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  1. 08 Sep, 2014 1 commit
    • Artem Bityutskiy's avatar
      UBIFS: fix a race condition · 052c2807
      Artem Bityutskiy authored 
      Hu (hujianyang@huawei.com) discovered a race condition which may lead to a
situation when UBIFS is unable to mount the file-system after an unclean
reboot. The problem is theoretical, though.

In UBIFS, we have the log, which basically a set of LEBs in a certain area. The
log has the tail and the head.

Every time user writes data to the file-system, the UBIFS journal grows, and
the log grows as well, because we append new reference nodes to the head of the
log. So the head moves forward all the time, while the log tail stays at the
same position.

At any time, the UBIFS master node points to the tail of the log. When we mount
the file-system, we scan the log, and we always start from its tail, because
this is where the master node points to. The only occasion when the tail of the
log changes is the commit operation.

The commit operation has 2 phases - "commit start" and "commit end". The former
is relatively short, and does not involve much I/O. During this phase we mostly
just build various in-memory lists of the things which have to be written to
the flash media during "commit end" phase.

During the commit start phase, what we do is we "clean" the log. Indeed, the
commit operation will index all the data in the journal, so the entire journal
"disappears", and therefore the data in the log become unneeded. So we just
move the head of the log to the next LEB, and write the CS node there. This LEB
will be the tail of the new log when the commit operation finishes.

When the "commit start" phase finishes, users may write more data to the
file-system, in parallel with the ongoing "commit end" operation. At this point
the log tail was not changed yet, it is the same as it had been before we
started the commit. The log head keeps moving forward, though.

The commit operation now needs to write the new master node, and the new master
node should point to the new log tail. After this the LEBs between the old log
tail and the new log tail can be unmapped and re-used again.

And here is the possible problem. We do 2 operations: (a) We first update the
log tail position in memory (see 'ubifs_log_end_commit()'). (b) And then we
write the master node (see the big lock of code in 'do_commit()').

But nothing prevents the log head from moving forward between (a) and (b), and
the log head may "wrap" now to the old log tail. And when the "wrap" happens,
the contends of the log tail gets erased. Now a power cut happens and we are in
trouble. We end up with the old master node pointing to the old tail, which was
erased. And replay fails because it expects the master node to point to the
correct log tail at all times.

This patch merges the abovementioned (a) and (b) operations by moving the master
node change code to the 'ubifs_log_end_commit()' function, so that it runs with
the log mutex locked, which will prevent the log from being changed benween
operations (a) and (b).

Cc: stable@vger.kernel.org # 07e19dff UBIFS: remove mst_mutex
Cc: stable@vger.kernel.org
Reported-by: default avatarhujianyang <hujianyang@huawei.com>
Tested-by: default avatarhujianyang <hujianyang@huawei.com>
Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
      052c2807
  3. 07 Sep, 2014 11 commits
  5. 06 Sep, 2014 6 commits
    • Linus Torvalds's avatar
      Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm · 2b12164b
      Linus Torvalds authored 
      Pull kvm fixes from Paolo Bonzini:
 "A smattering of bug fixes across most architectures"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  powerpc/kvm/cma: Fix panic introduces by signed shift operation
  KVM: s390/mm: Fix guest storage key corruption in ptep_set_access_flags
  KVM: s390/mm: Fix storage key corruption during swapping
  arm/arm64: KVM: Complete WFI/WFE instructions
  ARM/ARM64: KVM: Nuke Hyp-mode tlbs before enabling MMU
  KVM: s390/mm: try a cow on read only pages for key ops
  KVM: s390: Fix user triggerable bug in dead code
      2b12164b
    • Linus Torvalds's avatar
      Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc · 56c22854
      Linus Torvalds authored 
      Pull ARM SoC fixes from Kevin Hilman:
 "Another round of fixes from arm-soc land, which are mostly DT fixes
  for:

   - OMAP: handful of DT fixes devices on newly supported hardware
   - davinci: fix 2nd EDMA channel
   - ux500: extend previous pinctrl fix to another board
   - at91: clock registration fixes, compatibility string precision

  And one more fix for event cleanup in drivers/bus/arm-ccn"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  bus: arm-ccn: Move event cleanup routine
  ARM: at91/dt: rm9200: fix usb clock definition
  ARM: at91: rm9200: fix clock registration
  ARM: at91/dt: sam9g20: set at91sam9g20 pllb driver
  ARM: dts: dra7-evm: Add vtt regulator support
  ARM: dts: dra7-evm: Fix spi1 mux documentation
  ARM: dts: am43x-epos-evm: Disable QSPI to prevent conflict with GPMC-NAND
  ARM: OMAP2+: gpmc: Don't complain if wait pin is used without r/w monitoring
  ARM: dts: am43xx-epos-evm: Don't use read/write wait monitoring
  ARM: dts: am437x-gp-evm: Don't use read/write wait monitoring
  ARM: dts: am437x-gp-evm: Use BCH16 ECC scheme instead of BCH8
  ARM: dts: am43x-epos-evm: Use BCH16 ECC scheme instead of BCH8
  ARM: dts: am4372: fix USB regs size
  ARM: dts: am437x-gp: switch i2c0 to 100KHz
  ARM: dts: dra7-evm: Fix 8th NAND partition's name
  ARM: dts: dra7-evm: Fix i2c3 pinmux and frequency
  ARM: ux500: disable msp2 node on Snowball
  ARM: edma: Fix configuration parsing for SoCs with multiple eDMA3 CC
  ARM: dts: set 'ti,set-rate-parent' for dpll4_m5x2 clock
      56c22854
    • Linus Torvalds's avatar
      Merge tag 'xfs-for-linus-3.17-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs · 11e97398
      Linus Torvalds authored 
      Pull xfs fixes from Dave Chinner:
 "The fixes all address recently discovered data corruption issues.

  The original Direct IO issue was discovered by Chris Mason @ Facebook
  on a production workload which mixed buffered reads with direct reads
  and writes IO to the same file.  The fix for that exposed other issues
  with page invalidation (exposed by millions of fsx operations) failing
  due to dirty buffers beyond EOF.

  Finally, the collapse_range code could also cause problems due to
  racing writeback changing the extent map while it was being shifted
  around.  The commits for that problem are simple mitigation fixes that
  prevent the problem from occuring.  A more robust fix for 3.18 that
  addresses the underlying problem is currently being worked on by
  Brian.

  Summary of fixes:
   - a direct IO read/buffered read data corruption
   - the associated fallout from the DIO data corruption fix
   - collapse range bugs that are potential data corruption issues"

* tag 'xfs-for-linus-3.17-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs:
  xfs: trim eofblocks before collapse range
  xfs: xfs_file_collapse_range is delalloc challenged
  xfs: don't log inode unless extent shift makes extent modifications
  xfs: use ranged writeback and invalidation for direct IO
  xfs: don't zero partial page cache pages during O_DIRECT writes
  xfs: don't zero partial page cache pages during O_DIRECT writes
  xfs: don't dirty buffers beyond EOF
      11e97398
    • Linus Torvalds's avatar
      Merge tag 'for-linus-20140905' of git://git.infradead.org/linux-mtd · 925e0ea4
      Linus Torvalds authored 
      Pull mtd fixes from Brian Norris:
 "Two trivial MTD updates for 3.17-rc4:

   - a tiny comment tweak, to kill a bunch of DocBook warnings added
     during the merge window

   - a small fixup to the OTP routines' error handling"

* tag 'for-linus-20140905' of git://git.infradead.org/linux-mtd:
  mtd: nand: fix DocBook warnings on nand_sdr_timings doc
  mtd: cfi_cmdset_0002: check return code for get_chip()
      925e0ea4
    • Thomas Gleixner's avatar
      timekeeping: Update timekeeper before updating vsyscall and pvclock · 9bf2419f
      Thomas Gleixner authored 
      The update_walltime() code works on the shadow timekeeper to make the
seqcount protected region as short as possible. But that update to the
shadow timekeeper does not update all timekeeper fields because it's
sufficient to do that once before it becomes life. One of these fields
is tkr.base_mono. That stays stale in the shadow timekeeper unless an
operation happens which copies the real timekeeper to the shadow.

The update function is called after the update calls to vsyscall and
pvclock. While not correct, it did not cause any problems because none
of the invoked update functions used base_mono.

commit cbcf2dd3 (x86: kvm: Make kvm_get_time_and_clockread()
nanoseconds based) changed that in the kvm pvclock update function, so
the stale mono_base value got used and caused kvm-clock to malfunction.

Put the update where it belongs and fix the issue.
Reported-by: default avatarChris J Arges <chris.j.arges@canonical.com>
Reported-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1409050000570.3333@nanosSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      9bf2419f
    • Thomas Gleixner's avatar
      compat: nanosleep: Clarify error handling · 849151dd
      Thomas Gleixner authored 
      The error handling in compat_sys_nanosleep() is correct, but
completely non obvious. Document it and restrict it to the
-ERESTART_RESTARTBLOCK return value for clarity.
Reported-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      849151dd
  7. 05 Sep, 2014 17 commits
  9. 04 Sep, 2014 5 commits
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