linux.git/arch, branch v3.0.42

xen: mark local pages as FOREIGN in the m2p_override

2012-08-26T22:12:11+00:00

commit b9e0d95c041ca2d7ad297ee37c2e9cfab67a188f upstream.

When the frontend and the backend reside on the same domain, even if we
add pages to the m2p_override, these pages will never be returned by
mfn_to_pfn because the check "get_phys_to_machine(pfn) != mfn" will
always fail, so the pfn of the frontend will be returned instead
(resulting in a deadlock because the frontend pages are already locked).

INFO: task qemu-system-i38:1085 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
qemu-system-i38 D ffff8800cfc137c0     0  1085      1 0x00000000
 ffff8800c47ed898 0000000000000282 ffff8800be4596b0 00000000000137c0
 ffff8800c47edfd8 ffff8800c47ec010 00000000000137c0 00000000000137c0
 ffff8800c47edfd8 00000000000137c0 ffffffff82213020 ffff8800be4596b0
Call Trace:
 [] ? __lock_page+0x70/0x70
 [] schedule+0x29/0x70
 [] io_schedule+0x60/0x80
 [] sleep_on_page+0xe/0x20
 [] __wait_on_bit_lock+0x5a/0xc0
 [] __lock_page+0x67/0x70
 [] ? autoremove_wake_function+0x40/0x40
 [] ? bio_add_page+0x36/0x40
 [] set_page_dirty_lock+0x52/0x60
 [] bio_set_pages_dirty+0x51/0x70
 [] do_blockdev_direct_IO+0xb24/0xeb0
 [] ? ext3_get_blocks_handle+0xe00/0xe00
 [] __blockdev_direct_IO+0x55/0x60
 [] ? ext3_get_blocks_handle+0xe00/0xe00
 [] ext3_direct_IO+0xf8/0x390
 [] ? ext3_get_blocks_handle+0xe00/0xe00
 [] ? xen_mc_flush+0xb0/0x1b0
 [] generic_file_aio_read+0x737/0x780
 [] ? gnttab_map_refs+0x15b/0x1e0
 [] ? find_get_pages+0x150/0x150
 [] aio_rw_vect_retry+0x7c/0x1d0
 [] ? lookup_ioctx+0x90/0x90
 [] aio_run_iocb+0x66/0x1a0
 [] do_io_submit+0x708/0xb90
 [] sys_io_submit+0x10/0x20
 [] system_call_fastpath+0x16/0x1b

The explanation is in the comment within the code:

We need to do this because the pages shared by the frontend
(xen-blkfront) can be already locked (lock_page, called by
do_read_cache_page); when the userspace backend tries to use them
with direct_IO, mfn_to_pfn returns the pfn of the frontend, so
do_blockdev_direct_IO is going to try to lock the same pages
again resulting in a deadlock.

A simplified call graph looks like this:

pygrub                          QEMU
-----------------------------------------------
do_read_cache_page              io_submit
  |                              |
lock_page                       ext3_direct_IO
                                 |
                                bio_add_page
                                 |
                                lock_page

Internally the xen-blkback uses m2p_add_override to swizzle (temporarily)
a 'struct page' to have a different MFN (so that it can point to another
guest). It also can easily find out whether another pfn corresponding
to the mfn exists in the m2p, and can set the FOREIGN bit
in the p2m, making sure that mfn_to_pfn returns the pfn of the backend.

This allows the backend to perform direct_IO on these pages, but as a
side effect prevents the frontend from using get_user_pages_fast on
them while they are being shared with the backend.

Signed-off-by: Stefano Stabellini 
Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Greg Kroah-Hartman

s390/compat: fix mmap compat system calls

2012-08-26T22:12:10+00:00

commit e85871218513c54f7dfdb6009043cb638f2fecbe upstream.

The native 31 bit and the compat behaviour for the mmap system calls differ:

In native 31 bit mode the passed in address for the mmap system call will be
unmodified passed to sys_mmap_pgoff().
In compat mode however the passed in address will be modified with
compat_ptr() which masks out the most significant bit.

The result is that in native 31 bit mode each mmap request (with MAP_FIXED)
will fail where the most significat bit is set, while in compat mode it
may succeed.

This odd behaviour was introduced with d3815898 "[S390] mmap: add missing
compat_ptr conversion to both mmap compat syscalls".

To restore a consistent behaviour accross native and compat mode this
patch functionally reverts the above mentioned commit.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

ARM: mxs: Remove MMAP_MIN_ADDR setting from mxs_defconfig

2012-08-15T19:04:29+00:00

commit 3bed491c8d28329e34f8a31e3fe64d03f3a350f1 upstream.

The CONFIG_DEFAULT_MMAP_MIN_ADDR was set to 65536 in mxs_defconfig,
this caused severe breakage of userland applications since the upper
limit for ARM is 32768. By default CONFIG_DEFAULT_MMAP_MIN_ADDR is
set to 4096 and can also be changed via /proc/sys/vm/mmap_min_addr
if needed.

Quoting Russell King [1]:

"4096 is also fine for ARM too. There's not much point in having
defconfigs change it - that would just be pure noise in the config
files."

the CONFIG_DEFAULT_MMAP_MIN_ADDR can be removed from the defconfig
altogether.

This problem was introduced by commit cde7c41 (ARM: configs: add
defconfig for mach-mxs).

[1] http://marc.info/?l=linux-arm-kernel&m=134401593807820&w=2

Signed-off-by: Marek Vasut 
Cc: Russell King 
Cc: Wolfgang Denk 
Signed-off-by: Shawn Guo 
Signed-off-by: Greg Kroah-Hartman

x86, microcode: Sanitize per-cpu microcode reloading interface

2012-08-15T19:04:29+00:00

commit c9fc3f778a6a215ace14ee556067c73982b6d40f upstream.

Microcode reloading in a per-core manner is a very bad idea for both
major x86 vendors. And the thing is, we have such interface with which
we can end up with different microcode versions applied on different
cores of an otherwise homogeneous wrt (family,model,stepping) system.

So turn off the possibility of doing that per core and allow it only
system-wide.

This is a minimal fix which we'd like to see in stable too thus the
more-or-less arbitrary decision to allow system-wide reloading only on
the BSP:

$ echo 1 > /sys/devices/system/cpu/cpu0/microcode/reload
...

and disable the interface on the other cores:

$ echo 1 > /sys/devices/system/cpu/cpu23/microcode/reload
-bash: echo: write error: Invalid argument

Also, allowing the reload only from one CPU (the BSP in
that case) doesn't allow the reload procedure to degenerate
into an O(n^2) deal when triggering reloads from all
/sys/devices/system/cpu/cpuX/microcode/reload sysfs nodes
simultaneously.

A more generic fix will follow.

Signed-off-by: Borislav Petkov 
Cc: Henrique de Moraes Holschuh 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1340280437-7718-2-git-send-email-bp@amd64.org
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

x86, microcode: microcode_core.c simple_strtoul cleanup

2012-08-15T19:04:29+00:00

commit e826abd523913f63eb03b59746ffb16153c53dc4 upstream.

Change reload_for_cpu() in kernel/microcode_core.c to call kstrtoul()
instead of calling obsoleted simple_strtoul().

Signed-off-by: Shuah Khan 
Reviewed-by: Borislav Petkov 
Link: http://lkml.kernel.org/r/1336324264.2897.9.camel@lorien2
Signed-off-by: H. Peter Anvin 
Cc: Henrique de Moraes Holschuh 
Signed-off-by: Greg Kroah-Hartman

random: remove rand_initialize_irq()

2012-08-15T19:04:28+00:00

commit c5857ccf293968348e5eb4ebedc68074de3dcda6 upstream.

With the new interrupt sampling system, we are no longer using the
timer_rand_state structure in the irq descriptor, so we can stop
initializing it now.

[ Merged in fixes from Sedat to find some last missing references to
  rand_initialize_irq() ]

Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Sedat Dilek 
Signed-off-by: Greg Kroah-Hartman

x86, nops: Missing break resulting in incorrect selection on Intel

2012-08-15T19:04:11+00:00

commit d6250a3f12edb3a86db9598ffeca3de8b4a219e9 upstream.

The Intel case falls through into the generic case which then changes
the values.  For cases like the P6 it doesn't do the right thing so
this seems to be a screwup.

Signed-off-by: Alan Cox 
Link: http://lkml.kernel.org/n/tip-lww2uirad4skzjlmrm0vru8o@git.kernel.org
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

ARM: 7479/1: mm: avoid NULL dereference when flushing gate_vma with VIVT caches

2012-08-15T19:04:10+00:00

commit b74253f78400f9a4b42da84bb1de7540b88ce7c4 upstream.

The vivt_flush_cache_{range,page} functions check that the mm_struct
of the VMA being flushed has been active on the current CPU before
performing the cache maintenance.

The gate_vma has a NULL mm_struct pointer and, as such, will cause a
kernel fault if we try to flush it with the above operations. This
happens during ELF core dumps, which include the gate_vma as it may be
useful for debugging purposes.

This patch adds checks to the VIVT cache flushing functions so that VMAs
with a NULL mm_struct are flushed unconditionally (the vectors page may
be dirty if we use it to store the current TLS pointer).

Reported-by: Gilles Chanteperdrix 
Tested-by: Uros Bizjak 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King 
Signed-off-by: Greg Kroah-Hartman

ARM: 7478/1: errata: extend workaround for erratum #720789

2012-08-15T19:04:10+00:00

commit 5a783cbc48367cfc7b65afc75430953dfe60098f upstream.

Commit cdf357f1 ("ARM: 6299/1: errata: TLBIASIDIS and TLBIMVAIS
operations can broadcast a faulty ASID") replaced by-ASID TLB flushing
operations with all-ASID variants to workaround A9 erratum #720789.

This patch extends the workaround to include the tlb_range operations,
which were overlooked by the original patch.

Tested-by: Steve Capper 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King 
Signed-off-by: Greg Kroah-Hartman

Redefine ATOMIC_INIT and ATOMIC64_INIT to drop the casts

2012-08-15T19:04:09+00:00

commit a119365586b0130dfea06457f584953e0ff6481d upstream.

The following build error occured during a ia64 build with
swap-over-NFS patches applied.

net/core/sock.c:274:36: error: initializer element is not constant
net/core/sock.c:274:36: error: (near initialization for 'memalloc_socks')
net/core/sock.c:274:36: error: initializer element is not constant

This is identical to a parisc build error. Fengguang Wu, Mel Gorman
and James Bottomley did all the legwork to track the root cause of
the problem. This fix and entire commit log is shamelessly copied
from them with one extra detail to change a dubious runtime use of
ATOMIC_INIT() to atomic_set() in drivers/char/mspec.c

Dave Anglin says:
> Here is the line in sock.i:
>
> struct static_key memalloc_socks = ((struct static_key) { .enabled =
> ((atomic_t) { (0) }) });

The above line contains two compound literals.  It also uses a designated
initializer to initialize the field enabled.  A compound literal is not a
constant expression.

The location of the above statement isn't fully clear, but if a compound
literal occurs outside the body of a function, the initializer list must
consist of constant expressions.

Signed-off-by: Tony Luck 
Signed-off-by: Greg Kroah-Hartman