Adding a brief overview of hugetlbfs reservation design and
implementation as an aid to those making code modifications in this
area.

Link: http://lkml.kernel.org/r/1491586995-13085-1-git-send-email-mike.kravetz@oracle.comSigned-off-by: NMike Kravetz <mike.kravetz@oracle.com>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is a code cleanup patch, no functionality changes.  There are 2
unused function prototype in swap.h, they are removed.

Link: http://lkml.kernel.org/r/20170405071017.23677-1-ying.huang@intel.comSigned-off-by: N"Huang, Ying" <ying.huang@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The memory controllers stat function names are awkwardly long and
arbitrarily different from the zone and node stat functions.

The current interface is named:

  mem_cgroup_read_stat()
  mem_cgroup_update_stat()
  mem_cgroup_inc_stat()
  mem_cgroup_dec_stat()
  mem_cgroup_update_page_stat()
  mem_cgroup_inc_page_stat()
  mem_cgroup_dec_page_stat()

This patch renames it to match the corresponding node stat functions:

  memcg_page_state()		[node_page_state()]
  mod_memcg_state()		[mod_node_state()]
  inc_memcg_state()		[inc_node_state()]
  dec_memcg_state()		[dec_node_state()]
  mod_memcg_page_state()	[mod_node_page_state()]
  inc_memcg_page_state()	[inc_node_page_state()]
  dec_memcg_page_state()	[dec_node_page_state()]

Link: http://lkml.kernel.org/r/20170404220148.28338-4-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NVladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current duplication is a high-maintenance mess, and it's painful to
add new items or query memcg state from the rest of the VM.

This increases the size of the stat array marginally, but we should aim
to track all these stats on a per-cgroup level anyway.

Link: http://lkml.kernel.org/r/20170404220148.28338-3-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NVladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current duplication is a high-maintenance mess, and it's painful to
add new items.

This increases the size of the event array, but we'll eventually want
most of the VM events tracked on a per-cgroup basis anyway.

Link: http://lkml.kernel.org/r/20170404220148.28338-2-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NVladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We only ever count single events, drop the @nr parameter.  Rename the
function accordingly.  Remove low-information kerneldoc.

Link: http://lkml.kernel.org/r/20170404220148.28338-1-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NVladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since commit 59dc76b0 ("mm: vmscan: reduce size of inactive file
list") we noticed bigger IO spikes during changes in cache access
patterns.

The patch in question shrunk the inactive list size to leave more room
for the current workingset in the presence of streaming IO.  However,
workingset transitions that previously happened on the inactive list are
now pushed out of memory and incur more refaults to complete.

This patch disables active list protection when refaults are being
observed.  This accelerates workingset transitions, and allows more of
the new set to establish itself from memory, without eating into the
ability to protect the established workingset during stable periods.

The workloads that were measurably affected for us were hit pretty bad
by it, with refault/majfault rates doubling and tripling during cache
transitions, and the machines sustaining half-hour periods of 100% IO
utilization, where they'd previously have sub-minute peaks at 60-90%.

Stateful services that handle user data tend to be more conservative
with kernel upgrades.  As a result we hit most page cache issues with
some delay, as was the case here.

The severity seemed to warrant a stable tag.

Fixes: 59dc76b0 ("mm: vmscan: reduce size of inactive file list")
Link: http://lkml.kernel.org/r/20170404220052.27593-1-hannes@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>	[4.7+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 091d0d55 ("shm: fix null pointer deref when userspace
specifies invalid hugepage size") had replaced MAP_HUGE_MASK with
SHM_HUGE_MASK.  Though both of them contain the same numeric value of
0x3f, MAP_HUGE_MASK flag sounds more appropriate than the other one in
the context.  Hence change it back.

Link: http://lkml.kernel.org/r/20170404045635.616-1-khandual@linux.vnet.ibm.comSigned-off-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
Reviewed-by: NMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: NBalbir Singh <bsingharora@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Tetsuo has reported that sysrq triggered OOM killer will print a
misleading information when no tasks are selected:

  sysrq: SysRq : Manual OOM execution
  Out of memory: Kill process 4468 ((agetty)) score 0 or sacrifice child
  Killed process 4468 ((agetty)) total-vm:43704kB, anon-rss:1760kB, file-rss:0kB, shmem-rss:0kB
  sysrq: SysRq : Manual OOM execution
  Out of memory: Kill process 4469 (systemd-cgroups) score 0 or sacrifice child
  Killed process 4469 (systemd-cgroups) total-vm:10704kB, anon-rss:120kB, file-rss:0kB, shmem-rss:0kB
  sysrq: SysRq : Manual OOM execution
  sysrq: OOM request ignored because killer is disabled
  sysrq: SysRq : Manual OOM execution
  sysrq: OOM request ignored because killer is disabled
  sysrq: SysRq : Manual OOM execution
  sysrq: OOM request ignored because killer is disabled

The real reason is that there are no eligible tasks for the OOM killer
to select but since commit 7c5f64f8 ("mm: oom: deduplicate victim
selection code for memcg and global oom") the semantic of out_of_memory
has changed without updating moom_callback.

This patch updates moom_callback to tell that no task was eligible which
is the case for both oom killer disabled and no eligible tasks.  In
order to help distinguish first case from the second add printk to both
oom_killer_{enable,disable}.  This information is useful on its own
because it might help debugging potential memory allocation failures.

Fixes: 7c5f64f8 ("mm: oom: deduplicate victim selection code for memcg and global oom")
Link: http://lkml.kernel.org/r/20170404134705.6361-1-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Reported-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, selftest for userfaultfd is compiled three times: for
anonymous, shared and hugetlb memory.  Let's combine all the cases into
a single executable which will have a command line option for selection
of the test type.

Link: http://lkml.kernel.org/r/1490869741-5913-1-git-send-email-rppt@linux.vnet.ibm.comSigned-off-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: NMike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix variable name error in comments. No code changes.

Link: http://lkml.kernel.org/r/20170403161655.5081-1-haolee.swjtu@gmail.comSigned-off-by: NHao Lee <haolee.swjtu@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a warning diagnostics to user if we failed to allocate swap slots
cache and use it.

[akpm@linux-foundation.org: use WARN_ONCE return value, fix grammar in message]
Link: http://lkml.kernel.org/r/20170328234827.GA10107@linux.intel.comSigned-off-by: NTim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It is preferred, and the rest of migrate.h gets it right.

Link: http://lkml.kernel.org/r/1490336009-8024-1-git-send-email-pushkar.iit@gmail.comSigned-off-by: NPushkar Jambhlekar <pushkar.iit@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

On SPARSEMEM systems page poisoning is enabled after buddy is up,
because of the dependency on page extension init.  This causes the pages
released by free_all_bootmem not to be poisoned.  This either delays or
misses the identification of some issues because the pages have to
undergo another cycle of alloc-free-alloc for any corruption to be
detected.

Enable page poisoning early by getting rid of the PAGE_EXT_DEBUG_POISON
flag.  Since all the free pages will now be poisoned, the flag need not
be verified before checking the poison during an alloc.

[vinmenon@codeaurora.org: fix Kconfig]
  Link: http://lkml.kernel.org/r/1490878002-14423-1-git-send-email-vinmenon@codeaurora.org
Link: http://lkml.kernel.org/r/1490358246-11001-1-git-send-email-vinmenon@codeaurora.orgSigned-off-by: NVinayak Menon <vinmenon@codeaurora.org>
Acked-by: NLaura Abbott <labbott@redhat.com>
Tested-by: NLaura Abbott <labbott@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Cluster lock is used to protect the swap_cluster_info and corresponding
elements in swap_info_struct->swap_map[].  But it is found that now in
scan_swap_map_slots(), swap_avail_lock may be acquired when cluster lock
is held.  This does no good except making the locking more complex and
improving the potential locking contention, because the
swap_info_struct->lock is used to protect the data structure operated in
the code already.  Fix this via moving the corresponding operations in
scan_swap_map_slots() out of cluster lock.

Link: http://lkml.kernel.org/r/20170317064635.12792-3-ying.huang@intel.comSigned-off-by: N"Huang, Ying" <ying.huang@intel.com>
Acked-by: NTim Chen <tim.c.chen@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is just a cleanup patch, no functionality change.

In cluster_list_add_tail(), spin_lock_nested() is used to lock the
cluster, while unlock_cluster() is used to unlock the cluster.  To
improve the code readability, use spin_unlock() directly to unlock the
cluster.

Link: http://lkml.kernel.org/r/20170317064635.12792-2-ying.huang@intel.comSigned-off-by: N"Huang, Ying" <ying.huang@intel.com>
Acked-by: NTim Chen <tim.c.chen@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit cbab0e4e ("swap: avoid read_swap_cache_async() race to
deadlock while waiting on discard I/O completion") fixed a deadlock in
read_swap_cache_async().  Because at that time, in swap allocation path,
a swap entry may be set as SWAP_HAS_CACHE, then wait for discarding to
complete before the page for the swap entry is added to the swap cache.

But in commit 815c2c54 ("swap: make swap discard async"), the
discarding for swap become asynchronous, waiting for discarding to
complete will be done before the swap entry is set as SWAP_HAS_CACHE.
So the comments in code is incorrect now.  This patch fixes the
comments.

The cond_resched() added in the commit cbab0e4e is not necessary now
too.  But if we added some sleep in swap allocation path in the future,
there may be some hard to debug/reproduce deadlock bug.  So it is kept.

Link: http://lkml.kernel.org/r/20170317064635.12792-1-ying.huang@intel.comSigned-off-by: N"Huang, Ying" <ying.huang@intel.com>
Acked-by: NRafael Aquini <aquini@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is no user for it.  Remove it.

[minchan@kernel.org: use false instead of SWAP_FAIL]
  Link: http://lkml.kernel.org/r/20170316053313.GA19241@bbox
Link: http://lkml.kernel.org/r/1489555493-14659-11-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

rmap_one's return value controls whether rmap_work should contine to
scan other ptes or not so it's target for changing to boolean.  Return
true if the scan should be continued.  Otherwise, return false to stop
the scanning.

This patch makes rmap_one's return value to boolean.

Link: http://lkml.kernel.org/r/1489555493-14659-10-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is no user of the return value from rmap_walk() and friends so
this patch makes them void-returning functions.

Link: http://lkml.kernel.org/r/1489555493-14659-9-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

try_to_unmap() returns SWAP_SUCCESS or SWAP_FAIL so it's suitable for
boolean return.  This patch changes it.

Link: http://lkml.kernel.org/r/1489555493-14659-8-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In 2002, [1] introduced SWAP_AGAIN.  At that time, try_to_unmap_one used
spin_trylock(&mm->page_table_lock) so it's really easy to contend and
fail to hold a lock so SWAP_AGAIN to keep LRU status makes sense.

However, now we changed it to mutex-based lock and be able to block
without skip pte so there is few of small window to return SWAP_AGAIN so
remove SWAP_AGAIN and just return SWAP_FAIL.

[1] c48c43e4, minimal rmap

Link: http://lkml.kernel.org/r/1489555493-14659-7-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

ttu doesn't need to return SWAP_MLOCK.  Instead, just return SWAP_FAIL
because it means the page is not-swappable so it should move to another
LRU list(active or unevictable).  putback friends will move it to right
list depending on the page's LRU flag.

Link: http://lkml.kernel.org/r/1489555493-14659-6-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

try_to_munlock returns SWAP_MLOCK if the one of VMAs mapped the page has
VM_LOCKED flag.  In that time, VM set PG_mlocked to the page if the page
is not pte-mapped THP which cannot be mlocked, either.

With that, __munlock_isolated_page can use PageMlocked to check whether
try_to_munlock is successful or not without relying on try_to_munlock's
retval.  It helps to make try_to_unmap/try_to_unmap_one simple with
upcoming patches.

[minchan@kernel.org: remove PG_Mlocked VM_BUG_ON check]
  Link: http://lkml.kernel.org/r/20170411025615.GA6545@bbox
Link: http://lkml.kernel.org/r/1489555493-14659-5-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If the page is mapped and rescue in try_to_unmap_one, the
page_mapcount() of a page cannot be zero, so the page_mapcount check in
try_to_unmap is enough to return SWAP_SUCCESS.  IOW, SWAP_MLOCK check is
redundant so remove it.

Link: http://lkml.kernel.org/r/1489555493-14659-4-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If we found lazyfree page is dirty, try_to_unmap_one can just
SetPageSwapBakced in there like PG_mlocked page and just return with
SWAP_FAIL which is very natural because the page is not swappable right
now so that vmscan can activate it.  There is no point to introduce new
return value SWAP_DIRTY in try_to_unmap at the moment.

Link: http://lkml.kernel.org/r/1489555493-14659-3-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Nobody uses ret variable. Remove it.

Link: http://lkml.kernel.org/r/1489555493-14659-2-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

By reviewing code, I find that when enter do_try_to_free_pages, the
may_thrash is always clear, and it will retry shrink zones to tap
cgroup's reserves memory by setting may_thrash when the former
shrink_zones reclaim nothing.

However, when memcg is disabled or on legacy hierarchy, or there do not
have any memcg protected by low limit, it should not do this useless
retry at all, for we do not have any cgroup's reserves memory to tap,
and we have already done hard work but made no progress, which as Michal
pointed out in former version, we are trying hard to control the retry
logical of page alloctor, and the current additional round of reclaim is
just lame.

Therefore, to avoid this unneeded retrying and make code more readable,
we remove the may_thrash field in scan_control, instead, introduce
memcg_low_reclaim and memcg_low_skipped, and only retry when
memcg_low_skipped, by setting memcg_low_reclaim.

[xieyisheng1@huawei.com: remove may_thrash field, introduce mem_cgroup_reclaim]
  Link: http://lkml.kernel.org/r/1490191893-5923-1-git-send-email-ysxie@foxmail.com
Link: http://lkml.kernel.org/r/1490191893-5923-1-git-send-email-ysxie@foxmail.comSigned-off-by: NYisheng Xie <xieyisheng1@huawei.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Suggested-by: NJohannes Weiner <hannes@cmpxchg.org>
Suggested-by: NMichal Hocko <mhocko@kernel.org>
Suggested-by: NShakeel Butt <shakeelb@google.com>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

By reviewing code, I find that if the migrate target is a large free
page and we ignore suitable, it may splite large target free page into
smaller block which is not good for defrag.  So move the ignore block
suitable after check large free page.

As Vlastimil pointed out in RFC version that this patch is just based on
logical analyses which might be better for future-proofing the function
and it is most likely won't have any visible effect right now, for
direct compaction shouldn't have to be called if there's a
>=pageblock_order page already available.

Link: http://lkml.kernel.org/r/1489490743-5364-1-git-send-email-xieyisheng1@huawei.comSigned-off-by: NYisheng Xie <xieyisheng1@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current implementation calculates usemap_size in two steps:
    * calculate number of bytes to cover these bits
    * calculate number of "unsigned long" to cover these bytes

It would be more clear by:
    * calculate number of "unsigned long" to cover these bits
    * multiple it with sizeof(unsigned long)

This patch refine usemap_size() a little to make it more easy to
understand.

Link: http://lkml.kernel.org/r/20170310043713.96871-1-richard.weiyang@gmail.comSigned-off-by: NWei Yang <richard.weiyang@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__GFP_NOWARN, which is usually added to avoid warnings from callsites
that expect to fail and have fallbacks, currently also suppresses
allocation stall warnings.  These trigger when an allocation is stuck
inside the allocator for 10 seconds or longer.

But there is no class of allocations that can get legitimately stuck in
the allocator for this long.  This always indicates a problem.

Always emit stall warnings.  Restrict __GFP_NOWARN to alloc failures.

Link: http://lkml.kernel.org/r/20170125181150.GA16398@cmpxchg.orgSigned-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMinchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kswapd is woken to reclaim a node based on a failed allocation request
from any eligible zone.  Once reclaiming in balance_pgdat(), it will
continue reclaiming until there is an eligible zone available for the
zone it was woken for.  kswapd tracks what zone it was recently woken
for in pgdat->kswapd_classzone_idx.  If it has not been woken recently,
this zone will be 0.

However, the decision on whether to sleep is made on
kswapd_classzone_idx which is 0 without a recent wakeup request and that
classzone does not account for lowmem reserves.  This allows kswapd to
sleep when a low small zone such as ZONE_DMA is balanced for a GFP_DMA
request even if a stream of allocations cannot use that zone.  While
kswapd may be woken again shortly in the near future there are two
consequences -- the pgdat bits that control congestion are cleared
prematurely and direct reclaim is more likely as kswapd slept
prematurely.

This patch flips kswapd_classzone_idx to default to MAX_NR_ZONES (an
invalid index) when there has been no recent wakeups.  If there are no
wakeups, it'll decide whether to sleep based on the highest possible
zone available (MAX_NR_ZONES - 1).  It then becomes critical that the
"pgdat balanced" decisions during reclaim and when deciding to sleep are
the same.  If there is a mismatch, kswapd can stay awake continually
trying to balance tiny zones.

simoop was used to evaluate it again.  Two of the preparation patches
regressed the workload so they are included as the second set of
results.  Otherwise this patch looks artifically excellent

                                         4.11.0-rc1            4.11.0-rc1            4.11.0-rc1
                                            vanilla              clear-v2          keepawake-v2
Amean    p50-Read             21670074.18 (  0.00%) 19786774.76 (  8.69%) 22668332.52 ( -4.61%)
Amean    p95-Read             25456267.64 (  0.00%) 24101956.27 (  5.32%) 26738688.00 ( -5.04%)
Amean    p99-Read             29369064.73 (  0.00%) 27691872.71 (  5.71%) 30991404.52 ( -5.52%)
Amean    p50-Write                1390.30 (  0.00%)     1011.91 ( 27.22%)      924.91 ( 33.47%)
Amean    p95-Write              412901.57 (  0.00%)    34874.98 ( 91.55%)     1362.62 ( 99.67%)
Amean    p99-Write             6668722.09 (  0.00%)   575449.60 ( 91.37%)    16854.04 ( 99.75%)
Amean    p50-Allocation          78714.31 (  0.00%)    84246.26 ( -7.03%)    74729.74 (  5.06%)
Amean    p95-Allocation         175533.51 (  0.00%)   400058.43 (-127.91%)   101609.74 ( 42.11%)
Amean    p99-Allocation         247003.02 (  0.00%) 10905600.00 (-4315.17%)   125765.57 ( 49.08%)

With this patch on top, write and allocation latencies are massively
improved.  The read latencies are slightly impaired but it's worth
noting that this is mostly due to the IO scheduler and not directly
related to reclaim.  The vmstats are a bit of a mix but the relevant
ones are as follows;

                            4.10.0-rc7  4.10.0-rc7  4.10.0-rc7
                          mmots-20170209 clear-v1r25keepawake-v1r25
Swap Ins                             0           0           0
Swap Outs                            0         608           0
Direct pages scanned           6910672     3132699     6357298
Kswapd pages scanned          57036946    82488665    56986286
Kswapd pages reclaimed        55993488    63474329    55939113
Direct pages reclaimed         6905990     2964843     6352115
Kswapd efficiency                  98%         76%         98%
Kswapd velocity              12494.375   17597.507   12488.065
Direct efficiency                  99%         94%         99%
Direct velocity               1513.835     668.306    1393.148
Page writes by reclaim           0.000 4410243.000       0.000
Page writes file                     0     4409635           0
Page writes anon                     0         608           0
Page reclaim immediate         1036792    14175203     1042571

                            4.11.0-rc1  4.11.0-rc1  4.11.0-rc1
                               vanilla  clear-v2  keepawake-v2
Swap Ins                             0          12           0
Swap Outs                            0         838           0
Direct pages scanned           6579706     3237270     6256811
Kswapd pages scanned          61853702    79961486    54837791
Kswapd pages reclaimed        60768764    60755788    53849586
Direct pages reclaimed         6579055     2987453     6256151
Kswapd efficiency                  98%         75%         98%
Page writes by reclaim           0.000 4389496.000       0.000
Page writes file                     0     4388658           0
Page writes anon                     0         838           0
Page reclaim immediate         1073573    14473009      982507

Swap-outs are equivalent to baseline.

Direct reclaim is reduced but not eliminated.  It's worth noting that
there are two periods of direct reclaim for this workload.  The first is
when it switches from preparing the files for the actual test itself.
It's a lot of file IO followed by a lot of allocs that reclaims heavily
for a brief window.  While direct reclaim is lower with clear-v2, it is
due to kswapd scanning aggressively and trying to reclaim the world
which is not the right thing to do.  With the patches applied, there is
still direct reclaim but the phase change from "creating work files" to
starting multiple threads that allocate a lot of anonymous memory faster
than kswapd can reclaim.

Scanning/reclaim efficiency is restored by this patch.

Page writes from reclaim context are back at 0 which is ideal.

Pages immediately reclaimed after IO completes is slightly improved but
it is expected this will vary slightly.

On UMA, there is almost no change so this is not expected to be a
universal win.

[mgorman@suse.de: fix ->kswapd_classzone_idx initialization]
  Link: http://lkml.kernel.org/r/20170406174538.5msrznj6nt6qpbx5@suse.de
Link: http://lkml.kernel.org/r/20170309075657.25121-4-mgorman@techsingularity.netSigned-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A pgdat tracks if recent reclaim encountered too many dirty, writeback
or congested pages.  The flags control whether kswapd writes pages back
from reclaim context, tags pages for immediate reclaim when IO
completes, whether processes block on wait_iff_congested and whether
kswapd blocks when too many pages marked for immediate reclaim are
encountered.

The state is cleared in a check function with side-effects.  With the
patch "mm, vmscan: fix zone balance check in prepare_kswapd_sleep", the
timing of when the bits get cleared changed.  Due to the way the check
works, it'll clear the bits if ZONE_DMA is balanced for a GFP_DMA
allocation because it does not account for lowmem reserves properly.

For the simoop workload, kswapd is not stalling when it should due to
the premature clearing, writing pages from reclaim context like crazy
and generally being unhelpful.

This patch resets the pgdat bits related to page reclaim only when
kswapd is going to sleep.  The comparison with simoop is then

                                         4.11.0-rc1            4.11.0-rc1            4.11.0-rc1
                                            vanilla           fixcheck-v2              clear-v2
Amean    p50-Read             21670074.18 (  0.00%) 20464344.18 (  5.56%) 19786774.76 (  8.69%)
Amean    p95-Read             25456267.64 (  0.00%) 25721423.64 ( -1.04%) 24101956.27 (  5.32%)
Amean    p99-Read             29369064.73 (  0.00%) 30174230.76 ( -2.74%) 27691872.71 (  5.71%)
Amean    p50-Write                1390.30 (  0.00%)     1395.28 ( -0.36%)     1011.91 ( 27.22%)
Amean    p95-Write              412901.57 (  0.00%)    37737.74 ( 90.86%)    34874.98 ( 91.55%)
Amean    p99-Write             6668722.09 (  0.00%)   666489.04 ( 90.01%)   575449.60 ( 91.37%)
Amean    p50-Allocation          78714.31 (  0.00%)    86286.22 ( -9.62%)    84246.26 ( -7.03%)
Amean    p95-Allocation         175533.51 (  0.00%)   351812.27 (-100.42%)   400058.43 (-127.91%)
Amean    p99-Allocation         247003.02 (  0.00%)  6291171.56 (-2447.00%) 10905600.00 (-4315.17%)

Read latency is improved, write latency is mostly improved but
allocation latency is regressed.  kswapd is still reclaiming
inefficiently, pages are being written back from writeback context and a
host of other issues.  However, given the change, it needed to be
spelled out why the side-effect was moved.

Link: http://lkml.kernel.org/r/20170309075657.25121-3-mgorman@techsingularity.netSigned-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "Reduce amount of time kswapd sleeps prematurely", v2.

The series is unusual in that the first patch fixes one problem and
introduces other issues that are noted in the changelog.  Patch 2 makes
a minor modification that is worth considering on its own but leaves the
kernel in a state where it behaves badly.  It's not until patch 3 that
there is an improvement against baseline.

This was mostly motivated by examining Chris Mason's "simoop" benchmark
which puts the VM under similar pressure to HADOOP.  It has been
reported that the benchmark has regressed severely during the last
number of releases.  While I cannot reproduce all the same problems
Chris experienced due to hardware limitations, there was a number of
problems on a 2-socket machine with a single disk.

simoop latencies
                                         4.11.0-rc1            4.11.0-rc1
                                            vanilla          keepawake-v2
Amean    p50-Read             21670074.18 (  0.00%) 22668332.52 ( -4.61%)
Amean    p95-Read             25456267.64 (  0.00%) 26738688.00 ( -5.04%)
Amean    p99-Read             29369064.73 (  0.00%) 30991404.52 ( -5.52%)
Amean    p50-Write                1390.30 (  0.00%)      924.91 ( 33.47%)
Amean    p95-Write              412901.57 (  0.00%)     1362.62 ( 99.67%)
Amean    p99-Write             6668722.09 (  0.00%)    16854.04 ( 99.75%)
Amean    p50-Allocation          78714.31 (  0.00%)    74729.74 (  5.06%)
Amean    p95-Allocation         175533.51 (  0.00%)   101609.74 ( 42.11%)
Amean    p99-Allocation         247003.02 (  0.00%)   125765.57 ( 49.08%)

These are latencies.  Read/write are threads reading fixed-size random
blocks from a simulated database.  The allocation latency is mmaping and
faulting regions of memory.  The p50, 95 and p99 reports the worst
latencies for 50% of the samples, 95% and 99% respectively.

For example, the report indicates that while the test was running 99% of
writes completed 99.75% faster.  It's worth noting that on a UMA machine
that no difference in performance with simoop was observed so milage
will vary.

It's noted that there is a slight impact to read latencies but it's
mostly due to IO scheduler decisions and offset by the large reduction
in other latencies.

This patch (of 3):

The check in prepare_kswapd_sleep needs to match the one in
balance_pgdat since the latter will return as soon as any one of the
zones in the classzone is above the watermark.  This is specially
important for higher order allocations since balance_pgdat will
typically reset the order to zero relying on compaction to create the
higher order pages.  Without this patch, prepare_kswapd_sleep fails to
wake up kcompactd since the zone balance check fails.

It was first reported against 4.9.7 that kswapd is failing to wake up
kcompactd due to a mismatch in the zone balance check between
balance_pgdat() and prepare_kswapd_sleep().

balance_pgdat() returns as soon as a single zone satisfies the
allocation but prepare_kswapd_sleep() requires all zones to do +the
same.  This causes prepare_kswapd_sleep() to never succeed except in the
order == 0 case and consequently, wakeup_kcompactd() is never called.
For the machine that originally motivated this patch, the state of
compaction from /proc/vmstat looked this way after a day and a half +of
uptime:

compact_migrate_scanned 240496
compact_free_scanned 76238632
compact_isolated 123472
compact_stall 1791
compact_fail 29
compact_success 1762
compact_daemon_wake 0

After applying the patch and about 10 hours of uptime the state looks
like this:

compact_migrate_scanned 59927299
compact_free_scanned 2021075136
compact_isolated 640926
compact_stall 4
compact_fail 2
compact_success 2
compact_daemon_wake 5160

Further notes from Mel that motivated him to pick this patch up and
resend it;

It was observed for the simoop workload (pressures the VM similar to
HADOOP) that kswapd was failing to keep ahead of direct reclaim.  The
investigation noted that there was a need to rationalise kswapd
decisions to reclaim with kswapd decisions to sleep.  With this patch on
a 2-socket box, there was a 49% reduction in direct reclaim scanning.

However, the impact otherwise is extremely negative.  Kswapd reclaim
efficiency dropped from 98% to 76%.  simoop has three latency-related
metrics for read, write and allocation (an anonymous mmap and fault).

                                         4.11.0-rc1            4.11.0-rc1
                                            vanilla           fixcheck-v2
Amean    p50-Read             21670074.18 (  0.00%) 20464344.18 (  5.56%)
Amean    p95-Read             25456267.64 (  0.00%) 25721423.64 ( -1.04%)
Amean    p99-Read             29369064.73 (  0.00%) 30174230.76 ( -2.74%)
Amean    p50-Write                1390.30 (  0.00%)     1395.28 ( -0.36%)
Amean    p95-Write              412901.57 (  0.00%)    37737.74 ( 90.86%)
Amean    p99-Write             6668722.09 (  0.00%)   666489.04 ( 90.01%)
Amean    p50-Allocation          78714.31 (  0.00%)    86286.22 ( -9.62%)
Amean    p95-Allocation         175533.51 (  0.00%)   351812.27 (-100.42%)
Amean    p99-Allocation         247003.02 (  0.00%)  6291171.56 (-2447.00%)

Of greater concern is that the patch causes swapping and page writes
from kswapd context rose from 0 pages to 4189753 pages during the hour
the workload ran for.  By and large, the patch has very bad behaviour
but easily missed as the impact on a UMA machine is negligible.

This patch is included with the data in case a bisection leads to this
area.  This patch is also a pre-requisite for the rest of the series.

Link: http://lkml.kernel.org/r/20170309075657.25121-2-mgorman@techsingularity.netSigned-off-by: NShantanu Goel <sgoel01@yahoo.com>
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

With the discussion[1], I found it seems there are every PageFlags
functions return bool at this moment so we don't need double negation
any more.  Although it's not a problem to keep it, it makes future users
confused to use double negation for them, too.

Remove such possibility.

[1] https://marc.info/?l=linux-kernel&m=148881578820434

Frankly sepaking, I like every PageFlags to return bool instead of int.
It will make it clear.  AFAIR, Chen Gang had tried it but don't know why
it was not merged at that time.

http://lkml.kernel.org/r/1469336184-1904-1-git-send-email-chengang@emindsoft.com.cn

Link: http://lkml.kernel.org/r/1488868597-32222-1-git-send-email-minchan@kernel.orgSigned-off-by: NMinchan Kim <minchan@kernel.org>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since commit 3ad38ceb ("x86/mm: Remove CONFIG_DEBUG_NX_TEST"),
nothing is using the exported rodata_test_data variable, so drop the
export.

This additionally updates the pr_fmt to avoid redundant strings and
adjusts some whitespace.

Link: http://lkml.kernel.org/r/20170307005313.GA85809@beastSigned-off-by: NKees Cook <keescook@chromium.org>
Cc: Jinbum Park <jinb.park7@gmail.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The round_up() macro generates a couple of unnecessary instructions
in this usage:

    48cd:       49 8b 47 50             mov    0x50(%r15),%rax
    48d1:       48 83 e8 01             sub    $0x1,%rax
    48d5:       48 0d ff 0f 00 00       or     $0xfff,%rax
    48db:       48 83 c0 01             add    $0x1,%rax
    48df:       48 c1 f8 0c             sar    $0xc,%rax
    48e3:       48 39 c3                cmp    %rax,%rbx
    48e6:       72 2e                   jb     4916 <filemap_fault+0x96>

If we change round_up() to ((x) + __round_mask(x, y)) & ~__round_mask(x, y)
then GCC can see through it and remove the mask (because that would be
dead code given the subsequent shift):

    48cd:       49 8b 47 50             mov    0x50(%r15),%rax
    48d1:       48 05 ff 0f 00 00       add    $0xfff,%rax
    48d7:       48 c1 e8 0c             shr    $0xc,%rax
    48db:       48 39 c3                cmp    %rax,%rbx
    48de:       72 2e                   jb     490e <filemap_fault+0x8e>

But that's problematic because we'd evaluate 'y' twice.  Converting
round_up into an inline function prevents it from being used in other
definitions.  The easiest thing to do is just change these three usages
of round_up to use DIV_ROUND_UP.  Also add an unlikely() because GCC's
heuristic is wrong in this case.

Link: http://lkml.kernel.org/r/20170207192812.5281-1-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kjournald2 is central to the transaction commit processing.  As such any
potential allocation from this kernel thread has to be GFP_NOFS.  Make
sure to mark the whole kernel thread GFP_NOFS by the memalloc_nofs_save.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170306131408.9828-8-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Suggested-by: NJan Kara <jack@suse.cz>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

now that we have memalloc_nofs_{save,restore} api we can mark the whole
transaction context as implicitly GFP_NOFS.  All allocations will
automatically inherit GFP_NOFS this way.  This means that we do not have
to mark any of those requests with GFP_NOFS and moreover all the
ext4_kv[mz]alloc(GFP_NOFS) are also safe now because even the hardcoded
GFP_KERNEL allocations deep inside the vmalloc will be NOFS now.

[akpm@linux-foundation.org: tweak comments]
Link: http://lkml.kernel.org/r/20170306131408.9828-7-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kmem_zalloc_large and _xfs_buf_map_pages use memalloc_noio_{save,restore}
API to prevent from reclaim recursion into the fs because vmalloc can
invoke unconditional GFP_KERNEL allocations and these functions might be
called from the NOFS contexts.  The memalloc_noio_save will enforce
GFP_NOIO context which is even weaker than GFP_NOFS and that seems to be
unnecessary.  Let's use memalloc_nofs_{save,restore} instead as it
should provide exactly what we need here - implicit GFP_NOFS context.

Link: http://lkml.kernel.org/r/20170306131408.9828-6-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>