1. 13 Oct, 2016 9 commits
  2. 12 Oct, 2016 17 commits
  3. 11 Oct, 2016 14 commits
    • Michal Hocko's avatar
      mm: split gfp_mask and mapping flags into separate fields · 9c5d760b
      Michal Hocko authored
      mapping->flags currently encodes two different things into a single flag.
      It contains sticky gfp_mask for page cache allocations and AS_ codes used
      to report errors/enospace and other states which are mapping specific.
      Condensing the two semantically unrelated things saves few bytes but it
      also complicates other things.  For one thing the gfp flags space is
      reduced and in fact we are already running out of available bits.  It can
      be assumed that more gfp flags will be necessary later on.
      
      To not introduce the address_space grow (at least on x86_64) we can stick
      it right after private_lock because we have a hole there.
      
      struct address_space {
              struct inode *             host;                 /*     0     8 */
              struct radix_tree_root     page_tree;            /*     8    16 */
              spinlock_t                 tree_lock;            /*    24     4 */
              atomic_t                   i_mmap_writable;      /*    28     4 */
              struct rb_root             i_mmap;               /*    32     8 */
              struct rw_semaphore        i_mmap_rwsem;         /*    40    40 */
              /* --- cacheline 1 boundary (64 bytes) was 16 bytes ago --- */
              long unsigned int          nrpages;              /*    80     8 */
              long unsigned int          nrexceptional;        /*    88     8 */
              long unsigned int          writeback_index;      /*    96     8 */
              const struct address_space_operations  * a_ops;  /*   104     8 */
              long unsigned int          flags;                /*   112     8 */
              spinlock_t                 private_lock;         /*   120     4 */
      
              /* XXX 4 bytes hole, try to pack */
      
              /* --- cacheline 2 boundary (128 bytes) --- */
              struct list_head           private_list;         /*   128    16 */
              void *                     private_data;         /*   144     8 */
      
              /* size: 152, cachelines: 3, members: 14 */
              /* sum members: 148, holes: 1, sum holes: 4 */
              /* last cacheline: 24 bytes */
      };
      
      Link: http://lkml.kernel.org/r/20160912114852.GI14524@dhcp22.suse.czSigned-off-by: default avatarMichal Hocko <mhocko@suse.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9c5d760b
    • Michal Hocko's avatar
      fs: use mapping_set_error instead of opencoded set_bit · 5114a97a
      Michal Hocko authored
      The mapping_set_error() helper sets the correct AS_ flag for the mapping
      so there is no reason to open code it.  Use the helper directly.
      
      [akpm@linux-foundation.org: be honest about conversion from -ENXIO to -EIO]
      Link: http://lkml.kernel.org/r/20160912111608.2588-2-mhocko@kernel.orgSigned-off-by: default avatarMichal Hocko <mhocko@suse.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5114a97a
    • Masahiro Yamada's avatar
      treewide: remove redundant #include <linux/kconfig.h> · 97139d4a
      Masahiro Yamada authored
      Kernel source files need not include <linux/kconfig.h> explicitly
      because the top Makefile forces to include it with:
      
        -include $(srctree)/include/linux/kconfig.h
      
      This commit removes explicit includes except the following:
      
        * arch/s390/include/asm/facilities_src.h
        * tools/testing/radix-tree/linux/kernel.h
      
      These two are used for host programs.
      
      Link: http://lkml.kernel.org/r/1473656164-11929-1-git-send-email-yamada.masahiro@socionext.comSigned-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      97139d4a
    • John Siddle's avatar
      hung_task: allow hung_task_panic when hung_task_warnings is 0 · 48a6d64e
      John Siddle authored
      Previously hung_task_panic would not be respected if enabled after
      hung_task_warnings had already been decremented to 0.
      
      Permit the kernel to panic if hung_task_panic is enabled after
      hung_task_warnings has already been decremented to 0 and another task
      hangs for hung_task_timeout_secs seconds.
      
      Check if hung_task_panic is enabled so we don't return prematurely, and
      check if hung_task_warnings is non-zero so we don't print the warning
      unnecessarily.
      
      [akpm@linux-foundation.org: fix off-by-one]
      Link: http://lkml.kernel.org/r/1473450214-4049-1-git-send-email-jsiddle@redhat.comSigned-off-by: default avatarJohn Siddle <jsiddle@redhat.com>
      Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      48a6d64e
    • Jonathan Corbet's avatar
      kthread: add kerneldoc for kthread_create() · e154ccc8
      Jonathan Corbet authored
      This macro is referenced in other kerneldoc comments, but lacks one of its
      own; fix that.
      
      Link: http://lkml.kernel.org/r/20160826072313.726a3485@lwn.netSigned-off-by: default avatarJonathan Corbet <corbet@lwn.net>
      Reported-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e154ccc8
    • Petr Mladek's avatar
      kthread: better support freezable kthread workers · dbf52682
      Petr Mladek authored
      This patch allows to make kthread worker freezable via a new @flags
      parameter. It will allow to avoid an init work in some kthreads.
      
      It currently does not affect the function of kthread_worker_fn()
      but it might help to do some optimization or fixes eventually.
      
      I currently do not know about any other use for the @flags
      parameter but I believe that we will want more flags
      in the future.
      
      Finally, I hope that it will not cause confusion with @flags member
      in struct kthread. Well, I guess that we will want to rework the
      basic kthreads implementation once all kthreads are converted into
      kthread workers or workqueues. It is possible that we will merge
      the two structures.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-12-git-send-email-pmladek@suse.comSigned-off-by: default avatarPetr Mladek <pmladek@suse.com>
      Acked-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      dbf52682
    • Petr Mladek's avatar
      kthread: allow to modify delayed kthread work · 9a6b06c8
      Petr Mladek authored
      There are situations when we need to modify the delay of a delayed kthread
      work. For example, when the work depends on an event and the initial delay
      means a timeout. Then we want to queue the work immediately when the event
      happens.
      
      This patch implements kthread_mod_delayed_work() as inspired workqueues.
      It cancels the timer, removes the work from any worker list and queues it
      again with the given timeout.
      
      A very special case is when the work is being canceled at the same time.
      It might happen because of the regular kthread_cancel_delayed_work_sync()
      or by another kthread_mod_delayed_work(). In this case, we do nothing and
      let the other operation win. This should not normally happen as the caller
      is supposed to synchronize these operations a reasonable way.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-11-git-send-email-pmladek@suse.comSigned-off-by: default avatarPetr Mladek <pmladek@suse.com>
      Acked-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9a6b06c8
    • Petr Mladek's avatar
      kthread: allow to cancel kthread work · 37be45d4
      Petr Mladek authored
      We are going to use kthread workers more widely and sometimes we will need
      to make sure that the work is neither pending nor running.
      
      This patch implements cancel_*_sync() operations as inspired by
      workqueues.  Well, we are synchronized against the other operations via
      the worker lock, we use del_timer_sync() and a counter to count parallel
      cancel operations.  Therefore the implementation might be easier.
      
      First, we check if a worker is assigned.  If not, the work has newer been
      queued after it was initialized.
      
      Second, we take the worker lock.  It must be the right one.  The work must
      not be assigned to another worker unless it is initialized in between.
      
      Third, we try to cancel the timer when it exists.  The timer is deleted
      synchronously to make sure that the timer call back is not running.  We
      need to temporary release the worker->lock to avoid a possible deadlock
      with the callback.  In the meantime, we set work->canceling counter to
      avoid any queuing.
      
      Fourth, we try to remove the work from a worker list. It might be
      the list of either normal or delayed works.
      
      Fifth, if the work is running, we call kthread_flush_work().  It might
      take an arbitrary time.  We need to release the worker-lock again.  In the
      meantime, we again block any queuing by the canceling counter.
      
      As already mentioned, the check for a pending kthread work is done under a
      lock.  In compare with workqueues, we do not need to fight for a single
      PENDING bit to block other operations.  Therefore we do not suffer from
      the thundering storm problem and all parallel canceling jobs might use
      kthread_flush_work().  Any queuing is blocked until the counter gets zero.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-10-git-send-email-pmladek@suse.comSigned-off-by: default avatarPetr Mladek <pmladek@suse.com>
      Acked-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      37be45d4
    • Petr Mladek's avatar
      kthread: initial support for delayed kthread work · 22597dc3
      Petr Mladek authored
      We are going to use kthread_worker more widely and delayed works
      will be pretty useful.
      
      The implementation is inspired by workqueues.  It uses a timer to queue
      the work after the requested delay.  If the delay is zero, the work is
      queued immediately.
      
      In compare with workqueues, each work is associated with a single worker
      (kthread).  Therefore the implementation could be much easier.  In
      particular, we use the worker->lock to synchronize all the operations with
      the work.  We do not need any atomic operation with a flags variable.
      
      In fact, we do not need any state variable at all.  Instead, we add a list
      of delayed works into the worker.  Then the pending work is listed either
      in the list of queued or delayed works.  And the existing check of pending
      works is the same even for the delayed ones.
      
      A work must not be assigned to another worker unless reinitialized.
      Therefore the timer handler might expect that dwork->work->worker is valid
      and it could simply take the lock.  We just add some sanity checks to help
      with debugging a potential misuse.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-9-git-send-email-pmladek@suse.comSigned-off-by: default avatarPetr Mladek <pmladek@suse.com>
      Acked-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      22597dc3
    • Petr Mladek's avatar
      kthread: detect when a kthread work is used by more workers · 8197b3d4
      Petr Mladek authored
      Nothing currently prevents a work from queuing for a kthread worker when
      it is already running on another one.  This means that the work might run
      in parallel on more than one worker.  Also some operations are not
      reliable, e.g.  flush.
      
      This problem will be even more visible after we add kthread_cancel_work()
      function.  It will only have "work" as the parameter and will use
      worker->lock to synchronize with others.
      
      Well, normally this is not a problem because the API users are sane.
      But bugs might happen and users also might be crazy.
      
      This patch adds a warning when we try to insert the work for another
      worker.  It does not fully prevent the misuse because it would make the
      code much more complicated without a big benefit.
      
      It adds the same warning also into kthread_flush_work() instead of the
      repeated attempts to get the right lock.
      
      A side effect is that one needs to explicitly reinitialize the work if it
      must be queued into another worker.  This is needed, for example, when the
      worker is stopped and started again.  It is a bit inconvenient.  But it
      looks like a good compromise between the stability and complexity.
      
      I have double checked all existing users of the kthread worker API and
      they all seems to initialize the work after the worker gets started.
      
      Just for completeness, the patch adds a check that the work is not already
      in a queue.
      
      The patch also puts all the checks into a separate function.  It will be
      reused when implementing delayed works.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-8-git-send-email-pmladek@suse.comSigned-off-by: default avatarPetr Mladek <pmladek@suse.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      8197b3d4
    • Petr Mladek's avatar
      kthread: add kthread_destroy_worker() · 35033fe9
      Petr Mladek authored
      The current kthread worker users call flush() and stop() explicitly.
      This function does the same plus it frees the kthread_worker struct
      in one call.
      
      It is supposed to be used together with kthread_create_worker*() that
      allocates struct kthread_worker.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-7-git-send-email-pmladek@suse.comSigned-off-by: default avatarPetr Mladek <pmladek@suse.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      35033fe9
    • Petr Mladek's avatar
      kthread: add kthread_create_worker*() · fbae2d44
      Petr Mladek authored
      Kthread workers are currently created using the classic kthread API,
      namely kthread_run().  kthread_worker_fn() is passed as the @threadfn
      parameter.
      
      This patch defines kthread_create_worker() and
      kthread_create_worker_on_cpu() functions that hide implementation details.
      
      They enforce using kthread_worker_fn() for the main thread.  But I doubt
      that there are any plans to create any alternative.  In fact, I think that
      we do not want any alternative main thread because it would be hard to
      support consistency with the rest of the kthread worker API.
      
      The naming and function of kthread_create_worker() is inspired by the
      workqueues API like the rest of the kthread worker API.
      
      The kthread_create_worker_on_cpu() variant is motivated by the original
      kthread_create_on_cpu().  Note that we need to bind per-CPU kthread
      workers already when they are created.  It makes the life easier.
      kthread_bind() could not be used later for an already running worker.
      
      This patch does _not_ convert existing kthread workers.  The kthread
      worker API need more improvements first, e.g.  a function to destroy the
      worker.
      
      IMPORTANT:
      
      kthread_create_worker_on_cpu() allows to use any format of the worker
      name, in compare with kthread_create_on_cpu().  The good thing is that it
      is more generic.  The bad thing is that most users will need to pass the
      cpu number in two parameters, e.g.  kthread_create_worker_on_cpu(cpu,
      "helper/%d", cpu).
      
      To be honest, the main motivation was to avoid the need for an empty
      va_list.  The only legal way was to create a helper function that would be
      called with an empty list.  Other attempts caused compilation warnings or
      even errors on different architectures.
      
      There were also other alternatives, for example, using #define or
      splitting __kthread_create_worker().  The used solution looked like the
      least ugly.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-6-git-send-email-pmladek@suse.comSigned-off-by: default avatarPetr Mladek <pmladek@suse.com>
      Acked-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fbae2d44
    • Petr Mladek's avatar
      kthread: allow to call __kthread_create_on_node() with va_list args · 255451e4
      Petr Mladek authored
      kthread_create_on_node() implements a bunch of logic to create the
      kthread.  It is already called by kthread_create_on_cpu().
      
      We are going to extend the kthread worker API and will need to call
      kthread_create_on_node() with va_list args there.
      
      This patch does only a refactoring and does not modify the existing
      behavior.
      
      Link: http://lkml.kernel.org/r/1470754545-17632-5-git-send-email-pmladek@suse.comSigned-off-by: default avatarPetr Mladek <pmladek@suse.com>
      Acked-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      255451e4
    • Petr Mladek's avatar
      kthread/smpboot: do not park in kthread_create_on_cpu() · a65d4096
      Petr Mladek authored
      kthread_create_on_cpu() was added by the commit 2a1d4460
      ("kthread: Implement park/unpark facility").  It is currently used only
      when enabling new CPU.  For this purpose, the newly created kthread has to
      be parked.
      
      The CPU binding is a bit tricky.  The kthread is parked when the CPU has
      not been allowed yet.  And the CPU is bound when the kthread is unparked.
      
      The function would be useful for more per-CPU kthreads, e.g.
      bnx2fc_thread, fcoethread.  For this purpose, the newly created kthread
      should stay in the uninterruptible state.
      
      This patch moves the parking into smpboot.  It binds the thread already
      when created.  Then the function might be used universally.  Also the
      behavior is consistent with kthread_create() and kthread_create_on_node().
      
      Link: http://lkml.kernel.org/r/1470754545-17632-4-git-send-email-pmladek@suse.comSigned-off-by: default avatarPetr Mladek <pmladek@suse.com>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Jiri Kosina <jkosina@suse.cz>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a65d4096