Update Kconfig and add a depricated warning.

[raven@themaw.net: make autofs4 Kconfig depend on AUTOFS_FS]
  Link: http://lkml.kernel.org/r/152687649097.8263.7046086367407522029.stgit@pluto.themaw.net
Link: http://lkml.kernel.org/r/152626706133.28589.11994171621899212952.stgit@pluto.themaw.netSigned-off-by: NIan Kent <raven@themaw.net>
Tested-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Copy source files from the autofs4 directory to the autofs directory.

Link: http://lkml.kernel.org/r/152626705013.28589.931913083997578251.stgit@pluto.themaw.netSigned-off-by: NIan Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Update naming within autofs source to be consistent by changing
occurrences of autofs4 to autofs.

Link: http://lkml.kernel.org/r/152626703688.28589.8315406711135226803.stgit@pluto.themaw.netSigned-off-by: NIan Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The autofs module has long since been removed so there's no need to have
two separate include files for autofs.

Link: http://lkml.kernel.org/r/152626703024.28589.9571964661718767929.stgit@pluto.themaw.netSigned-off-by: NIan Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

WHen registering a new binfmt_misc handler, it is possible to overflow
the offset to get a negative value, which might crash the system, or
possibly leak kernel data.

Here is a crash log when 2500000000 was used as an offset:

  BUG: unable to handle kernel paging request at ffff989cfd6edca0
  IP: load_misc_binary+0x22b/0x470 [binfmt_misc]
  PGD 1ef3e067 P4D 1ef3e067 PUD 0
  Oops: 0000 [#1] SMP NOPTI
  Modules linked in: binfmt_misc kvm_intel ppdev kvm irqbypass joydev input_leds serio_raw mac_hid parport_pc qemu_fw_cfg parpy
  CPU: 0 PID: 2499 Comm: bash Not tainted 4.15.0-22-generic #24-Ubuntu
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.1-1 04/01/2014
  RIP: 0010:load_misc_binary+0x22b/0x470 [binfmt_misc]
  Call Trace:
    search_binary_handler+0x97/0x1d0
    do_execveat_common.isra.34+0x667/0x810
    SyS_execve+0x31/0x40
    do_syscall_64+0x73/0x130
    entry_SYSCALL_64_after_hwframe+0x3d/0xa2

Use kstrtoint instead of simple_strtoul.  It will work as the code
already set the delimiter byte to '\0' and we only do it when the field
is not empty.

Tested with offsets -1, 2500000000, UINT_MAX and INT_MAX.  Also tested
with examples documented at Documentation/admin-guide/binfmt-misc.rst
and other registrations from packages on Ubuntu.

Link: http://lkml.kernel.org/r/20180529135648.14254-1-cascardo@canonical.com
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: NThadeu Lima de Souza Cascardo <cascardo@canonical.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There are mode change and rename only patches that are unrecognized by
checkpatch.

Recognize them.

[joe@perches.com: fix missing close parenthesis]
  Link: http://lkml.kernel.org/r/af44c893f6973393f2a5b11f1a8e5cd4c8bbbba5.camel@perches.com
Link: http://lkml.kernel.org/r/974a407e6fa18abd5a965da39cc68986a4c4f091.1526949367.git.joe@perches.comSigned-off-by: NJoe Perches <joe@perches.com>
Reported-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix missing MODULE_LICENSE() warning in lib/ucs2_string.c:

  WARNING: modpost: missing MODULE_LICENSE() in lib/ucs2_string.o
  see include/linux/module.h for more information

Link: http://lkml.kernel.org/r/b2505bb4-dcf5-fc46-443d-e47db1cb2f59@infradead.orgSigned-off-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

MPI headers contain definitions for huge number of non-existing
functions.

Most part of these functions was removed in 2012 by Dmitry Kasatkin
 - 7cf4206a ("Remove unused code from MPI library")
 - 9e235dca ("Revert "crypto: GnuPG based MPI lib - additional ...")
 - bc95eead ("lib/mpi: removed unused functions")
however headers wwere not updated properly.

Also I deleted some unused macros.

Link: http://lkml.kernel.org/r/fb2fc1ef-1185-f0a3-d8d0-173d2f97bbaf@virtuozzo.comSigned-off-by: NVasily Averin <vvs@virtuozzo.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

percpu_ida() decouples disabling interrupts from the locking operations.
This breaks some assumptions if the locking operations are replaced like
they are under -RT.

The same locking can be achieved by avoiding local_irq_save() and using
spin_lock_irqsave() instead.  percpu_ida_alloc() gains one more preemption
point because after unlocking the fastpath and before the pool lock is
acquired, the interrupts are briefly enabled.

Link: http://lkml.kernel.org/r/20180504153218.7301-1-bigeasy@linutronix.deSigned-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Improve the scalability of the IDA by using the per-IDA xa_lock rather
than the global simple_ida_lock.  IDAs are not typically used in
performance-sensitive locations, but since we have this lock anyway, we
can use it.  It is also a step towards converting the IDA from the radix
tree to the XArray.

[akpm@linux-foundation.org: idr.c needs xarray.h]
Link: http://lkml.kernel.org/r/20180331125332.GF13332@bombadil.infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use BITS_TO_LONGS() macro to avoid calculation of reminder (bits %
BITS_PER_LONG) On ARM64 it saves 5 instruction for function - 16 before
and 11 after.

Link: http://lkml.kernel.org/r/20180411145914.6011-1-ynorov@caviumnetworks.comSigned-off-by: NYury Norov <ynorov@caviumnetworks.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There are mode change and rename only patches that are unrecognized
by the get_maintainer.pl script.

Recognize them.

Link: http://lkml.kernel.org/r/bf63101a908d0ff51948164aa60e672368066186.1526949367.git.joe@perches.comSigned-off-by: NJoe Perches <joe@perches.com>
Reported-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When we get a hung task it can often be valuable to see _all_ the hung
tasks on the system before calling panic().

Quoting from https://syzkaller.appspot.com/text?tag=CrashReport&id=5316056503549952
----------------------------------------
INFO: task syz-executor0:6540 blocked for more than 120 seconds.
      Not tainted 4.16.0+ #13
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D23560  6540   4521 0x80000004
Call Trace:
 context_switch kernel/sched/core.c:2848 [inline]
 __schedule+0x8fb/0x1ef0 kernel/sched/core.c:3490
 schedule+0xf5/0x430 kernel/sched/core.c:3549
 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3607
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0xb7f/0x1810 kernel/locking/mutex.c:893
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
 lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355
 __blkdev_driver_ioctl block/ioctl.c:303 [inline]
 blkdev_ioctl+0x1759/0x1e00 block/ioctl.c:601
 ioctl_by_bdev+0xa5/0x110 fs/block_dev.c:2060
 isofs_get_last_session fs/isofs/inode.c:567 [inline]
 isofs_fill_super+0x2ba9/0x3bc0 fs/isofs/inode.c:660
 mount_bdev+0x2b7/0x370 fs/super.c:1119
 isofs_mount+0x34/0x40 fs/isofs/inode.c:1560
 mount_fs+0x66/0x2d0 fs/super.c:1222
 vfs_kern_mount.part.26+0xc6/0x4a0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:2514 [inline]
 do_new_mount fs/namespace.c:2517 [inline]
 do_mount+0xea4/0x2b90 fs/namespace.c:2847
 ksys_mount+0xab/0x120 fs/namespace.c:3063
 SYSC_mount fs/namespace.c:3077 [inline]
 SyS_mount+0x39/0x50 fs/namespace.c:3074
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
(...snipped...)
Showing all locks held in the system:
(...snipped...)
2 locks held by syz-executor0/6540:
 #0: 00000000566d4c39 (&type->s_umount_key#49/1){+.+.}, at: alloc_super fs/super.c:211 [inline]
 #0: 00000000566d4c39 (&type->s_umount_key#49/1){+.+.}, at: sget_userns+0x3b2/0xe60 fs/super.c:502 /* down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); */
 #1: 0000000043ca8836 (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 /* mutex_lock_nested(&lo->lo_ctl_mutex, 1); */
(...snipped...)
3 locks held by syz-executor7/6541:
 #0: 0000000043ca8836 (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 /* mutex_lock_nested(&lo->lo_ctl_mutex, 1); */
 #1: 000000007bf3d3f9 (&bdev->bd_mutex){+.+.}, at: blkdev_reread_part+0x1e/0x40 block/ioctl.c:192
 #2: 00000000566d4c39 (&type->s_umount_key#50){.+.+}, at: __get_super.part.10+0x1d3/0x280 fs/super.c:663 /* down_read(&sb->s_umount); */
----------------------------------------

When reporting an AB-BA deadlock like shown above, it would be nice if
trace of PID=6541 is printed as well as trace of PID=6540 before calling
panic().

Showing hung tasks up to /proc/sys/kernel/hung_task_warnings could delay
calling panic() but normally there should not be so many hung tasks.

Link: http://lkml.kernel.org/r/201804050705.BHE57833.HVFOFtSOMQJFOL@I-love.SAKURA.ne.jpSigned-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This header file is not exported.  It is safe to reference types without
double-underscore prefix.

Link: http://lkml.kernel.org/r/1526350925-14922-3-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Lihao Liang <lianglihao@huawei.com>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

<uapi/linux/types.h> has the same typedefs except that it prefixes them
with double-underscore for user space.  Use them for the kernel space
typedefs.

Link: http://lkml.kernel.org/r/1526350925-14922-2-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Lihao Liang <lianglihao@huawei.com>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

<uapi/asm-generic/int-ll64.h> has the same typedefs except that it
prefixes them with double-underscore for user space.  Use them for
the kernel space typedefs.

Link: http://lkml.kernel.org/r/1526350925-14922-1-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Lihao Liang <lianglihao@huawei.com>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* Test lookup in /proc/self/fd.
  "map_files" lookup story showed that lookup is not that simple.

* Test that all those symlinks open the same file.
  Check with (st_dev, st_info).

* Test that kernel threads do not have anything in their /proc/*/fd/
  directory.

Now this is where things get interesting.

First, kernel threads aren't pinned by /proc/self or equivalent,
thus some "atomicity" is required.

Second, ->comm can contain whitespace and ')'.
No, they are not escaped.

Third, the only reliable way to check if process is kernel thread
appears to be field #9 in /proc/*/stat.

This field is struct task_struct::flags in decimal!
Check is done by testing PF_KTHREAD flags like we do in kernel.

	PF_KTREAD value is a part of userspace ABI !!!

Other methods for determining kernel threadness are not reliable:
* RSS can be 0 if everything is swapped, even while reading
  from /proc/self.

* ->total_vm CAN BE ZERO if process is finishing

	munmap(NULL, whole address space);

* /proc/*/maps and similar files can be empty because unmapping
  everything works. Read returning 0 can't distinguish between
  kernel thread and such suicide process.

Link: http://lkml.kernel.org/r/20180505000414.GA15090@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

struct stack_trace::nr_entries is defined as "unsigned int" (YAY!) so
the iterator should be unsigned as well.

It saves 1 byte of code or something like that.

Link: http://lkml.kernel.org/r/20180423215248.GG9043@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It's defined as atomic_t and really long signal queues are unheard of.

Link: http://lkml.kernel.org/r/20180423215119.GF9043@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

All those lengths are unsigned as they should be.

Link: http://lkml.kernel.org/r/20180423213751.GC9043@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

struct kstat is thread local.

Link: http://lkml.kernel.org/r/20180423213626.GB9043@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Code can be sonsolidated if a dummy region of 0 length is used in normal
case of \0-separated command line:

1) [arg_start, arg_end) + [dummy len=0]
2) [arg_start, arg_end) + [env_start, env_end)

Link: http://lkml.kernel.org/r/20180221193335.GB28678@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

"rv" variable is used both as a counter of bytes transferred and an
error value holder but it can be reduced solely to error values if
original start of userspace buffer is stashed and used at the very end.

[akpm@linux-foundation.org: simplify cleanup code]
Link: http://lkml.kernel.org/r/20180221193009.GA28678@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

"final" variable is OK but we can get away with less lines.

Link: http://lkml.kernel.org/r/20180221192751.GC28548@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

access_remote_vm() doesn't return negative errors, it returns number of
bytes read/written (0 if error occurs).  This allows to delete some
comparisons which never trigger.

Reuse "nr_read" variable while I'm at it.

Link: http://lkml.kernel.org/r/20180221192605.GB28548@avx2Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When commit bd33ef36 ("mm: enable page poisoning early at boot") got
rid of the PAGE_EXT_DEBUG_POISON, page_is_poisoned in the header left
behind.  This patch cleans up the leftovers under the table.

Link: http://lkml.kernel.org/r/1528101069-21637-1-git-send-email-kpark3469@gmail.comSigned-off-by: NSahara <keun-o.park@darkmatter.ae>
Acked-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The LKP robot found a 27% will-it-scale/page_fault3 performance
regression regarding commit e27be240("mm: memcg: make sure
memory.events is uptodate when waking pollers").

What the test does is:
 1 mkstemp() a 128M file on a tmpfs;
 2 start $nr_cpu processes, each to loop the following:
   2.1 mmap() this file in shared write mode;
   2.2 write 0 to this file in a PAGE_SIZE step till the end of the file;
   2.3 unmap() this file and repeat this process.
 3 After 5 minutes, check how many loops they managed to complete, the
   higher the better.

The commit itself looks innocent enough as it merely changed some event
counting mechanism and this test didn't trigger those events at all.
Perf shows increased cycles spent on accessing root_mem_cgroup->stat_cpu
in count_memcg_event_mm()(called by handle_mm_fault()) and in
__mod_memcg_state() called by page_add_file_rmap().  So it's likely due
to the changed layout of 'struct mem_cgroup' that either make stat_cpu
falling into a constantly modifying cacheline or some hot fields stop
being in the same cacheline.

I verified this by moving memory_events[] back to where it was:

: --- a/include/linux/memcontrol.h
: +++ b/include/linux/memcontrol.h
: @@ -205,7 +205,6 @@ struct mem_cgroup {
:  	int		oom_kill_disable;
:
:  	/* memory.events */
: -	atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
:  	struct cgroup_file events_file;
:
:  	/* protect arrays of thresholds */
: @@ -238,6 +237,7 @@ struct mem_cgroup {
:  	struct mem_cgroup_stat_cpu __percpu *stat_cpu;
:  	atomic_long_t		stat[MEMCG_NR_STAT];
:  	atomic_long_t		events[NR_VM_EVENT_ITEMS];
: +	atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
:
:  	unsigned long		socket_pressure;

And performance restored.

Later investigation found that as long as the following 3 fields
moving_account, move_lock_task and stat_cpu are in the same cacheline,
performance will be good.  To avoid future performance surprise by other
commits changing the layout of 'struct mem_cgroup', this patch makes
sure the 3 fields stay in the same cacheline.

One concern of this approach is, moving_account and move_lock_task could
be modified when a process changes memory cgroup while stat_cpu is a
always read field, it might hurt to place them in the same cacheline.  I
assume it is rare for a process to change memory cgroup so this should
be OK.

Link: https://lkml.kernel.org/r/20180528114019.GF9904@yexl-desktop
Link: http://lkml.kernel.org/r/20180601071115.GA27302@intel.comSigned-off-by: NAaron Lu <aaron.lu@intel.com>
Reported-by: Nkernel test robot <xiaolong.ye@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kvmalloc warned about incompatible gfp_mask to catch abusers (mostly
GFP_NOFS) with an intention that this will motivate authors of the code
to fix those.  Linus argues that this just motivates people to do even
more hacks like

	if (gfp == GFP_KERNEL)
		kvmalloc
	else
		kmalloc

I haven't seen this happening much (Linus pointed to bucket_lock special
cases an atomic allocation but my git foo hasn't found much more) but it
is true that we can grow those in future.  Therefore Linus suggested to
simply not fallback to vmalloc for incompatible gfp flags and rather
stick with the kmalloc path.

Link: http://lkml.kernel.org/r/20180601115329.27807-1-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Tom Herbert <tom@quantonium.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When bit is equal to 0x4, it means OPT_ZONE_DMA32 should be got from
GFP_ZONE_TABLE.  OPT_ZONE_DMA32 shall be equal to ZONE_DMA32 or
ZONE_NORMAL according to the status of CONFIG_ZONE_DMA32.

Similarly, when bit is equal to 0xc, that means OPT_ZONE_DMA32 should be
got with an allocation policy GFP_MOVABLE.  So ZONE_DMA32 or ZONE_NORMAL
is the possible result value.

Link: http://lkml.kernel.org/r/20180601163403.1032-1-yehs2007@zoho.comSigned-off-by: NHuaisheng Ye <yehs1@lenovo.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

shmem/tmpfs uses pseudo vma to allocate page with correct NUMA policy.

The pseudo vma doesn't have vm_page_prot set.  We are going to encode
encryption KeyID in vm_page_prot.  Having garbage there causes problems.

Zero out all unused fields in the pseudo vma.

Link: http://lkml.kernel.org/r/20180531135602.20321-1-kirill.shutemov@linux.intel.comSigned-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In __alloc_pages_slowpath() we reset zonelist and preferred_zoneref for
allocations that can ignore memory policies.  The zonelist is obtained
from current CPU's node.  This is a problem for __GFP_THISNODE
allocations that want to allocate on a different node, e.g.  because the
allocating thread has been migrated to a different CPU.

This has been observed to break SLAB in our 4.4-based kernel, because
there it relies on __GFP_THISNODE working as intended.  If a slab page
is put on wrong node's list, then further list manipulations may corrupt
the list because page_to_nid() is used to determine which node's
list_lock should be locked and thus we may take a wrong lock and race.

Current SLAB implementation seems to be immune by luck thanks to commit
511e3a05 ("mm/slab: make cache_grow() handle the page allocated on
arbitrary node") but there may be others assuming that __GFP_THISNODE
works as promised.

We can fix it by simply removing the zonelist reset completely.  There
is actually no reason to reset it, because memory policies and cpusets
don't affect the zonelist choice in the first place.  This was different
when commit 183f6371 ("mm: ignore mempolicies when using
ALLOC_NO_WATERMARK") introduced the code, as mempolicies provided their
own restricted zonelists.

We might consider this for 4.17 although I don't know if there's
anything currently broken.

SLAB is currently not affected, but in kernels older than 4.7 that don't
yet have 511e3a05 ("mm/slab: make cache_grow() handle the page
allocated on arbitrary node") it is.  That's at least 4.4 LTS.  Older
ones I'll have to check.

So stable backports should be more important, but will have to be
reviewed carefully, as the code went through many changes.  BTW I think
that also the ac->preferred_zoneref reset is currently useless if we
don't also reset ac->nodemask from a mempolicy to NULL first (which we
probably should for the OOM victims etc?), but I would leave that for a
separate patch.

Link: http://lkml.kernel.org/r/20180525130853.13915-1-vbabka@suse.czSigned-off-by: NVlastimil Babka <vbabka@suse.cz>
Fixes: 183f6371 ("mm: ignore mempolicies when using ALLOC_NO_WATERMARK")
Acked-by: NMel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If a process monitored with userfaultfd changes it's memory mappings or
forks() at the same time as uffd monitor fills the process memory with
UFFDIO_COPY, the actual creation of page table entries and copying of
the data in mcopy_atomic may happen either before of after the memory
mapping modifications and there is no way for the uffd monitor to
maintain consistent view of the process memory layout.

For instance, let's consider fork() running in parallel with
userfaultfd_copy():

process        		         |	uffd monitor
---------------------------------+------------------------------
fork()        		         | userfaultfd_copy()
...        		         | ...
    dup_mmap()        	         |     down_read(mmap_sem)
    down_write(mmap_sem)         |     /* create PTEs, copy data */
        dup_uffd()               |     up_read(mmap_sem)
        copy_page_range()        |
        up_write(mmap_sem)       |
        dup_uffd_complete()      |
            /* notify monitor */ |

If the userfaultfd_copy() takes the mmap_sem first, the new page(s) will
be present by the time copy_page_range() is called and they will appear
in the child's memory mappings.  However, if the fork() is the first to
take the mmap_sem, the new pages won't be mapped in the child's address
space.

If the pages are not present and child tries to access them, the monitor
will get page fault notification and everything is fine.  However, if
the pages *are present*, the child can access them without uffd
noticing.  And if we copy them into child it'll see the wrong data.
Since we are talking about background copy, we'd need to decide whether
the pages should be copied or not regardless #PF notifications.

Since userfaultfd monitor has no way to determine what was the order,
let's disallow userfaultfd_copy in parallel with the non-cooperative
events.  In such case we return -EAGAIN and the uffd monitor can
understand that userfaultfd_copy() clashed with a non-cooperative event
and take an appropriate action.

Link: http://lkml.kernel.org/r/1527061324-19949-1-git-send-email-rppt@linux.vnet.ibm.comSigned-off-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: NPavel Emelyanov <xemul@virtuozzo.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently an attempt to set swap.max into a value lower than the actual
swap usage fails, which causes configuration problems as there's no way
of lowering the configuration below the current usage short of turning
off swap entirely.  This makes swap.max difficult to use and allows
delegatees to lock the delegator out of reducing swap allocation.

This patch updates swap_max_write() so that the limit can be lowered
below the current usage.  It doesn't implement active reclaiming of swap
entries for the following reasons.

* mem_cgroup_swap_full() already tells the swap machinary to
  aggressively reclaim swap entries if the usage is above 50% of
  limit, so simply lowering the limit automatically triggers gradual
  reclaim.

* Forcing back swapped out pages is likely to heavily impact the
  workload and mess up the working set.  Given that swap usually is a
  lot less valuable and less scarce, letting the existing usage
  dissipate over time through the above gradual reclaim and as they're
  falted back in is likely the better behavior.

Link: http://lkml.kernel.org/r/20180523185041.GR1718769@devbig577.frc2.facebook.comSigned-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NRoman Gushchin <guro@fb.com>
Acked-by: NRik van Riel <riel@surriel.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use new return type vm_fault_t for fault handler.  For now, this is just
documenting that the function returns a VM_FAULT value rather than an
errno.  Once all instances are converted, vm_fault_t will become a
distinct type.

See commit 1c8f4220 ("mm: change return type to vm_fault_t")

vmf_error() is the newly introduce inline function in 4.17-rc6.

Link: http://lkml.kernel.org/r/20180521202410.GA17912@jordon-HP-15-Notebook-PCSigned-off-by: NSouptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: NMatthew Wilcox <mawilcox@microsoft.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Christoph doubts anyone was using the 'reserved' file in sysfs, so remove
it.

Link: http://lkml.kernel.org/r/20180518194519.3820-17-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The reserved field was only used for embedding an rcu_head in the data
structure.  With the previous commit, we no longer need it.  That lets us
remove the 'reserved' argument to a lot of functions.

Link: http://lkml.kernel.org/r/20180518194519.3820-16-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

rcu_head may now grow larger than list_head without affecting slab or
slub.

Link: http://lkml.kernel.org/r/20180518194519.3820-15-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make hmm_data an explicit member of the struct page union.

Link: http://lkml.kernel.org/r/20180518194519.3820-14-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

For pgd page table pages, x86 overloads the page->index field to store a
pointer to the mm_struct.  Rename this to pt_mm so it's visible to other
users.

Link: http://lkml.kernel.org/r/20180518194519.3820-13-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Rewrite the documentation to describe what you can use in struct page
rather than what you can't.

Link: http://lkml.kernel.org/r/20180518194519.3820-12-willy@infradead.orgSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: NRandy Dunlap <rdunlap@infradead.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>