1. 24 Nov, 2014 37 commits
  2. 23 Nov, 2014 3 commits
    • Linus Torvalds's avatar
      Linux 3.18-rc6 · 5d01410f
      Linus Torvalds authored
      5d01410f
    • Andy Lutomirski's avatar
      uprobes, x86: Fix _TIF_UPROBE vs _TIF_NOTIFY_RESUME · 82975bc6
      Andy Lutomirski authored
      x86 call do_notify_resume on paranoid returns if TIF_UPROBE is set but
      not on non-paranoid returns.  I suspect that this is a mistake and that
      the code only works because int3 is paranoid.
      
      Setting _TIF_NOTIFY_RESUME in the uprobe code was probably a workaround
      for the x86 bug.  With that bug fixed, we can remove _TIF_NOTIFY_RESUME
      from the uprobes code.
      Reported-by: default avatarOleg Nesterov <oleg@redhat.com>
      Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
      Acked-by: default avatarBorislav Petkov <bp@suse.de>
      Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      82975bc6
    • Thomas Gleixner's avatar
      sched: Provide update_curr callbacks for stop/idle scheduling classes · 90e362f4
      Thomas Gleixner authored
      Chris bisected a NULL pointer deference in task_sched_runtime() to
      commit 6e998916 'sched/cputime: Fix clock_nanosleep()/clock_gettime()
      inconsistency'.
      
      Chris observed crashes in atop or other /proc walking programs when he
      started fork bombs on his machine.  He assumed that this is a new exit
      race, but that does not make any sense when looking at that commit.
      
      What's interesting is that, the commit provides update_curr callbacks
      for all scheduling classes except stop_task and idle_task.
      
      While nothing can ever hit that via the clock_nanosleep() and
      clock_gettime() interfaces, which have been the target of the commit in
      question, the author obviously forgot that there are other code paths
      which invoke task_sched_runtime()
      
      do_task_stat(()
       thread_group_cputime_adjusted()
         thread_group_cputime()
           task_cputime()
             task_sched_runtime()
              if (task_current(rq, p) && task_on_rq_queued(p)) {
                update_rq_clock(rq);
                up->sched_class->update_curr(rq);
              }
      
      If the stats are read for a stomp machine task, aka 'migration/N' and
      that task is current on its cpu, this will happily call the NULL pointer
      of stop_task->update_curr.  Ooops.
      
      Chris observation that this happens faster when he runs the fork bomb
      makes sense as the fork bomb will kick migration threads more often so
      the probability to hit the issue will increase.
      
      Add the missing update_curr callbacks to the scheduler classes stop_task
      and idle_task.  While idle tasks cannot be monitored via /proc we have
      other means to hit the idle case.
      
      Fixes: 6e998916 'sched/cputime: Fix clock_nanosleep()/clock_gettime() inconsistency'
      Reported-by: default avatarChris Mason <clm@fb.com>
      Reported-and-tested-by: default avatarBorislav Petkov <bp@alien8.de>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Stanislaw Gruszka <sgruszka@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      90e362f4