Commits · d66ba15bde22703b3c0cec6782519cb0765a6777 · Kirill Smelkov / linux

08 Oct, 2016 40 commits

memory-hotplug: fix store_mem_state() return value · d66ba15b

Reza Arbab authored Oct 07, 2016

If store_mem_state() is called to online memory which is already online,
it will return 1, the value it got from device_online().

This is wrong because store_mem_state() is a device_attribute .store
function.  Thus a non-negative return value represents input bytes read.

Set the return value to -EINVAL in this case.

Link: http://lkml.kernel.org/r/1472743777-24266-1-git-send-email-arbab@linux.vnet.ibm.comSigned-off-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Chen Yucong <slaoub@gmail.com>
Cc: Andrew Banman <abanman@sgi.com>
Cc: Seth Jennings <sjenning@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

d66ba15b

mm/memcontrol.c: make the walk_page_range() limit obvious · 0247f3f4

James Morse authored Oct 07, 2016

mem_cgroup_count_precharge() and mem_cgroup_move_charge() both call
walk_page_range() on the range 0 to ~0UL, neither provide a pte_hole
callback, which causes the current implementation to skip non-vma
regions.  This is all fine but follow up changes would like to make
walk_page_range more generic so it is better to be explicit about which
range to traverse so let's use highest_vm_end to explicitly traverse
only user mmaped memory.

[mhocko@kernel.org: rewrote changelog]
Link: http://lkml.kernel.org/r/1472655897-22532-1-git-send-email-james.morse@arm.comSigned-off-by: James Morse <james.morse@arm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

0247f3f4

thp: reduce usage of huge zero page's atomic counter · 6fcb52a5

Aaron Lu authored Oct 07, 2016

The global zero page is used to satisfy an anonymous read fault.  If
THP(Transparent HugePage) is enabled then the global huge zero page is
used.  The global huge zero page uses an atomic counter for reference
counting and is allocated/freed dynamically according to its counter
value.

CPU time spent on that counter will greatly increase if there are a lot
of processes doing anonymous read faults.  This patch proposes a way to
reduce the access to the global counter so that the CPU load can be
reduced accordingly.

To do this, a new flag of the mm_struct is introduced:
MMF_USED_HUGE_ZERO_PAGE.  With this flag, the process only need to touch
the global counter in two cases:

 1 The first time it uses the global huge zero page;
 2 The time when mm_user of its mm_struct reaches zero.

Note that right now, the huge zero page is eligible to be freed as soon
as its last use goes away.  With this patch, the page will not be
eligible to be freed until the exit of the last process from which it
was ever used.

And with the use of mm_user, the kthread is not eligible to use huge
zero page either.  Since no kthread is using huge zero page today, there
is no difference after applying this patch.  But if that is not desired,
I can change it to when mm_count reaches zero.

Case used for test on Haswell EP:

  usemem -n 72 --readonly -j 0x200000 100G

Which spawns 72 processes and each will mmap 100G anonymous space and
then do read only access to that space sequentially with a step of 2MB.

  CPU cycles from perf report for base commit:
      54.03%  usemem   [kernel.kallsyms]   [k] get_huge_zero_page
  CPU cycles from perf report for this commit:
       0.11%  usemem   [kernel.kallsyms]   [k] mm_get_huge_zero_page

Performance(throughput) of the workload for base commit: 1784430792
Performance(throughput) of the workload for this commit: 4726928591
164% increase.

Runtime of the workload for base commit: 707592 us
Runtime of the workload for this commit: 303970 us
50% drop.

Link: http://lkml.kernel.org/r/fe51a88f-446a-4622-1363-ad1282d71385@intel.comSigned-off-by: Aaron Lu <aaron.lu@intel.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

6fcb52a5

fs/proc/task_mmu.c: make the task_mmu walk_page_range() limit in clear_refs_write() obvious · 0f30206b

James Morse authored Oct 07, 2016

Trying to walk all of virtual memory requires architecture specific
knowledge.  On x86_64, addresses must be sign extended from bit 48,
whereas on arm64 the top VA_BITS of address space have their own set of
page tables.

clear_refs_write() calls walk_page_range() on the range 0 to ~0UL, it
provides a test_walk() callback that only expects to be walking over
VMAs.  Currently walk_pmd_range() will skip memory regions that don't
have a VMA, reporting them as a hole.

As this call only expects to walk user address space, make it walk 0 to
'highest_vm_end'.

Link: http://lkml.kernel.org/r/1472655792-22439-1-git-send-email-james.morse@arm.comSigned-off-by: James Morse <james.morse@arm.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

0f30206b

cpu: fix node state for whether it contains CPU · 03e86dba

Tim Chen authored Oct 07, 2016

In current kernel code, we only call node_set_state(cpu_to_node(cpu),
N_CPU) when a cpu is hot plugged.  But we do not set the node state for
N_CPU when the cpus are brought online during boot.

So this could lead to failure when we check to see if a node contains
cpu with node_state(node_id, N_CPU).

One use case is in the node_reclaime function:

        /*
         * Only run node reclaim on the local node or on nodes that do
         * not
         * have associated processors. This will favor the local
         * processor
         * over remote processors and spread off node memory allocations
         * as wide as possible.
         */
        if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id !=
                numa_node_id())
                return NODE_RECLAIM_NOSCAN;

I instrumented the kernel to call this function after boot and it always
returns 0 on a x86 desktop machine until I apply the attached patch.

   int num_cpu_node(void)
   {
       int i, nr_cpu_nodes = 0;

       for_each_node(i) {
               if (node_state(i, N_CPU))
                       ++ nr_cpu_nodes;
       }

       return nr_cpu_nodes;
   }

Fix this by checking each node for online CPU when we initialize
vmstat that's responsible for maintaining node state.

Link: http://lkml.kernel.org/r/20160829175922.GA21775@linux.intel.comSigned-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: <Huang@linux.intel.com>
Cc: Ying <ying.huang@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

03e86dba

ext2/4, xfs: call thp_get_unmapped_area() for pmd mappings · dbe6ec81

Toshi Kani authored Oct 07, 2016

To support DAX pmd mappings with unmodified applications, filesystems
need to align an mmap address by the pmd size.

Call thp_get_unmapped_area() from f_op->get_unmapped_area.

Note, there is no change in behavior for a non-DAX file.

Link: http://lkml.kernel.org/r/1472497881-9323-3-git-send-email-toshi.kani@hpe.comSigned-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

dbe6ec81

thp, dax: add thp_get_unmapped_area for pmd mappings · 74d2fad1

Toshi Kani authored Oct 07, 2016

When CONFIG_FS_DAX_PMD is set, DAX supports mmap() using pmd page size.
This feature relies on both mmap virtual address and FS block (i.e.
physical address) to be aligned by the pmd page size.  Users can use
mkfs options to specify FS to align block allocations.  However,
aligning mmap address requires code changes to existing applications for
providing a pmd-aligned address to mmap().

For instance, fio with "ioengine=mmap" performs I/Os with mmap() [1].
It calls mmap() with a NULL address, which needs to be changed to
provide a pmd-aligned address for testing with DAX pmd mappings.
Changing all applications that call mmap() with NULL is undesirable.

Add thp_get_unmapped_area(), which can be called by filesystem's
get_unmapped_area to align an mmap address by the pmd size for a DAX
file.  It calls the default handler, mm->get_unmapped_area(), to find a
range and then aligns it for a DAX file.

The patch is based on Matthew Wilcox's change that allows adding support
of the pud page size easily.

[1]: https://github.com/axboe/fio/blob/master/engines/mmap.c
Link: http://lkml.kernel.org/r/1472497881-9323-2-git-send-email-toshi.kani@hpe.comSigned-off-by: Toshi Kani <toshi.kani@hpe.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>