Starting with Linux 3.12 processes get stuck in D state forever in
UserModeLinux under sync heavy workloads. This bug was introduced by
commit 805f11a0 (um: ubd: Add REQ_FLUSH suppport).
Fix bug by adding a check if FLUSH request was successfully submitted to
the I/O thread and keeping the FLUSH request on the request queue on
submission failures.

Fixes: 805f11a0 (um: ubd: Add REQ_FLUSH suppport)
Signed-off-by: NThorsten Knabe <linux@thorsten-knabe.de>
Cc: stable@kernel.org # >= 3.12
Signed-off-by: NRichard Weinberger <richard@nod.at>

1) uml kernel bootmem managed through bootmem_data->node_bootmem_map,
not the struct page array, so the array is unnecessary.

2) the bootmem struct page array has been pointed by a *local* pointer,
struct page *map, in init_maps function. The array can be accessed only
in init_maps's scope. As a result, uml kernel wastes about 1% of total
memory.
Signed-off-by: NHonggang Li <enjoymindful@gmail.com>
Signed-off-by: NRichard Weinberger <richard@nod.at>

arch/x86/um/checksum_32.S had been copy & paste from x86. When build
x86 uml, csum_partial_copy_generic_i386 mess up the exception table.
In fact, exception table dose not work in uml kernel.

And csum_partial_copy_generic_i386 never been called. So, delete it.
Signed-off-by: NHonggang Li <enjoymindful@gmail.com>
Signed-off-by: NRichard Weinberger <richard@nod.at>

Pull percpu updates from Tejun Heo:
 "A lot of activities on percpu front.  Notable changes are...

   - percpu allocator now can take @gfp.  If @gfp doesn't contain
     GFP_KERNEL, it tries to allocate from what's already available to
     the allocator and a work item tries to keep the reserve around
     certain level so that these atomic allocations usually succeed.

     This will replace the ad-hoc percpu memory pool used by
     blk-throttle and also be used by the planned blkcg support for
     writeback IOs.

     Please note that I noticed a bug in how @gfp is interpreted while
     preparing this pull request and applied the fix 6ae833c7
     ("percpu: fix how @gfp is interpreted by the percpu allocator")
     just now.

   - percpu_ref now uses longs for percpu and global counters instead of
     ints.  It leads to more sparse packing of the percpu counters on
     64bit machines but the overhead should be negligible and this
     allows using percpu_ref for refcnting pages and in-memory objects
     directly.

   - The switching between percpu and single counter modes of a
     percpu_ref is made independent of putting the base ref and a
     percpu_ref can now optionally be initialized in single or killed
     mode.  This allows avoiding percpu shutdown latency for cases where
     the refcounted objects may be synchronously created and destroyed
     in rapid succession with only a fraction of them reaching fully
     operational status (SCSI probing does this when combined with
     blk-mq support).  It's also planned to be used to implement forced
     single mode to detect underflow more timely for debugging.

  There's a separate branch percpu/for-3.18-consistent-ops which cleans
  up the duplicate percpu accessors.  That branch causes a number of
  conflicts with s390 and other trees.  I'll send a separate pull
  request w/ resolutions once other branches are merged"

* 'for-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (33 commits)
  percpu: fix how @gfp is interpreted by the percpu allocator
  blk-mq, percpu_ref: start q->mq_usage_counter in atomic mode
  percpu_ref: make INIT_ATOMIC and switch_to_atomic() sticky
  percpu_ref: add PERCPU_REF_INIT_* flags
  percpu_ref: decouple switching to percpu mode and reinit
  percpu_ref: decouple switching to atomic mode and killing
  percpu_ref: add PCPU_REF_DEAD
  percpu_ref: rename things to prepare for decoupling percpu/atomic mode switch
  percpu_ref: replace pcpu_ prefix with percpu_
  percpu_ref: minor code and comment updates
  percpu_ref: relocate percpu_ref_reinit()
  Revert "blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe"
  Revert "percpu: free percpu allocation info for uniprocessor system"
  percpu-refcount: make percpu_ref based on longs instead of ints
  percpu-refcount: improve WARN messages
  percpu: fix locking regression in the failure path of pcpu_alloc()
  percpu-refcount: add @gfp to percpu_ref_init()
  proportions: add @gfp to init functions
  percpu_counter: add @gfp to percpu_counter_init()
  percpu_counter: make percpu_counters_lock irq-safe
  ...

Pull cgroup updates from Tejun Heo:
 "Nothing too interesting.  Just a handful of cleanup patches"

* 'for-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  Revert "cgroup: remove redundant variable in cgroup_mount()"
  cgroup: remove redundant variable in cgroup_mount()
  cgroup: fix missing unlock in cgroup_release_agent()
  cgroup: remove CGRP_RELEASABLE flag
  perf/cgroup: Remove perf_put_cgroup()
  cgroup: remove redundant check in cgroup_ino()
  cpuset: simplify proc_cpuset_show()
  cgroup: simplify proc_cgroup_show()
  cgroup: use a per-cgroup work for release agent
  cgroup: remove bogus comments
  cgroup: remove redundant code in cgroup_rmdir()
  cgroup: remove some useless forward declarations
  cgroup: fix a typo in comment.

Pull libata update from Tejun Heo:
 "AHCI is getting per-port irq handling and locks for better
  scalability.  The gain is not huge but measureable with multiple high
  iops devices connected to the same host; however, the value of
  threaded IRQ handling seems negligible for AHCI and it likely will
  revert to non-threaded handling soon.

  Another noteworthy change is George Spelvin's "libata: Un-break ATA
  blacklist".  During 3.17 devel cycle, the libata blacklist glob
  matching got generalized and rewritten; unfortunately, the patch
  forgot to swap arguments to match the new match function and ended up
  breaking blacklist matching completely.  It got noticed only a couple
  days ago so it couldn't make for-3.17-fixes either.  :(

  Other than the above two, nothing too interesting - the usual cleanup
  churns and device-specific changes"

* 'for-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata: (22 commits)
  pata_serverworks: disable 64-KB DMA transfers on Broadcom OSB4 IDE Controller
  libata: Un-break ATA blacklist
  AHCI: Do not acquire ata_host::lock from single IRQ handler
  AHCI: Optimize single IRQ interrupt processing
  AHCI: Do not read HOST_IRQ_STAT reg in multi-MSI mode
  AHCI: Make few function names more descriptive
  AHCI: Move host activation code into ahci_host_activate()
  AHCI: Move ahci_host_activate() function to libahci.c
  AHCI: Pass SCSI host template as arg to ahci_host_activate()
  ata: pata_imx: Use the SIMPLE_DEV_PM_OPS() macro
  AHCI: Cleanup checking of multiple MSIs/SLM modes
  libata-sff: Fix controllers with no ctl port
  ahci_xgene: Fix the error print invalid resource for APM X-Gene SoC AHCI SATA Host Controller driver.
  libata: change ata_<foo>_printk routines to return void
  ata: qcom: Add device tree bindings information
  ahci-platform: Bump max number of clocks to 5
  ahci: ahci_p5wdh_workaround - constify DMI table
  libahci_platform: Staticize ahci_platform_<en/dis>able_phys()
  pata_platform: Remove useless irq_flags field
  pata_of_platform: Remove "electra-ide" quirk
  ...

Merge patch-bomb from Andrew Morton:
 - part of OCFS2 (review is laggy again)
 - procfs
 - slab
 - all of MM
 - zram, zbud
 - various other random things: arch, filesystems.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (164 commits)
  nosave: consolidate __nosave_{begin,end} in <asm/sections.h>
  include/linux/screen_info.h: remove unused ORIG_* macros
  kernel/sys.c: compat sysinfo syscall: fix undefined behavior
  kernel/sys.c: whitespace fixes
  acct: eliminate compile warning
  kernel/async.c: switch to pr_foo()
  include/linux/blkdev.h: use NULL instead of zero
  include/linux/kernel.h: deduplicate code implementing clamp* macros
  include/linux/kernel.h: rewrite min3, max3 and clamp using min and max
  alpha: use Kbuild logic to include <asm-generic/sections.h>
  frv: remove deprecated IRQF_DISABLED
  frv: remove unused cpuinfo_frv and friends to fix future build error
  zbud: avoid accessing last unused freelist
  zsmalloc: simplify init_zspage free obj linking
  mm/zsmalloc.c: correct comment for fullness group computation
  zram: use notify_free to account all free notifications
  zram: report maximum used memory
  zram: zram memory size limitation
  zsmalloc: change return value unit of zs_get_total_size_bytes
  zsmalloc: move pages_allocated to zs_pool
  ...

The different architectures used their own (and different) declarations:

    extern __visible const void __nosave_begin, __nosave_end;
    extern const void __nosave_begin, __nosave_end;
    extern long __nosave_begin, __nosave_end;

Consolidate them using the first variant in <asm/sections.h>.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The ORIG_* macros definitions to access struct screen_info members and all
of their users were removed 7 years ago by commit 3ea33510
("Remove magic macros for screen_info structure members"), but (only) the
definitions reappeared a few days later in commit ee8e7cfe ("Make
asm-x86/bootparam.h includable from userspace.").

Remove them for good. Amen.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix undefined behavior and compiler warning by replacing right shift 32
with upper_32_bits macro
Signed-off-by: NScotty Bauer <sbauer@eng.utah.edu>
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix minor errors and warning messages in kernel/sys.c.  These errors were
reported by checkpatch while working with some modifications in sys.c
file.  Fixing this first will help me to improve my further patches.

ERROR: trailing whitespace - 9
ERROR: do not use assignment in if condition - 4
ERROR: spaces required around that '?' (ctx:VxO) - 10
ERROR: switch and case should be at the same indent - 3

total 26 errors & 3 warnings fixed.
Signed-off-by: Nvishnu.ps <vishnu.ps@samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If ACCT_VERSION is not defined to 3, below warning appears:
  CC      kernel/acct.o
  kernel/acct.c: In function `do_acct_process':
  kernel/acct.c:475:24: warning: unused variable `ns' [-Wunused-variable]

[akpm@linux-foundation.org: retain the local for code size improvements
Signed-off-by: NYing Xue <ying.xue@windriver.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NIonut Alexa <ionut.m.alexa@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Quite useless but it shuts up some warnings.
Signed-off-by: NMichele Curti <michele.curti@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Instead of open-coding clamp_t macro min_t and max_t the way clamp macro
does and instead of open-coding clamp_val simply use clamp_t.
Furthermore, normalise argument naming in the macros to be lo and hi.
Signed-off-by: NMichal Nazarewicz <mina86@mina86.com>
Cc: Mark Rustad <mark.d.rustad@intel.com>
Cc: "Kirsher, Jeffrey T" <jeffrey.t.kirsher@intel.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It appears that gcc is better at optimising a double call to min and max
rather than open coded min3 and max3.  This can be observed here:

    $ cat min-max.c
    #define min(x, y) ({				\
    	typeof(x) _min1 = (x);			\
    	typeof(y) _min2 = (y);			\
    	(void) (&_min1 == &_min2);		\
    	_min1 < _min2 ? _min1 : _min2; })
    #define min3(x, y, z) ({			\
    	typeof(x) _min1 = (x);			\
    	typeof(y) _min2 = (y);			\
    	typeof(z) _min3 = (z);			\
    	(void) (&_min1 == &_min2);		\
    	(void) (&_min1 == &_min3);		\
    	_min1 < _min2 ? (_min1 < _min3 ? _min1 : _min3) : \
    		(_min2 < _min3 ? _min2 : _min3); })

    int fmin3(int x, int y, int z) { return min3(x, y, z); }
    int fmin2(int x, int y, int z) { return min(min(x, y), z); }

    $ gcc -O2 -o min-max.s -S min-max.c; cat min-max.s
    	.file	"min-max.c"
    	.text
    	.p2align 4,,15
    	.globl	fmin3
    	.type	fmin3, @function
    fmin3:
    .LFB0:
    	.cfi_startproc
    	cmpl	%esi, %edi
    	jl	.L5
    	cmpl	%esi, %edx
    	movl	%esi, %eax
    	cmovle	%edx, %eax
    	ret
    	.p2align 4,,10
    	.p2align 3
    .L5:
    	cmpl	%edi, %edx
    	movl	%edi, %eax
    	cmovle	%edx, %eax
    	ret
    	.cfi_endproc
    .LFE0:
    	.size	fmin3, .-fmin3
    	.p2align 4,,15
    	.globl	fmin2
    	.type	fmin2, @function
    fmin2:
    .LFB1:
    	.cfi_startproc
    	cmpl	%edi, %esi
    	movl	%edx, %eax
    	cmovle	%esi, %edi
    	cmpl	%edx, %edi
    	cmovle	%edi, %eax
    	ret
    	.cfi_endproc
    .LFE1:
    	.size	fmin2, .-fmin2
    	.ident	"GCC: (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3"
    	.section	.note.GNU-stack,"",@progbits

fmin3 function, which uses open-coded min3 macro, is compiled into total
of ten instructions including a conditional branch, whereas fmin2
function, which uses two calls to min2 macro, is compiled into six
instructions with no branches.

Similarly, open-coded clamp produces the same code as clamp using min and
max macros, but the latter is much shorter:

    $ cat clamp.c
    #define clamp(val, min, max) ({			\
    	typeof(val) __val = (val);		\
    	typeof(min) __min = (min);		\
    	typeof(max) __max = (max);		\
    	(void) (&__val == &__min);		\
    	(void) (&__val == &__max);		\
    	__val = __val < __min ? __min: __val;	\
    	__val > __max ? __max: __val; })
    #define min(x, y) ({				\
    	typeof(x) _min1 = (x);			\
    	typeof(y) _min2 = (y);			\
    	(void) (&_min1 == &_min2);		\
    	_min1 < _min2 ? _min1 : _min2; })
    #define max(x, y) ({				\
    	typeof(x) _max1 = (x);			\
    	typeof(y) _max2 = (y);			\
    	(void) (&_max1 == &_max2);		\
    	_max1 > _max2 ? _max1 : _max2; })

    int fclamp(int v, int min, int max) { return clamp(v, min, max); }
    int fclampmm(int v, int min, int max) { return min(max(v, min), max); }

    $ gcc -O2 -o clamp.s -S clamp.c; cat clamp.s
    	.file	"clamp.c"
    	.text
    	.p2align 4,,15
    	.globl	fclamp
    	.type	fclamp, @function
    fclamp:
    .LFB0:
    	.cfi_startproc
    	cmpl	%edi, %esi
    	movl	%edx, %eax
    	cmovge	%esi, %edi
    	cmpl	%edx, %edi
    	cmovle	%edi, %eax
    	ret
    	.cfi_endproc
    .LFE0:
    	.size	fclamp, .-fclamp
    	.p2align 4,,15
    	.globl	fclampmm
    	.type	fclampmm, @function
    fclampmm:
    .LFB1:
    	.cfi_startproc
    	cmpl	%edi, %esi
    	cmovge	%esi, %edi
    	cmpl	%edi, %edx
    	movl	%edi, %eax
    	cmovle	%edx, %eax
    	ret
    	.cfi_endproc
    .LFE1:
    	.size	fclampmm, .-fclampmm
    	.ident	"GCC: (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3"
    	.section	.note.GNU-stack,"",@progbits

    Linux mpn-glaptop 3.13.0-29-generic #53~precise1-Ubuntu SMP Wed Jun 4 22:06:25 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
    gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
    Copyright (C) 2011 Free Software Foundation, Inc.
    This is free software; see the source for copying conditions.  There is NO
    warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

    -rwx------ 1 mpn eng 51224656 Jun 17 14:15 vmlinux.before
    -rwx------ 1 mpn eng 51224608 Jun 17 13:57 vmlinux.after

48 bytes reduction.  The do_fault_around was a few instruction shorter
and as far as I can tell saved 12 bytes on the stack, i.e.:

    $ grep -e rsp -e pop -e push do_fault_around.*
    do_fault_around.before.s:push   %rbp
    do_fault_around.before.s:mov    %rsp,%rbp
    do_fault_around.before.s:push   %r13
    do_fault_around.before.s:push   %r12
    do_fault_around.before.s:push   %rbx
    do_fault_around.before.s:sub    $0x38,%rsp
    do_fault_around.before.s:add    $0x38,%rsp
    do_fault_around.before.s:pop    %rbx
    do_fault_around.before.s:pop    %r12
    do_fault_around.before.s:pop    %r13
    do_fault_around.before.s:pop    %rbp

    do_fault_around.after.s:push   %rbp
    do_fault_around.after.s:mov    %rsp,%rbp
    do_fault_around.after.s:push   %r12
    do_fault_around.after.s:push   %rbx
    do_fault_around.after.s:sub    $0x30,%rsp
    do_fault_around.after.s:add    $0x30,%rsp
    do_fault_around.after.s:pop    %rbx
    do_fault_around.after.s:pop    %r12
    do_fault_around.after.s:pop    %rbp

or here side-by-side:

    Before                    After
    push   %rbp               push   %rbp
    mov    %rsp,%rbp          mov    %rsp,%rbp
    push   %r13
    push   %r12               push   %r12
    push   %rbx               push   %rbx
    sub    $0x38,%rsp         sub    $0x30,%rsp
    add    $0x38,%rsp         add    $0x30,%rsp
    pop    %rbx               pop    %rbx
    pop    %r12               pop    %r12
    pop    %r13
    pop    %rbp               pop    %rbp

There are also fewer branches:

    $ grep ^j do_fault_around.*
    do_fault_around.before.s:jae    ffffffff812079b7
    do_fault_around.before.s:jmp    ffffffff812079c5
    do_fault_around.before.s:jmp    ffffffff81207a14
    do_fault_around.before.s:ja     ffffffff812079f9
    do_fault_around.before.s:jb     ffffffff81207a10
    do_fault_around.before.s:jmp    ffffffff81207a63
    do_fault_around.before.s:jne    ffffffff812079df

    do_fault_around.after.s:jmp    ffffffff812079fd
    do_fault_around.after.s:ja     ffffffff812079e2
    do_fault_around.after.s:jb     ffffffff812079f9
    do_fault_around.after.s:jmp    ffffffff81207a4c
    do_fault_around.after.s:jne    ffffffff812079c8

And here's with allyesconfig on a different machine:

    $ uname -a; gcc --version; ls -l vmlinux.*
    Linux erwin 3.14.7-mn #54 SMP Sun Jun 15 11:25:08 CEST 2014 x86_64 AMD Phenom(tm) II X3 710 Processor AuthenticAMD GNU/Linux
    gcc (GCC) 4.8.3
    Copyright (C) 2013 Free Software Foundation, Inc.
    This is free software; see the source for copying conditions.  There is NO
    warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

    -rwx------ 1 mpn eng 437027411 Jun 20 16:04 vmlinux.before
    -rwx------ 1 mpn eng 437026881 Jun 20 15:30 vmlinux.after

530 bytes reduction.
Signed-off-by: NMichal Nazarewicz <mina86@mina86.com>
Signed-off-by: NHagen Paul Pfeifer <hagen@jauu.net>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: David Rientjes <rientjes@google.com>
Cc: "Rustad, Mark D" <mark.d.rustad@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove the IRQF_DISABLED flag from FRV architecture code.  It's a NOOP
since 2.6.35 and it will be removed one day.
Signed-off-by: NMichael Opdenacker <michael.opdenacker@free-electrons.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Frv has a macro named cpu_data, interfering with variables and struct
members with the same name:

include/linux/pm_domain.h:75:24: error: expected identifier or '('
before '&' token
  struct gpd_cpu_data *cpu_data;

As struct cpuinfo_frv, boot_cpu_data, cpu_data, and current_cpu_data are
not used, removed them to fix this.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

For now, there are NCHUNKS of 64 freelists in zbud_pool, the last
unbuddied[63] freelist linked with all zbud pages which have free chunks
of 63.  Calculating according to context of num_free_chunks(), our max
chunk number of unbuddied zbud page is 62, so none of zbud pages will be
added/removed in last freelist, but still we will try to find an unbuddied
zbud page in the last unused freelist, it is unneeded.

This patch redefines NCHUNKS to 63 as free chunk number in one zbud page,
hence we can decrease size of zpool and avoid accessing the last unused
freelist whenever failing to allocate zbud from freelist in zbud_alloc.
Signed-off-by: NChao Yu <chao2.yu@samsung.com>
Cc: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change zsmalloc init_zspage() logic to iterate through each object on each
of its pages, checking the offset to verify the object is on the current
page before linking it into the zspage.

The current zsmalloc init_zspage free object linking code has logic that
relies on there only being one page per zspage when PAGE_SIZE is a
multiple of class->size.  It calculates the number of objects for the
current page, and iterates through all of them plus one, to account for
the assumed partial object at the end of the page.  While this currently
works, the logic can be simplified to just link the object at each
successive offset until the offset is larger than PAGE_SIZE, which does
not rely on PAGE_SIZE being a multiple of class->size.
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Acked-by: NMinchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The letter 'f' in "n <= N/f" stands for fullness_threshold_frac, not
1/fullness_threshold_frac.
Signed-off-by: NWang Sheng-Hui <shhuiw@gmail.com>
Acked-by: NMinchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

`notify_free' device attribute accounts the number of slot free
notifications and internally represents the number of zram_free_page()
calls.  Slot free notifications are sent only when device is used as a
swap device, hence `notify_free' is used only for swap devices.  Since
f4659d8e (zram: support REQ_DISCARD) ZRAM handles yet another one
free notification (also via zram_free_page() call) -- REQ_DISCARD
requests, which are sent by a filesystem, whenever some data blocks are
discarded.  However, there is no way to know the number of notifications
in the latter case.

Use `notify_free' to account the number of pages freed by
zram_bio_discard() and zram_slot_free_notify().  Depending on usage
scenario `notify_free' represents:

 a) the number of pages freed because of slot free notifications, which is
   equal to the number of swap_slot_free_notify() calls, so there is no
   behaviour change

 b) the number of pages freed because of REQ_DISCARD notifications
Signed-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NJerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Normally, zram user could get maximum memory usage zram consumed via
polling mem_used_total with sysfs in userspace.

But it has a critical problem because user can miss peak memory usage
during update inverval of polling.  For avoiding that, user should poll it
with shorter interval(ie, 0.0000000001s) with mlocking to avoid page fault
delay when memory pressure is heavy.  It would be troublesome.

This patch adds new knob "mem_used_max" so user could see the maximum
memory usage easily via reading the knob and reset it via "echo 0 >
/sys/block/zram0/mem_used_max".
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Reviewed-by: NDan Streetman <ddstreet@ieee.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: <juno.choi@lge.com>
Cc: <seungho1.park@lge.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Reviewed-by: NDavid Horner <ds2horner@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since zram has no control feature to limit memory usage, it makes hard to
manage system memrory.

This patch adds new knob "mem_limit" via sysfs to set up the a limit so
that zram could fail allocation once it reaches the limit.

In addition, user could change the limit in runtime so that he could
manage the memory more dynamically.

Initial state is no limit so it doesn't break old behavior.

[akpm@linux-foundation.org: fix typo, per Sergey]
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: <juno.choi@lge.com>
Cc: <seungho1.park@lge.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: David Horner <ds2horner@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

zs_get_total_size_bytes returns a amount of memory zsmalloc consumed with
*byte unit* but zsmalloc operates *page unit* rather than byte unit so
let's change the API so benefit we could get is that reduce unnecessary
overhead (ie, change page unit with byte unit) in zsmalloc.

Since return type is pages, "zs_get_total_pages" is better than
"zs_get_total_size_bytes".
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Reviewed-by: NDan Streetman <ddstreet@ieee.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: <juno.choi@lge.com>
Cc: <seungho1.park@lge.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: David Horner <ds2horner@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, zram has no feature to limit memory so theoretically zram can
deplete system memory.  Users have asked for a limit several times as even
without exhaustion zram makes it hard to control memory usage of the
platform.  This patchset adds the feature.

Patch 1 makes zs_get_total_size_bytes faster because it would be used
frequently in later patches for the new feature.

Patch 2 changes zs_get_total_size_bytes's return unit from bytes to page
so that zsmalloc doesn't need unnecessary operation(ie, << PAGE_SHIFT).

Patch 3 adds new feature.  I added the feature into zram layer, not
zsmalloc because limiation is zram's requirement, not zsmalloc so any
other user using zsmalloc(ie, zpool) shouldn't affected by unnecessary
branch of zsmalloc.  In future, if every users of zsmalloc want the
feature, then, we could move the feature from client side to zsmalloc
easily but vice versa would be painful.

Patch 4 adds news facility to report maximum memory usage of zram so that
this avoids user polling frequently via /sys/block/zram0/ mem_used_total
and ensures transient max are not missed.

This patch (of 4):

pages_allocated has counted in size_class structure and when user of
zsmalloc want to see total_size_bytes, it should gather all of count from
each size_class to report the sum.

It's not bad if user don't see the value often but if user start to see
the value frequently, it would be not a good deal for performance pov.

This patch moves the count from size_class to zs_pool so it could reduce
memory footprint (from [255 * 8byte] to [sizeof(atomic_long_t)]).
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Reviewed-by: NDan Streetman <ddstreet@ieee.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: <juno.choi@lge.com>
Cc: <seungho1.park@lge.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Reviewed-by: NDavid Horner <ds2horner@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Performing vma lookups without taking the mm->mmap_sem is asking for
trouble.  While doing the search, the vma in question can be modified or
even removed before returning to the caller.  Take the lock (shared) in
order to avoid races while iterating through the vmacache and/or rbtree.
In addition, this guarantees that the address space will remain intact
during the CPU flushing.
Signed-off-by: NDavidlohr Bueso <davidlohr@hp.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

vmstat workers are used for folding counter differentials into the zone,
per node and global counters at certain time intervals.  They currently
run at defined intervals on all processors which will cause some holdoff
for processors that need minimal intrusion by the OS.

The current vmstat_update mechanism depends on a deferrable timer firing
every other second by default which registers a work queue item that runs
on the local CPU, with the result that we have 1 interrupt and one
additional schedulable task on each CPU every 2 seconds If a workload
indeed causes VM activity or multiple tasks are running on a CPU, then
there are probably bigger issues to deal with.

However, some workloads dedicate a CPU for a single CPU bound task.  This
is done in high performance computing, in high frequency financial
applications, in networking (Intel DPDK, EZchip NPS) and with the advent
of systems with more and more CPUs over time, this may become more and
more common to do since when one has enough CPUs one cares less about
efficiently sharing a CPU with other tasks and more about efficiently
monopolizing a CPU per task.

The difference of having this timer firing and workqueue kernel thread
scheduled per second can be enormous.  An artificial test measuring the
worst case time to do a simple "i++" in an endless loop on a bare metal
system and under Linux on an isolated CPU with dynticks and with and
without this patch, have Linux match the bare metal performance (~700
cycles) with this patch and loose by couple of orders of magnitude (~200k
cycles) without it[*].  The loss occurs for something that just calculates
statistics.  For networking applications, for example, this could be the
difference between dropping packets or sustaining line rate.

Statistics are important and useful, but it would be great if there would
be a way to not cause statistics gathering produce a huge performance
difference.  This patche does just that.

This patch creates a vmstat shepherd worker that monitors the per cpu
differentials on all processors.  If there are differentials on a
processor then a vmstat worker local to the processors with the
differentials is created.  That worker will then start folding the diffs
in regular intervals.  Should the worker find that there is no work to be
done then it will make the shepherd worker monitor the differentials
again.

With this patch it is possible then to have periods longer than
2 seconds without any OS event on a "cpu" (hardware thread).

The patch shows a very minor increased in system performance.

hackbench -s 512 -l 2000 -g 15 -f 25 -P

Results before the patch:

Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks)
Each sender will pass 2000 messages of 512 bytes
Time: 4.992
Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks)
Each sender will pass 2000 messages of 512 bytes
Time: 4.971
Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks)
Each sender will pass 2000 messages of 512 bytes
Time: 5.063

Hackbench after the patch:

Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks)
Each sender will pass 2000 messages of 512 bytes
Time: 4.973
Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks)
Each sender will pass 2000 messages of 512 bytes
Time: 4.990
Running in process mode with 15 groups using 50 file descriptors each (== 750 tasks)
Each sender will pass 2000 messages of 512 bytes
Time: 4.993

[fengguang.wu@intel.com: cpu_stat_off can be static]
Signed-off-by: NChristoph Lameter <cl@linux.com>
Reviewed-by: NGilad Ben-Yossef <gilad@benyossef.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Hakan Akkan <hakanakkan@gmail.com>
Cc: Max Krasnyansky <maxk@qti.qualcomm.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It isn't obvious that CMA can be disabled on the kernel's command line, so
document it.
Signed-off-by: NJean Delvare <jdelvare@suse.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Chuck Ebbert <cebbert.lkml@gmail.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Increase the buffer-head per-CPU LRU size to allow efficient filesystem
operations that access many blocks for each transaction.  For example,
creating a file in a large ext4 directory with quota enabled will access
multiple buffer heads and will overflow the LRU at the default 8-block LRU
size:

* parent directory inode table block (ctime, nlinks for subdirs)
* new inode bitmap
* inode table block
* 2 quota blocks
* directory leaf block (not reused, but pollutes one cache entry)
* 2 levels htree blocks (only one is reused, other pollutes cache)
* 2 levels indirect/index blocks (only one is reused)

The buffer-head per-CPU LRU size is raised to 16, as it shows in metadata
performance benchmarks up to 10% gain for create, 4% for lookup and 7% for
destroy.
Signed-off-by: NLiang Zhen <liang.zhen@intel.com>
Signed-off-by: NAndreas Dilger <andreas.dilger@intel.com>
Signed-off-by: NSebastien Buisson <sebastien.buisson@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

PROT_NUMA VMAs are skipped to avoid problems distinguishing between
present, prot_none and special entries.  MPOL_MF_LAZY is not visible from
userspace since commit a720094d ("mm: mempolicy: Hide MPOL_NOOP and
MPOL_MF_LAZY from userspace for now") but it should still skip VMAs the
same way task_numa_work does.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Acked-by: NRik van Riel <riel@redhat.com>
Acked-by: NHugh Dickins <hughd@google.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This tool induces memory fragmentation via sequential allocation of
transparent huge pages and splitting off everything except their last
sub-pages.  It easily generates pressure to the memory compaction code.

$ perf stat -e 'compaction:*' -e 'migrate:*' ./transhuge-stress
transhuge-stress: allocate 7858 transhuge pages, using 15716 MiB virtual memory and 61 MiB of ram
transhuge-stress: 1.653 s/loop, 0.210 ms/page,   9504.828 MiB/s	7858 succeed,    0 failed, 2439 different pages
transhuge-stress: 1.537 s/loop, 0.196 ms/page,  10226.227 MiB/s	7858 succeed,    0 failed, 2364 different pages
transhuge-stress: 1.658 s/loop, 0.211 ms/page,   9479.215 MiB/s	7858 succeed,    0 failed, 2179 different pages
transhuge-stress: 1.617 s/loop, 0.206 ms/page,   9716.992 MiB/s	7858 succeed,    0 failed, 2421 different pages
^C./transhuge-stress: Interrupt

 Performance counter stats for './transhuge-stress':

         1.744.051      compaction:mm_compaction_isolate_migratepages
             1.014      compaction:mm_compaction_isolate_freepages
         1.744.051      compaction:mm_compaction_migratepages
             1.647      compaction:mm_compaction_begin
             1.647      compaction:mm_compaction_end
         1.744.051      migrate:mm_migrate_pages
                 0      migrate:mm_numa_migrate_ratelimit

       7,964696835 seconds time elapsed
Signed-off-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Always mark pages with PageBalloon even if balloon compaction is disabled
and expose this mark in /proc/kpageflags as KPF_BALLOON.

Also this patch adds three counters into /proc/vmstat: "balloon_inflate",
"balloon_deflate" and "balloon_migrate".  They accumulate balloon
activity.  Current size of balloon is (balloon_inflate - balloon_deflate)
pages.

All generic balloon code now gathered under option CONFIG_MEMORY_BALLOON.
It should be selected by ballooning driver which wants use this feature.
Currently virtio-balloon is the only user.
Signed-off-by: NKonstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Now ballooned pages are detected using PageBalloon().  Fake mapping is no
longer required.  This patch links ballooned pages to balloon device using
field page->private instead of page->mapping.  Also this patch embeds
balloon_dev_info directly into struct virtio_balloon.
Signed-off-by: NKonstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Sasha Levin reported KASAN splash inside isolate_migratepages_range().
Problem is in the function __is_movable_balloon_page() which tests
AS_BALLOON_MAP in page->mapping->flags.  This function has no protection
against anonymous pages.  As result it tried to check address space flags
inside struct anon_vma.

Further investigation shows more problems in current implementation:

* Special branch in __unmap_and_move() never works:
  balloon_page_movable() checks page flags and page_count.  In
  __unmap_and_move() page is locked, reference counter is elevated, thus
  balloon_page_movable() always fails.  As a result execution goes to the
  normal migration path.  virtballoon_migratepage() returns
  MIGRATEPAGE_BALLOON_SUCCESS instead of MIGRATEPAGE_SUCCESS,
  move_to_new_page() thinks this is an error code and assigns
  newpage->mapping to NULL.  Newly migrated page lose connectivity with
  balloon an all ability for further migration.

* lru_lock erroneously required in isolate_migratepages_range() for
  isolation ballooned page.  This function releases lru_lock periodically,
  this makes migration mostly impossible for some pages.

* balloon_page_dequeue have a tight race with balloon_page_isolate:
  balloon_page_isolate could be executed in parallel with dequeue between
  picking page from list and locking page_lock.  Race is rare because they
  use trylock_page() for locking.

This patch fixes all of them.

Instead of fake mapping with special flag this patch uses special state of
page->_mapcount: PAGE_BALLOON_MAPCOUNT_VALUE = -256.  Buddy allocator uses
PAGE_BUDDY_MAPCOUNT_VALUE = -128 for similar purpose.  Storing mark
directly in struct page makes everything safer and easier.

PagePrivate is used to mark pages present in page list (i.e.  not
isolated, like PageLRU for normal pages).  It replaces special rules for
reference counter and makes balloon migration similar to migration of
normal pages.  This flag is protected by page_lock together with link to
the balloon device.
Signed-off-by: NKonstantin Khlebnikov <k.khlebnikov@samsung.com>
Reported-by: NSasha Levin <sasha.levin@oracle.com>
Link: http://lkml.kernel.org/p/53E6CEAA.9020105@oracle.com
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: <stable@vger.kernel.org>	[3.8+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Activate the RCU fast_gup for ARM64.  We also need to force THP splits to
broadcast an IPI s.t.  we block in the fast_gup page walker.  As THP
splits are comparatively rare, this should not lead to a noticeable
performance degradation.

Some pre-requisite functions pud_write and pud_page are also added.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NSteve Capper <steve.capper@linaro.org>
Tested-by: NDann Frazier <dann.frazier@canonical.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In order to implement fast_get_user_pages we need to ensure that the page
table walker is protected from page table pages being freed from under it.

This patch enables HAVE_RCU_TABLE_FREE, any page table pages belonging to
address spaces with multiple users will be call_rcu_sched freed.  Meaning
that disabling interrupts will block the free and protect the fast gup
page walker.
Signed-off-by: NSteve Capper <steve.capper@linaro.org>
Tested-by: NDann Frazier <dann.frazier@canonical.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Activate the RCU fast_gup for ARM.  We also need to force THP splits to
broadcast an IPI s.t.  we block in the fast_gup page walker.  As THP
splits are comparatively rare, this should not lead to a noticeable
performance degradation.

Some pre-requisite functions pud_write and pud_page are also added.
Signed-off-by: NSteve Capper <steve.capper@linaro.org>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In order to implement fast_get_user_pages we need to ensure that the page
table walker is protected from page table pages being freed from under it.

This patch enables HAVE_RCU_TABLE_FREE, any page table pages belonging to
address spaces with multiple users will be call_rcu_sched freed.  Meaning
that disabling interrupts will block the free and protect the fast gup
page walker.
Signed-off-by: NSteve Capper <steve.capper@linaro.org>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>