With enabled meta_bg option block group descriptors
reading IO is not sequential and requires optimization.
Signed-off-by: Andrew Perepechko <andrew.perepechko@seagate.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Make the ext4_shutdown() function static, as suggested by running sparse
('make C=2 fs/ext4/').  This was the only such warning in fs/ext4/.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Support the GETFSMAP ioctls so that we can use the xfs free space
management tools to probe ext4 as well.  Note that this is a partial
implementation -- we only report fixed-location metadata and free space;
everything else is reported as "unknown".
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Add the GETFSMAP headers to the VFS kernel headers
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Currently the case of writing via mmap to a file with inline data is not
handled.  This is maybe a rare case since it requires a writable memory
map of a very small file, but it is trivial to trigger with on
inline_data filesystem, and it causes the
'BUG_ON(ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA));' in
ext4_writepages() to be hit:

    mkfs.ext4 -O inline_data /dev/vdb
    mount /dev/vdb /mnt
    xfs_io -f /mnt/file \
	-c 'pwrite 0 1' \
	-c 'mmap -w 0 1m' \
	-c 'mwrite 0 1' \
	-c 'fsync'

	kernel BUG at fs/ext4/inode.c:2723!
	invalid opcode: 0000 [#1] SMP
	CPU: 1 PID: 2532 Comm: xfs_io Not tainted 4.11.0-rc1-xfstests-00301-g071d9acf3d1f #633
	Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014
	task: ffff88003d3a8040 task.stack: ffffc90000300000
	RIP: 0010:ext4_writepages+0xc89/0xf8a
	RSP: 0018:ffffc90000303ca0 EFLAGS: 00010283
	RAX: 0000028410000000 RBX: ffff8800383fa3b0 RCX: ffffffff812afcdc
	RDX: 00000a9d00000246 RSI: ffffffff81e660e0 RDI: 0000000000000246
	RBP: ffffc90000303dc0 R08: 0000000000000002 R09: 869618e8f99b4fa5
	R10: 00000000852287a2 R11: 00000000a03b49f4 R12: ffff88003808e698
	R13: 0000000000000000 R14: 7fffffffffffffff R15: 7fffffffffffffff
	FS:  00007fd3e53094c0(0000) GS:ffff88003e400000(0000) knlGS:0000000000000000
	CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
	CR2: 00007fd3e4c51000 CR3: 000000003d554000 CR4: 00000000003406e0
	Call Trace:
	 ? _raw_spin_unlock+0x27/0x2a
	 ? kvm_clock_read+0x1e/0x20
	 do_writepages+0x23/0x2c
	 ? do_writepages+0x23/0x2c
	 __filemap_fdatawrite_range+0x80/0x87
	 filemap_write_and_wait_range+0x67/0x8c
	 ext4_sync_file+0x20e/0x472
	 vfs_fsync_range+0x8e/0x9f
	 ? syscall_trace_enter+0x25b/0x2d0
	 vfs_fsync+0x1c/0x1e
	 do_fsync+0x31/0x4a
	 SyS_fsync+0x10/0x14
	 do_syscall_64+0x69/0x131
	 entry_SYSCALL64_slow_path+0x25/0x25

We could try to be smart and keep the inline data in this case, or at
least support delayed allocation when allocating the block, but these
solutions would be more complicated and don't seem worthwhile given how
rare this case seems to be.  So just fix the bug by calling
ext4_convert_inline_data() when we're asked to make a page writable, so
that any inline data gets evicted, with the block allocated immediately.
Reported-by: Nick Alcock <nick.alcock@oracle.com>
Cc: stable@vger.kernel.org
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

ext4_xattr_check_entry() was redundant with validation of the full xattr
entries list in ext4_xattr_check_entries(), which all callers also did.
ext4_xattr_check_entry() also didn't actually do correct validation;
specifically, it never checked that the value doesn't overlap the xattr
names, nor did it account for padding when checking whether the xattr
value overflows the available space.  So remove it to eliminate any
potential confusion.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

ext4_xattr_check_names() actually validates both the xattr names and
values, not just the names.  So rename it to ext4_xattr_check_entries()
to avoid confusion.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

There's no difference between ext4_xattr_list() and ext4_listxattr(), so
merge them together and just have ext4_listxattr().  Some years ago they
took different arguments, but that's no longer the case.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Constify static data in ext4 that is never (intentionally) modified so
that it is placed in .rodata and benefits from memory protection.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

In the initial implementation of ext4 encryption, the filename was
encrypted in ext4_insert_dentry(), which could fail and also required
access to the 'dir' inode.  Since then ext4 filename encryption has been
changed to encrypt the filename earlier, so we can revert the additions
to ext4_insert_dentry().
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Commit b685d3d6 "block: treat REQ_FUA and REQ_PREFLUSH as
synchronous" removed REQ_SYNC flag from WRITE_FUA implementation. Since
JBD2 strips REQ_FUA and REQ_FLUSH flags from submitted IO when the
filesystem is mounted with nobarrier mount option, journal superblock
writes ended up being async writes after this patch and that caused
heavy performance regression for dbench4 benchmark with high number of
processes. In my test setup with HP RAID array with non-volatile write
cache and 32 GB ram, dbench4 runs with 8 processes regressed by ~25%.

Fix the problem by making sure journal superblock writes are always
treated as synchronous since they generally block progress of the
journalling machinery and thus the whole filesystem.

Fixes: b685d3d6
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

I've hit a lockdep splat with generic/270 test complaining that:

3216.fsstress.b/3533 is trying to acquire lock:
 (jbd2_handle){++++..}, at: [<ffffffff813152e0>] jbd2_log_wait_commit+0x0/0x150

but task is already holding lock:
 (jbd2_handle){++++..}, at: [<ffffffff8130bd3b>] start_this_handle+0x35b/0x850

The underlying problem is that jbd2_journal_force_commit_nested()
(called from ext4_should_retry_alloc()) may get called while a
transaction handle is started. In such case it takes care to not wait
for commit of the running transaction (which would deadlock) but only
for a commit of a transaction that is already committing (which is safe
as that doesn't wait for any filesystem locks).

In fact there are also other callers of jbd2_log_wait_commit() that take
care to pass tid of a transaction that is already committing and for
those cases, the lockdep instrumentation is too restrictive and leading
to false positive reports. Fix the problem by calling
jbd2_might_wait_for_commit() from jbd2_log_wait_commit() only if the
transaction isn't already committing.

Fixes: 1eaa566dSigned-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Currently, file system's writepages() function must not fail with an
ENOMEM, since if they do, it's possible for buffered data to be lost.
This is because on a data integrity writeback writepages() gets called
but once, and if it returns ENOMEM, if you're lucky the error will get
reflected back to the userspace process calling fsync().  If you
aren't lucky, the user is unmounting the file system, and the dirty
pages will simply be lost.

For this reason, file system code generally will use GFP_NOFS, and in
some cases, will retry the allocation in a loop, on the theory that
"kernel livelocks are temporary; data loss is forever".
Unfortunately, this can indeed cause livelocks, since inside the
writepages() call, the file system is holding various mutexes, and
these mutexes may prevent the OOM killer from killing its targetted
victim if it is also holding on to those mutexes.

A better solution would be to allow writepages() to call the memory
allocator with flags that give greater latitude to the allocator to
fail, and then release its locks and return ENOMEM, and in the case of
background writeback, the writes can be retried at a later time.  In
the case of data-integrity writeback retry after waiting a brief
amount of time.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Pull CIFS fixes from Steve French:
 "This is a set of CIFS/SMB3 fixes for stable.

  There is another set of four SMB3 reconnect fixes for stable in
  progress but they are still being reviewed/tested, so didn't want to
  wait any longer to send these five below"

* 'for-next' of git://git.samba.org/sfrench/cifs-2.6:
  Reset TreeId to zero on SMB2 TREE_CONNECT
  CIFS: Fix build failure with smb2
  Introduce cifs_copy_file_range()
  SMB3: Rename clone_range to copychunk_range
  Handle mismatched open calls

Pull ARM fixes from Russell King:
 "A number of ARM fixes:

   - prevent oopses caused by dma_get_sgtable() and declared DMA
     coherent memory

   - fix boot failure on nommu caused by ID_PFR1 access

   - a number of kprobes fixes from Jon Medhurst and Masami Hiramatsu"

* 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 8665/1: nommu: access ID_PFR1 only if CPUID scheme
  ARM: dma-mapping: disallow dma_get_sgtable() for non-kernel managed memory
  arm: kprobes: Align stack to 8-bytes in test code
  arm: kprobes: Fix the return address of multiple kretprobes
  arm: kprobes: Skip single-stepping in recursing path if possible
  arm: kprobes: Allow to handle reentered kprobe on single-stepping

Merge tag 'driver-core-4.11-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core fixes from Greg KH:
 "Here are 3 small fixes for 4.11-rc6.

  One resolves a reported issue with sysfs files that NeilBrown found,
  one is a documenatation fix for the stable kernel rules, and the last
  is a small MAINTAINERS file update for kernfs"

* tag 'driver-core-4.11-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  MAINTAINERS: separate out kernfs maintainership
  sysfs: be careful of error returns from ops->show()
  Documentation: stable-kernel-rules: fix stable-tag format

Pull staging/IIO driver rfixes from Greg KH:
 "Here are a number of small IIO and staging driver fixes for 4.11-rc6.
  Nothing big here, just iio fixes for reported issues, and an ashmem
  fix for a very old bug that has been reported by a number of Android
  vendors"

* tag 'staging-4.11-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: android: ashmem: lseek failed due to no FMODE_LSEEK.
  iio: hid-sensor-attributes: Fix sensor property setting failure.
  iio: accel: hid-sensor-accel-3d: Fix duplicate scan index error
  iio: core: Fix IIO_VAL_FRACTIONAL_LOG2 for negative values
  iio: st_pressure: initialize lps22hb bootime
  iio: bmg160: reset chip when probing
  iio: cros_ec_sensors: Fix return value to get raw and calibbias data.

Pull VFS fixes from Al Viro:
 "statx followup fixes and a fix for stack-smashing on alpha"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  alpha: fix stack smashing in old_adjtimex(2)
  statx: Include a mask for stx_attributes in struct statx
  statx: Reserve the top bit of the mask for future struct expansion
  xfs: report crtime and attribute flags to statx
  ext4: Add statx support
  statx: optimize copy of struct statx to userspace
  statx: remove incorrect part of vfs_statx() comment
  statx: reject unknown flags when using NULL path
  Documentation/filesystems: fix documentation for ->getattr()

Pull block fixes from Jens Axboe:
 "Here's a pull request for 4.11-rc, fixing a set of issues mostly
  centered around the new scheduling framework. These have been brewing
  for a while, but split up into what we absolutely need in 4.11, and
  what we can defer until 4.12. These are well tested, on both single
  queue and multiqueue setups, and with and without shared tags. They
  fix several hangs that have happened in testing.

  This is obviously larger than I would have preferred at this point in
  time, but I don't think we can shave much off this and still get the
  desired results.

  In detail, this pull request contains:

   - a set of five fixes for NVMe, mostly from Christoph and one from
     Roland.

   - a series from Bart, fixing issues with dm-mq and SCSI shared tags
     and scheduling. Note that one of those patches commit messages may
     read like an optimization, but it is in fact an important fix for
     queue restarts in particular.

   - a series from Omar, most importantly fixing a hang with multiple
     hardware queues when we fail to get a driver tag. Another important
     fix in there is for resizing hardware queues, which nbd does when
     handling multiple sockets for one connection.

   - fixing an imbalance in putting the ctx for hctx request allocations
     from Minchan"

* 'for-linus' of git://git.kernel.dk/linux-block:
  blk-mq: Restart a single queue if tag sets are shared
  dm rq: Avoid that request processing stalls sporadically
  scsi: Avoid that SCSI queues get stuck
  blk-mq: Introduce blk_mq_delay_run_hw_queue()
  blk-mq: remap queues when adding/removing hardware queues
  blk-mq-sched: fix crash in switch error path
  blk-mq-sched: set up scheduler tags when bringing up new queues
  blk-mq-sched: refactor scheduler initialization
  blk-mq: use the right hctx when getting a driver tag fails
  nvmet: fix byte swap in nvmet_parse_io_cmd
  nvmet: fix byte swap in nvmet_execute_write_zeroes
  nvmet: add missing byte swap in nvmet_get_smart_log
  nvme: add missing byte swap in nvme_setup_discard
  nvme: Correct NVMF enum values to match NVMe-oF rev 1.0
  block: do not put mq context in blk_mq_alloc_request_hctx

Pull pin control fix from Linus Walleij:
 "This late fix for pin control is hopefully the last I send this cycle.

  The problem was detected early in the v4.11 release cycle and there
  has been some back and forth on how to solve it. Sadly the proper fix
  arrives late, but at least not too late.

  An issue was detected with pin control on the Freescale i.MX after the
  refactorings for more general group and function handling.

  We now have the proper fix for this"

* tag 'pinctrl-v4.11-4' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: core: Fix pinctrl_register_and_init() with pinctrl_enable()

Pull powerpc fixes from Michael Ellerman:
 "Some more powerpc fixes for 4.11:

  Headed to stable:

   - disable HFSCR[TM] if TM is not supported, fixes a potential host
     kernel crash triggered by a hostile guest, but only in
     configurations that no one uses

   - don't try to fix up misaligned load-with-reservation instructions

   - fix flush_(d|i)cache_range() called from modules on little endian
     kernels

   - add missing global TLB invalidate if cxl is active

   - fix missing preempt_disable() in crc32c-vpmsum

  And a fix for selftests build changes that went in this release:

   - selftests/powerpc: Fix standalone powerpc build

  Thanks to: Benjamin Herrenschmidt, Frederic Barrat, Oliver O'Halloran,
  Paul Mackerras"

* tag 'powerpc-4.11-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/crypto/crc32c-vpmsum: Fix missing preempt_disable()
  powerpc/mm: Add missing global TLB invalidate if cxl is active
  powerpc/64: Fix flush_(d|i)cache_range() called from modules
  powerpc: Don't try to fix up misaligned load-with-reservation instructions
  powerpc: Disable HFSCR[TM] if TM is not supported
  selftests/powerpc: Fix standalone powerpc build

In the case that compat_get_bitmap fails we do not want to copy the
bitmap to the user as it will contain uninitialized stack data and leak
sensitive data.
Signed-off-by: Chris Salls <salls@cs.ucsb.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Currently, inputting the following command will succeed but actually the
value will be truncated:

  # echo 0x12ffffffff > /proc/sys/net/ipv4/tcp_notsent_lowat

This is not friendly to the user, so instead, we should report error
when the value is larger than UINT_MAX.

Fixes: e7d316a0 ("sysctl: handle error writing UINT_MAX to u32 fields")
Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
Cc: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Separate out kernfs from driver core and add myself as a
co-maintainer.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ops->show() can return a negative error code.
Commit 65da3484 ("sysfs: correctly handle short reads on PREALLOC attrs.")
(in v4.4) caused this to be stored in an unsigned 'size_t' variable, so errors
would look like large numbers.
As a result, if an error is returned, sysfs_kf_read() will return the
value of 'count', typically 4096.

Commit 17d0774f ("sysfs: correctly handle read offset on PREALLOC attrs")
(in v4.8) extended this error to use the unsigned large 'len' as a size for
memmove().
Consequently, if ->show returns an error, then the first read() on the
sysfs file will return 4096 and could return uninitialized memory to
user-space.
If the application performs a subsequent read, this will trigger a memmove()
with extremely large count, and is likely to crash the machine is bizarre ways.

This bug can currently only be triggered by reading from an md
sysfs attribute declared with __ATTR_PREALLOC() during the
brief period between when mddev_put() deletes an mddev from
the ->all_mddevs list, and when mddev_delayed_delete() - which is
scheduled on a workqueue - completes.
Before this, an error won't be returned by the ->show()
After this, the ->show() won't be called.

I can reproduce it reliably only by putting delay like
	usleep_range(500000,700000);
early in mddev_delayed_delete(). Then after creating an
md device md0 run
  echo clear > /sys/block/md0/md/array_state; cat /sys/block/md0/md/array_state

The bug can be triggered without the usleep.

Fixes: 65da3484 ("sysfs: correctly handle short reads on PREALLOC attrs.")
Fixes: 17d0774f ("sysfs: correctly handle read offset on PREALLOC attrs")
Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

A patch documenting how to specify which kernels a particular fix should
be backported to (seemingly) inadvertently added a minus sign after the
kernel version. This particular stable-tag format had never been used
prior to this patch, and was neither present when the patch in question
was first submitted (it was added in v2 without any comment).

Drop the minus sign to avoid any confusion.

Fixes: fdc81b79 ("stable_kernel_rules: Add clause about specification of kernel versions to patch.")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

vfs_llseek will check whether the file mode has
FMODE_LSEEK, no return failure. But ashmem can be
lseek, so add FMODE_LSEEK to ashmem file.

Comment From Greg Hackmann:
	ashmem_llseek() passes the llseek() call through to the backing
	shmem file.  91360b02 ("ashmem: use vfs_llseek()") changed
	this from directly calling the file's llseek() op into a VFS
	layer call.  This also adds a check for the FMODE_LSEEK bit, so
	without that bit ashmem_llseek() now always fails with -ESPIPE.

Fixes: 91360b02 ("ashmem: use vfs_llseek()")
Signed-off-by: Shuxiao Zhang <zhangshuxiao@xiaomi.com>
Tested-by: Greg Hackmann <ghackmann@google.com>
Cc: stable <stable@vger.kernel.org> # 3.18+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull sparc fixes from David Miller:
 "Several fixes here, mostly having to due with either build errors or
  memory corruptions depending upon whether you have THP enabled or not"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
  sparc: remove unused wp_works_ok macro
  sparc32: Export vac_cache_size to fix build error
  sparc64: Fix memory corruption when THP is enabled
  sparc64: Fix kernel panic due to erroneous #ifdef surrounding pmd_write()
  arch/sparc: Avoid DCTI Couples
  sparc64: kern_addr_valid regression
  sparc64: Add support for 2G hugepages
  sparc64: Fix size check in huge_pte_alloc

Pull KVM fixes from Radim Krčmář:
 "ARM:
   - Fix a problem with GICv3 userspace save/restore
   - Clarify GICv2 userspace save/restore ABI
   - Be more careful in clearing GIC LRs
   - Add missing synchronization primitive to our MMU handling code

  PPC:
   - Check for a NULL return from kzalloc

  s390:
   - Prevent translation exception errors on valid page tables for the
     instruction-exection-protection support

  x86:
   - Fix Page-Modification Logging when running a nested guest"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: PPC: Book3S HV: Check for kmalloc errors in ioctl
  KVM: nVMX: initialize PML fields in vmcs02
  KVM: nVMX: do not leak PML full vmexit to L1
  KVM: arm/arm64: vgic: Fix GICC_PMR uaccess on GICv3 and clarify ABI
  KVM: arm64: Ensure LRs are clear when they should be
  kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd
  KVM: s390: remove change-recording override support
  arm/arm64: KVM: Take mmap_sem in kvm_arch_prepare_memory_region
  arm/arm64: KVM: Take mmap_sem in stage2_unmap_vm

Pull audit cleanup from Paul Moore:
 "A week later than I had hoped, but as promised, here is the audit
  uninline-fix we talked about during the last audit pull request.

  The patch is slightly different than what we originally discussed as
  it made more sense to keep the audit_signal_info() function in
  auditsc.c rather than move it and bunch of other related
  variables/definitions into audit.c/audit.h.

  At some point in the future I need to look at how the audit code is
  organized across kernel/audit*, I suspect we could do things a bit
  better, but it doesn't seem like a -rc release is a good place for
  that ;)

  Regardless, this patch passes our tests without problem and looks good
  for v4.11"

* 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit:
  audit: move audit_signal_info() into kernel/auditsc.c

Merge misc fixes from Andrew Morton:
 "10 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm: move pcp and lru-pcp draining into single wq
  mailmap: update Yakir Yang email address
  mm, swap_cgroup: reschedule when neeed in swap_cgroup_swapoff()
  dax: fix radix tree insertion race
  mm, thp: fix setting of defer+madvise thp defrag mode
  ptrace: fix PTRACE_LISTEN race corrupting task->state
  vmlinux.lds: add missing VMLINUX_SYMBOL macros
  mm/page_alloc.c: fix print order in show_free_areas()
  userfaultfd: report actual registered features in fdinfo
  mm: fix page_vma_mapped_walk() for ksm pages

We currently have 2 specific WQ_RECLAIM workqueues in the mm code.
vmstat_wq for updating pcp stats and lru_add_drain_wq dedicated to drain
per cpu lru caches.  This seems more than necessary because both can run
on a single WQ.  Both do not block on locks requiring a memory
allocation nor perform any allocations themselves.  We will save one
rescuer thread this way.

On the other hand drain_all_pages() queues work on the system wq which
doesn't have rescuer and so this depend on memory allocation (when all
workers are stuck allocating and new ones cannot be created).

Initially we thought this would be more of a theoretical problem but
Hugh Dickins has reported:

: 4.11-rc has been giving me hangs after hours of swapping load.  At
: first they looked like memory leaks ("fork: Cannot allocate memory");
: but for no good reason I happened to do "cat /proc/sys/vm/stat_refresh"
: before looking at /proc/meminfo one time, and the stat_refresh stuck
: in D state, waiting for completion of flush_work like many kworkers.
: kthreadd waiting for completion of flush_work in drain_all_pages().

This worker should be using WQ_RECLAIM as well in order to guarantee a
forward progress.  We can reuse the same one as for lru draining and
vmstat.

Link: http://lkml.kernel.org/r/20170307131751.24936-1-mhocko@kernel.orgSigned-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Tested-by: Yang Li <pku.leo@gmail.com>
Tested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Set current email address to replace previous employers email addresses.

Link: http://lkml.kernel.org/r/1491450722-6633-1-git-send-email-jeffy.chen@rock-chips.comSigned-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We got need_resched() warnings in swap_cgroup_swapoff() because
swap_cgroup_ctrl[type].length is particularly large.

Reschedule when needed.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1704061315270.80559@chino.kir.corp.google.comSigned-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

While running generic/340 in my test setup I hit the following race.  It
can happen with kernels that support FS DAX PMDs, so v4.10 thru
v4.11-rc5.

Thread 1				Thread 2
--------				--------
dax_iomap_pmd_fault()
  grab_mapping_entry()
    spin_lock_irq()
    get_unlocked_mapping_entry()
    'entry' is NULL, can't call lock_slot()
    spin_unlock_irq()
    radix_tree_preload()
					dax_iomap_pmd_fault()
					  grab_mapping_entry()
					    spin_lock_irq()
					    get_unlocked_mapping_entry()
					    ...
					    lock_slot()
					    spin_unlock_irq()
					  dax_pmd_insert_mapping()
					    <inserts a PMD mapping>
    spin_lock_irq()
    __radix_tree_insert() fails with -EEXIST
    <fall back to 4k fault, and die horribly
     when inserting a 4k entry where a PMD exists>

The issue is that we have to drop mapping->tree_lock while calling
radix_tree_preload(), but since we didn't have a radix tree entry to
lock (unlike in the pmd_downgrade case) we have no protection against
Thread 2 coming along and inserting a PMD at the same index.  For 4k
entries we handled this with a special-case response to -EEXIST coming
from the __radix_tree_insert(), but this doesn't save us for PMDs
because the -EEXIST case can also mean that we collided with a 4k entry
in the radix tree at a different index, but one that is covered by our
PMD range.

So, correctly handle both the 4k and 2M collision cases by explicitly
re-checking the radix tree for an entry at our index once we reacquire
mapping->tree_lock.

This patch has made it through a clean xfstests run with the current
v4.11-rc5 based linux/master, and it also ran generic/340 500 times in a
loop.  It used to fail within the first 10 iterations.

Link: http://lkml.kernel.org/r/20170406212944.2866-1-ross.zwisler@linux.intel.comSigned-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: <stable@vger.kernel.org>    [4.10+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Setting thp defrag mode of "defer+madvise" actually sets "defer" in the
kernel due to the name similarity and the out-of-order way the string is
checked in defrag_store().

Check the string in the correct order so that
TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG is set appropriately for
"defer+madvise".

Fixes: 21440d7e ("mm, thp: add new defer+madvise defrag option")
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1704051814420.137626@chino.kir.corp.google.comSigned-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In PT_SEIZED + LISTEN mode STOP/CONT signals cause a wakeup against
__TASK_TRACED.  If this races with the ptrace_unfreeze_traced at the end
of a PTRACE_LISTEN, this can wake the task /after/ the check against
__TASK_TRACED, but before the reset of state to TASK_TRACED.  This
causes it to instead clobber TASK_WAKING, allowing a subsequent wakeup
against TRACED while the task is still on the rq wake_list, corrupting
it.

Oleg said:
 "The kernel can crash or this can lead to other hard-to-debug problems.
  In short, "task->state = TASK_TRACED" in ptrace_unfreeze_traced()
  assumes that nobody else can wake it up, but PTRACE_LISTEN breaks the
  contract. Obviusly it is very wrong to manipulate task->state if this
  task is already running, or WAKING, or it sleeps again"

[akpm@linux-foundation.org: coding-style fixes]
Fixes: 9899d11f ("ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL")
Link: http://lkml.kernel.org/r/xm26y3vfhmkp.fsf_-_@bsegall-linux.mtv.corp.google.comSigned-off-by: Ben Segall <bsegall@google.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When __{start,end}_ro_after_init is referenced from C code, we run into
the following build errors on blackfin:

  kernel/extable.c:169: undefined reference to `__start_ro_after_init'
  kernel/extable.c:169: undefined reference to `__end_ro_after_init'

The build error is due to the fact that blackfin is one of the few
arches that prepends an underscore '_' to all symbols defined in C.

Fix this by wrapping __{start,end}_ro_after_init in vmlinux.lds.h with
VMLINUX_SYMBOL(), which adds the necessary prefix for arches that have
HAVE_UNDERSCORE_SYMBOL_PREFIX.

Link: http://lkml.kernel.org/r/1491259387-15869-1-git-send-email-jeyu@redhat.comSigned-off-by: Jessica Yu <jeyu@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Eddie Kovsky <ewk@edkovsky.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Fixes: 11fb9989 ("mm: move most file-based accounting to the node")
Link: http://lkml.kernel.org/r/1490377730.30219.2.camel@beget.ruSigned-off-by: Alexander Polyakov <apolyakov@beget.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>	[4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>