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  1. 21 Aug, 2012 11 commits
    • Michal Hocko's avatar
      mm: hugetlbfs: correctly populate shared pmd · eb48c071
      Michal Hocko authored 
      Each page mapped in a process's address space must be correctly
accounted for in _mapcount.  Normally the rules for this are
straightforward but hugetlbfs page table sharing is different.  The page
table pages at the PMD level are reference counted while the mapcount
remains the same.

If this accounting is wrong, it causes bugs like this one reported by
Larry Woodman:

  kernel BUG at mm/filemap.c:135!
  invalid opcode: 0000 [#1] SMP
  CPU 22
  Modules linked in: bridge stp llc sunrpc binfmt_misc dcdbas microcode pcspkr acpi_pad acpi]
  Pid: 18001, comm: mpitest Tainted: G        W    3.3.0+ #4 Dell Inc. PowerEdge R620/07NDJ2
  RIP: 0010:[<ffffffff8112cfed>]  [<ffffffff8112cfed>] __delete_from_page_cache+0x15d/0x170
  Process mpitest (pid: 18001, threadinfo ffff880428972000, task ffff880428b5cc20)
  Call Trace:
    delete_from_page_cache+0x40/0x80
    truncate_hugepages+0x115/0x1f0
    hugetlbfs_evict_inode+0x18/0x30
    evict+0x9f/0x1b0
    iput_final+0xe3/0x1e0
    iput+0x3e/0x50
    d_kill+0xf8/0x110
    dput+0xe2/0x1b0
    __fput+0x162/0x240

During fork(), copy_hugetlb_page_range() detects if huge_pte_alloc()
shared page tables with the check dst_pte == src_pte.  The logic is if
the PMD page is the same, they must be shared.  This assumes that the
sharing is between the parent and child.  However, if the sharing is
with a different process entirely then this check fails as in this
diagram:

  parent
    |
    ------------>pmd
                 src_pte----------> data page
                                        ^
  other--------->pmd--------------------|
                  ^
  child-----------|
                 dst_pte

For this situation to occur, it must be possible for Parent and Other to
have faulted and failed to share page tables with each other.  This is
possible due to the following style of race.

  PROC A                                          PROC B
  copy_hugetlb_page_range                         copy_hugetlb_page_range
    src_pte == huge_pte_offset                      src_pte == huge_pte_offset
    !src_pte so no sharing                          !src_pte so no sharing

  (time passes)

  hugetlb_fault                                   hugetlb_fault
    huge_pte_alloc                                  huge_pte_alloc
      huge_pmd_share                                 huge_pmd_share
        LOCK(i_mmap_mutex)
        find nothing, no sharing
        UNLOCK(i_mmap_mutex)
                                                      LOCK(i_mmap_mutex)
                                                      find nothing, no sharing
                                                      UNLOCK(i_mmap_mutex)
      pmd_alloc                                       pmd_alloc
      LOCK(instantiation_mutex)
      fault
      UNLOCK(instantiation_mutex)
                                                  LOCK(instantiation_mutex)
                                                  fault
                                                  UNLOCK(instantiation_mutex)

These two processes are not poing to the same data page but are not
sharing page tables because the opportunity was missed.  When either
process later forks, the src_pte == dst pte is potentially insufficient.
As the check falls through, the wrong PTE information is copied in
(harmless but wrong) and the mapcount is bumped for a page mapped by a
shared page table leading to the BUG_ON.

This patch addresses the issue by moving pmd_alloc into huge_pmd_share
which guarantees that the shared pud is populated in the same critical
section as pmd.  This also means that huge_pte_offset test in
huge_pmd_share is serialized correctly now which in turn means that the
success of the sharing will be higher as the racing tasks see the pud
and pmd populated together.

Race identified and changelog written mostly by Mel Gorman.

{akpm@linux-foundation.org: attempt to make the huge_pmd_share() comment comprehensible, clean up coding style]
Reported-by: default avatarLarry Woodman <lwoodman@redhat.com>
Tested-by: default avatarLarry Woodman <lwoodman@redhat.com>
Reviewed-by: default avatarMel Gorman <mgorman@suse.de>
Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Ken Chen <kenchen@google.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      eb48c071
    • Stephen M. Cameron's avatar
      cciss: fix incorrect scsi status reporting · b0cf0b11
      Stephen M. Cameron authored 
      Delete code which sets SCSI status incorrectly as it's already been set
correctly above this incorrect code.  The bug was introduced in 2009 by
commit b0e15f6d ("cciss: fix typo that causes scsi status to be
lost.")
Signed-off-by: default avatarStephen M. Cameron <scameron@beardog.cce.hp.com>
Reported-by: default avatarRoel van Meer <roel.vanmeer@bokxing.nl>
Tested-by: default avatarRoel van Meer <roel.vanmeer@bokxing.nl>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b0cf0b11
    • Namjae Jeon's avatar
      Documentation: update mount option in filesystem/vfat.txt · d65226e2
      Namjae Jeon authored 
      Update two mount options(discard, nfs) in vfat.txt.
Signed-off-by: default avatarNamjae Jeon <linkinjeon@gmail.com>
Acked-by: default avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d65226e2
    • Hugh Dickins's avatar
      mm: change nr_ptes BUG_ON to WARN_ON · f9aed62a
      Hugh Dickins authored 
      Occasionally an isolated BUG_ON(mm->nr_ptes) gets reported, indicating
that not all the page tables allocated could be found and freed when
exit_mmap() tore down the user address space.

There's usually nothing we can say about it, beyond that it's probably a
sign of some bad memory or memory corruption; though it might still
indicate a bug in vma or page table management (and did recently reveal a
race in THP, fixed a few months ago).

But one overdue change we can make is from BUG_ON to WARN_ON.

It's fairly likely that the system will crash shortly afterwards in some
other way (for example, the BUG_ON(page_mapped(page)) in
__delete_from_page_cache(), once an inode mapped into the lost page tables
gets evicted); but might tell us more before that.

Change the BUG_ON(page_mapped) to WARN_ON too?  Later perhaps: I'm less
eager, since that one has several times led to fixes.
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f9aed62a
    • Jens Rottmann's avatar
      cs5535-clockevt: typo, it's MFGPT, not MFPGT · 61e01be2
      Jens Rottmann authored 
      Signed-off-by: default avatarJens Rottmann <JRottmann@LiPPERTEmbedded.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      61e01be2
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu · a6b881a5
      Linus Torvalds authored 
      Pull m68knommu arch fixes from Greg Ungerer:
 "This contains 2 fixes.  One fixes compilation of ColdFire clk code,
  the other makes sure we use the generic atomic64 support on all m68k
  targets."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu:
  m68k: select CONFIG_GENERIC_ATOMIC64 for all m68k CPU types
  m68knommu: select CONFIG_HAVE_CLK for ColdFire CPU types
      a6b881a5
    • Linus Torvalds's avatar
      Merge tag 'pinctrl-fixes-v3.6-rc3' of... · 8f6c1ca9
      Linus Torvalds authored 
      Merge tag 'pinctrl-fixes-v3.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl

Pull pin control fixes from Linus Walleij:
 - Fixed Nomadik errorpath
 - Fixed documentation spelling errors
 - Forward-declare struct device in a header file
 - Remove some extraneous code lines when getting pinctrl states
 - Correct the i.MX51 configure register number
 - Fix the Nomadik keypad function group list

* tag 'pinctrl-fixes-v3.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl/nomadik: add kp_b_2 keyboard function group list
  pinctrl: imx51: fix .conf_reg of MX51_PAD_SD2_CMD__CSPI_MOSI
  trivial: pinctrl core: remove extraneous code lines
  pinctrl: header: trivial: declare struct device
  Documentation/pinctrl.txt: Fix some misspelled macros
  pinctrl/nomadik: fix null in irqdomain errorpath
      8f6c1ca9
    • Linus Torvalds's avatar
      Merge tag 'sound-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound · 4459f397
      Linus Torvalds authored 
      Pull sound fixes from Takashi Iwai:
 "This update became slightly bigger than usual for rc3, but most of the
  commits are small and trivial.  A large chunk is found for HD-audio
  ca0132 codec, which is mostly a clean up of the specific code, to make
  SPDIF working properly, and also in the new ASoC Arizona driver.

  One important fix is for usb-audio Oops fix since 3.5.  We still see
  some EHCI related bandwidth problem, but usb-audio should be more
  stabilized now.

  Other than that, a Kconfig fix is spread over files, and various
  HD-audio and ASoC fixes as usual, in addition to Julia's error path
  fixes."

* tag 'sound-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (42 commits)
  ALSA: snd-als100: fix suspend/resume
  ALSA: hda - Fix leftover codec->power_transition
  ALSA: hda - don't create dysfunctional mixer controls for ca0132
  ALSA: sound/ppc/snd_ps3.c: fix error return code
  ALSA: sound/pci/rme9652/hdspm.c: fix error return code
  ALSA: sound/pci/sis7019.c: fix error return code
  ALSA: sound/pci/ctxfi/ctatc.c: fix error return code
  ALSA: sound/atmel/ac97c.c: fix error return code
  ALSA: sound/atmel/abdac.c: fix error return code
  ALSA: fix pcm.h kernel-doc warning and notation
  sound: oss/sb_audio: prevent divide by zero bug
  ASoC: wm9712: Fix inverted capture volume
  ASoC: wm9712: Fix microphone source selection
  ASoC: wm5102: Remove DRC2
  ALSA: hda - Don't send invalid volume knob command on IDT 92hd75bxx
  ALSA: usb-audio: Fix scheduling-while-atomic bug in PCM capture stream
  ALSA: lx6464es: Add a missing error check
  ALSA: hda - Fix 'Beep Playback Switch' with no underlying mute switch
  ASoC: jack: Always notify full jack status
  ASoC: wm5110: Add missing input PGA routes
  ...
      4459f397
    • Eric Dumazet's avatar
      task_work: add a scheduling point in task_work_run() · f341861f
      Eric Dumazet authored 
      It seems commit 4a9d4b02 ("switch fput to task_work_add") re-
introduced the problem addressed in 944be0b2 ("close_files(): add
scheduling point")

If a server process with a lot of files (say 2 million tcp sockets) is
killed, we can spend a lot of time in task_work_run() and trigger a soft
lockup.
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f341861f
    • Dave Airlie's avatar
      fbcon: fix race condition between console lock and cursor timer · ec5da7f8
      Dave Airlie authored 
      So we've had a fair few reports of fbcon handover breakage between
efi/vesafb and i915 surface recently, so I dedicated a couple of
days to finding the problem.

Essentially the last thing we saw was the conflicting framebuffer
message and that was all.

So after much tracing with direct netconsole writes (printks
under console_lock not so useful), I think I found the race.

  Thread A (driver load)    Thread B (timer thread)
    unbind_con_driver ->              |
    bind_con_driver ->                |
    vc->vc_sw->con_deinit ->          |
    fbcon_deinit ->                   |
    console_lock()                    |
        |                             |
        |                       fbcon_flashcursor timer fires
        |                       console_lock() <- blocked for A
        |
        |
  fbcon_del_cursor_timer ->
    del_timer_sync
    (BOOM)

Of course because all of this is under the console lock,
we never see anything, also since we also just unbound the active
console guess what we never see anything.

Hopefully this fixes the problem for anyone seeing vesafb->kms
driver handoff.
Signed-off-by: default avatarDavid Airlie <airlied@redhat.com>
Acked-by: default avatarAlan Cox <alan@lxorguk.ukuu.org.uk>
Cc: stable@vger.kernel.org
Tested-by: default avatarJosh Boyer <jwboyer@gmail.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ec5da7f8
    • Ondrej Zary's avatar
      ALSA: snd-als100: fix suspend/resume · 53e1719f
      Ondrej Zary authored 
      snd_card_als100_probe() does not set pcm field in struct snd_sb.
As a result, PCM is not suspended and applications don't know that they need
to resume the playback.

Tested with Labway A381-F20 card (ALS120).
Signed-off-by: default avatarOndrej Zary <linux@rainbow-software.org>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      53e1719f
  3. 20 Aug, 2012 29 commits
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