For consistency, it worth converting all page_check_address() to
page_vma_mapped_walk(), so we could drop the former.

PMD handling here is future-proofing, we don't have users yet.  ext4
with huge pages will be the first.

Link: http://lkml.kernel.org/r/20170129173858.45174-7-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Current rmap code can miss a VMA that maps PTE-mapped THP if the first
suppage of the THP was unmapped from the VMA.

We need to walk rmap for the whole range of offsets that THP covers, not
only the first one.

vma_address() also need to be corrected to check the range instead of
the first subpage.

Link: http://lkml.kernel.org/r/20170129173858.45174-6-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

For PTE-mapped THP page_check_address_transhuge() is not adequate: it
cannot find all relevant PTEs, only the first one.i

Let's switch it to page_vma_mapped_walk().

I don't think it's subject for stable@: it's not fatal.

Link: http://lkml.kernel.org/r/20170129173858.45174-5-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

For PTE-mapped THP page_check_address_transhuge() is not adequate: it
cannot find all relevant PTEs, only the first one.  It means we can miss
some references of the page and it can result in suboptimal decisions by
vmscan.

Let's switch it to page_vma_mapped_walk().

I don't think it's subject for stable@: it's not fatal.  The only side
effect is that THP can be swapped out when it shouldn't.

Link: http://lkml.kernel.org/r/20170129173858.45174-4-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Introduce a new interface to check if a page is mapped into a vma.  It
aims to address shortcomings of page_check_address{,_transhuge}.

Existing interface is not able to handle PTE-mapped THPs: it only finds
the first PTE.  The rest lefted unnoticed.

page_vma_mapped_walk() iterates over all possible mapping of the page in
the vma.

Link: http://lkml.kernel.org/r/20170129173858.45174-3-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "Fix few rmap-related THP bugs", v3.

The patchset fixes handing PTE-mapped THPs in page_referenced() and
page_idle_clear_pte_refs().

To achieve that I've intrdocued new helper -- page_vma_mapped_walk() --
which replaces all page_check_address{,_transhuge}() and covers all THP
cases.

Patchset overview:
  - First patch fixes one uprobe bug (unrelated to the rest of the
    patchset, just spotted it at the same time);

  - Patches 2-5 fix handling PTE-mapped THPs in page_referenced(),
    page_idle_clear_pte_refs() and rmap core;

  - Patches 6-12 convert all page_check_address{,_transhuge}() users
    (plus remove_migration_pte()) to page_vma_mapped_walk() and drop
    unused helpers.

I think the fixes are not critical enough for stable@ as they don't lead
to crashes or hangs, only suboptimal behaviour.

This patch (of 12):

For THPs page_check_address() always fails.  It leads to endless loop in
uprobe_write_opcode().

Testcase with huge-tmpfs (uprobes cannot probe anonymous memory).

	mount -t debugfs none /sys/kernel/debug
	mount -t tmpfs -o huge=always none /mnt
	gcc -Wall -O2 -o /mnt/test -x c - <<EOF
	int main(void)
	{
		return 0;
	}
	/* Padding to map the code segment with huge pmd */
	asm (".zero 2097152");
	EOF
	echo 'p /mnt/test:0' > /sys/kernel/debug/tracing/uprobe_events
	echo 1 > /sys/kernel/debug/tracing/events/uprobes/enable
	/mnt/test

Let's split THPs before trying to replace.

Link: http://lkml.kernel.org/r/20170129173858.45174-2-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We had considered all of the non-lru pages as unmovable before commit
bda807d4

 ("mm: migrate: support non-lru movable page migration").
But now some of non-lru pages like zsmalloc, virtio-balloon pages also
become movable.  So we can offline such blocks by using non-lru page
migration.

This patch straightforwardly adds non-lru migration code, which means
adding non-lru related code to the functions which scan over pfn and
collect pages to be migrated and isolate them before migration.

Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Yisheng Xie <xieyisheng1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Extend soft offlining framework to support non-lru page, which already
support migration after commit bda807d4

 ("mm: migrate: support
non-lru movable page migration")

When memory corrected errors occur on a non-lru movable page, we can
choose to stop using it by migrating data onto another page and disable
the original (maybe half-broken) one.

Link: http://lkml.kernel.org/r/1485867981-16037-4-git-send-email-ysxie@foxmail.com
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Suggested-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Define isolate_movable_page as a static inline function when
CONFIG_MIGRATION is not enable.  It should return -EBUSY here which
means failed to isolate movable pages.

This patch do not have any functional change but prepare for later
patch.

Link: http://lkml.kernel.org/r/1485867981-16037-3-git-send-email-ysxie@foxmail.com
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "HWPOISON: soft offlining for non-lru movable page", v6.

After Minchan's commit bda807d4

 ("mm: migrate: support non-lru
movable page migration"), some type of non-lru page like zsmalloc and
virtio-balloon page also support migration.

Therefore, we can:

1) soft offlining no-lru movable pages, which means when memory
   corrected errors occur on a non-lru movable page, we can stop to use
   it by migrating data onto another page and disable the original
   (maybe half-broken) one.

2) enable memory hotplug for non-lru movable pages, i.e. we may offline
   blocks, which include such pages, by using non-lru page migration.

This patchset is heavily dependent on non-lru movable page migration.

This patch (of 4):

Change the return type of isolate_movable_page() from bool to int.  It
will return 0 when isolate movable page successfully, and return -EBUSY
when it isolates failed.

There is no functional change within this patch but prepare for later
patch.

[xieyisheng1@huawei.com: v6]
  Link: http://lkml.kernel.org/r/1486108770-630-2-git-send-email-xieyisheng1@huawei.com
Link: http://lkml.kernel.org/r/1485867981-16037-2-git-send-email-ysxie@foxmail.com
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

With both coming and already present locking optimizations, introducing
kref to reference-count z3fold objects is the right thing to do.
Moreover, it makes buddied list no longer necessary, and allows for a
simpler handling of headless pages.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170131214650.8ea78033d91ded233f552bc0@gmail.com
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Reviewed-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Most of z3fold operations are in-page, such as modifying z3fold page
header or moving z3fold objects within a page.  Taking per-pool spinlock
to protect per-page objects is therefore suboptimal, and the idea of
having a per-page spinlock (or rwlock) has been around for some time.

This patch implements spinlock-based per-page locking mechanism which is
lightweight enough to normally fit ok into the z3fold header.

Link: http://lkml.kernel.org/r/20170131214438.433e0a5fda908337b63206d3@gmail.com
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Reviewed-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

z3fold_compact_page() currently only handles the situation when there's
a single middle chunk within the z3fold page.  However it may be worth
it to move middle chunk closer to either first or last chunk, whichever
is there, if the gap between them is big enough.

This patch adds the relevant code, using BIG_CHUNK_GAP define as a
threshold for middle chunk to be worth moving.

Link: http://lkml.kernel.org/r/20170131214334.c4f3eac9a477af0fa9a22c46@gmail.com
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Reviewed-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Currently the whole kernel build will be stopped if the size of struct
z3fold_header is greater than the size of one chunk, which is 64 bytes
by default.  This patch instead defines the offset for z3fold objects as
the size of the z3fold header in chunks.

Fixed also are the calculation of num_free_chunks() and the address to
move the middle chunk to in case of in-page compaction in
z3fold_compact_page().

Link: http://lkml.kernel.org/r/20170131214057.d98677032bc7b1c6c59a80c9@gmail.com
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Reviewed-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Convert pages_nr per-pool counter to atomic64_t.

Link: http://lkml.kernel.org/r/20170131213946.b828676ab17bbea42022c213@gmail.com
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Reviewed-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

A new unit test for the device-dax 1GB enabling currently fails with
this warning before hanging the test thread:

 WARNING: CPU: 0 PID: 21 at lib/percpu-refcount.c:155 percpu_ref_switch_to_atomic_rcu+0x1e3/0x1f0
 percpu ref (dax_pmem_percpu_release [dax_pmem]) <= 0 (0) after switching to atomic
 [..]
 CPU: 0 PID: 21 Comm: rcuos/1 Tainted: G           O    4.10.0-rc7-next-20170207+ #944
 [..]
 Call Trace:
  dump_stack+0x86/0xc3
  __warn+0xcb/0xf0
  warn_slowpath_fmt+0x5f/0x80
  ? rcu_nocb_kthread+0x27a/0x510
  ? dax_pmem_percpu_exit+0x50/0x50 [dax_pmem]
  percpu_ref_switch_to_atomic_rcu+0x1e3/0x1f0
  ? percpu_ref_exit+0x60/0x60
  rcu_nocb_kthread+0x339/0x510
  ? rcu_nocb_kthread+0x27a/0x510
  kthread+0x101/0x140

The get_user_pages() path needs to arrange for references to be taken
against the dev_pagemap instance backing the pud mapping.  Refactor the
existing __gup_device_huge_pmd() to also account for the pud case.

Link: http://lkml.kernel.org/r/148653181153.38226.9605457830505509385.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@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: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Since the introduction of FAULT_FLAG_SIZE to the vm_fault flag, it has
been somewhat painful with getting the flags set and removed at the
correct locations.  More than one kernel oops was introduced due to
difficulties of getting the placement correctly.

Remove the flag values and introduce an input parameter to huge_fault
that indicates the size of the page entry.  This makes the code easier
to trace and should avoid the issues we see with the fault flags where
removal of the flag was necessary in the fallback paths.

Link: http://lkml.kernel.org/r/148615748258.43180.1690152053774975329.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add transparent huge PUD pages support for device DAX by adding a
pud_fault handler.

Link: http://lkml.kernel.org/r/148545060002.17912.6765687780007547551.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The current transparent hugepage code only supports PMDs.  This patch
adds support for transparent use of PUDs with DAX.  It does not include
support for anonymous pages.  x86 support code also added.

Most of this patch simply parallels the work that was done for huge
PMDs.  The only major difference is how the new ->pud_entry method in
mm_walk works.  The ->pmd_entry method replaces the ->pte_entry method,
whereas the ->pud_entry method works along with either ->pmd_entry or
->pte_entry.  The pagewalk code takes care of locking the PUD before
calling ->pud_walk, so handlers do not need to worry whether the PUD is
stable.

[dave.jiang@intel.com: fix SMP x86 32bit build for native_pud_clear()]
  Link: http://lkml.kernel.org/r/148719066814.31111.3239231168815337012.stgit@djiang5-desk3.ch.intel.com
[dave.jiang@intel.com: native_pud_clear missing on i386 build]
  Link: http://lkml.kernel.org/r/148640375195.69754.3315433724330910314.stgit@djiang5-desk3.ch.intel.com
Link: http://lkml.kernel.org/r/148545059381.17912.8602162635537598445.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Alexander Kapshuk <alexander.kapshuk@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "1G transparent hugepage support for device dax", v2.

The following series implements support for 1G trasparent hugepage on
x86 for device dax.  The bulk of the code was written by Mathew Wilcox a
while back supporting transparent 1G hugepage for fs DAX.  I have
forward ported the relevant bits to 4.10-rc.  The current submission has
only the necessary code to support device DAX.

Comments from Dan Williams: So the motivation and intended user of this
functionality mirrors the motivation and users of 1GB page support in
hugetlbfs.  Given expected capacities of persistent memory devices an
in-memory database may want to reduce tlb pressure beyond what they can
already achieve with 2MB mappings of a device-dax file.  We have
customer feedback to that effect as Willy mentioned in his previous
version of these patches [1].

[1]: https://lkml.org/lkml/2016/1/31/52

Comments from Nilesh @ Oracle:

There are applications which have a process model; and if you assume
10,000 processes attempting to mmap all the 6TB memory available on a
server; we are looking at the following:

processes         : 10,000
memory            :    6TB
pte @ 4k page size: 8 bytes / 4K of memory * #processes = 6TB / 4k * 8 * 10000 = 1.5GB * 80000 = 120,000GB
pmd @ 2M page size: 120,000 / 512 = ~240GB
pud @ 1G page size: 240GB / 512 = ~480MB

As you can see with 2M pages, this system will use up an exorbitant
amount of DRAM to hold the page tables; but the 1G pages finally brings
it down to a reasonable level.  Memory sizes will keep increasing; so
this number will keep increasing.

An argument can be made to convert the applications from process model
to thread model, but in the real world that may not be always practical.
Hopefully this helps explain the use case where this is valuable.

This patch (of 3):

In preparation for adding the ability to handle PUD pages, convert
vm_operations_struct.pmd_fault to vm_operations_struct.huge_fault.  The
vm_fault structure is extended to include a union of the different page
table pointers that may be needed, and three flag bits are reserved to
indicate which type of pointer is in the union.

[ross.zwisler@linux.intel.com: remove unused function ext4_dax_huge_fault()]
  Link: http://lkml.kernel.org/r/1485813172-7284-1-git-send-email-ross.zwisler@linux.intel.com
[dave.jiang@intel.com: clear PMD or PUD size flags when in fall through path]
  Link: http://lkml.kernel.org/r/148589842696.5820.16078080610311444794.stgit@djiang5-desk3.ch.intel.com
Link: http://lkml.kernel.org/r/148545058784.17912.6353162518188733642.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

As suggested by Vlastimil Babka and Tejun Heo, this patch uses a static
work_struct to co-ordinate the draining of per-cpu pages on the
workqueue.  Only one task can drain at a time but this is better than
the previous scheme that allowed multiple tasks to send IPIs at a time.

One consideration is whether parallel requests should synchronise
against each other.  This patch does not synchronise for a global drain
as the common case for such callers is expected to be multiple parallel
direct reclaimers competing for pages when the watermark is close to
min.  Draining the per-cpu list is unlikely to make much progress and
serialising the drain is of dubious merit.  Drains are synchonrised for
callers such as memory hotplug and CMA that care about the drain being
complete when the function returns.

Link: http://lkml.kernel.org/r/20170125083038.rzb5f43nptmk7aed@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Suggested-by: Tejun Heo <tj@kernel.org>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Since commit 682a3385

 ("mm, page_alloc: inline the fast path of the
zonelist iterator") we replace a NULL nodemask with
cpuset_current_mems_allowed in the fast path, so that
get_page_from_freelist() filters nodes allowed by the cpuset via
for_next_zone_zonelist_nodemask().

In that case it's pointless to additionaly check __cpuset_zone_allowed()
in each iteration, which we can avoid by not adding ALLOC_CPUSET to
alloc_flags in that scenario.

This saves some cycles in the allocator fast path on systems with one or
more non-root cpuset configured.  In the slow path, ALLOC_CPUSET is
reset according to __alloc_pages_slowpath().  Without configured
cpusets, this code is disabled by a static key.

Link: http://lkml.kernel.org/r/20170124150511.5710-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The allocation fast path contains two similar checks for zoneref->zone
being NULL, where zoneref points either to the first zone in the
zonelist, or to the preferred zone.  These can be NULL either due to
empty zonelist, or no zone being compatible with given nodemask or
task's cpuset.

These checks are unnecessary, because the zonelist walks in
first_zones_zonelist() and get_page_from_freelist() handle a NULL
starting zoneref->zone or preferred_zoneref->zone safely.  It's safe to
fallback to __alloc_pages_slowpath() where we also have the check early
enough.

Link: http://lkml.kernel.org/r/20170124150511.5710-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

zram_reset_device() waits for ongoing writepage pages to be completed by
zram->refcount logic.  However, it's pointless because before the reset,
we prevent further opening of zram by zram->claim and flush all of
pending IO by fsync_bdev so there should be no pending IO at the
zram_reset_device().

So let's remove that code which is even broken due to the lack of
wake_up elsewhere.

Link: http://lkml.kernel.org/r/1485145031-11661-1-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mmap_init() is no longer associated with VMA slab.  So fix it.

Link: http://lkml.kernel.org/r/1485182601-9294-1-git-send-email-iamyooon@gmail.com
Signed-off-by: seokhoon.yoon <iamyooon@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

->fault(), ->page_mkwrite(), and ->pfn_mkwrite() calls do not need to
take a vma and vmf parameter when the vma already resides in vmf.

Remove the vma parameter to simplify things.

[arnd@arndb.de: fix ARM build]
  Link: http://lkml.kernel.org/r/20170125223558.1451224-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/148521301778.19116.10840599906674778980.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Many workloads that allocate pages are not handling an interrupt at a
time.  As allocation requests may be from IRQ context, it's necessary to
disable/enable IRQs for every page allocation.  This cost is the bulk of
the free path but also a significant percentage of the allocation path.

This patch alters the locking and checks such that only irq-safe
allocation requests use the per-cpu allocator.  All others acquire the
irq-safe zone->lock and allocate from the buddy allocator.  It relies on
disabling preemption to safely access the per-cpu structures.  It could
be slightly modified to avoid soft IRQs using it but it's not clear it's
worthwhile.

This modification may slow allocations from IRQ context slightly but the
main gain from the per-cpu allocator is that it scales better for
allocations from multiple contexts.  There is an implicit assumption
that intensive allocations from IRQ contexts on multiple CPUs from a
single NUMA node are rare and that the fast majority of scaling issues
are encountered in !IRQ contexts such as page faulting.  It's worth
noting that this patch is not required for a bulk page allocator but it
significantly reduces the overhead.

The following is results from a page allocator micro-benchmark.  Only
order-0 is interesting as higher orders do not use the per-cpu allocator

                                          4.10.0-rc2                 4.10.0-rc2
                                             vanilla               irqsafe-v1r5
Amean    alloc-odr0-1               287.15 (  0.00%)           219.00 ( 23.73%)
Amean    alloc-odr0-2               221.23 (  0.00%)           183.23 ( 17.18%)
Amean    alloc-odr0-4               187.00 (  0.00%)           151.38 ( 19.05%)
Amean    alloc-odr0-8               167.54 (  0.00%)           132.77 ( 20.75%)
Amean    alloc-odr0-16              156.00 (  0.00%)           123.00 ( 21.15%)
Amean    alloc-odr0-32              149.00 (  0.00%)           118.31 ( 20.60%)
Amean    alloc-odr0-64              138.77 (  0.00%)           116.00 ( 16.41%)
Amean    alloc-odr0-128             145.00 (  0.00%)           118.00 ( 18.62%)
Amean    alloc-odr0-256             136.15 (  0.00%)           125.00 (  8.19%)
Amean    alloc-odr0-512             147.92 (  0.00%)           121.77 ( 17.68%)
Amean    alloc-odr0-1024            147.23 (  0.00%)           126.15 ( 14.32%)
Amean    alloc-odr0-2048            155.15 (  0.00%)           129.92 ( 16.26%)
Amean    alloc-odr0-4096            164.00 (  0.00%)           136.77 ( 16.60%)
Amean    alloc-odr0-8192            166.92 (  0.00%)           138.08 ( 17.28%)
Amean    alloc-odr0-16384           159.00 (  0.00%)           138.00 ( 13.21%)
Amean    free-odr0-1                165.00 (  0.00%)            89.00 ( 46.06%)
Amean    free-odr0-2                113.00 (  0.00%)            63.00 ( 44.25%)
Amean    free-odr0-4                 99.00 (  0.00%)            54.00 ( 45.45%)
Amean    free-odr0-8                 88.00 (  0.00%)            47.38 ( 46.15%)
Amean    free-odr0-16                83.00 (  0.00%)            46.00 ( 44.58%)
Amean    free-odr0-32                80.00 (  0.00%)            44.38 ( 44.52%)
Amean    free-odr0-64                72.62 (  0.00%)            43.00 ( 40.78%)
Amean    free-odr0-128               78.00 (  0.00%)            42.00 ( 46.15%)
Amean    free-odr0-256               80.46 (  0.00%)            57.00 ( 29.16%)
Amean    free-odr0-512               96.38 (  0.00%)            64.69 ( 32.88%)
Amean    free-odr0-1024             107.31 (  0.00%)            72.54 ( 32.40%)
Amean    free-odr0-2048             108.92 (  0.00%)            78.08 ( 28.32%)
Amean    free-odr0-4096             113.38 (  0.00%)            82.23 ( 27.48%)
Amean    free-odr0-8192             112.08 (  0.00%)            82.85 ( 26.08%)
Amean    free-odr0-16384            110.38 (  0.00%)            81.92 ( 25.78%)
Amean    total-odr0-1               452.15 (  0.00%)           308.00 ( 31.88%)
Amean    total-odr0-2               334.23 (  0.00%)           246.23 ( 26.33%)
Amean    total-odr0-4               286.00 (  0.00%)           205.38 ( 28.19%)
Amean    total-odr0-8               255.54 (  0.00%)           180.15 ( 29.50%)
Amean    total-odr0-16              239.00 (  0.00%)           169.00 ( 29.29%)
Amean    total-odr0-32              229.00 (  0.00%)           162.69 ( 28.96%)
Amean    total-odr0-64              211.38 (  0.00%)           159.00 ( 24.78%)
Amean    total-odr0-128             223.00 (  0.00%)           160.00 ( 28.25%)
Amean    total-odr0-256             216.62 (  0.00%)           182.00 ( 15.98%)
Amean    total-odr0-512             244.31 (  0.00%)           186.46 ( 23.68%)
Amean    total-odr0-1024            254.54 (  0.00%)           198.69 ( 21.94%)
Amean    total-odr0-2048            264.08 (  0.00%)           208.00 ( 21.24%)
Amean    total-odr0-4096            277.38 (  0.00%)           219.00 ( 21.05%)
Amean    total-odr0-8192            279.00 (  0.00%)           220.92 ( 20.82%)
Amean    total-odr0-16384           269.38 (  0.00%)           219.92 ( 18.36%)

This is the alloc, free and total overhead of allocating order-0 pages
in batches of 1 page up to 16384 pages.  Avoiding disabling/enabling
overhead massively reduces overhead.  Alloc overhead is roughly reduced
by 14-20% in most cases.  The free path is reduced by 26-46% and the
total reduction is significant.

Many users require zeroing of pages from the page allocator which is the
vast cost of allocation.  Hence, the impact on a basic page faulting
benchmark is not that significant

                              4.10.0-rc2            4.10.0-rc2
                                 vanilla          irqsafe-v1r5
Hmean    page_test   656632.98 (  0.00%)   675536.13 (  2.88%)
Hmean    brk_test   3845502.67 (  0.00%)  3867186.94 (  0.56%)
Stddev   page_test    10543.29 (  0.00%)     4104.07 ( 61.07%)
Stddev   brk_test     33472.36 (  0.00%)    15538.39 ( 53.58%)
CoeffVar page_test        1.61 (  0.00%)        0.61 ( 62.15%)
CoeffVar brk_test         0.87 (  0.00%)        0.40 ( 53.84%)
Max      page_test   666513.33 (  0.00%)   678640.00 (  1.82%)
Max      brk_test   3882800.00 (  0.00%)  3887008.66 (  0.11%)

This is from aim9 and the most notable outcome is that fault variability
is reduced by the patch.  The headline improvement is small as the
overall fault cost, zeroing, page table insertion etc dominate relative
to disabling/enabling IRQs in the per-cpu allocator.

Similarly, little benefit was seen on networking benchmarks both
localhost and between physical server/clients where other costs
dominate.  It's possible that this will only be noticable on very high
speed networks.

Jesper Dangaard Brouer independently tested this with a separate
microbenchmark from
  https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/bench

Micro-benchmarked with [1] page_bench02:
 modprobe page_bench02 page_order=0 run_flags=$((2#010)) loops=$((10**8)); \
  rmmod page_bench02 ; dmesg --notime | tail -n 4

Compared to baseline: 213 cycles(tsc) 53.417 ns
 - against this     : 184 cycles(tsc) 46.056 ns
 - Saving           : -29 cycles
 - Very close to expected 27 cycles saving [see below [2]]

Micro benchmarking via time_bench_sample[3], we get the cost of these
operations:

 time_bench: Type:for_loop                 Per elem: 0 cycles(tsc) 0.232 ns (step:0)
 time_bench: Type:spin_lock_unlock         Per elem: 33 cycles(tsc) 8.334 ns (step:0)
 time_bench: Type:spin_lock_unlock_irqsave Per elem: 62 cycles(tsc) 15.607 ns (step:0)
 time_bench: Type:irqsave_before_lock      Per elem: 57 cycles(tsc) 14.344 ns (step:0)
 time_bench: Type:spin_lock_unlock_irq     Per elem: 34 cycles(tsc) 8.560 ns (step:0)
 time_bench: Type:simple_irq_disable_before_lock Per elem: 37 cycles(tsc) 9.289 ns (step:0)
 time_bench: Type:local_BH_disable_enable  Per elem: 19 cycles(tsc) 4.920 ns (step:0)
 time_bench: Type:local_IRQ_disable_enable Per elem: 7 cycles(tsc) 1.864 ns (step:0)
 time_bench: Type:local_irq_save_restore   Per elem: 38 cycles(tsc) 9.665 ns (step:0)
 [Mel's patch removes a ^^^^^^^^^^^^^^^^]            ^^^^^^^^^ expected saving - preempt cost
 time_bench: Type:preempt_disable_enable   Per elem: 11 cycles(tsc) 2.794 ns (step:0)
 [adds a preempt  ^^^^^^^^^^^^^^^^^^^^^^]            ^^^^^^^^^ adds this cost
 time_bench: Type:funcion_call_cost        Per elem: 6 cycles(tsc) 1.689 ns (step:0)
 time_bench: Type:func_ptr_call_cost       Per elem: 11 cycles(tsc) 2.767 ns (step:0)
 time_bench: Type:page_alloc_put           Per elem: 211 cycles(tsc) 52.803 ns (step:0)

Thus, expected improvement is: 38-11 = 27 cycles.

[mgorman@techsingularity.net: s/preempt_enable_no_resched/preempt_enable/]
  Link: http://lkml.kernel.org/r/20170208143128.25ahymqlyspjcixu@techsingularity.net
Link: http://lkml.kernel.org/r/20170123153906.3122-5-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Dmitry has reported the following lockdep splat
  lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3753
  __mutex_lock_common kernel/locking/mutex.c:521 [inline]
  mutex_lock_nested+0x24e/0xff0 kernel/locking/mutex.c:621
  pcpu_alloc+0xbda/0x1280 mm/percpu.c:896
  __alloc_percpu+0x24/0x30 mm/percpu.c:1075
  smpcfd_prepare_cpu+0x73/0xd0 kernel/smp.c:44
  cpuhp_invoke_callback+0x254/0x1480 kernel/cpu.c:136
  cpuhp_up_callbacks+0x81/0x2a0 kernel/cpu.c:493
  _cpu_up+0x1e3/0x2a0 kernel/cpu.c:1057
  do_cpu_up+0x73/0xa0 kernel/cpu.c:1087
  cpu_up+0x18/0x20 kernel/cpu.c:1095
  smp_init+0xe9/0xee kernel/smp.c:564
  kernel_init_freeable+0x439/0x690 init/main.c:1010
  kernel_init+0x13/0x180 init/main.c:941
  ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433

cpu_hotplug_begin
  cpu_hotplug.lock
pcpu_alloc
  pcpu_alloc_mutex

  get_online_cpus+0x62/0x90 kernel/cpu.c:248
  drain_all_pages+0xf8/0x710 mm/page_alloc.c:2385
  __alloc_pages_direct_reclaim mm/page_alloc.c:3440 [inline]
  __alloc_pages_slowpath+0x8fd/0x2370 mm/page_alloc.c:3778
  __alloc_pages_nodemask+0x8f5/0xc60 mm/page_alloc.c:3980
  __alloc_pages include/linux/gfp.h:426 [inline]
  __alloc_pages_node include/linux/gfp.h:439 [inline]
  alloc_pages_node include/linux/gfp.h:453 [inline]
  pcpu_alloc_pages mm/percpu-vm.c:93 [inline]
  pcpu_populate_chunk+0x1e1/0x900 mm/percpu-vm.c:282
  pcpu_alloc+0xe01/0x1280 mm/percpu.c:998
  __alloc_percpu_gfp+0x27/0x30 mm/percpu.c:1062
  bpf_array_alloc_percpu kernel/bpf/arraymap.c:34 [inline]
  array_map_alloc+0x532/0x710 kernel/bpf/arraymap.c:99
  find_and_alloc_map kernel/bpf/syscall.c:34 [inline]
  map_create kernel/bpf/syscall.c:188 [inline]
  SYSC_bpf kernel/bpf/syscall.c:870 [inline]
  SyS_bpf+0xd64/0x2500 kernel/bpf/syscall.c:827
  entry_SYSCALL_64_fastpath+0x1f/0xc2

pcpu_alloc
  pcpu_alloc_mutex
drain_all_pages
  get_online_cpus
    cpu_hotplug.lock

  cpu_hotplug_begin+0x206/0x2e0 kernel/cpu.c:304
  _cpu_up+0xca/0x2a0 kernel/cpu.c:1011
  do_cpu_up+0x73/0xa0 kernel/cpu.c:1087
  cpu_up+0x18/0x20 kernel/cpu.c:1095
  smp_init+0xe9/0xee kernel/smp.c:564
  kernel_init_freeable+0x439/0x690 init/main.c:1010
  kernel_init+0x13/0x180 init/main.c:941
  ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433

cpu_hotplug_begin
  cpu_hotplug.lock

Pulling cpu hotplug locks inside the page allocator is just too
dangerous.  Let's remove the dependency by dropping get_online_cpus()
from drain_all_pages.  This is not so simple though because now we do
not have a protection against cpu hotplug which means 2 things:

  - the work item might be executed on a different cpu in worker from
    unbound pool so it doesn't run on pinned on the cpu

  - we have to make sure that we do not race with page_alloc_cpu_dead
    calling drain_pages_zone

Disabling preemption in drain_local_pages_wq will solve the first
problem drain_local_pages will determine its local CPU from the WQ
context which will be stable after that point, page_alloc_cpu_dead is
pinned to the CPU already.  The later condition is achieved by disabling
IRQs in drain_pages_zone.

Fixes: mm, page_alloc: drain per-cpu pages from workqueue context
Link: http://lkml.kernel.org/r/20170207201950.20482-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The per-cpu page allocator can be drained immediately via
drain_all_pages() which sends IPIs to every CPU.  In the next patch, the
per-cpu allocator will only be used for interrupt-safe allocations which
prevents draining it from IPI context.  This patch uses workqueues to
drain the per-cpu lists instead.

This is slower but no slowdown during intensive reclaim was measured and
the paths that use drain_all_pages() are not that sensitive to
performance.  This is particularly true as the path would only be
triggered when reclaim is failing.  It also makes a some sense to avoid
storming a machine with IPIs when it's under memory pressure.  Arguably,
it should be further adjusted so that only one caller at a time is
draining pages but it's beyond the scope of the current patch.

Link: http://lkml.kernel.org/r/20170123153906.3122-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

alloc_pages_nodemask does a number of preperation steps that determine
what zones can be used for the allocation depending on a variety of
factors.  This is fine but a hypothetical caller that wanted multiple
order-0 pages has to do the preparation steps multiple times.  This
patch structures __alloc_pages_nodemask such that it's relatively easy
to build a bulk order-0 page allocator.  There is no functional change.

Link: http://lkml.kernel.org/r/20170123153906.3122-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "Use per-cpu allocator for !irq requests and prepare for a
bulk allocator", v5.

This series is motivated by a conversation led by Jesper Dangaard Brouer
at the last LSF/MM proposing a generic page pool for DMA-coherent pages.
Part of his motivation was due to the overhead of allocating multiple
order-0 that led some drivers to use high-order allocations and
splitting them.  This is very slow in some cases.

The first two patches in this series restructure the page allocator such
that it is relatively easy to introduce an order-0 bulk page allocator.
A patch exists to do that and has been handed over to Jesper until an
in-kernel users is created.  The third patch prevents the per-cpu
allocator being drained from IPI context as that can potentially corrupt
the list after patch four is merged.  The final patch alters the per-cpu
alloctor to make it exclusive to !irq requests.  This cuts
allocation/free overhead by roughly 30%.

Performance tests from both Jesper and me are included in the patch.

This patch (of 4):

buffered_rmqueue removes a page from a given zone and uses the per-cpu
list for order-0.  This is fine but a hypothetical caller that wanted
multiple order-0 pages has to disable/reenable interrupts multiple
times.  This patch structures buffere_rmqueue such that it's relatively
easy to build a bulk order-0 page allocator.  There is no functional
change.

[mgorman@techsingularity.net: failed per-cpu refill may blow up]
  Link: http://lkml.kernel.org/r/20170124112723.mshmgwq2ihxku2um@techsingularity.net
Link: http://lkml.kernel.org/r/20170123153906.3122-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We noticed a performance regression when moving hadoop workloads from
3.10 kernels to 4.0 and 4.6.  This is accompanied by increased pageout
activity initiated by kswapd as well as frequent bursts of allocation
stalls and direct reclaim scans.  Even lowering the dirty ratios to the
equivalent of less than 1% of memory would not eliminate the issue,
suggesting that dirty pages concentrate where the scanner is looking.

This can be traced back to recent efforts of thrash avoidance.  Where
3.10 would not detect refaulting pages and continuously supply clean
cache to the inactive list, a thrashing workload on 4.0+ will detect and
activate refaulting pages right away, distilling used-once pages on the
inactive list much more effectively.  This is by design, and it makes
sense for clean cache.  But for the most part our workload's cache
faults are refaults and its use-once cache is from streaming writes.  We
end up with most of the inactive list dirty, and we don't go after the
active cache as long as we have use-once pages around.

But waiting for writes to avoid reclaiming clean cache that *might*
refault is a bad trade-off.  Even if the refaults happen, reads are
faster than writes.  Before getting bogged down on writeback, reclaim
should first look at *all* cache in the system, even active cache.

To accomplish this, activate pages that are dirty or under writeback
when they reach the end of the inactive LRU.  The pages are marked for
immediate reclaim, meaning they'll get moved back to the inactive LRU
tail as soon as they're written back and become reclaimable.  But in the
meantime, by reducing the inactive list to only immediately reclaimable
pages, we allow the scanner to deactivate and refill the inactive list
with clean cache from the active list tail to guarantee forward
progress.

[hannes@cmpxchg.org: update comment]
  Link: http://lkml.kernel.org/r/20170202191957.22872-8-hannes@cmpxchg.org
Link: http://lkml.kernel.org/r/20170123181641.23938-6-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Dirty pages can easily reach the end of the LRU while there are still
clean pages to reclaim around.  Don't let kswapd write them back just
because there are a lot of them.  It costs more CPU to find the clean
pages, but that's almost certainly better than to disrupt writeback from
the flushers with LRU-order single-page writes from reclaim.  And the
flushers have been woken up by that point, so we spend IO capacity on
flushing and CPU capacity on finding the clean cache.

Only start writing dirty pages if they have cycled around the LRU twice
now and STILL haven't been queued on the IO device.  It's possible that
the dirty pages are so sparsely distributed across different bdis,
inodes, memory cgroups, that the flushers take forever to get to the
ones we want reclaimed.  Once we see them twice on the LRU, we know
that's the quicker way to find them, so do LRU writeback.

Link: http://lkml.kernel.org/r/20170123181641.23938-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Direct reclaim has been replaced by kswapd reclaim in pretty much all
common memory pressure situations, so this code most likely doesn't
accomplish the described effect anymore.  The previous patch wakes up
flushers for all reclaimers when we encounter dirty pages at the tail
end of the LRU.  Remove the crufty old direct reclaim invocation.

Link: http://lkml.kernel.org/r/20170123181641.23938-4-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Memory pressure can put dirty pages at the end of the LRU without
anybody running into dirty limits.  Don't start writing individual pages
from kswapd while the flushers might be asleep.

Unlike the old direct reclaim flusher wakeup (removed in the next patch)
that flushes the number of pages just scanned, this patch wakes the
flushers for all outstanding dirty pages.  That seemed to perform better
in a synthetic test that pushes dirty pages to the end of the LRU and
into reclaim, because we know LRU aging outstrips writeback already, and
this way we give younger dirty pages a headstart rather than wait until
reclaim runs into them as well.  It also means less plugging and risk of
exhausting the struct request pool from reclaim.

There is a concern that this will cause temporary files that used to get
dirtied and truncated before writeback to now get written to disk under
memory pressure.  If this turns out to be a real problem, we'll have to
revisit this and tame the reclaim flusher wakeups.

[hannes@cmpxchg.org: mention dirty expiration as a condition]
  Link: http://lkml.kernel.org/r/20170126174739.GA30636@cmpxchg.org
Link: http://lkml.kernel.org/r/20170123181641.23938-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "mm: vmscan: fix kswapd writeback regression".

We noticed a regression on multiple hadoop workloads when moving from
3.10 to 4.0 and 4.6, which involves kswapd getting tangled up in page
writeout, causing direct reclaim herds that also don't make progress.

I tracked it down to the thrash avoidance efforts after 3.10 that make
the kernel better at keeping use-once cache and use-many cache sorted on
the inactive and active list, with more aggressive protection of the
active list as long as there is inactive cache.  Unfortunately, our
workload's use-once cache is mostly from streaming writes.  Waiting for
writes to avoid potential reloads in the future is not a good tradeoff.

These patches do the following:

1. Wake the flushers when kswapd sees a lump of dirty pages. It's
   possible to be below the dirty background limit and still have cache
   velocity push them through the LRU. So start a-flushin'.

2. Let kswapd only write pages that have been rotated twice. This makes
   sure we really tried to get all the clean pages on the inactive list
   before resorting to horrible LRU-order writeback.

3. Move rotating dirty pages off the inactive list. Instead of churning
   or waiting on page writeback, we'll go after clean active cache. This
   might lead to thrashing, but in this state memory demand outstrips IO
   speed anyway, and reads are faster than writes.

Mel backported the series to 4.10-rc5 with one minor conflict and ran a
couple of tests on it.  Mix of read/write random workload didn't show
anything interesting.  Write-only database didn't show much difference
in performance but there were slight reductions in IO -- probably in the
noise.

simoop did show big differences although not as big as Mel expected.
This is Chris Mason's workload that similate the VM activity of hadoop.
Mel won't go through the full details but over the samples measured
during an hour it reported

                                         4.10.0-rc5            4.10.0-rc5
                                            vanilla         johannes-v1r1
Amean    p50-Read             21346531.56 (  0.00%) 21697513.24 ( -1.64%)
Amean    p95-Read             24700518.40 (  0.00%) 25743268.98 ( -4.22%)
Amean    p99-Read             27959842.13 (  0.00%) 28963271.11 ( -3.59%)
Amean    p50-Write                1138.04 (  0.00%)      989.82 ( 13.02%)
Amean    p95-Write             1106643.48 (  0.00%)    12104.00 ( 98.91%)
Amean    p99-Write             1569213.22 (  0.00%)    36343.38 ( 97.68%)
Amean    p50-Allocation          85159.82 (  0.00%)    79120.70 (  7.09%)
Amean    p95-Allocation         204222.58 (  0.00%)   129018.43 ( 36.82%)
Amean    p99-Allocation         278070.04 (  0.00%)   183354.43 ( 34.06%)
Amean    final-p50-Read       21266432.00 (  0.00%) 21921792.00 ( -3.08%)
Amean    final-p95-Read       24870912.00 (  0.00%) 26116096.00 ( -5.01%)
Amean    final-p99-Read       28147712.00 (  0.00%) 29523968.00 ( -4.89%)
Amean    final-p50-Write          1130.00 (  0.00%)      977.00 ( 13.54%)
Amean    final-p95-Write       1033216.00 (  0.00%)     2980.00 ( 99.71%)
Amean    final-p99-Write       1517568.00 (  0.00%)    32672.00 ( 97.85%)
Amean    final-p50-Allocation    86656.00 (  0.00%)    78464.00 (  9.45%)
Amean    final-p95-Allocation   211712.00 (  0.00%)   116608.00 ( 44.92%)
Amean    final-p99-Allocation   287232.00 (  0.00%)   168704.00 ( 41.27%)

The latencies are actually completely horrific in comparison to 4.4 (and
4.10-rc5 is worse than 4.9 according to historical data for reasons Mel
hasn't analysed yet).

Still, 95% of write latency (p95-write) is halved by the series and
allocation latency is way down.  Direct reclaim activity is one fifth of
what it was according to vmstats.  Kswapd activity is higher but this is
not necessarily surprising.  Kswapd efficiency is unchanged at 99% (99%
of pages scanned were reclaimed) but direct reclaim efficiency went from
77% to 99%

In the vanilla kernel, 627MB of data was written back from reclaim
context.  With the series, no data was written back.  With or without
the patch, pages are being immediately reclaimed after writeback
completes.  However, with the patch, only 1/8th of the pages are
reclaimed like this.

This patch (of 5):

We have an elaborate dirty/writeback throttling mechanism inside the
reclaim scanner, but for that to work the pages have to go through
shrink_page_list() and get counted for what they are.  Otherwise, we
mess up the LRU order and don't match reclaim speed to writeback.

Especially during deactivation, there is never a reason to skip dirty
pages; nothing is even trying to write them out from there.  Don't mess
up the LRU order for nothing, shuffle these pages along.

Link: http://lkml.kernel.org/r/20170123181641.23938-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Now when madvise(MADV_REMOVE) notifies uffd reader, we should verify
that appliciation actually sees zeros at the removed range.

Link: http://lkml.kernel.org/r/1484814154-1557-4-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When a page is removed from a shared mapping, the uffd reader should be
notified, so that it won't attempt to handle #PF events for the removed
pages.

We can reuse the UFFD_EVENT_REMOVE because from the uffd monitor point
of view, the semantices of madvise(MADV_DONTNEED) and
madvise(MADV_REMOVE) is exactly the same.

Link: http://lkml.kernel.org/r/1484814154-1557-3-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Patch series "userfaultfd: non-cooperative: add madvise() event for
MADV_REMOVE request".

These patches add notification of madvise(MADV_REMOVE) event to
non-cooperative userfaultfd monitor.

The first pacth renames EVENT_MADVDONTNEED to EVENT_REMOVE along with
relevant functions and structures.  Using _REMOVE instead of
_MADVDONTNEED describes the event semantics more clearly and I hope it's
not too late for such change in the ABI.

This patch (of 3):

The UFFD_EVENT_MADVDONTNEED purpose is to notify uffd monitor about
removal of certain range from address space tracked by userfaultfd.
Hence, UFFD_EVENT_REMOVE seems to better reflect the operation
semantics.  Respectively, 'madv_dn' field of uffd_msg is renamed to
'remove' and the madvise_userfault_dontneed callback is renamed to
userfaultfd_remove.

Link: http://lkml.kernel.org/r/1484814154-1557-2-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Provide the name of each memblock type with struct memblock_type.  This
allows to get rid of the function memblock_type_name() and duplicating
the type names in __memblock_dump_all().

The only memblock_type usage out of mm/memblock.c seems to be
arch/s390/kernel/crash_dump.c.  While at it, give it a name.

Link: http://lkml.kernel.org/r/20170120123456.46508-4-heiko.carstens@de.ibm.com
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>