Impact: fix to prevent NMI lockup

If the page fault handler produces a WARN_ON in the modifying of
text, and the system is setup to have a high frequency of NMIs,
we can lock up the system on a failure to modify code.

The modifying of code with NMIs allows all NMIs to modify the code
if it is about to run. This prevents a modifier on one CPU from
modifying code running in NMI context on another CPU. The modifying
is done through stop_machine, so only NMIs must be considered.

But if the write causes the page fault handler to produce a warning,
the print can slow it down enough that as soon as it is done
it will take another NMI before going back to the process context.
The new NMI will perform the write again causing another print and
this will hang the box.

This patch turns off the writing as soon as a failure is detected
and does not wait for it to be turned off by the process context.
This will keep NMIs from getting stuck in this back and forth
of print outs.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Impact: keep kernel text read only

Because dynamic ftrace converts the calls to mcount into and out of
nops at run time, we needed to always keep the kernel text writable.

But this defeats the point of CONFIG_DEBUG_RODATA. This patch converts
the kernel code to writable before ftrace modifies the text, and converts
it back to read only afterward.

The kernel text is converted to read/write, stop_machine is called to
modify the code, then the kernel text is converted back to read only.

The original version used SYSTEM_STATE to determine when it was OK
or not to change the code to rw or ro. Andrew Morton pointed out that
using SYSTEM_STATE is a bad idea since there is no guarantee to what
its state will actually be.

Instead, I moved the check into the set_kernel_text_* functions
themselves, and use a local variable to determine when it is
OK to change the kernel text RW permissions.

[ Update: Ingo Molnar suggested moving the prototypes to cacheflush.h ]
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

This patch creates the weak functions: ftrace_arch_code_modify_prepare
and ftrace_arch_code_modify_post_process that are called before and
after the stop machine is called to modify the kernel text.

If the arch needs to do pre or post processing, it only needs to define
these functions.

[ Update: Ingo Molnar suggested using the name ftrace_arch_code_modify_*
          over using ftrace_arch_modify_* ]
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Steven Rostedt found a bug in where in his modified kernel
ftrace was unable to modify the kernel text, due to the PMD
itself having been marked read-only as well in
split_large_page().

The fix, suggested by Linus, is to not try to 'clone' the
reference protection of a huge-page, but to use the standard
(and permissive) page protection bits of KERNPG_TABLE.

The 'cloning' makes sense for the ptes but it's a confused and
incorrect concept at the page table level - because the
pagetable entry is a set of all ptes and hence cannot
'clone' any single protection attribute - the ptes can be any
mixture of protections.

With the permissive KERNPG_TABLE, even if the pte protections
get changed after this point (due to ftrace doing code-patching
or other similar activities like kprobes), the resulting combined
protections will still be correct and the pte's restrictive
(or permissive) protections will control it.

Also update the comment.

This bug was there for a long time but has not caused visible
problems before as it needs a rather large read-only area to
trigger. Steve possibly hacked his kernel with some really
large arrays or so. Anyway, the bug is definitely worth fixing.

[ Huang Ying also experienced problems in this area when writing
  the EFI code, but the real bug in split_large_page() was not
  realized back then. ]
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Huang Ying <ying.huang@intel.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Impact: fix time warps under vmware

Similar to the check for TSC going backwards in the TSC clocksource,
we also need this check for VMI clocksource.
Signed-off-by: Alok N Kataria <akataria@vmware.com>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: stable@kernel.org

* master.kernel.org:/home/rmk/linux-2.6-arm:
  [ARM] 5405/1: ep93xx: remove unused gesbc9312.h header
  [ARM] 5404/1: Fix condition in arm_elf_read_implies_exec() to set READ_IMPLIES_EXEC
  [ARM] omap: fix clock reparenting in omap2_clk_set_parent()
  [ARM] 5403/1: pxa25x_ep_fifo_flush() *ep->reg_udccs always set to 0
  [ARM] 5402/1: fix a case of wrap-around in sanity_check_meminfo()
  [ARM] 5401/1: Orion: fix edge triggered GPIO interrupt support
  [ARM] 5400/1: Add support for inverted rdy_busy pin for Atmel nand device controller
  [ARM] 5391/1: AT91: Enable GPIO clocks earlier
  [ARM] 5390/1: AT91: Watchdog fixes
  [ARM] 5398/1: Add Wan ZongShun to MAINTAINERS for W90P910
  [ARM] omap: fix _omap2_clksel_get_src_field()
  [ARM] omap: fix omap2_divisor_to_clksel() error return value

Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, mce: fix ifdef for 64bit thermal apic vector clear on shutdown
  x86, mce: use force_sig_info to kill process in machine check
  x86, mce: reinitialize per cpu features on resume
  x86, rcu: fix strange load average and ksoftirqd behavior

Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  tracing: limit the number of loops the ring buffer self test can make
  tracing: have function trace select kallsyms
  tracing: disable tracing while testing ring buffer
  tracing/function-graph-tracer: trace the idle tasks

* 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6:
  [S390] fix "mem=" handling in case of standby memory
  [S390] Fix timeval regression on s390
  [S390] sclp: handle empty event buffers

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  sound: virtuoso: revert "do not overwrite EEPROM on Xonar D2/D2X"
  ALSA: jack - Use card->shortname for input name
  ALSA: usb-audio - Workaround for misdetected sample rate with CM6207
  ALSA: usb-audio - Fix non-continuous rate detection
  sound: usb-audio: fix uninitialized variable with M-Audio MIDI interfaces
  Revert "Sound: hda - Restore PCI configuration space with interrupts off"

Remove the gesbc9312.h header since it is unused.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

READ_IMPLIES_EXEC must be set when:
o binary _is_ an executable stack (i.e. not EXSTACK_DISABLE_X)
o processor architecture is _under_ ARMv6 (XN bit is supported from ARMv6)
Signed-off-by: Makito SHIOKAWA <lkhmkt@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Standby memory detected with the sclp interface gets always registered
with add_memory calls without considering the limitationt that the
"mem=" kernel paramater implies.
So fix this and only register standby memory that is below the specified
limit.
This fixes zfcpdump since it uses "mem=32M". In case there is appr.
2GB standby memory present all of usable memory would be used for the
struct pages needed for standby memory.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

commit aa5e97ce
[PATCH] improve precision of process accounting.

Introduced a timing regression:
-bash-3.2# time ls
real    0m0.006s
user    0m1.754s
sys     0m1.094s

The problem was introduced by an error in cputime_to_timeval.
Cputime is now 1/4096 microsecond, therefore, we have to divide
the remainder with 4096 to get the microseconds.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Handle a malformed hardware response which some versions of the
Support Element (SE) may present during SE restart and which otherwise
would result in an endless loop in function sclp_dispatch_evbufs.
Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

When changing the parent of a clock, it is necessary to keep the
clock use counts balanced otherwise things the parent state will
get corrupted.  Since we already disable and re-enable the clock,
we might as well use the recursive versions instead.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

*ep->reg_udccs is always set to 0.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

In the non highmem case, if two memory banks of 1GB each are provided,
the second bank would evade suppression since its virtual base would
be 0.  Fix this by disallowing any memory bank which virtual base
address is found to be lower than PAGE_OFFSET.
Reported-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Merge branch 'tip/tracing/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/urgent

This reverts commit 7e86c0e6 ("do not
overwrite EEPROM on Xonar D2/D2X") because it did not actually help with
the problem.

More user reports show that the overwriting of the EEPROM is not
triggered by using this driver but by installing Linux, and that the
installation of any other operating system (even one without any CMI8788
driver) has the same effect.  In other words, the presence of this
driver does not have any effect on the occurrence of the error.  (So
far, the available evidence seems to point to a BIOS bug.)

Furthermore, it turns out that the EEPROM chip is protected against
stray write commands by the command format and by requiring a separate
write-enable command, so the error scenario in the previous commit (that
SPI writes can be misinterpreted as an EEPROM write command) is not even
theoretically possible.

The mixer control that was removed as a consequence of the previous
commit can only be partially emulated in userspace, which also means it
cannot be seen be the in-kernel OSS API emulation, so it is better to
revert that change.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Impact: prevent deadlock if ring buffer gets corrupted

This patch adds a paranoid check to make sure the ring buffer consumer
does not go into an infinite loop. Since the ring buffer has been set
to read only, the consumer should not loop for more than the ring buffer
size. A check is added to make sure the consumer does not loop more than
the ring buffer size.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Impact: fix output of function tracer to be useful

The function tracer is pretty useless if KALLSYMS is not configured.
Unless you are good at reading hex values, the function tracer should
select the KALLSYMS configuration.

Also, the dynamic function tracer will fail its self test if KALLSYMS
is not selected.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

Impact: fix to prevent hard lockup on self tests

If one of the tracers are broken and is constantly filling the ring
buffer while the test of the ring buffer is running, it will hang
the box. The reason is that the test is a consumer that will not
stop till the ring buffer is empty. But if the tracer is broken and
is constantly producing input to the buffer, this test will never
end. The result is a lockup of the box.

This happened when KALLSYMS was not defined and the dynamic ftrace
test constantly filled the ring buffer, because the filter failed
and all functions were being traced. Something was being called
that constantly filled the buffer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  block: fix deadlock in blk_abort_queue() for drivers that readd to timeout list
  block: fix booting from partitioned md array
  block: revert part of 18ce3751
  cciss: PCI power management reset for kexec
  paride/pg.c: xs(): &&/|| confusion
  fs/bio: bio_alloc_bioset: pass right object ptr to mempool_free
  block: fix bad definition of BIO_RW_SYNC
  bsg: Fix sense buffer bug in SG_IO

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/drzeus/mmc:
  omap_hsmmc: Change while(); loops with finite version
  omap_hsmmc: recover from transfer failures
  omap_hsmmc: only MMC1 allows HCTL.SDVS != 1.8V
  omap_hsmmc: card detect irq bugfix
  sdhci: fix led naming
  mmc_test: fix basic read test
  s3cmci: Fix hangup in do_pio_write()
  Revert "sdhci: force high speed capability on some controllers"
  MMC: fix bug - SDHC card capacity not correct

Enhanced lockdep coverage of __GFP_NOFS turned up this new lockdep
assert:

[ 1093.677775]
[ 1093.677781] =================================
[ 1093.680031] [ INFO: inconsistent lock state ]
[ 1093.680031] 2.6.29-rc5-tip-01504-gb49eca1-dirty #1
[ 1093.680031] ---------------------------------
[ 1093.680031] inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage.
[ 1093.680031] kswapd0/308 [HC0[0]:SC0[0]:HE1:SE1] takes:
[ 1093.680031]  (&inode->inotify_mutex){+.+.?.}, at: [<c0205942>] inotify_inode_is_dead+0x20/0x80
[ 1093.680031] {RECLAIM_FS-ON-W} state was registered at:
[ 1093.680031]   [<c01696b9>] mark_held_locks+0x43/0x5b
[ 1093.680031]   [<c016baa4>] lockdep_trace_alloc+0x6c/0x6e
[ 1093.680031]   [<c01cf8b0>] kmem_cache_alloc+0x20/0x150
[ 1093.680031]   [<c040d0ec>] idr_pre_get+0x27/0x6c
[ 1093.680031]   [<c02056e3>] inotify_handle_get_wd+0x25/0xad
[ 1093.680031]   [<c0205f43>] inotify_add_watch+0x7a/0x129
[ 1093.680031]   [<c020679e>] sys_inotify_add_watch+0x20f/0x250
[ 1093.680031]   [<c010389e>] sysenter_do_call+0x12/0x35
[ 1093.680031]   [<ffffffff>] 0xffffffff
[ 1093.680031] irq event stamp: 60417
[ 1093.680031] hardirqs last  enabled at (60417): [<c018d5f5>] call_rcu+0x53/0x59
[ 1093.680031] hardirqs last disabled at (60416): [<c018d5b9>] call_rcu+0x17/0x59
[ 1093.680031] softirqs last  enabled at (59656): [<c0146229>] __do_softirq+0x157/0x16b
[ 1093.680031] softirqs last disabled at (59651): [<c0106293>] do_softirq+0x74/0x15d
[ 1093.680031]
[ 1093.680031] other info that might help us debug this:
[ 1093.680031] 2 locks held by kswapd0/308:
[ 1093.680031]  #0:  (shrinker_rwsem){++++..}, at: [<c01b0502>] shrink_slab+0x36/0x189
[ 1093.680031]  #1:  (&type->s_umount_key#4){+++++.}, at: [<c01e6d77>] shrink_dcache_memory+0x110/0x1fb
[ 1093.680031]
[ 1093.680031] stack backtrace:
[ 1093.680031] Pid: 308, comm: kswapd0 Not tainted 2.6.29-rc5-tip-01504-gb49eca1-dirty #1
[ 1093.680031] Call Trace:
[ 1093.680031]  [<c016947a>] valid_state+0x12a/0x13d
[ 1093.680031]  [<c016954e>] mark_lock+0xc1/0x1e9
[ 1093.680031]  [<c016a5b4>] ? check_usage_forwards+0x0/0x3f
[ 1093.680031]  [<c016ab74>] __lock_acquire+0x2c6/0xac8
[ 1093.680031]  [<c01688d9>] ? register_lock_class+0x17/0x228
[ 1093.680031]  [<c016b3d3>] lock_acquire+0x5d/0x7a
[ 1093.680031]  [<c0205942>] ? inotify_inode_is_dead+0x20/0x80
[ 1093.680031]  [<c08824c4>] __mutex_lock_common+0x3a/0x4cb
[ 1093.680031]  [<c0205942>] ? inotify_inode_is_dead+0x20/0x80
[ 1093.680031]  [<c08829ed>] mutex_lock_nested+0x2e/0x36
[ 1093.680031]  [<c0205942>] ? inotify_inode_is_dead+0x20/0x80
[ 1093.680031]  [<c0205942>] inotify_inode_is_dead+0x20/0x80
[ 1093.680031]  [<c01e6672>] dentry_iput+0x90/0xc2
[ 1093.680031]  [<c01e67a3>] d_kill+0x21/0x45
[ 1093.680031]  [<c01e6a46>] __shrink_dcache_sb+0x27f/0x355
[ 1093.680031]  [<c01e6dc5>] shrink_dcache_memory+0x15e/0x1fb
[ 1093.680031]  [<c01b05ed>] shrink_slab+0x121/0x189
[ 1093.680031]  [<c01b0d12>] kswapd+0x39f/0x561
[ 1093.680031]  [<c01ae499>] ? isolate_pages_global+0x0/0x233
[ 1093.680031]  [<c0157eae>] ? autoremove_wake_function+0x0/0x43
[ 1093.680031]  [<c01b0973>] ? kswapd+0x0/0x561
[ 1093.680031]  [<c0157daf>] kthread+0x41/0x82
[ 1093.680031]  [<c0157d6e>] ? kthread+0x0/0x82
[ 1093.680031]  [<c01043ab>] kernel_thread_helper+0x7/0x10

inotify_handle_get_wd() does idr_pre_get() which does a
kmem_cache_alloc() without __GFP_FS - and is hence deadlockable under
extreme MM pressure.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: MinChan Kim <minchan.kim@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

gpio_get_value() returns 0 or nonzero, but getmiso() expects 0 or 1.
Sanitize the value to a 0/1 boolean.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Since I don't work for SUSE any more and the bwalle@suse.de address is
invalid, correct it in the copyright headers and documentation.
Signed-off-by: Bernhard Walle <bernhard.walle@gmx.de>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Build breaks when DELL_LAPTOP=y and POWER_SUPPLY=m.  DELL_LAPTOP needs to
depend on POWER_SUPPLY.

dell-laptop.c:(.text+0x1ef3c4): undefined reference to `power_supply_is_system_supplied'
dell-laptop.c:(.text+0x1ef45e): undefined reference to `power_supply_is_system_supplied'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Otherwise, these don't work when called from 32-bit userspace on 64-bit
kernels.

Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: <stable@kernel.org>		[2.6.25.x, 2.6.26.x, 2.6.27.x, 2.6.28.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Submenus of the graphics support "Support for frame buffer devices" and
"Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)" are
broken in half after latest changes for Intel 915 mode setting support.

The DRM subsection is broken because one option is put outside the choice
section it depends on.

The frame buffers part is broken then due to circular dependency.  Fix
this by make Intel frame buffers depend on CONFIG_INTEL_AGP.

Kconfigs are broken by d2f59357
("drm/i915: select framebuffer support automatically").

This is probably not only way to fix this.
Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The floppy driver requests an I/O port it doesn't need, and sometimes this
causes a conflict with a motherboard device reported by PNPBIOS.

This patch makes the floppy driver request and release only the ports it
actually uses.  It also factors out the request/release stuff and the
io-ports list so they're all in one place now.

The current floppy driver uses only these ports:

    0x3f2 (FD_DOR)
    0x3f4 (FD_STATUS)
    0x3f5 (FD_DATA)
    0x3f7 (FD_DCR/FD_DIR)

but it requests 0x3f2-0x3f5 and 0x3f7, which includes the unused port
0x3f3.

Some BIOSes report 0x3f3 as a motherboard resource.  The PNP system driver
reserves that, which causes a conflict when the floppy driver requests
0x3f2-0x3f5 later.

Philippe reported that this conflict broke the floppy driver between
2.6.11 and 2.6.22.  His PNPBIOS reports these devices:

    $ cat 00:07/id 00:07/resources	# motherboard device
    PNP0c02
    state = active
    io 0x80-0x80
    io 0x10-0x1f
    io 0x22-0x3f
    io 0x44-0x5f
    io 0x90-0x9f
    io 0xa2-0xbf
    io 0x3f0-0x3f1
    io 0x3f3-0x3f3

    $ cat 00:03/id 00:03/resources	# floppy device
    PNP0700
    state = active
    io 0x3f4-0x3f5
    io 0x3f2-0x3f2

Reference:
    http://lkml.org/lkml/2009/1/31/162Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Reported-by: Philippe De Muyter <phdm@macqel.be>
Tested-by: Philippe De Muyter <phdm@macqel.be>
Cc: Adam M Belay <abelay@mit.edu>
Cc: Robert Hancock <hancockrwd@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

I have a Digi Neo 8 PCI card (114f:00b1) Serial controller: Digi
International Digi Neo 8 (rev 05)

that works with the jsm driver after using the following patch.
Signed-off-by: Adam Lackorzynski <adam@os.inf.tu-dresden.de>
Cc: Scott H Kilau <Scott_Kilau@digi.com>
Cc: Wendy Xiong <wendyx@us.ibm.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Now, early_pfn_in_nid(PFN, NID) may returns false if PFN is a hole.
and memmap initialization was not done. This was a trouble for
sparc boot.

To fix this, the PFN should be initialized and marked as PG_reserved.
This patch changes early_pfn_in_nid() return true if PFN is a hole.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reported-by: David Miller <davem@davemlloft.net>
Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: <stable@kernel.org>		[2.6.25.x, 2.6.26.x, 2.6.27.x, 2.6.28.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

What's happening is that the assertion in mm/page_alloc.c:move_freepages()
is triggering:

	BUG_ON(page_zone(start_page) != page_zone(end_page));

Once I knew this is what was happening, I added some annotations:

	if (unlikely(page_zone(start_page) != page_zone(end_page))) {
		printk(KERN_ERR "move_freepages: Bogus zones: "
		       "start_page[%p] end_page[%p] zone[%p]\n",
		       start_page, end_page, zone);
		printk(KERN_ERR "move_freepages: "
		       "start_zone[%p] end_zone[%p]\n",
		       page_zone(start_page), page_zone(end_page));
		printk(KERN_ERR "move_freepages: "
		       "start_pfn[0x%lx] end_pfn[0x%lx]\n",
		       page_to_pfn(start_page), page_to_pfn(end_page));
		printk(KERN_ERR "move_freepages: "
		       "start_nid[%d] end_nid[%d]\n",
		       page_to_nid(start_page), page_to_nid(end_page));
 ...

And here's what I got:

	move_freepages: Bogus zones: start_page[2207d0000] end_page[2207dffc0] zone[fffff8103effcb00]
	move_freepages: start_zone[fffff8103effcb00] end_zone[fffff8003fffeb00]
	move_freepages: start_pfn[0x81f600] end_pfn[0x81f7ff]
	move_freepages: start_nid[1] end_nid[0]

My memory layout on this box is:

[    0.000000] Zone PFN ranges:
[    0.000000]   Normal   0x00000000 -> 0x0081ff5d
[    0.000000] Movable zone start PFN for each node
[    0.000000] early_node_map[8] active PFN ranges
[    0.000000]     0: 0x00000000 -> 0x00020000
[    0.000000]     1: 0x00800000 -> 0x0081f7ff
[    0.000000]     1: 0x0081f800 -> 0x0081fe50
[    0.000000]     1: 0x0081fed1 -> 0x0081fed8
[    0.000000]     1: 0x0081feda -> 0x0081fedb
[    0.000000]     1: 0x0081fedd -> 0x0081fee5
[    0.000000]     1: 0x0081fee7 -> 0x0081ff51
[    0.000000]     1: 0x0081ff59 -> 0x0081ff5d

So it's a block move in that 0x81f600-->0x81f7ff region which triggers
the problem.

This patch:

Declaration of early_pfn_to_nid() is scattered over per-arch include
files, and it seems it's complicated to know when the declaration is used.
 I think it makes fix-for-memmap-init not easy.

This patch moves all declaration to include/linux/mm.h

After this,
  if !CONFIG_NODES_POPULATES_NODE_MAP && !CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID
     -> Use static definition in include/linux/mm.h
  else if !CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID
     -> Use generic definition in mm/page_alloc.c
  else
     -> per-arch back end function will be called.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reported-by: David Miller <davem@davemlloft.net>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: <stable@kernel.org>		[2.6.25.x, 2.6.26.x, 2.6.27.x, 2.6.28.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Li Zefan said:

Thread 1:
  for ((; ;))
  {
      mount -t cpuset xxx /mnt > /dev/null 2>&1
      cat /mnt/cpus > /dev/null 2>&1
      umount /mnt > /dev/null 2>&1
  }

Thread 2:
  for ((; ;))
  {
      mount -t cpuset xxx /mnt > /dev/null 2>&1
      umount /mnt > /dev/null 2>&1
  }

(Note: It is irrelevant which cgroup subsys is used.)

After a while a lockdep warning showed up:

=============================================
[ INFO: possible recursive locking detected ]
2.6.28 #479
---------------------------------------------
mount/13554 is trying to acquire lock:
 (&type->s_umount_key#19){--..}, at: [<c049d888>] sget+0x5e/0x321

but task is already holding lock:
 (&type->s_umount_key#19){--..}, at: [<c049da0c>] sget+0x1e2/0x321

other info that might help us debug this:
1 lock held by mount/13554:
 #0:  (&type->s_umount_key#19){--..}, at: [<c049da0c>] sget+0x1e2/0x321

stack backtrace:
Pid: 13554, comm: mount Not tainted 2.6.28-mc #479
Call Trace:
 [<c044ad2e>] validate_chain+0x4c6/0xbbd
 [<c044ba9b>] __lock_acquire+0x676/0x700
 [<c044bb82>] lock_acquire+0x5d/0x7a
 [<c049d888>] ? sget+0x5e/0x321
 [<c061b9b8>] down_write+0x34/0x50
 [<c049d888>] ? sget+0x5e/0x321
 [<c049d888>] sget+0x5e/0x321
 [<c045a2e7>] ? cgroup_set_super+0x0/0x3e
 [<c045959f>] ? cgroup_test_super+0x0/0x2f
 [<c045bcea>] cgroup_get_sb+0x98/0x2e7
 [<c045cfb6>] cpuset_get_sb+0x4a/0x5f
 [<c049dfa4>] vfs_kern_mount+0x40/0x7b
 [<c049e02d>] do_kern_mount+0x37/0xbf
 [<c04af4a0>] do_mount+0x5c3/0x61a
 [<c04addd2>] ? copy_mount_options+0x2c/0x111
 [<c04af560>] sys_mount+0x69/0xa0
 [<c0403251>] sysenter_do_call+0x12/0x31

The cause is after alloc_super() and then retry, an old entry in list
fs_supers is found, so grab_super(old) is called, but both functions hold
s_umount lock:

struct super_block *sget(...)
{
	...
retry:
	spin_lock(&sb_lock);
	if (test) {
		list_for_each_entry(old, &type->fs_supers, s_instances) {
			if (!test(old, data))
				continue;
			if (!grab_super(old))  <--- 2nd: down_write(&old->s_umount);
				goto retry;
			if (s)
				destroy_super(s);
			return old;
		}
	}
	if (!s) {
		spin_unlock(&sb_lock);
		s = alloc_super(type);   <--- 1th: down_write(&s->s_umount)
		if (!s)
			return ERR_PTR(-ENOMEM);
		goto retry;
	}
	...
}

It seems like a false positive, and seems like VFS but not cgroup needs to
be fixed.

Peter said:

We can simply put the new s_umount instance in a but lockdep doesn't
particularly cares about subclass order.

If there's any issue with the callers of sget() assuming the s_umount lock
being of sublcass 0, then there is another annotation we can use to fix
that, but lets not bother with that if this is sufficient.

Addresses http://bugzilla.kernel.org/show_bug.cgi?id=12673Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Li Zefan <lizf@cn.fujitsu.com>
Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Paul Menage <menage@google.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

I found a problem of handling of modem status of atmel_serial driver.

With the commit 1ecc26 ("atmel_serial: split the interrupt handler"),
handling of modem status signal was splitted into two parts.  The
atmel_tasklet_func() compares new status with irq_status_prev, but
irq_status_prev is not correct if signal status was changed while the port
is closed.

Here is a sequence to cause problem:

1. Remote side sets CTS (and DSR).
2. Local side close the port.
3. Local side clears RTS and DTR.
4. Remote side clears CTS and DSR.
5. Local side reopen the port.  hw_stopped becomes 1.
6. Local side sets RTS and DTR.
7. Remote side sets CTS and DSR.

Then CTS change interrupt can be received, but since CTS bit in
irq_status_prev and new status is same, uart_handle_cts_change() will not
be called (so hw_stopped will not be cleared, i.e.  cannot send any data).

I suppose irq_status_prev should be initialized at somewhere in open
sequence.

Itai Levi pointed out that we need to initialize atmel_port->irq_status
as well here. His analysis is as follows:

> Regarding the second part of the patch (which resets irq_status_prev),
> it turns out that both versions of the patch (mine and Atsushi's)
> still leave enough room for faulty behavior when opening the port.
>
> This is because we are not resetting both irq_status_prev and
> irq_status in atmel_startup() to CSR, which leads faulty behavior in
> the following sequences:
>
> First case:
> 1. closing the port while CTS line = 1 (TX not allowed)
> 2. setting CTS line = 0 (TX allowed)
> 3. opening the port
> 4. transmitting one char
> 5. Cannot transmit more chars, although CTS line is 0
>
> Second case:
> 1. closing the port while CTS line = 0 (TX allowed)
> 2. setting CTS line = 1 (TX not allowed)
> 3. opening the port
> 4. receiving some chars
> 5. Now we can transmit, although CTS line is 1
>
> This reason for this is that the tasklet is scheduled as a result of
> TX or RX interrupts (not a status change!), in steps 4 above. Inside
> the tasklet, the atmel_port->irq_status (which holds the value from
> the previous session) is compared to atmel_port->irq_status_prev.
> Hence, a status-change of the CTS line is faultily detected.
>
> Both cases were verified on 9260 hardware.

[haavard.skinnemoen@atmel.com: folded with patch from Itai Levi]
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Cc: Remy Bohmer <linux@bohmer.net>
Cc: Marc Pignat <marc.pignat@hevs.ch>
Cc: Itai Levi <itai.levi.devel@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>