient, as boot is still broken
      on the Tyan S8812 mainboard.
      
      To fix that issue, split the ACPI early initialization code into
      two pieces so the majority of it still located in acpi_early_init()
      and the part switching over the platform into the ACPI mode goes into
      a new function, acpi_subsystem_init(), executed at the original early
      ACPI initialization spot.
      
      That fixes the Tyan S8812 boot problem, but still allows ACPI
      tables to be loaded earlier which is useful to the EFI code in
      efi_enter_virtual_mode().
      
      Link: https://bugzilla.kernel.org/show_bug.cgi?id=97141
      Fixes: 73f7d1ca "ACPI / init: Run acpi_early_init() before timekeeping_init()"
      Reported-and-tested-by: default avatarMarius Tolzmann <tolzmann@molgen.mpg.de>
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      Acked-by: default avatarToshi Kani <toshi.kani@hp.com>
      Reviewed-by: default avatarHanjun Guo <hanjun.guo@linaro.org>
      Reviewed-by: default avatarLee, Chun-Yi <jlee@suse.com>
      b064a8fa
  23. 20 May, 2015 1 commit
    • Luis R. Rodriguez's avatar
      module: add extra argument for parse_params() callback · ecc86170
      Luis R. Rodriguez authored
      This adds an extra argument onto parse_params() to be used
      as a way to make the unused callback a bit more useful and
      generic by allowing the caller to pass on a data structure
      of its choice. An example use case is to allow us to easily
      make module parameters for every module which we will do
      next.
      
      @ parse @
      identifier name, args, params, num, level_min, level_max;
      identifier unknown, param, val, doing;
      type s16;
      @@
       extern char *parse_args(const char *name,
       			 char *args,
       			 const struct kernel_param *params,
       			 unsigned num,
       			 s16 level_min,
       			 s16 level_max,
      +			 void *arg,
       			 int (*unknown)(char *param, char *val,
      					const char *doing
      +					, void *arg
      					));
      
      @ parse_mod @
      identifier name, args, params, num, level_min, level_max;
      identifier unknown, param, val, doing;
      type s16;
      @@
       char *parse_args(const char *name,
       			 char *args,
       			 const struct kernel_param *params,
       			 unsigned num,
       			 s16 level_min,
       			 s16 level_max,
      +			 void *arg,
       			 int (*unknown)(char *param, char *val,
      					const char *doing
      +					, void *arg
      					))
      {
      	...
      }
      
      @ parse_args_found @
      expression R, E1, E2, E3, E4, E5, E6;
      identifier func;
      @@
      
      (
      	R =
      	parse_args(E1, E2, E3, E4, E5, E6,
      +		   NULL,
      		   func);
      |
      	R =
      	parse_args(E1, E2, E3, E4, E5, E6,
      +		   NULL,
      		   &func);
      |
      	R =
      	parse_args(E1, E2, E3, E4, E5, E6,
      +		   NULL,
      		   NULL);
      |
      	parse_args(E1, E2, E3, E4, E5, E6,
      +		   NULL,
      		   func);
      |
      	parse_args(E1, E2, E3, E4, E5, E6,
      +		   NULL,
      		   &func);
      |
      	parse_args(E1, E2, E3, E4, E5, E6,
      +		   NULL,
      		   NULL);
      )
      
      @ parse_args_unused depends on parse_args_found @
      identifier parse_args_found.func;
      @@
      
      int func(char *param, char *val, const char *unused
      +		 , void *arg
      		 )
      {
      	...
      }
      
      @ mod_unused depends on parse_args_found @
      identifier parse_args_found.func;
      expression A1, A2, A3;
      @@
      
      -	func(A1, A2, A3);
      +	func(A1, A2, A3, NULL);
      
      Generated-by: Coccinelle SmPL
      Cc: cocci@systeme.lip6.fr
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Arjan van de Ven <arjan@linux.intel.com>
      Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Felipe Contreras <felipe.contreras@gmail.com>
      Cc: Ewan Milne <emilne@redhat.com>
      Cc: Jean Delvare <jdelvare@suse.de>
      Cc: Hannes Reinecke <hare@suse.de>
      Cc: Jani Nikula <jani.nikula@intel.com>
      Cc: linux-kernel@vger.kernel.org
      Reviewed-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      Signed-off-by: default avatarLuis R. Rodriguez <mcgrof@suse.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      ecc86170
  24. 17 Apr, 2015 1 commit
    • Heinrich Schuchardt's avatar
      kernel/fork.c: new function for max_threads · ff691f6e
      Heinrich Schuchardt authored
      PAGE_SIZE is not guaranteed to be equal to or less than 8 times the
      THREAD_SIZE.
      
      E.g.  architecture hexagon may have page size 1M and thread size 4096.
      This would lead to a division by zero in the calculation of max_threads.
      
      With this patch the buggy code is moved to a separate function
      set_max_threads.  The error is not fixed.
      
      After fixing the problem in a separate patch the new function can be
      reused to adjust max_threads after adding or removing memory.
      
      Argument mempages of function fork_init() is removed as totalram_pages is
      an exported symbol.
      
      The creation of separate patches for refactoring to a new function and for
      fixing the logic was suggested by Ingo Molnar.
      Signed-off-by: default avatarHeinrich Schuchardt <xypron.glpk@gmx.de>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Guenter Roeck <linux@roeck-us.net>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ff691f6e
  25. 14 Apr, 2015 1 commit
    • Toshi Kani's avatar
      lib/ioremap.c: add huge I/O map capability interfaces · 0ddab1d2
      Toshi Kani authored
      Add ioremap_pud_enabled() and ioremap_pmd_enabled(), which return 1 when
      I/O mappings with pud/pmd are enabled on the kernel.
      
      ioremap_huge_init() calls arch_ioremap_pud_supported() and
      arch_ioremap_pmd_supported() to initialize the capabilities at boot-time.
      
      A new kernel option "nohugeiomap" is also added, so that user can disable
      the huge I/O map capabilities when necessary.
      Signed-off-by: default avatarToshi Kani <toshi.kani@hp.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Robert Elliott <Elliott@hp.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0ddab1d2
  26. 13 Apr, 2015 1 commit
    • Paul E. McKenney's avatar
      cpu: Defer smpboot kthread unparking until CPU known to scheduler · 00df35f9
      Paul E. McKenney authored
      Currently, smpboot_unpark_threads() is invoked before the incoming CPU
      has been added to the scheduler's runqueue structures.  This might
      potentially cause the unparked kthread to run on the wrong CPU, since the
      correct CPU isn't fully set up yet.
      
      That causes a sporadic, hard to debug boot crash triggering on some
      systems, reported by Borislav Petkov, and bisected down to:
      
        2a442c9c ("x86: Use common outgoing-CPU-notification code")
      
      This patch places smpboot_unpark_threads() in a CPU hotplug
      notifier with priority set so that these kthreads are unparked just after
      the CPU has been added to the runqueues.
      Reported-and-tested-by: default avatarBorislav Petkov <bp@suse.de>
      Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      00df35f9
  27. 06 Mar, 2015 1 commit
  28. 05 Mar, 2015 1 commit
  29. 14 Feb, 2015 1 commit
  30. 22 Jan, 2015 1 commit
  31. 15 Dec, 2014 1 commit
  32. 13 Dec, 2014 1 commit
    • Joonsoo Kim's avatar
      mm/page_ext: resurrect struct page extending code for debugging · eefa864b
      Joonsoo Kim authored
      When we debug something, we'd like to insert some information to every
      page.  For this purpose, we sometimes modify struct page itself.  But,
      this has drawbacks.  First, it requires re-compile.  This makes us
      hesitate to use the powerful debug feature so development process is
      slowed down.  And, second, sometimes it is impossible to rebuild the
      kernel due to third party module dependency.  At third, system behaviour
      would be largely different after re-compile, because it changes size of
      struct page greatly and this structure is accessed by every part of
      kernel.  Keeping this as it is would be better to reproduce errornous
      situation.
      
      This feature is intended to overcome above mentioned problems.  This
      feature allocates memory for extended data per page in certain place
      rather than the struct page itself.  This memory can be accessed by the
      accessor functions provided by this code.  During the boot process, it
      checks whether allocation of huge chunk of memory is needed or not.  If
      not, it avoids allocating memory at all.  With this advantage, we can
      include this feature into the kernel in default and can avoid rebuild and
      solve related problems.
      
      Until now, memcg uses this technique.  But, now, memcg decides to embed
      their variable to struct page itself and it's code to extend struct page
      has been removed.  I'd like to use this code to develop debug feature, so
      this patch resurrect it.
      
      To help these things to work well, this patch introduces two callbacks for
      clients.  One is the need callback which is mandatory if user wants to
      avoid useless memory allocation at boot-time.  The other is optional, init
      callback, which is used to do proper initialization after memory is
      allocated.  Detailed explanation about purpose of these functions is in
      code comment.  Please refer it.
      
      Others are completely same with previous extension code in memcg.
      Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Dave Hansen <dave@sr71.net>
      Cc: Michal Nazarewicz <mina86@mina86.com>
      Cc: Jungsoo Son <jungsoo.son@lge.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      eefa864b
  33. 11 Dec, 2014 3 commits
    • Al Viro's avatar
      take the targets of /proc/*/ns/* symlinks to separate fs · e149ed2b
      Al Viro authored
      New pseudo-filesystem: nsfs.  Targets of /proc/*/ns/* live there now.
      It's not mountable (not even registered, so it's not in /proc/filesystems,
      etc.).  Files on it *are* bindable - we explicitly permit that in do_loopback().
      
      This stuff lives in fs/nsfs.c now; proc_ns_fget() moved there as well.
      get_proc_ns() is a macro now (it's simply returning ->i_private; would
      have been an inline, if not for header ordering headache).
      proc_ns_inode() is an ex-parrot.  The interface used in procfs is
      ns_get_path(path, task, ops) and ns_get_name(buf, size, task, ops).
      
      Dentries and inodes are never hashed; a non-counting reference to dentry
      is stashed in ns_common (removed by ->d_prune()) and reused by ns_get_path()
      if present.  See ns_get_path()/ns_prune_dentry/nsfs_evict() for details
      of that mechanism.
      
      As the result, proc_ns_follow_link() has stopped poking in nd->path.mnt;
      it does nd_jump_link() on a consistent <vfsmount,dentry> pair it gets
      from ns_get_path().
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      e149ed2b
    • Andy Lutomirski's avatar
      init: allow CONFIG_INIT_FALLBACK=n to disable defaults if init= fails · 6ef4536e
      Andy Lutomirski authored
      If a user puts init=/whatever on the command line and /whatever can't be
      run, then the kernel will try a few default options before giving up.  If
      init=/whatever came from a bootloader prompt, then this is unexpected but
      probably harmless.  On the other hand, if it comes from a script (e.g.  a
      tool like virtme or perhaps a future kselftest script), then the fallbacks
      are likely to exist, but they'll do the wrong thing.  For example, they
      might unexpectedly invoke systemd.
      
      This adds a config option CONFIG_INIT_FALLBACK.  If unset, then a failure
      to run the specified init= process be fatal.
      
      The tentative plan is to remove CONFIG_INIT_FALLBACK for 3.20.
      
      [akpm@linux-foundation.org: coding-style fixes]
      Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
      Cc: Rob Landley <rob@landley.net>
      Cc: Chuck Ebbert <cebbert.lkml@gmail.com>
      Cc: Randy Dunlap <rdunlap@infradead.org>
      Cc: Shuah Khan <shuah.kh@samsung.com>
      Cc: Frank Rowand <frowand.list@gmail.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Acked-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6ef4536e
    • Johannes Weiner's avatar
      mm: embed the memcg pointer directly into struct page · 1306a85a
      Johannes Weiner authored
      Memory cgroups used to have 5 per-page pointers.  To allow users to
      disable that amount of overhead during runtime, those pointers were
      allocated in a separate array, with a translation layer between them and
      struct page.
      
      There is now only one page pointer remaining: the memcg pointer, that
      indicates which cgroup the page is associated with when charged.  The
      complexity of runtime allocation and the runtime translation overhead is
      no longer justified to save that *potential* 0.19% of memory.  With
      CONFIG_SLUB, page->mem_cgroup actually sits in the doubleword padding
      after the page->private member and doesn't even increase struct page,
      and then this patch actually saves space.  Remaining users that care can
      still compile their kernels without CONFIG_MEMCG.
      
           text    data     bss     dec     hex     filename
        8828345 1725264  983040 11536649 b00909  vmlinux.old
        8827425 1725264  966656 11519345 afc571  vmlinux.new
      
      [mhocko@suse.cz: update Documentation/cgroups/memory.txt]
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarVladimir Davydov <vdavydov@parallels.com>
      Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
      Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vladimir Davydov <vdavydov@parallels.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
      Acked-by: default avatarKonstantin Khlebnikov <koct9i@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1306a85a