misc: uidstat: avoid create_stat() race and blockage.

* create_stat() race would lead to:
  [   58.132324] proc_dir_entry 'uid_stat/10061' already registered

* blocking kmalloc reported by sbranden
 tcp_read_sock()
  uid_stat_tcp_rcv()
    create_stat()
      kmalloc(GFP_KERNEL)

Signed-off-by: JP Abgrall <jpa@google.com>
Fix problems of the squashed update to 3.4.48 kernel version by reverting "mm/pagewalk.c: walk_page_range should avoid VM_PFNMAP areas"

This reverts commit:
https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=c8a097fd8d73584d7c1577e0aee41c2a177394f7

The changes made by this commit caused kernel panics while performing
memory operations with subsequent hangs, reboots or shutdowns.
Squashed update of BFQ-v6 to BFQ-v6r1

- Fix use-after-free of queues in __bfq_bfqq_expire(). It may happen that
  a call to bfq_del_bfqq_busy() puts the last reference taken on a queue
  and frees it. Subsequent accesses to that same queue would result in a
  use-after-free. Make sure that a queue that has just been deleted from
  busy is no more touched.
- Use the uninitialized_var() macro when needed. It may happen that a
  variable is initialized in a function that is called by the function
  that defined it. Use the uninitialized_var() macro in these cases.
cpufreq: interactive: handle errors from cpufreq_frequency_table_target

Add checks for error return from cpufreq_frequency_table_target, and be
less noisy on the existing call with an error check.  CPU hotplug and
system shutdown may cause this call to return -EINVAL.

Bug: 8613560
Change-Id: Id78d8829920462c0db1c7e14e717d91740d6cb44
Signed-off-by: Todd Poynor <toddpoynor@google.com>
cpufreq: interactive: reduce chance of zero time delta on load eval

Reschedule load sampling timer after timestamp of sample start taken,
hold spinlock across entire sequence to avoid preemption.  Avoid the
WARN for zero time delta in the load sampling timer function.

Change-Id: Idc10a756f09141decb6df92669521a1ebf0dbc10
Signed-off-by: Todd Poynor <toddpoynor@google.com>
cpufreq: interactive: avoid underflow on active time calculation

Check for idle time delta less than elapsed time delta, avoid
underflow computing active time.

Change-Id: I3e4c6ef1ad794eec49ed379c0c50fa727fd6ad28
Signed-off-by: Minsung Kim <ms925.kim@samsung.com>