None of these declarations is required outside of kernel/time. Move them to
an internal header.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/20170530211656.394803853@linutronix.de

As a preparation for further changes, cleanup the formatting of the
k_itimer structure and add kernel doc comments.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170530211656.316574129@linutronix.de

Move it below the actual implementations as there are new callbacks coming
which would require even more forward declarations.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170530211656.238209952@linutronix.de

The only user of this facility is ptp_clock, which does not implement any of
those functions.

Remove them to prevent accidental users. Especially the interval timer
interfaces are now more or less impossible to implement because the
necessary infrastructure has been confined to the core code. Aside of that
it's really complex to make these callbacks implemented according to spec
as the alarm timer implementation demonstrates. If at all then a nanosleep
callback might be a reasonable extension. For now keep just what ptp_clock
needs.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170530211656.145036286@linutronix.de

Since the removal of the mmtimer driver the export is not longer needed.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170530211656.052744418@linutronix.de

Having a IF_ENABLED(CONFIG_POSIX_TIMERS) inside of a
#ifdef CONFIG_POSIX_TIMERS section is pointless.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170530211655.975218056@linutronix.de

Pick up urgent fixes to avoid conflicts.

The alarmtimer code has another source of potentially rearming itself too
fast. Interval timers with a very samll interval have a similar CPU hog
effect as the previously fixed overflow issue.

The reason is that alarmtimers do not implement the normal protection
against this kind of problem which the other posix timer use:

  timer expires -> queue signal -> deliver signal -> rearm timer

This scheme brings the rearming under scheduler control and prevents
permanently firing timers which hog the CPU.

Bringing this scheme to the alarm timer code is a major overhaul because it
lacks all the necessary mechanisms completely.

So for a quick fix limit the interval to one jiffie. This is not
problematic in practice as alarmtimers are usually backed by an RTC for
suspend which have 1 second resolution. It could be therefor argued that
the resolution of this clock should be set to 1 second in general, but
that's outside the scope of this fix.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kostya Serebryany <kcc@google.com>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170530211655.896767100@linutronix.de

Andrey reported a alartimer related RCU stall while fuzzing the kernel with
syzkaller.

The reason for this is an overflow in ktime_add() which brings the
resulting time into negative space and causes immediate expiry of the
timer. The following rearm with a small interval does not bring the timer
back into positive space due to the same issue.

This results in a permanent firing alarmtimer which hogs the CPU.

Use ktime_add_safe() instead which detects the overflow and clamps the
result to KTIME_SEC_MAX.
Reported-by: NAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kostya Serebryany <kcc@google.com>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170530211655.802921648@linutronix.de

By moving the kernel side __SI_* defintions right next to the userspace
ones we can kill the non-uapi versions of <asm/siginfo.h> include
include/asm-generic/siginfo.h and untangle the unholy mess of includes.

[ tglx: Removed uapi/asm/siginfo.h from m32r, microblaze, mn10300 and score ]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-ia64@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: sparclinux@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20170603190102.28866-6-hch@lst.de

Having it in asm-generic/siginfo.h doesn't make any sense as it is in no way
architecture specific.  Move it to signal.h instead where several related
functions already reside.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-ia64@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: sparclinux@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20170603190102.28866-5-hch@lst.de

Having it in asm-generic/siginfo.h doesn't make any sense as it is in no way
architecture specific.  Move it to posix-timers.h instead.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-ia64@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: sparclinux@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20170603190102.28866-4-hch@lst.de

Since ia64 defines __ARCH_SI_PREAMBLE_SIZE it can just use the generic
copy_siginfo implementation, which is identical to the architecture
specific one.

With that support for HAVE_ARCH_COPY_SIGINFO can go away entirely.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-ia64@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: sparclinux@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20170603190102.28866-3-hch@lst.de

There is no need for the forward declaration of compat_siginfo provided
here.  We can't yet use the generic header as we need to pull in the
sparc-specific version of the uapi <asm/siginfo.h>, but this prepares
for removing the non-uapi <asm/siginfo.h> entirely.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: N"David S. Miller" <davem@davemloft.net>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-ia64@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/20170603190102.28866-2-hch@lst.de

Pull ACPI fixes from Rafael Wysocki:
 "These revert one more problematic commit related to the ACPI-based
  handling of laptop lids and make some unuseful error messages coming
  from ACPICA go away.

  Specifics:

   - Revert one more commit related to the ACPI-based handling of laptop
     lids that changed the default behavior on laptops that booted with
     closed lids and introduced a regression there (Benjamin Tissoires).

   - Add a missing acpi_put_table() to the code implementing the
     /sys/firmware/acpi/tables interface to prevent a counter in the
     ACPICA core from overflowing (Dan Williams).

   - Drop error messages printed by ACPICA on acpi_get_table() reference
     counting mismatches as they need not indicate real errors at this
     point (Lv Zheng)"

* tag 'acpi-4.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPICA: Tables: Fix regression introduced by a too early mechanism enabling
  Revert "ACPI / button: Change default behavior to lid_init_state=open"
  ACPI / sysfs: fix acpi_get_table() leak / acpi-sysfs denial of service

Pull power management fixes from Rafael Wysocki:
 "These fix two bugs in error code paths in the cpufreq core and in the
  kirkwood-cpufreq driver.

  Specifics:

   - Make cpufreq_register_driver() return an error if the ->init()
     calls fail for all CPUs to prevent non-functional drivers from
     hanging around for no reason (David Arcari).

   - Make kirkwood-cpufreq check the return value of
     clk_prepare_enable() (which may fail) as appropriate (Arvind
     Yadav)"

* tag 'pm-4.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: kirkwood-cpufreq:- Handle return value of clk_prepare_enable()
  cpufreq: cpufreq_register_driver() should return -ENODEV if init fails

Pull /dev/random bug fix from Ted Ts'o:
 "Fix a race on architectures with prioritized interrupts (such as m68k)
  which can causes crashes in drivers/char/random.c:get_reg()"

* tag 'random_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  fix race in drivers/char/random.c:get_reg()

Merge misc fixes from Andrew Morton:
 "15 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  scripts/gdb: make lx-dmesg command work (reliably)
  mm: consider memblock reservations for deferred memory initialization sizing
  mm/hugetlb: report -EHWPOISON not -EFAULT when FOLL_HWPOISON is specified
  mlock: fix mlock count can not decrease in race condition
  mm/migrate: fix refcount handling when !hugepage_migration_supported()
  dax: fix race between colliding PMD & PTE entries
  mm: avoid spurious 'bad pmd' warning messages
  mm/page_alloc.c: make sure OOM victim can try allocations with no watermarks once
  pcmcia: remove left-over %Z format
  slub/memcg: cure the brainless abuse of sysfs attributes
  initramfs: fix disabling of initramfs (and its compression)
  mm: clarify why we want kmalloc before falling backto vmallock
  frv: declare jiffies to be located in the .data section
  include/linux/gfp.h: fix ___GFP_NOLOCKDEP value
  ksm: prevent crash after write_protect_page fails

lx-dmesg needs access to the log_buf symbol from printk.c.
Unfortunately, the symbol log_buf also exists in BPF's verifier.c and
hence gdb can pick one or the other.  If it happens to pick BPF's
log_buf, lx-dmesg doesn't work:

  (gdb) lx-dmesg
  Python Exception <class 'gdb.MemoryError'> Cannot access memory at address 0x0:
  Error occurred in Python command: Cannot access memory at address 0x0
  (gdb) p log_buf
  $15 = 0x0

Luckily, GDB has a way to deal with this, see
  https://sourceware.org/gdb/onlinedocs/gdb/Symbols.html

  (gdb) info variables ^log_buf$
  All variables matching regular expression "^log_buf$":

  File <linux.git>/kernel/bpf/verifier.c:
  static char *log_buf;

  File <linux.git>/kernel/printk/printk.c:
  static char *log_buf;
  (gdb) p 'verifier.c'::log_buf
  $1 = 0x0
  (gdb) p 'printk.c'::log_buf
  $2 = 0x811a6aa0 <__log_buf> ""
  (gdb) p &log_buf
  $3 = (char **) 0x8120fe40 <log_buf>
  (gdb) p &'verifier.c'::log_buf
  $4 = (char **) 0x8120fe40 <log_buf>
  (gdb) p &'printk.c'::log_buf
  $5 = (char **) 0x8048b7d0 <log_buf>

By being explicit about the location of the symbol, we can make lx-dmesg
work again.  While at it, do the same for the other symbols we need from
printk.c

Link: http://lkml.kernel.org/r/20170526112222.3414-1-git@andred.netSigned-off-by: NAndré Draszik <git@andred.net>
Tested-by: NKieran Bingham <kieran@bingham.xyz>
Acked-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We have seen an early OOM killer invocation on ppc64 systems with
crashkernel=4096M:

	kthreadd invoked oom-killer: gfp_mask=0x16040c0(GFP_KERNEL|__GFP_COMP|__GFP_NOTRACK), nodemask=7, order=0, oom_score_adj=0
	kthreadd cpuset=/ mems_allowed=7
	CPU: 0 PID: 2 Comm: kthreadd Not tainted 4.4.68-1.gd7fe927-default #1
	Call Trace:
	  dump_stack+0xb0/0xf0 (unreliable)
	  dump_header+0xb0/0x258
	  out_of_memory+0x5f0/0x640
	  __alloc_pages_nodemask+0xa8c/0xc80
	  kmem_getpages+0x84/0x1a0
	  fallback_alloc+0x2a4/0x320
	  kmem_cache_alloc_node+0xc0/0x2e0
	  copy_process.isra.25+0x260/0x1b30
	  _do_fork+0x94/0x470
	  kernel_thread+0x48/0x60
	  kthreadd+0x264/0x330
	  ret_from_kernel_thread+0x5c/0xa4

	Mem-Info:
	active_anon:0 inactive_anon:0 isolated_anon:0
	 active_file:0 inactive_file:0 isolated_file:0
	 unevictable:0 dirty:0 writeback:0 unstable:0
	 slab_reclaimable:5 slab_unreclaimable:73
	 mapped:0 shmem:0 pagetables:0 bounce:0
	 free:0 free_pcp:0 free_cma:0
	Node 7 DMA free:0kB min:0kB low:0kB high:0kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:52428800kB managed:110016kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:320kB slab_unreclaimable:4672kB kernel_stack:1152kB pagetables:0kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes
	lowmem_reserve[]: 0 0 0 0
	Node 7 DMA: 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB 0*8192kB 0*16384kB = 0kB
	0 total pagecache pages
	0 pages in swap cache
	Swap cache stats: add 0, delete 0, find 0/0
	Free swap  = 0kB
	Total swap = 0kB
	819200 pages RAM
	0 pages HighMem/MovableOnly
	817481 pages reserved
	0 pages cma reserved
	0 pages hwpoisoned

the reason is that the managed memory is too low (only 110MB) while the
rest of the the 50GB is still waiting for the deferred intialization to
be done.  update_defer_init estimates the initial memoty to initialize
to 2GB at least but it doesn't consider any memory allocated in that
range.  In this particular case we've had

	Reserving 4096MB of memory at 128MB for crashkernel (System RAM: 51200MB)

so the low 2GB is mostly depleted.

Fix this by considering memblock allocations in the initial static
initialization estimation.  Move the max_initialise to
reset_deferred_meminit and implement a simple memblock_reserved_memory
helper which iterates all reserved blocks and sums the size of all that
start below the given address.  The cumulative size is than added on top
of the initial estimation.  This is still not ideal because
reset_deferred_meminit doesn't consider holes and so reservation might
be above the initial estimation whihch we ignore but let's make the
logic simpler until we really need to handle more complicated cases.

Fixes: 3a80a7fa ("mm: meminit: initialise a subset of struct pages if CONFIG_DEFERRED_STRUCT_PAGE_INIT is set")
Link: http://lkml.kernel.org/r/20170531104010.GI27783@dhcp22.suse.czSigned-off-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Tested-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org>	[4.2+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

KVM uses get_user_pages() to resolve its stage2 faults.  KVM sets the
FOLL_HWPOISON flag causing faultin_page() to return -EHWPOISON when it
finds a VM_FAULT_HWPOISON.  KVM handles these hwpoison pages as a
special case.  (check_user_page_hwpoison())

When huge pages are involved, this doesn't work so well.
get_user_pages() calls follow_hugetlb_page(), which stops early if it
receives VM_FAULT_HWPOISON from hugetlb_fault(), eventually returning
-EFAULT to the caller.  The step to map this to -EHWPOISON based on the
FOLL_ flags is missing.  The hwpoison special case is skipped, and
-EFAULT is returned to user-space, causing Qemu or kvmtool to exit.

Instead, move this VM_FAULT_ to errno mapping code into a header file
and use it from faultin_page() and follow_hugetlb_page().

With this, KVM works as expected.

This isn't a problem for arm64 today as we haven't enabled
MEMORY_FAILURE, but I can't see any reason this doesn't happen on x86
too, so I think this should be a fix.  This doesn't apply earlier than
stable's v4.11.1 due to all sorts of cleanup.

[james.morse@arm.com: add vm_fault_to_errno() call to faultin_page()]
suggested.
  Link: http://lkml.kernel.org/r/20170525171035.16359-1-james.morse@arm.com
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170524160900.28786-1-james.morse@arm.comSigned-off-by: NJames Morse <james.morse@arm.com>
Acked-by: NPunit Agrawal <punit.agrawal@arm.com>
Acked-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>	[4.11.1+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Kefeng reported that when running the follow test, the mlock count in
meminfo will increase permanently:

 [1] testcase
 linux:~ # cat test_mlockal
 grep Mlocked /proc/meminfo
  for j in `seq 0 10`
  do
 	for i in `seq 4 15`
 	do
 		./p_mlockall >> log &
 	done
 	sleep 0.2
 done
 # wait some time to let mlock counter decrease and 5s may not enough
 sleep 5
 grep Mlocked /proc/meminfo

 linux:~ # cat p_mlockall.c
 #include <sys/mman.h>
 #include <stdlib.h>
 #include <stdio.h>

 #define SPACE_LEN	4096

 int main(int argc, char ** argv)
 {
	 	int ret;
	 	void *adr = malloc(SPACE_LEN);
	 	if (!adr)
	 		return -1;

	 	ret = mlockall(MCL_CURRENT | MCL_FUTURE);
	 	printf("mlcokall ret = %d\n", ret);

	 	ret = munlockall();
	 	printf("munlcokall ret = %d\n", ret);

	 	free(adr);
	 	return 0;
	 }

In __munlock_pagevec() we should decrement NR_MLOCK for each page where
we clear the PageMlocked flag.  Commit 1ebb7cc6 ("mm: munlock: batch
NR_MLOCK zone state updates") has introduced a bug where we don't
decrement NR_MLOCK for pages where we clear the flag, but fail to
isolate them from the lru list (e.g.  when the pages are on some other
cpu's percpu pagevec).  Since PageMlocked stays cleared, the NR_MLOCK
accounting gets permanently disrupted by this.

Fix it by counting the number of page whose PageMlock flag is cleared.

Fixes: 1ebb7cc6 (" mm: munlock: batch NR_MLOCK zone state updates")
Link: http://lkml.kernel.org/r/1495678405-54569-1-git-send-email-xieyisheng1@huawei.comSigned-off-by: NYisheng Xie <xieyisheng1@huawei.com>
Reported-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Tested-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Joern Engel <joern@logfs.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michel Lespinasse <walken@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: zhongjiang <zhongjiang@huawei.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

On failing to migrate a page, soft_offline_huge_page() performs the
necessary update to the hugepage ref-count.

But when !hugepage_migration_supported() , unmap_and_move_hugepage()
also decrements the page ref-count for the hugepage.  The combined
behaviour leaves the ref-count in an inconsistent state.

This leads to soft lockups when running the overcommitted hugepage test
from mce-tests suite.

  Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
  soft offline: 0x83ed600: migration failed 1, type 1fffc00000008008 (uptodate|head)
  INFO: rcu_preempt detected stalls on CPUs/tasks:
   Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
    (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
    thugetlb_overco R  running task        0  2715   2685 0x00000008
    Call trace:
      dump_backtrace+0x0/0x268
      show_stack+0x24/0x30
      sched_show_task+0x134/0x180
      rcu_print_detail_task_stall_rnp+0x54/0x7c
      rcu_check_callbacks+0xa74/0xb08
      update_process_times+0x34/0x60
      tick_sched_handle.isra.7+0x38/0x70
      tick_sched_timer+0x4c/0x98
      __hrtimer_run_queues+0xc0/0x300
      hrtimer_interrupt+0xac/0x228
      arch_timer_handler_phys+0x3c/0x50
      handle_percpu_devid_irq+0x8c/0x290
      generic_handle_irq+0x34/0x50
      __handle_domain_irq+0x68/0xc0
      gic_handle_irq+0x5c/0xb0

Address this by changing the putback_active_hugepage() in
soft_offline_huge_page() to putback_movable_pages().

This only triggers on systems that enable memory failure handling
(ARCH_SUPPORTS_MEMORY_FAILURE) but not hugepage migration
(!ARCH_ENABLE_HUGEPAGE_MIGRATION).

I imagine this wasn't triggered as there aren't many systems running
this configuration.

[akpm@linux-foundation.org: remove dead comment, per Naoya]
Link: http://lkml.kernel.org/r/20170525135146.32011-1-punit.agrawal@arm.comReported-by: NManoj Iyer <manoj.iyer@canonical.com>
Tested-by: NManoj Iyer <manoj.iyer@canonical.com>
Suggested-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: NPunit Agrawal <punit.agrawal@arm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>	[3.14+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We currently have two related PMD vs PTE races in the DAX code.  These
can both be easily triggered by having two threads reading and writing
simultaneously to the same private mapping, with the key being that
private mapping reads can be handled with PMDs but private mapping
writes are always handled with PTEs so that we can COW.

Here is the first race:

  CPU 0					CPU 1

  (private mapping write)
  __handle_mm_fault()
    create_huge_pmd() - FALLBACK
    handle_pte_fault()
      passes check for pmd_devmap()

					(private mapping read)
					__handle_mm_fault()
					  create_huge_pmd()
					    dax_iomap_pmd_fault() inserts PMD

      dax_iomap_pte_fault() does a PTE fault, but we already have a DAX PMD
      			  installed in our page tables at this spot.

Here's the second race:

  CPU 0					CPU 1

  (private mapping read)
  __handle_mm_fault()
    passes check for pmd_none()
    create_huge_pmd()
      dax_iomap_pmd_fault() inserts PMD

  (private mapping write)
  __handle_mm_fault()
    create_huge_pmd() - FALLBACK
					(private mapping read)
					__handle_mm_fault()
					  passes check for pmd_none()
					  create_huge_pmd()

    handle_pte_fault()
      dax_iomap_pte_fault() inserts PTE
					    dax_iomap_pmd_fault() inserts PMD,
					       but we already have a PTE at
					       this spot.

The core of the issue is that while there is isolation between faults to
the same range in the DAX fault handlers via our DAX entry locking,
there is no isolation between faults in the code in mm/memory.c.  This
means for instance that this code in __handle_mm_fault() can run:

	if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
		ret = create_huge_pmd(&vmf);

But by the time we actually get to run the fault handler called by
create_huge_pmd(), the PMD is no longer pmd_none() because a racing PTE
fault has installed a normal PMD here as a parent.  This is the cause of
the 2nd race.  The first race is similar - there is the following check
in handle_pte_fault():

	} else {
		/* See comment in pte_alloc_one_map() */
		if (pmd_devmap(*vmf->pmd) || pmd_trans_unstable(vmf->pmd))
			return 0;

So if a pmd_devmap() PMD (a DAX PMD) has been installed at vmf->pmd, we
will bail and retry the fault.  This is correct, but there is nothing
preventing the PMD from being installed after this check but before we
actually get to the DAX PTE fault handlers.

In my testing these races result in the following types of errors:

  BUG: Bad rss-counter state mm:ffff8800a817d280 idx:1 val:1
  BUG: non-zero nr_ptes on freeing mm: 15

Fix this issue by having the DAX fault handlers verify that it is safe
to continue their fault after they have taken an entry lock to block
other racing faults.

[ross.zwisler@linux.intel.com: improve fix for colliding PMD & PTE entries]
  Link: http://lkml.kernel.org/r/20170526195932.32178-1-ross.zwisler@linux.intel.com
Link: http://lkml.kernel.org/r/20170522215749.23516-2-ross.zwisler@linux.intel.comSigned-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Reported-by: NPawel Lebioda <pawel.lebioda@intel.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Pawel Lebioda <pawel.lebioda@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Xiong Zhou <xzhou@redhat.com>
Cc: Eryu Guan <eguan@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When the pmd_devmap() checks were added by 5c7fb56e ("mm, dax:
dax-pmd vs thp-pmd vs hugetlbfs-pmd") to add better support for DAX huge
pages, they were all added to the end of if() statements after existing
pmd_trans_huge() checks.  So, things like:

  -       if (pmd_trans_huge(*pmd))
  +       if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd))

When further checks were added after pmd_trans_unstable() checks by
commit 7267ec00 ("mm: postpone page table allocation until we have
page to map") they were also added at the end of the conditional:

  +       if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd))

This ordering is fine for pmd_trans_huge(), but doesn't work for
pmd_trans_unstable().  This is because DAX huge pages trip the bad_pmd()
check inside of pmd_none_or_trans_huge_or_clear_bad() (called by
pmd_trans_unstable()), which prints out a warning and returns 1.  So, we
do end up doing the right thing, but only after spamming dmesg with
suspicious looking messages:

  mm/pgtable-generic.c:39: bad pmd ffff8808daa49b88(84000001006000a5)

Reorder these checks in a helper so that pmd_devmap() is checked first,
avoiding the error messages, and add a comment explaining why the
ordering is important.

Fixes: commit 7267ec00 ("mm: postpone page table allocation until we have page to map")
Link: http://lkml.kernel.org/r/20170522215749.23516-1-ross.zwisler@linux.intel.comSigned-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: Pawel Lebioda <pawel.lebioda@intel.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Xiong Zhou <xzhou@redhat.com>
Cc: Eryu Guan <eguan@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Roman Gushchin has reported that the OOM killer can trivially selects
next OOM victim when a thread doing memory allocation from page fault
path was selected as first OOM victim.

    allocate invoked oom-killer: gfp_mask=0x14280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=(null),  order=0, oom_score_adj=0
    allocate cpuset=/ mems_allowed=0
    CPU: 1 PID: 492 Comm: allocate Not tainted 4.12.0-rc1-mm1+ #181
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
    Call Trace:
     oom_kill_process+0x219/0x3e0
     out_of_memory+0x11d/0x480
     __alloc_pages_slowpath+0xc84/0xd40
     __alloc_pages_nodemask+0x245/0x260
     alloc_pages_vma+0xa2/0x270
     __handle_mm_fault+0xca9/0x10c0
     handle_mm_fault+0xf3/0x210
     __do_page_fault+0x240/0x4e0
     trace_do_page_fault+0x37/0xe0
     do_async_page_fault+0x19/0x70
     async_page_fault+0x28/0x30
    ...
    Out of memory: Kill process 492 (allocate) score 899 or sacrifice child
    Killed process 492 (allocate) total-vm:2052368kB, anon-rss:1894576kB, file-rss:4kB, shmem-rss:0kB
    allocate: page allocation failure: order:0, mode:0x14280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=(null)
    allocate cpuset=/ mems_allowed=0
    CPU: 1 PID: 492 Comm: allocate Not tainted 4.12.0-rc1-mm1+ #181
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
    Call Trace:
     __alloc_pages_slowpath+0xd32/0xd40
     __alloc_pages_nodemask+0x245/0x260
     alloc_pages_vma+0xa2/0x270
     __handle_mm_fault+0xca9/0x10c0
     handle_mm_fault+0xf3/0x210
     __do_page_fault+0x240/0x4e0
     trace_do_page_fault+0x37/0xe0
     do_async_page_fault+0x19/0x70
     async_page_fault+0x28/0x30
    ...
    oom_reaper: reaped process 492 (allocate), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
    ...
    allocate invoked oom-killer: gfp_mask=0x0(), nodemask=(null),  order=0, oom_score_adj=0
    allocate cpuset=/ mems_allowed=0
    CPU: 1 PID: 492 Comm: allocate Not tainted 4.12.0-rc1-mm1+ #181
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
    Call Trace:
     oom_kill_process+0x219/0x3e0
     out_of_memory+0x11d/0x480
     pagefault_out_of_memory+0x68/0x80
     mm_fault_error+0x8f/0x190
     ? handle_mm_fault+0xf3/0x210
     __do_page_fault+0x4b2/0x4e0
     trace_do_page_fault+0x37/0xe0
     do_async_page_fault+0x19/0x70
     async_page_fault+0x28/0x30
    ...
    Out of memory: Kill process 233 (firewalld) score 10 or sacrifice child
    Killed process 233 (firewalld) total-vm:246076kB, anon-rss:20956kB, file-rss:0kB, shmem-rss:0kB

There is a race window that the OOM reaper completes reclaiming the
first victim's memory while nothing but mutex_trylock() prevents the
first victim from calling out_of_memory() from pagefault_out_of_memory()
after memory allocation for page fault path failed due to being selected
as an OOM victim.

This is a side effect of commit 9a67f648 ("mm: consolidate
GFP_NOFAIL checks in the allocator slowpath") because that commit
silently changed the behavior from

    /* Avoid allocations with no watermarks from looping endlessly */

to

    /*
     * Give up allocations without trying memory reserves if selected
     * as an OOM victim
     */

in __alloc_pages_slowpath() by moving the location to check TIF_MEMDIE
flag.  I have noticed this change but I didn't post a patch because I
thought it is an acceptable change other than noise by warn_alloc()
because !__GFP_NOFAIL allocations are allowed to fail.  But we
overlooked that failing memory allocation from page fault path makes
difference due to the race window explained above.

While it might be possible to add a check to pagefault_out_of_memory()
that prevents the first victim from calling out_of_memory() or remove
out_of_memory() from pagefault_out_of_memory(), changing
pagefault_out_of_memory() does not suppress noise by warn_alloc() when
allocating thread was selected as an OOM victim.  There is little point
with printing similar backtraces and memory information from both
out_of_memory() and warn_alloc().

Instead, if we guarantee that current thread can try allocations with no
watermarks once when current thread looping inside
__alloc_pages_slowpath() was selected as an OOM victim, we can follow "who
can use memory reserves" rules and suppress noise by warn_alloc() and
prevent memory allocations from page fault path from calling
pagefault_out_of_memory().

If we take the comment literally, this patch would do

  -    if (test_thread_flag(TIF_MEMDIE))
  -        goto nopage;
  +    if (alloc_flags == ALLOC_NO_WATERMARKS || (gfp_mask & __GFP_NOMEMALLOC))
  +        goto nopage;

because gfp_pfmemalloc_allowed() returns false if __GFP_NOMEMALLOC is
given.  But if I recall correctly (I couldn't find the message), the
condition is meant to apply to only OOM victims despite the comment.
Therefore, this patch preserves TIF_MEMDIE check.

Fixes: 9a67f648 ("mm: consolidate GFP_NOFAIL checks in the allocator slowpath")
Link: http://lkml.kernel.org/r/201705192112.IAF69238.OQOHSJLFOFFMtV@I-love.SAKURA.ne.jpSigned-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: NRoman Gushchin <guro@fb.com>
Tested-by: NRoman Gushchin <guro@fb.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>	[4.11]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 5b5e0928 ("lib/vsprintf.c: remove %Z support") removed some
usages of format %Z but forgot "%.2Zx".  This makes clang 4.0 reports a
-Wformat-extra-args warning because it does not know about %Z.

Replace %Z with %z.

Link: http://lkml.kernel.org/r/20170520090946.22562-1-nicolas.iooss_linux@m4x.orgSigned-off-by: NNicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: Harald Welte <laforge@gnumonks.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: <stable@vger.kernel.org>	[4.11+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

memcg_propagate_slab_attrs() abuses the sysfs attribute file functions
to propagate settings from the root kmem_cache to a newly created
kmem_cache.  It does that with:

     attr->show(root, buf);
     attr->store(new, buf, strlen(bug);

Aside of being a lazy and absurd hackery this is broken because it does
not check the return value of the show() function.

Some of the show() functions return 0 w/o touching the buffer.  That
means in such a case the store function is called with the stale content
of the previous show().  That causes nonsense like invoking
kmem_cache_shrink() on a newly created kmem_cache.  In the worst case it
would cause handing in an uninitialized buffer.

This should be rewritten proper by adding a propagate() callback to
those slub_attributes which must be propagated and avoid that insane
conversion to and from ASCII, but that's too large for a hot fix.

Check at least the return value of the show() function, so calling
store() with stale content is prevented.

Steven said:
 "It can cause a deadlock with get_online_cpus() that has been uncovered
  by recent cpu hotplug and lockdep changes that Thomas and Peter have
  been doing.

     Possible unsafe locking scenario:

           CPU0                    CPU1
           ----                    ----
      lock(cpu_hotplug.lock);
                                   lock(slab_mutex);
                                   lock(cpu_hotplug.lock);
      lock(slab_mutex);

     *** DEADLOCK ***"

Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1705201244540.2255@nanosSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
Reported-by: NSteven Rostedt <rostedt@goodmis.org>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit db2aa7fd ("initramfs: allow again choice of the embedded
initram compression algorithm") introduced the possibility to select the
initramfs compression algorithm from Kconfig and while this is a nice
feature it broke the use case described below.

Here is what my build system does:

 - kernel is initially configured not to have an initramfs included

 - build the user space root file system

 - re-configure the kernel to have an initramfs included
   (CONFIG_INITRAMFS_SOURCE="/path/to/romfs") and set relevant
   CONFIG_INITRAMFS options, in my case, no compression option
   (CONFIG_INITRAMFS_COMPRESSION_NONE)

 - kernel is re-built with these options -> kernel+initramfs image is
   copied

 - kernel is re-built again without these options -> kernel image is
   copied

Building a kernel without an initramfs means setting this option:

  CONFIG_INITRAMFS_SOURCE="" (and this one only)

whereas building a kernel with an initramfs means setting these options:

  CONFIG_INITRAMFS_SOURCE="/home/fainelli/work/uclinux-rootfs/romfs /home/fainelli/work/uclinux-rootfs/misc/initramfs.dev"
  CONFIG_INITRAMFS_ROOT_UID=1000
  CONFIG_INITRAMFS_ROOT_GID=1000
  CONFIG_INITRAMFS_COMPRESSION_NONE=y
  CONFIG_INITRAMFS_COMPRESSION=""

Commit db2aa7fd ("initramfs: allow again choice of the embedded
initram compression algorithm") is problematic because
CONFIG_INITRAMFS_COMPRESSION which is used to determine the
initramfs_data.cpio extension/compression is a string, and due to how
Kconfig works it will evaluate in order, how to assign it.

Setting CONFIG_INITRAMFS_COMPRESSION_NONE with CONFIG_INITRAMFS_SOURCE=""
cannot possibly work (because of the depends on INITRAMFS_SOURCE!=""
imposed on CONFIG_INITRAMFS_COMPRESSION ) yet we still get
CONFIG_INITRAMFS_COMPRESSION assigned to ".gz" because CONFIG_RD_GZIP=y
is set in my kernel, even when there is no initramfs being built.

So we basically end-up generating two initramfs_data.cpio* files, one
without extension, and one with .gz.  This causes usr/Makefile to track
usr/initramfs_data.cpio.gz, and not usr/initramfs_data.cpio anymore,
that is also largely problematic after 9e3596b0 ("kbuild:
initramfs cleanup, set target from Kconfig") because we used to track
all possible initramfs_data files in the $(targets) variable before that
commit.

The end result is that the kernel with an initramfs clearly does not
contain what we expect it to, it has a stale initramfs_data.cpio file
built into it, and we keep re-generating an initramfs_data.cpio.gz file
which is not the one that we want to include in the kernel image proper.

The fix consists in hiding CONFIG_INITRAMFS_COMPRESSION when
CONFIG_INITRAMFS_SOURCE="".  This puts us back in a state to the
pre-4.10 behavior where we can properly disable and re-enable initramfs
within the same kernel .config file, and be in control of what
CONFIG_INITRAMFS_COMPRESSION is set to.

Fixes: db2aa7fd ("initramfs: allow again choice of the embedded initram compression algorithm")
Fixes: 9e3596b0 ("kbuild: initramfs cleanup, set target from Kconfig")
Link: http://lkml.kernel.org/r/20170521033337.6197-1-f.fainelli@gmail.comSigned-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Acked-by: NNicholas Piggin <npiggin@gmail.com>
Cc: P J P <ppandit@redhat.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

While converting drm_[cm]alloc* helpers to kvmalloc* variants Chris
Wilson has wondered why we want to try kmalloc before vmalloc fallback
even for larger allocations requests.  Let's clarify that one larger
physically contiguous block is less likely to fragment memory than many
scattered pages which can prevent more large blocks from being created.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170517080932.21423-1-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Suggested-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 7c30f352 ("jiffies.h: declare jiffies and jiffies_64 with
____cacheline_aligned_in_smp") removed a section specification from the
jiffies declaration that caused conflicts on some platforms.

Unfortunately this change broke the build for frv:

  kernel/built-in.o: In function `__do_softirq': (.text+0x6460): relocation truncated to fit: R_FRV_GPREL12 against symbol
      `jiffies' defined in *ABS* section in .tmp_vmlinux1
  kernel/built-in.o: In function `__do_softirq': (.text+0x6574): relocation truncated to fit: R_FRV_GPREL12 against symbol
      `jiffies' defined in *ABS* section in .tmp_vmlinux1
  kernel/built-in.o: In function `pwq_activate_delayed_work': workqueue.c:(.text+0x15b9c): relocation truncated to fit: R_FRV_GPREL12 against
      symbol `jiffies' defined in *ABS* section in .tmp_vmlinux1
  ...

Add __jiffy_arch_data to the declaration of jiffies and use it on frv to
include the section specification.  For all other platforms
__jiffy_arch_data (currently) has no effect.

Fixes: 7c30f352 ("jiffies.h: declare jiffies and jiffies_64 with ____cacheline_aligned_in_smp")
Link: http://lkml.kernel.org/r/20170516221333.177280-1-mka@chromium.orgSigned-off-by: NMatthias Kaehlcke <mka@chromium.org>
Reported-by: NGuenter Roeck <linux@roeck-us.net>
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Reviewed-by: NDavid Howells <dhowells@redhat.com>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Igor Stoppa has noticed that __GFP_NOLOCKDEP can use a lower bit.  At
the time commit 7e784422 ("lockdep: allow to disable reclaim lockup
detection") was written we still had __GFP_OTHER_NODE but I have removed
it in commit 41b6167e ("mm: get rid of __GFP_OTHER_NODE") and forgot
to lower the bit value.

The current value is outside of __GFP_BITS_SHIFT so it cannot be used
actually.

Fixes: 7e784422 ("lockdep: allow to disable reclaim lockup detection")
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Reported-by: NIgor Stoppa <igor.stoppa@nokia.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

"err" needs to be left set to -EFAULT if split_huge_page succeeds.
Otherwise if "err" gets clobbered with zero and write_protect_page
fails, try_to_merge_one_page() will succeed instead of returning -EFAULT
and then try_to_merge_with_ksm_page() will continue thinking kpage is a
PageKsm when in fact it's still an anonymous page.  Eventually it'll
crash in page_add_anon_rmap.

This has been reproduced on Fedora25 kernel but I can reproduce with
upstream too.

The bug was introduced in commit f765f540 ("ksm: prepare to new THP
semantics") introduced in v4.5.

    page:fffff67546ce1cc0 count:4 mapcount:2 mapping:ffffa094551e36e1 index:0x7f0f46673
    flags: 0x2ffffc0004007c(referenced|uptodate|dirty|lru|active|swapbacked)
    page dumped because: VM_BUG_ON_PAGE(!PageLocked(page))
    page->mem_cgroup:ffffa09674bf0000
    ------------[ cut here ]------------
    kernel BUG at mm/rmap.c:1222!
    CPU: 1 PID: 76 Comm: ksmd Not tainted 4.9.3-200.fc25.x86_64 #1
    RIP: do_page_add_anon_rmap+0x1c4/0x240
    Call Trace:
      page_add_anon_rmap+0x18/0x20
      try_to_merge_with_ksm_page+0x50b/0x780
      ksm_scan_thread+0x1211/0x1410
      ? prepare_to_wait_event+0x100/0x100
      ? try_to_merge_with_ksm_page+0x780/0x780
      kthread+0xd9/0xf0
      ? kthread_park+0x60/0x60
      ret_from_fork+0x25/0x30

Fixes: f765f540 ("ksm: prepare to new THP semantics")
Link: http://lkml.kernel.org/r/20170513131040.21732-1-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reported-by: NFederico Simoncelli <fsimonce@redhat.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* acpi-button:
  Revert "ACPI / button: Change default behavior to lid_init_state=open"

* acpica:
  ACPICA: Tables: Fix regression introduced by a too early mechanism enabling

* acpi-sysfs:
  ACPI / sysfs: fix acpi_get_table() leak / acpi-sysfs denial of service

* pm-cpufreq:
  cpufreq: kirkwood-cpufreq:- Handle return value of clk_prepare_enable()
  cpufreq: cpufreq_register_driver() should return -ENODEV if init fails

Pull XFS fix from Darrick Wong:
 "I've one more bugfix for you for 4.12-rc4: Fix an unmount hang due to
  a race in io buffer accounting"

* tag 'xfs-4.12-fixes-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: use ->b_state to fix buffer I/O accounting release race

Pull arm64 fixes from Catalin Marinas:
 "ACPI-related fixes for arm64:

   - GICC MADT entry validity check fix

   - Skip IRQ registration with pmu=off in an ACPI guest

   - struct acpi_pci_root_ops freeing on error path"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  ARM64/ACPI: Fix BAD_MADT_GICC_ENTRY() macro implementation
  drivers/perf: arm_pmu_acpi: avoid perf IRQ init when guest PMU is off
  ARM64: PCI: Fix struct acpi_pci_root_ops allocation failure path

Pull ceph fix from Ilya Dryomov:
 "A small fix for rbd FALLOC_FL_ZERO_RANGE/PUNCH_HOLE handling breakage
  introduced in -rc1"

* tag 'ceph-for-4.12-rc4' of git://github.com/ceph/ceph-client:
  rbd: implement REQ_OP_WRITE_ZEROES

Merge tag 'for-4.12/dm-fixes-3' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fixes from Mike Snitzer:

 - a DM verity fix for a mode when no salt is used

 - a fix to DM to account for the possibility that PREFLUSH or FUA are
   used without the SYNC flag if the underlying storage doesn't have a
   volatile write-cache

 - a DM ioctl memory allocation flag fix to use __GFP_HIGH to allow
   emergency forward progress (by using memory reserves as last resort)

 - a small DM integrity cleanup to use kvmalloc() instead of duplicating
   the same

* tag 'for-4.12/dm-fixes-3' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm: make flush bios explicitly sync
  dm ioctl: restore __GFP_HIGH in copy_params()
  dm integrity: use kvmalloc() instead of dm_integrity_kvmalloc()
  dm verity: fix no salt use case

Pull MD fixes from Shaohua Li:
 "Several patches for MD. One notable is making flush bios sync, others
  fix small issues"

* tag 'md/4.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md:
  md: Make flush bios explicitely sync
  md: report sector of stripes with check mismatches
  md: uuid debug statement now in processor byte order.
  md-cluster: fix potential lock issue in add_new_disk