With commit d8d14bd0 ("fs/compat: fix lookup_dcookie() parameter
handling") I changed the type of the len parameter of the
lookup_dcookie() syscall.

However I missed that there was still a stale declaration in
arch/tile/..  which now causes a compile error on tile:

  In file included from fs/dcookies.c:28:0:
  include/linux/compat.h:425:17: error: conflicting types for 'compat_sys_lookup_dcookie'
  fs/dcookies.c:207:1: error: conflicting types for 'compat_sys_lookup_dcookie'

Simply remove the declaration in the tile architecture, which is only a
leftover from before the different compat lookup_dcookie() versions have
been merged.  The correct declaration is now in include/linux/compat.h

The build error was reported by Fenguang's build bot.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: NChris Metcalf <cmetcalf@tilera.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The patch 3ddc5b46 breaks networking on
alpha (there is a follow-up fix 5cfe8f1b,
but networking is still broken even with the second patch).

The patch 3ddc5b46 makes
csum_partial_copy_from_user check the pointer with access_ok. However,
csum_partial_copy_from_user is called also from csum_partial_copy_nocheck
and csum_partial_copy_nocheck is called on kernel pointers and it is
supposed not to check pointer validity.

This bug results in ssh session hangs if the system is loaded and bulk
data are printed to ssh terminal.

This patch fixes csum_partial_copy_nocheck to call set_fs(KERNEL_DS), so
that access_ok in csum_partial_copy_from_user accepts kernel-space
addresses.

Cc: stable@vger.kernel.org
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NMatt Turner <mattst88@gmail.com>

Signed-off-by: NZhenglong.cai <zhenglong.cai@cs2c.com.cn>
Signed-off-by: NMatt Turner <mattst88@gmail.com>

Passing a freed 'pages' to free_xenballooned_pages will end badly
on kernels with slub debug enabled.

This looks out of place between the rc assign and the check, but
we do want to kfree pages regardless of which path we take.
Signed-off-by: NDave Jones <davej@fedoraproject.org>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The grant mapping API does m2p_override unnecessarily: only gntdev needs it,
for blkback and future netback patches it just cause a lock contention, as
those pages never go to userspace. Therefore this series does the following:
- the original functions were renamed to __gnttab_[un]map_refs, with a new
  parameter m2p_override
- based on m2p_override either they follow the original behaviour, or just set
  the private flag and call set_phys_to_machine
- gnttab_[un]map_refs are now a wrapper to call __gnttab_[un]map_refs with
  m2p_override false
- a new function gnttab_[un]map_refs_userspace provides the old behaviour

It also removes a stray space from page.h and change ret to 0 if
XENFEAT_auto_translated_physmap, as that is the only possible return value
there.

v2:
- move the storing of the old mfn in page->index to gnttab_map_refs
- move the function header update to a separate patch

v3:
- a new approach to retain old behaviour where it needed
- squash the patches into one

v4:
- move out the common bits from m2p* functions, and pass pfn/mfn as parameter
- clear page->private before doing anything with the page, so m2p_find_override
  won't race with this

v5:
- change return value handling in __gnttab_[un]map_refs
- remove a stray space in page.h
- add detail why ret = 0 now at some places

v6:
- don't pass pfn to m2p* functions, just get it locally
Signed-off-by: NZoltan Kiss <zoltan.kiss@citrix.com>
Suggested-by: NDavid Vrabel <david.vrabel@citrix.com>
Acked-by: NDavid Vrabel <david.vrabel@citrix.com>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

We have the following means for encoding writable or dirty ptes:

                                PTE_DIRTY       PTE_RDONLY
!pte_dirty && !pte_write        0               1
!pte_dirty && pte_write         0               1
pte_dirty && !pte_write         1               1
pte_dirty && pte_write          1               0

So we can't distinguish between writable clean ptes and read only
ptes. This can cause problems with ptes being incorrectly flagged as
read only when they are writable but not dirty.

This patch introduces a new software bit PTE_WRITE which allows us to
correctly identify writable ptes. PTE_RDONLY is now only clear for
valid ptes where a page is both writable and dirty.
Signed-off-by: NSteve Capper <steve.capper@arm.com>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Expand out the pte manipulation functions. This makes our life easier
when using things like tags and cscope.
Signed-off-by: NSteve Capper <steve.capper@arm.com>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

The SOFT_DIRTY bit shows that the content of memory was changed after a
defined point in the past.  mprotect() doesn't change the content of
memory, so it must not change the SOFT_DIRTY bit.

This bug causes a malfunction: on the first iteration all pages are
dumped.  On other iterations only pages with the SOFT_DIRTY bit are
dumped.  So if the SOFT_DIRTY bit is cleared from a page by mistake, the
page is not dumped and its content will be restored incorrectly.

This patch does nothing with _PAGE_SWP_SOFT_DIRTY, becase pte_modify()
is called only for present pages.

Fixes commit 0f8975ec ("mm: soft-dirty bits for user memory changes
tracking").
Signed-off-by: NAndrey Vagin <avagin@openvz.org>
Acked-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Both clang 3.5 and GCC 4.9 will support this (as of r199754 and r207196
respectively). Both have been tested to produce booting kernels when the
16-bit code is built with -m16. (Modulo LLVM PR3997, at least.)

[ hpa: folded test for -m16 into M16_CFLAGS ]
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
Link: http://lkml.kernel.org/r/1390997807.20153.133.camel@i7.infradead.orgSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Commit dd78b973 ("x86, boot: Move CPU
flags out of cpucheck") introduced ambiguous inline asm in the
has_eflag() function. In 16-bit mode want the instruction to be
'pushfl', but we just say 'pushf' and hope the compiler does what we
wanted.

When building with 'clang -m16', it won't, because clang doesn't use
the horrid '.code16gcc' hack that even 'gcc -m16' uses internally.

Say what we mean and don't make the compiler make assumptions.

[ hpa: ideally we would be able to use the gcc %zN construct here, but
  that is broken for 64-bit integers in gcc < 4.5.

  The code with plain "pushf/popf" is fine for 32- or 64-bit mode, but
  not for 16-bit mode; in 16-bit mode those are 16-bit instructions in
  .code16 mode, and 32-bit instructions in .code16gcc mode. ]
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
Link: http://lkml.kernel.org/r/1391079628.26079.82.camel@shinybook.infradead.orgSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

So any FIQ handling is superfluous at the moment.  The functions to
disable/enable FIQs is kept around if ever someone needs them in the
future, but existing calling sites including arch_cpu_idle_prepare()
may go for now.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

On ARM, address size can be 32 bits or 64 bits (if CONFIG_ARCH_PHYS_ADDR_T_64BIT
is enabled).
We can't assume that the grant frame base address will always fits in an
unsigned long. Use phys_addr_t instead of unsigned long as argument for
gnttab_setup_auto_xlat_frames.
Signed-off-by: NJulien Grall <julien.grall@linaro.org>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Reviewed-by: NDavid Vrabel <david.vrabel@citrix.com>

The use of phys_to_machine and machine_to_phys in the phys<=>bus conversions
causes us to lose the top bits of the DMA address if the size of a DMA address is not the same as the size of the phyiscal address.

This can happen in practice on ARM where foreign pages can be above 4GB even
though the local kernel does not have LPAE page tables enabled (which is
totally reasonable if the guest does not itself have >4GB of RAM). In this
case the kernel still maps the foreign pages at a phys addr below 4G (as it
must) but the resulting DMA address (returned by the grant map operation) is
much higher.

This is analogous to a hardware device which has its view of RAM mapped up
high for some reason.

This patch makes I/O to foreign pages (specifically blkif) work on 32-bit ARM
systems with more than 4GB of RAM.
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

Event channels driver needs to be initialized very early. Until now, Xen
initialization was done after all CPUs was bring up.

We can safely move the initialization to an early initcall.

Also use a cpu notifier to:
    - Register the VCPU when the CPU is prepared
    - Enable event channel IRQ when the CPU is running
Signed-off-by: NJulien Grall <julien.grall@linaro.org>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

LTO requires consistent types of symbols over all files.

So "nmi" cannot be declared as a char [] here, need to use the
correct function type.

Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1382458079-24450-8-git-send-email-andi@firstfloor.orgSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

These functions are called from inline assembler stubs, thus
need to be global and visible.

Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1382458079-24450-7-git-send-email-andi@firstfloor.orgSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

LTO in gcc 4.6/47. has trouble with global register variables. They were used
to read the stack pointer. Use a simple inline assembler statement with
a mov instead.

This also helps LLVM/clang, which does not support global register
variables.

[ hpa: Ideally this should become a builtin in both gcc and clang. ]

v2: More general asm constraint. Fix description (Jan Beulich)
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1382458079-24450-6-git-send-email-andi@firstfloor.orgSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

The paravirt thunks use a hack of using a static reference to a static
function to reference that function from the top level statement.

This assumes that gcc always generates static function names in a specific
format, which is not necessarily true.

Simply make these functions global and asmlinkage or __visible. This way the
static __used variables are not needed and everything works.

Functions with arguments are __visible to keep the register calling
convention on 32bit.

Changed in paravirt and in all users (Xen and vsmp)

v2: Use __visible for functions with arguments

Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ido Yariv <ido@wizery.com>
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1382458079-24450-5-git-send-email-andi@firstfloor.orgSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

The paravirt patching code assumes that it can reference a
local assembler label between two different top level assembler
statements. This does not work with LTO
where the assembler code may end up in different assembler files.

Replace it with extern / global /asm linkage labels.

This also removes one redundant copy of the macro.

Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1382458079-24450-4-git-send-email-andi@firstfloor.orgSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

- Make the C code used by the paravirt stubs visible
- Since they have to be global now, give them a more unique
name.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1382458079-24450-3-git-send-email-andi@firstfloor.orgSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Change parameter types of s390's compat ipc syscall from unsigned long
to compat_ulong_t to enforce zero extension of these parameters.

This is not really a bug, since s390_ipc compat syscall is only a
wrapper to the generic compat_sys_ipc() syscall, which performs correct
zero and sign extension.

This was introduced with commit 56e41d3c ("merge compat sys_ipc
instances").
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When Hyper-V hypervisor leaves are present, KVM must relocate
its own leaves at 0x40000100, because Windows does not look for
Hyper-V leaves at indices other than 0x40000000.  In this case,
the KVM features are at 0x40000101, but the old code would always
look at 0x40000001.

Fix by using kvm_cpuid_base().  This also requires making the
function non-inline, since kvm_cpuid_base() is static.

Fixes: 1085ba7f
Cc: stable@vger.kernel.org
Cc: mtosatti@redhat.com
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

It is unnecessary to go through hypervisor_cpuid_base every time
a leaf is found (which will be every time a feature is requested
after the next patch).

Fixes: 1085ba7f
Cc: stable@vger.kernel.org
Cc: mtosatti@redhat.com
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Self explanatory.
Reported-by: NRadim Krcmar <rkrcmar@redhat.com>
Cc: Vadim Rozenfeld <vrozenfe@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Geert reported:

arch/xtensa/platforms/iss/simdisk.c:108:23: error: 'struct bio' has no member named 'bi_sector'
arch/xtensa/platforms/iss/simdisk.c:110:2: error: incompatible types when assigning to type 'int' from type 'struct bvec_iter'
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bi_size' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bi_size' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bi_size' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bi_bvec_done' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bi_bvec_done' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bi_bvec_done' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:110:2: error: request for member 'bv_len' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_size' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_size' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_bvec_done' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_bvec_done' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_bvec_done' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_size' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_size' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_bvec_done' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_bvec_done' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_idx' in something not a structure or union
arch/xtensa/platforms/iss/simdisk.c:111:18: error: request for member 'bi_bvec_done' in something not a structure or union
make[2]: *** [arch/xtensa/platforms/iss/simdisk.o] Error 1

Fixup the usage of bio_for_each_segment(). Also fix wrong use
of __bio_kunmap_atomic() - it needs the mapped buffer passed in,
not the originally mapped page.
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The pci.o is built for SPARC64_PCI -- which is bool, and hence
this code is either present or absent.  It will never be modular,
so using module_init as an alias for __initcall can be somewhat
misleading.

Fix this up now, so that we can relocate module_init from
init.h into module.h in the future.  If we don't do this, we'd
have to add module.h to obviously non-modular code, and that
would be a worse thing.

Note that direct use of __initcall is discouraged, vs. one
of the priority categorized subgroups.  As __initcall gets
mapped onto device_initcall, our use of device_initcall
directly in this change means that the runtime impact is
zero -- it will remain at level 6 in initcall ordering.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

None of these files are actually using any __init type directives
and hence don't need to include <linux/init.h>.  Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch removes CONFIG_MTD_PARTITIONS in config files for blackfin.
Because CONFIG_MTD_PARTITIONS was removed by commit
6a8a98b2.
Signed-off-by: NEunbong Song <eunb.song@samsung.com>
Signed-off-by: NSteven Miao <realmz6@gmail.com>

Signed-off-by: NAaron Wu <Aaron.wu@analog.com>
Signed-off-by: NSteven Miao <realmz6@gmail.com>

Signed-off-by: NAaron Wu <Aaron.wu@analog.com>

fix build error for bf527-ezkit_defconfig for old silicon

Move code for the SEC faults from the IRQ hanlders into IRQ actions.
refine bfin fault routine handle
Signed-off-by: NSonic Zhang <sonic.zhang@analog.com>
Signed-off-by: NSteven Miao <realmz6@gmail.com>

Signed-off-by: NSonic Zhang <sonic.zhang@analog.com>

None of these files are actually using any __init type directives
and hence don't need to include <linux/init.h>.  Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.

Cc: Mike Frysinger <vapier@gentoo.org>
Cc: uclinux-dist-devel@blackfin.uclinux.org
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

blackfin: bf60x: clock: return 0 upon error from clk_round_rate()

clk_round_rate() should return 0 upon an error, rather than returning
a negative error code.  This is because clk_round_rate() is being
changed to return an unsigned return type rather than a signed type,
since some clock sources can generate rates higher than (2^31)-1 Hz.
Signed-off-by: NPaul Walmsley <pwalmsley@nvidia.com>
Signed-off-by: NSteven Miao <realmz6@gmail.com>

Commit 9a46ad6d "smp: make smp_call_function_many() use logic
similar to smp_call_function_single()" has unified the way to handle
single and multiple cross-CPU function calls. Now only one interrupt
is needed for architecture specific code to support generic SMP function
call interfaces, so kill the redundant single function call interrupt.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Shaohua Li <shli@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jiri Kosina <trivial@kernel.org>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: uclinux-dist-devel@blackfin.uclinux.org
Signed-off-by: NJiang Liu <liuj97@gmail.com>

For all uapi headers, need use "_UAPI" prefix for its guard macro
(which will be stripped by "scripts/headers_installer.sh").

Also be sure that all files have their guard macros.

Also be sure that all "#endif" are followed with comments, and no '\t'
for guard macro
Signed-off-by: NChen Gang <gang.chen@asianux.com>

Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Replace __get_cpu_var safely with get_cpu_var to avoid
the following call trace:

[ 7253.637591] BUG: using smp_processor_id() in preemptible [00000000 00000000]
code: hugemmap01/9048
[ 7253.637601] caller is free_hugepd_range.constprop.25+0x88/0x1a8
[ 7253.637605] CPU: 1 PID: 9048 Comm: hugemmap01 Not tainted 3.10.20-rt14+ #114
[ 7253.637606] Call Trace:
[ 7253.637617] [cb049d80] [c0007ea4] show_stack+0x4c/0x168 (unreliable)
[ 7253.637624] [cb049dc0] [c031c674] debug_smp_processor_id+0x114/0x134
[ 7253.637628] [cb049de0] [c0016d28] free_hugepd_range.constprop.25+0x88/0x1a8
[ 7253.637632] [cb049e00] [c001711c] hugetlb_free_pgd_range+0x6c/0x168
[ 7253.637639] [cb049e40] [c0117408] free_pgtables+0x12c/0x150
[ 7253.637646] [cb049e70] [c011ce38] unmap_region+0xa0/0x11c
[ 7253.637671] [cb049ef0] [c011f03c] do_munmap+0x224/0x3bc
[ 7253.637676] [cb049f20] [c011f2e0] vm_munmap+0x38/0x5c
[ 7253.637682] [cb049f40] [c000ef88] ret_from_syscall+0x0/0x3c
[ 7253.637686] --- Exception: c01 at 0xff16004

Signed-off-by: Tiejun Chen<tiejun.chen@windriver.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The code in remove_cache_dir() is supposed to remove the "cache"
subdirectory from the sysfs directory for a CPU when that CPU is
being offlined.  It tries to do this by calling kobject_put() on
the kobject for the subdirectory.  However, the subdirectory only
gets removed once the last reference goes away, and the reference
being put here may well not be the last reference.  That means
that the "cache" subdirectory may still exist when the offlining
operation has finished.  If the same CPU subsequently gets onlined,
the code tries to add a new "cache" subdirectory.  If the old
subdirectory has not yet been removed, we get a WARN_ON in the
sysfs code, with stack trace, and an error message printed on the
console.  Further, we ultimately end up with an online cpu with no
"cache" subdirectory.

This fixes it by doing an explicit kobject_del() at the point where
we want the subdirectory to go away.  kobject_del() removes the sysfs
directory even though the object still exists in memory.  The object
will get freed at some point in the future.  A subsequent onlining
operation can create a new sysfs directory, even if the old object
still exists in memory, without causing any problems.

Cc: stable@vger.kernel.org # v3.0+
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>