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Commit aefbef10 authored by Linus Torvalds's avatar Linus Torvalds
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Merge branch 'akpm' (patches from Andrew) 

Merge first patchbomb from Andrew Morton:

 - a few misc things

 - ocfs2 udpates

 - kernel/watchdog.c feature work (took ages to get right)

 - most of MM.  A few tricky bits are held up and probably won't make 4.2.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (91 commits)
  mm: kmemleak_alloc_percpu() should follow the gfp from per_alloc()
  mm, thp: respect MPOL_PREFERRED policy with non-local node
  tmpfs: truncate prealloc blocks past i_size
  mm/memory hotplug: print the last vmemmap region at the end of hot add memory
  mm/mmap.c: optimization of do_mmap_pgoff function
  mm: kmemleak: optimise kmemleak_lock acquiring during kmemleak_scan
  mm: kmemleak: avoid deadlock on the kmemleak object insertion error path
  mm: kmemleak: do not acquire scan_mutex in kmemleak_do_cleanup()
  mm: kmemleak: fix delete_object_*() race when called on the same memory block
  mm: kmemleak: allow safe memory scanning during kmemleak disabling
  memcg: convert mem_cgroup->under_oom from atomic_t to int
  memcg: remove unused mem_cgroup->oom_wakeups
  frontswap: allow multiple backends
  x86, mirror: x86 enabling - find mirrored memory ranges
  mm/memblock: allocate boot time data structures from mirrored memory
  mm/memblock: add extra "flags" to memblock to allow selection of memory based on attribute
  mm: do not ignore mapping_gfp_mask in page cache allocation paths
  mm/cma.c: fix typos in comments
  mm/oom_kill.c: print points as unsigned int
  mm/hugetlb: handle races in alloc_huge_page and hugetlb_reserve_pages
  ...
parents 266da6f1 8a8c35fa

Documentation/lockup-watchdogs.txt

+18 −0
Original line number Diff line number Diff line
@@ -61,3 +61,21 @@ As explained above, a kernel knob is provided that allows 
administrators to configure the period of the hrtimer and the perf

event. The right value for a particular environment is a trade-off

between fast response to lockups and detection overhead.



By default, the watchdog runs on all online cores.  However, on a

kernel configured with NO_HZ_FULL, by default the watchdog runs only

on the housekeeping cores, not the cores specified in the "nohz_full"

boot argument.  If we allowed the watchdog to run by default on

the "nohz_full" cores, we would have to run timer ticks to activate

the scheduler, which would prevent the "nohz_full" functionality

from protecting the user code on those cores from the kernel.

Of course, disabling it by default on the nohz_full cores means that

when those cores do enter the kernel, by default we will not be

able to detect if they lock up.  However, allowing the watchdog

to continue to run on the housekeeping (non-tickless) cores means

that we will continue to detect lockups properly on those cores.



In either case, the set of cores excluded from running the watchdog

may be adjusted via the kernel.watchdog_cpumask sysctl.  For

nohz_full cores, this may be useful for debugging a case where the

kernel seems to be hanging on the nohz_full cores.

Documentation/sysctl/kernel.txt

+21 −0
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@@ -923,6 +923,27 @@ and nmi_watchdog. 


==============================================================



watchdog_cpumask:



This value can be used to control on which cpus the watchdog may run.

The default cpumask is all possible cores, but if NO_HZ_FULL is

enabled in the kernel config, and cores are specified with the

nohz_full= boot argument, those cores are excluded by default.

Offline cores can be included in this mask, and if the core is later

brought online, the watchdog will be started based on the mask value.



Typically this value would only be touched in the nohz_full case

to re-enable cores that by default were not running the watchdog,

if a kernel lockup was suspected on those cores.



The argument value is the standard cpulist format for cpumasks,

so for example to enable the watchdog on cores 0, 2, 3, and 4 you

might say:



  echo 0,2-4 > /proc/sys/kernel/watchdog_cpumask



==============================================================



watchdog_thresh:



This value can be used to control the frequency of hrtimer and NMI

Documentation/vm/unevictable-lru.txt

+7 −1
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@@ -467,7 +467,13 @@ mmap(MAP_LOCKED) SYSTEM CALL HANDLING 


In addition the mlock()/mlockall() system calls, an application can request

that a region of memory be mlocked supplying the MAP_LOCKED flag to the mmap()

call.  Furthermore, any mmap() call or brk() call that expands the heap by a

call. There is one important and subtle difference here, though. mmap() + mlock()

will fail if the range cannot be faulted in (e.g. because mm_populate fails)

and returns with ENOMEM while mmap(MAP_LOCKED) will not fail. The mmaped

area will still have properties of the locked area - aka. pages will not get

swapped out - but major page faults to fault memory in might still happen.



Furthermore, any mmap() call or brk() call that expands the heap by a

task that has previously called mlockall() with the MCL_FUTURE flag will result

in the newly mapped memory being mlocked.  Before the unevictable/mlock

changes, the kernel simply called make_pages_present() to allocate pages and

arch/alpha/include/asm/mm-arch-hooks.h

0 → 100644
+15 −0
Original line number Diff line number Diff line 
/*

 * Architecture specific mm hooks

 *

 * Copyright (C) 2015, IBM Corporation

 * Author: Laurent Dufour <ldufour@linux.vnet.ibm.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */



#ifndef _ASM_ALPHA_MM_ARCH_HOOKS_H

#define _ASM_ALPHA_MM_ARCH_HOOKS_H



#endif /* _ASM_ALPHA_MM_ARCH_HOOKS_H */

arch/arc/include/asm/mm-arch-hooks.h

0 → 100644
+15 −0
Original line number Diff line number Diff line 
/*

 * Architecture specific mm hooks

 *

 * Copyright (C) 2015, IBM Corporation

 * Author: Laurent Dufour <ldufour@linux.vnet.ibm.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */



#ifndef _ASM_ARC_MM_ARCH_HOOKS_H

#define _ASM_ARC_MM_ARCH_HOOKS_H



#endif /* _ASM_ARC_MM_ARCH_HOOKS_H */