1. 25 Dec, 2008 31 commits
  2. 24 Dec, 2008 6 commits
  3. 23 Dec, 2008 3 commits
    • Kyle McMartin's avatar
      parisc: disable UP-optimized flush_tlb_mm · 5289f46b
      Kyle McMartin authored
      
      
      flush_tlb_mm's "optimized" uniprocessor case of allocating a new
      context for userspace is exposing a race where we can suddely return
      to a syscall with the protection id and space id out of sync, trapping
      on the next userspace access.
      Debugged-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      Tested-by: default avatarHelge Deller <deller@gmx.de>
      Signed-off-by: default avatarKyle McMartin <kyle@mcmartin.ca>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5289f46b
    • Linus Torvalds's avatar
      Merge branch 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6 · 8960223d
      Linus Torvalds authored
      * 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
        drm/radeon: fix correctness of irq_enabled check for radeon.
      8960223d
    • Harry Ciao's avatar
      edac: fix edac core deadlock when removing a device · d519c8d9
      Harry Ciao authored
      
      
      When deleting an edac device, we have to wait for its edac_dev.work to be
      completed before deleting the whole edac_dev structure.  Since we have no
      idea which work in current edac_poller's workqueue is the work we are
      conerned about, we wait for all work in the edac_poller's workqueue to be
      proceseed.  This is done via flush_cpu_workqueue() which inserts a
      wq_barrier into the tail of the workqueue and then sleeping on the
      completion of this wq_barrier.  The edac_poller will wake up sleepers when
      it is found.
      
      EDAC core creates only one kernel worker thread, edac_poller, to run the
      works of all current edac devices.  They share the same callback function
      of edac_device_workq_function(), which would grab the mutex of
      device_ctls_mutex first before it checks the device.  This is exactly
      where edac_poller and rmmod would have a great chance to deadlock.
      
      In below call trace of rmmod > ... >
      edac_device_del_device >
      edac_device_workq_teardown > flush_workqueue > flush_cpu_workqueue,
      
      device_ctls_mutex would have already been grabbed by
      edac_device_del_device().  So, on one hand rmmod would sleep on the
      completion of a wq_barrier, holding device_ctls_mutex; on the other hand
      edac_poller would be blocked on the same mutex when it's running any one
      of works of existing edac evices(Note, this edac_dev.work is likely to be
      totally irrelevant to the one that is being removed right now)and never
      would have a chance to run the work of above wq_barrier to wake rmmod up.
      
      edac_device_workq_teardown() should not be called within the critical
      region of device_ctls_mutex.  Just like is done in edac_pci_del_device()
      and edac_mc_del_mc(), where edac_pci_workq_teardown() and
      edac_mc_workq_teardown() are called after related mutex are released.
      
      Moreover, an edac_dev.work should check first if it is being removed.  If
      this is the case, then it should bail out immediately.  Since not all of
      existing edac devices are to be removed, this "shutting flag" should be
      contained to edac device being removed.  The current edac_dev.op_state can
      be used to serve this purpose.
      
      The original deadlock problem and the solution have been witnessed and
      tested on actual hardware.  Without the solution, rmmod an edac driver
      would result in below deadlock:
      
      root@localhost:/root> rmmod mv64x60_edac
      EDAC DEBUG: mv64x60_dma_err_remove()
      EDAC DEBUG: edac_device_del_device()
      EDAC DEBUG: find_edac_device_by_dev()
      
      (hang for a moment)
      
      INFO: task edac-poller:2030 blocked for more than 120 seconds.
      "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
      edac-poller   D 00000000     0  2030      2
      Call Trace:
      [df159dc0] [c0071e3c] free_hot_cold_page+0x17c/0x304 (unreliable)
      [df159e80] [c000a024] __switch_to+0x6c/0xa0
      [df159ea0] [c03587d8] schedule+0x2f4/0x4d8
      [df159f00] [c03598a8] __mutex_lock_slowpath+0xa0/0x174
      [df159f40] [e1030434] edac_device_workq_function+0x28/0xd8 [edac_core]
      [df159f60] [c003beb4] run_workqueue+0x114/0x218
      [df159f90] [c003c674] worker_thread+0x5c/0xc8
      [df159fd0] [c004106c] kthread+0x5c/0xa0
      [df159ff0] [c0013538] original_kernel_thread+0x44/0x60
      INFO: task rmmod:2062 blocked for more than 120 seconds.
      "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
      rmmod         D 0ff2c9fc     0  2062   1839
      Call Trace:
      [df119c00] [c0437a74] 0xc0437a74 (unreliable)
      [df119cc0] [c000a024] __switch_to+0x6c/0xa0
      [df119ce0] [c03587d8] schedule+0x2f4/0x4d8
      [df119d40] [c03591dc] schedule_timeout+0xb0/0xf4
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d519c8d9