Without memcg, there is a one-to-one mapping between the bdi and
bdi_writeback structures.  In this world, things are fairly
straightforward; the first thing bdi_unregister() does is to shutdown
the bdi_writeback structure (or wb), and part of that writeback ensures
that no other work queued against the wb, and that the wb is fully
drained.

With memcg, however, there is a one-to-many relationship between the bdi
and bdi_writeback structures; that is, there are multiple wb objects
which can all point to a single bdi.  There is a refcount which prevents
the bdi object from being released (and hence, unregistered).  So in
theory, the bdi_unregister() *should* only get called once its refcount
goes to zero (bdi_put will drop the refcount, and when it is zero,
release_bdi gets called, which calls bdi_unregister).

Unfortunately, del_gendisk() in block/gen_hd.c never got the memo about
the Brave New memcg World, and calls bdi_unregister directly.  It does
this without informing the file system, or the memcg code, or anything
else.  This causes the root wb associated with the bdi to be
unregistered, but none of the memcg-specific wb's are shutdown.  So when
one of these wb's are woken up to do delayed work, they try to
dereference their wb->bdi->dev to fetch the device name, but
unfortunately bdi->dev is now NULL, thanks to the bdi_unregister()
called by del_gendisk().  As a result, *boom*.

Fortunately, it looks like the rest of the writeback path is perfectly
happy with bdi->dev and bdi->owner being NULL, so the simplest fix is to
create a bdi_dev_name() function which can handle bdi->dev being NULL.
This also allows us to bulletproof the writeback tracepoints to prevent
them from dereferencing a NULL pointer and crashing the kernel if one is
tracing with memcg's enabled, and an iSCSI device dies or a USB storage
stick is pulled.

The most common way of triggering this will be hotremoval of a device
while writeback with memcg enabled is going on.  It was triggering
several times a day in a heavily loaded production environment.

Google Bug Id: 145475544

Link: https://lore.kernel.org/r/20191227194829.150110-1-tytso@mit.edu
Link: http://lkml.kernel.org/r/20191228005211.163952-1-tytso@mit.edu


Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

On 32-bit platform the size of long is only 32 bits which makes wrong
offset in the array of 64 bit size.

Calculate offset based on BITS_PER_LONG.

Link: http://lkml.kernel.org/r/20200109103601.45929-1-andriy.shevchenko@linux.intel.com
Fixes: 30544ed5

 ("lib/bitmap: introduce bitmap_replace() helper")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull mmu_notifier updates from Jason Gunthorpe:
 "This small series revises the names in mmu_notifier to make the code
  clearer and more readable"

* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
  mm/mmu_notifiers: Use 'interval_sub' as the variable for mmu_interval_notifier
  mm/mmu_notifiers: Use 'subscription' as the variable name for mmu_notifier
  mm/mmu_notifier: Rename struct mmu_notifier_mm to mmu_notifier_subscriptions

Pull thread management updates from Christian Brauner:
 "Sargun Dhillon over the last cycle has worked on the pidfd_getfd()
  syscall.

  This syscall allows for the retrieval of file descriptors of a process
  based on its pidfd. A task needs to have ptrace_may_access()
  permissions with PTRACE_MODE_ATTACH_REALCREDS (suggested by Oleg and
  Andy) on the target.

  One of the main use-cases is in combination with seccomp's user
  notification feature. As a reminder, seccomp's user notification
  feature was made available in v5.0. It allows a task to retrieve a
  file descriptor for its seccomp filter. The file descriptor is usually
  handed of to a more privileged supervising process. The supervisor can
  then listen for syscall events caught by the seccomp filter of the
  supervisee and perform actions in lieu of the supervisee, usually
  emulating syscalls. pidfd_getfd() is needed to expand its uses.

  There are currently two major users that wait on pidfd_getfd() and one
  future user:

   - Netflix, Sargun said, is working on a service mesh where users
     should be able to connect to a dns-based VIP. When a user connects
     to e.g. 1.2.3.4:80 that runs e.g. service "foo" they will be
     redirected to an envoy process. This service mesh uses seccomp user
     notifications and pidfd to intercept all connect calls and instead
     of connecting them to 1.2.3.4:80 connects them to e.g.
     127.0.0.1:8080.

   - LXD uses the seccomp notifier heavily to intercept and emulate
     mknod() and mount() syscalls for unprivileged containers/processes.
     With pidfd_getfd() more uses-cases e.g. bridging socket connections
     will be possible.

   - The patchset has also seen some interest from the browser corner.
     Right now, Firefox is using a SECCOMP_RET_TRAP sandbox managed by a
     broker process. In the future glibc will start blocking all signals
     during dlopen() rendering this type of sandbox impossible. Hence,
     in the future Firefox will switch to a seccomp-user-nofication
     based sandbox which also makes use of file descriptor retrieval.
     The thread for this can be found at
     https://sourceware.org/ml/libc-alpha/2019-12/msg00079.html

  With pidfd_getfd() it is e.g. possible to bridge socket connections
  for the supervisee (binding to a privileged port) and taking actions
  on file descriptors on behalf of the supervisee in general.

  Sargun's first version was using an ioctl on pidfds but various people
  pushed for it to be a proper syscall which he duely implemented as
  well over various review cycles. Selftests are of course included.
  I've also added instructions how to deal with merge conflicts below.

  There's also a small fix coming from the kernel mentee project to
  correctly annotate struct sighand_struct with __rcu to fix various
  sparse warnings. We've received a few more such fixes and even though
  they are mostly trivial I've decided to postpone them until after -rc1
  since they came in rather late and I don't want to risk introducing
  build warnings.

  Finally, there's a new prctl() command PR_{G,S}ET_IO_FLUSHER which is
  needed to avoid allocation recursions triggerable by storage drivers
  that have userspace parts that run in the IO path (e.g. dm-multipath,
  iscsi, etc). These allocation recursions deadlock the device.

  The new prctl() allows such privileged userspace components to avoid
  allocation recursions by setting the PF_MEMALLOC_NOIO and
  PF_LESS_THROTTLE flags. The patch carries the necessary acks from the
  relevant maintainers and is routed here as part of prctl()
  thread-management."

* tag 'threads-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  prctl: PR_{G,S}ET_IO_FLUSHER to support controlling memory reclaim
  sched.h: Annotate sighand_struct with __rcu
  test: Add test for pidfd getfd
  arch: wire up pidfd_getfd syscall
  pid: Implement pidfd_getfd syscall
  vfs, fdtable: Add fget_task helper

Pull io_uring updates from Jens Axboe:

 - Support for various new opcodes (fallocate, openat, close, statx,
   fadvise, madvise, openat2, non-vectored read/write, send/recv, and
   epoll_ctl)

 - Faster ring quiesce for fileset updates

 - Optimizations for overflow condition checking

 - Support for max-sized clamping

 - Support for probing what opcodes are supported

 - Support for io-wq backend sharing between "sibling" rings

 - Support for registering personalities

 - Lots of little fixes and improvements

* tag 'for-5.6/io_uring-vfs-2020-01-29' of git://git.kernel.dk/linux-block: (64 commits)
  io_uring: add support for epoll_ctl(2)
  eventpoll: support non-blocking do_epoll_ctl() calls
  eventpoll: abstract out epoll_ctl() handler
  io_uring: fix linked command file table usage
  io_uring: support using a registered personality for commands
  io_uring: allow registering credentials
  io_uring: add io-wq workqueue sharing
  io-wq: allow grabbing existing io-wq
  io_uring/io-wq: don't use static creds/mm assignments
  io-wq: make the io_wq ref counted
  io_uring: fix refcounting with batched allocations at OOM
  io_uring: add comment for drain_next
  io_uring: don't attempt to copy iovec for READ/WRITE
  io_uring: honor IOSQE_ASYNC for linked reqs
  io_uring: prep req when do IOSQE_ASYNC
  io_uring: use labeled array init in io_op_defs
  io_uring: optimise sqe-to-req flags translation
  io_uring: remove REQ_F_IO_DRAINED
  io_uring: file switch work needs to get flushed on exit
  io_uring: hide uring_fd in ctx
  ...

Pull SCSI updates from James Bottomley:
 "This series is slightly unusual because it includes Arnd's compat
  ioctl tree here:

    1c46a2cf Merge tag 'block-ioctl-cleanup-5.6' into 5.6/scsi-queue

  Excluding Arnd's changes, this is mostly an update of the usual
  drivers: megaraid_sas, mpt3sas, qla2xxx, ufs, lpfc, hisi_sas.

  There are a couple of core and base updates around error propagation
  and atomicity in the attribute container base we use for the SCSI
  transport classes.

  The rest is minor changes and updates"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (149 commits)
  scsi: hisi_sas: Rename hisi_sas_cq.pci_irq_mask
  scsi: hisi_sas: Add prints for v3 hw interrupt converge and automatic affinity
  scsi: hisi_sas: Modify the file permissions of trigger_dump to write only
  scsi: hisi_sas: Replace magic number when handle channel interrupt
  scsi: hisi_sas: replace spin_lock...

Merge tag 'for-5.6/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - Fix DM core's potential for q->make_request_fn NULL pointer in the
   unlikely case that a DM device is created without a DM table and then
   accessed due to upper-layer userspace code or user error.

 - Fix DM thin-provisioning's metadata_pre_commit_callback to not use
   memory after it is free'd. Also refactor code to disallow changing
   the thin-pool's data device once in use -- doing so guarantees smae
   lifetime of pool's data device relative to the pool metadata.

 - Fix DM space maps used by DM thinp and DM cache to avoid reuse of a
   already used block. This race was identified with extremely heavy
   snapshot use in the context of DM thin provisioning.

 - Fix DM raid's table status relative to an active rebuild.

 - Fix DM crypt to use GFP_NOIO rather than GFP_NOFS in call to
   skcipher_request_alloc(). Also fix benbi IV constructor crash if used
   in authenticated mode.

 - Add DM crypt support for Elephant diffuser to allow for Bitlocker
   compatibility.

 - Fix DM verity target to not prefetch hash blocks for data that has
   already been verified.

 - Fix DM writecache's incorrect flush sequence during commit when in
   SSD mode.

 - Improve DM writecache's sequential write performance on SSDs.

 - Add DM zoned target support for zone sizes smaller than 128MiB.

 - Add DM multipath 'queue_if_no_path_timeout_secs' module param to
   allow timeout if path isn't reinstated. This allows users a kernel
   safety-net against IO hanging indefinitely, due to no active paths,
   that has historically only been provided by multipathd userspace.

 - Various DM code cleanups to use true/false rather than 1/0, a
   variable rename in dm-dust, and fix for a math error in comment for
   DM thin metadata's ondisk format.

* tag 'for-5.6/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (21 commits)
  dm: fix potential for q->make_request_fn NULL pointer
  dm writecache: improve performance of large linear writes on SSDs
  dm mpath: Add timeout mechanism for queue_if_no_path
  dm thin: change data device's flush_bio to be member of struct pool
  dm thin: don't allow changing data device during thin-pool reload
  dm thin: fix use-after-free in metadata_pre_commit_callback
  dm thin metadata: use pool locking at end of dm_pool_metadata_close
  dm writecache: fix incorrect flush sequence when doing SSD mode commit
  dm crypt: fix benbi IV constructor crash if used in authenticated mode
  dm crypt: Implement Elephant diffuser for Bitlocker compatibility
  dm space map common: fix to ensure new block isn't already in use
  dm verity: don't prefetch hash blocks for already-verified data
  dm crypt: fix GFP flags passed to skcipher_request_alloc()
  dm thin metadata: Fix trivial math error in on-disk format documentation
  dm thin metadata: use true/false for bool variable
  dm snapshot: use true/false for bool variable
  dm bio prison v2: use true/false for bool variable
  dm mpath: use true/false for bool variable
  dm zoned: support zone sizes smaller than 128MiB
  dm raid: table line rebuild status fixes
  ...

Pull documentation updates from Jonathan Corbet:
 "It has been a relatively quiet cycle for documentation, but there's
  still a couple of things of note:

   - Conversion of the NFS documentation to RST

   - A new document on how to help with documentation (and a maintainer
     profile entry too)

  Plus the usual collection of typo fixes, etc"

* tag 'docs-5.6' of git://git.lwn.net/linux: (40 commits)
  docs: filesystems: add overlayfs to index.rst
  docs: usb: remove some broken references
  scripts/find-unused-docs: Fix massive false positives
  docs: nvdimm: use ReST notation for subsection
  zram: correct documentation about sysfs node of huge page writeback
  Documentation: zram: various fixes in zram.rst
  Add a maintainer entry profile for documentation
  Add a document on how to contribute to the documentation
  docs: Keep up with the location of NoUri
  Documentation: Call out example SYM_FUNC_* usage as x86-specific
  Documentation: nfs: fault_injection: convert to ReST
  Documentation: nfs: pnfs-scsi-server: convert to ReST
  Documentation: nfs: convert pnfs-block-server to ReST
  Documentation: nfs: idmapper: convert to ReST
  Documentation: convert nfsd-admin-interfaces to ReST
  Documentation: nfs-rdma: convert to ReST
  Documentation: nfsroot.rst: COSMETIC: refill a paragraph
  Documentation: nfsroot.txt: convert to ReST
  Documentation: convert nfs.txt to ReST
  Documentation: filesystems: convert vfat.txt to RST
  ...

Merge tag 'linux-kselftest-5.6-rc1-kunit' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull Kselftest kunit updates from Shuah Khan:
 "This kunit update consists of:

   - Support for building kunit as a module from Alan Maguire

   - AppArmor KUnit tests for policy unpack from Mike Salvatore"

* tag 'linux-kselftest-5.6-rc1-kunit' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  kunit: building kunit as a module breaks allmodconfig
  kunit: update documentation to describe module-based build
  kunit: allow kunit to be loaded as a module
  kunit: remove timeout dependence on sysctl_hung_task_timeout_seconds
  kunit: allow kunit tests to be loaded as a module
  kunit: hide unexported try-catch interface in try-catch-impl.h
  kunit: move string-stream.h to lib/kunit
  apparmor: add AppArmor KUnit tests for policy unpack

Merge tag 'linux-kselftest-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull Kselftest update from Shuah Khan:
 "This Kselftest update consists of several fixes to framework and
  individual tests.

  In addition, it enables LKDTM tests adding lkdtm target to kselftest
  Makefile"

* tag 'linux-kselftest-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  selftests/ftrace: fix glob selftest
  selftests: settings: tests can be in subsubdirs
  kselftest: Minimise dependency of get_size on C library interfaces
  selftests/livepatch: Remove unused local variable in set_ftrace_enabled()
  selftests/livepatch: Replace set_dynamic_debug() with setup_config() in README
  selftests/lkdtm: Add tests for LKDTM targets
  selftests: Uninitialized variable in test_cgcore_proc_migration()
  selftests: fix build behaviour on targets' failures

Merge tag 'y2038-drivers-for-v5.6-signed' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground

Pull y2038 updates from Arnd Bergmann:
 "Core, driver and file system changes

  These are updates to device drivers and file systems that for some
  reason or another were not included in the kernel in the previous
  y2038 series.

  I've gone through all users of time_t again to make sure the kernel is
  in a long-term maintainable state, replacing all remaining references
  to time_t with safe alternatives.

  Some related parts of the series were picked up into the nfsd, xfs,
  alsa and v4l2 trees. A final set of patches in linux-mm removes the
  now unused time_t/timeval/timespec types and helper functions after
  all five branches are merged for linux-5.6, ensuring that no new users
  get merged.

  As a result, linux-5.6, or my backport of the patches to 5.4 [1],
  should be the first release that can serve as a base for a 32-bit
  system designed to run beyond year 2038, with a few remaining caveats:

   - All user space must be compiled with a 64-bit time_t, which will be
     supported in the coming musl-1.2 and glibc-2.32 releases, along
     with installed kernel headers from linux-5.6 or higher.

   - Applications that use the system call interfaces directly need to
     be ported to use the time64 syscalls added in linux-5.1 in place of
     the existing system calls. This impacts most users of futex() and
     seccomp() as well as programming languages that have their own
     runtime environment not based on libc.

   - Applications that use a private copy of kernel uapi header files or
     their contents may need to update to the linux-5.6 version, in
     particular for sound/asound.h, xfs/xfs_fs.h, linux/input.h,
     linux/elfcore.h, linux/sockios.h, linux/timex.h and
     linux/can/bcm.h.

   - A few remaining interfaces cannot be changed to pass a 64-bit
     time_t in a compatible way, so they must be configured to use
     CLOCK_MONOTONIC times or (with a y2106 problem) unsigned 32-bit
     timestamps. Most importantly this impacts all users of 'struct
     input_event'.

   - All y2038 problems that are present on 64-bit machines also apply
     to 32-bit machines. In particular this affects file systems with
     on-disk timestamps using signed 32-bit seconds: ext4 with
     ext3-style small inodes, ext2, xfs (to be fixed soon) and ufs"

[1] https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git/log/?h=y2038-endgame

* tag 'y2038-drivers-for-v5.6-signed' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: (21 commits)
  Revert "drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC"
  y2038: sh: remove timeval/timespec usage from headers
  y2038: sparc: remove use of struct timex
  y2038: rename itimerval to __kernel_old_itimerval
  y2038: remove obsolete jiffies conversion functions
  nfs: fscache: use timespec64 in inode auxdata
  nfs: fix timstamp debug prints
  nfs: use time64_t internally
  sunrpc: convert to time64_t for expiry
  drm/etnaviv: avoid deprecated timespec
  drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC
  drm/msm: avoid using 'timespec'
  hfs/hfsplus: use 64-bit inode timestamps
  hostfs: pass 64-bit timestamps to/from user space
  packet: clarify timestamp overflow
  tsacct: add 64-bit btime field
  acct: stop using get_seconds()
  um: ubd: use 64-bit time_t where possible
  xtensa: ISS: avoid struct timeval
  dlm: use SO_SNDTIMEO_NEW instead of SO_SNDTIMEO_OLD
  ...

Pull printk update from Petr Mladek:
 "Prevent replaying log on all consoles"

* tag 'printk-for-5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
  printk: fix exclusive_console replaying

This adds IORING_OP_EPOLL_CTL, which can perform the same work as the
epoll_ctl(2) system call.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

Also make it available outside of epoll, along with the helper that
decides if we need to copy the passed in epoll_event.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

No functional changes in this patch.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

We're not consistent in how the file table is grabbed and assigned if we
have a command linked that requires the use of it.

Add ->file_table to the io_op_defs[] array, and use that to determine
when to grab the table instead of having the handlers set it if they
need to defer. This also means we can kill the IO_WQ_WORK_NEEDS_FILES
flag. We always initialize work->files, so io-wq can just check for
that.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull erofs updates from Gao Xiang:
 "A regression fix, several cleanups and (maybe) plus an upcoming new
  mount api convert patch as a part of vfs update are considered
  available for this cycle.

  All commits have been in linux-next and tested with no smoke out.

  Summary:

   - fix an out-of-bound read access introduced in v5.3, which could
     rarely cause data corruption

   - various cleanup patches"

* tag 'erofs-for-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: clean up z_erofs_submit_queue()
  erofs: fold in postsubmit_is_all_bypassed()
  erofs: fix out-of-bound read for shifted uncompressed block
  erofs: remove void tagging/untagging of workgroup pointers
  erofs: remove unused tag argument while registering a workgroup
  erofs: remove unused tag argument while finding a workgroup
  erofs: correct indentation of an assigned structure inside a function

Pull adfs updates from Al Viro:
 "adfs stuff for this cycle"

* 'work.adfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (42 commits)
  fs/adfs: bigdir: Fix an error code in adfs_fplus_read()
  Documentation: update adfs filesystem documentation
  fs/adfs: mostly divorse inode number from indirect disc address
  fs/adfs: super: add support for E and E+ floppy image formats
  fs/adfs: super: extract filesystem block probe
  fs/adfs: dir: remove debug in adfs_dir_update()
  fs/adfs: super: fix inode dropping
  fs/adfs: bigdir: implement directory update support
  fs/adfs: bigdir: calculate and validate directory checkbyte
  fs/adfs: bigdir: directory validation strengthening
  fs/adfs: bigdir: extract directory validation
  fs/adfs: bigdir: factor out directory entry offset calculation
  fs/adfs: newdir: split out directory commit from update
  fs/adfs: newdir: clean up adfs_f_update()
  fs/adfs: newdir: merge adfs_dir_read() into adfs_f_read()
  fs/adfs: newdir: improve directory validation
  fs/adfs: newdir: factor out directory format validation
  fs/adfs: dir: use pointers to access directory head/tails
  fs/adfs: dir: add more efficient iterate() per-format method
  fs/adfs: dir: switch to iterate_shared method
  ...

Pull openat2 support from Al Viro:
 "This is the openat2() series from Aleksa Sarai.

  I'm afraid that the rest of namei stuff will have to wait - it got
  zero review the last time I'd posted #work.namei, and there had been a
  leak in the posted series I'd caught only last weekend. I was going to
  repost it on Monday, but the window opened and the odds of getting any
  review during that... Oh, well.

  Anyway, openat2 part should be ready; that _did_ get sane amount of
  review and public testing, so here it comes"

From Aleksa's description of the series:
 "For a very long time, extending openat(2) with new features has been
  incredibly frustrating. This stems from the fact that openat(2) is
  possibly the most famous counter-example to the mantra "don't silently
  accept garbage from userspace" -- it doesn't check whether unknown
  flags are present[1].

  This means that (generally) the addition of new flags to openat(2) has
  been fraught with backwards-compatibility issues (O_TMPFILE has to be
  defined as __O_TMPFILE|O_DIRECTORY|[O_RDWR or O_WRONLY] to ensure old
  kernels gave errors, since it's insecure to silently ignore the
  flag[2]). All new security-related flags therefore have a tough road
  to being added to openat(2).

  Furthermore, the need for some sort of control over VFS's path
  resolution (to avoid malicious paths resulting in inadvertent
  breakouts) has been a very long-standing desire of many userspace
  applications.

  This patchset is a revival of Al Viro's old AT_NO_JUMPS[3] patchset
  (which was a variant of David Drysdale's O_BENEATH patchset[4] which
  was a spin-off of the Capsicum project[5]) with a few additions and
  changes made based on the previous discussion within [6] as well as
  others I felt were useful.

  In line with the conclusions of the original discussion of
  AT_NO_JUMPS, the flag has been split up into separate flags. However,
  instead of being an openat(2) flag it is provided through a new
  syscall openat2(2) which provides several other improvements to the
  openat(2) interface (see the patch description for more details). The
  following new LOOKUP_* flags are added:

  LOOKUP_NO_XDEV:

     Blocks all mountpoint crossings (upwards, downwards, or through
     absolute links). Absolute pathnames alone in openat(2) do not
     trigger this. Magic-link traversal which implies a vfsmount jump is
     also blocked (though magic-link jumps on the same vfsmount are
     permitted).

  LOOKUP_NO_MAGICLINKS:

     Blocks resolution through /proc/$pid/fd-style links. This is done
     by blocking the usage of nd_jump_link() during resolution in a
     filesystem. The term "magic-links" is used to match with the only
     reference to these links in Documentation/, but I'm happy to change
     the name.

     It should be noted that this is different to the scope of
     ~LOOKUP_FOLLOW in that it applies to all path components. However,
     you can do openat2(NO_FOLLOW|NO_MAGICLINKS) on a magic-link and it
     will *not* fail (assuming that no parent component was a
     magic-link), and you will have an fd for the magic-link.

     In order to correctly detect magic-links, the introduction of a new
     LOOKUP_MAGICLINK_JUMPED state flag was required.

  LOOKUP_BENEATH:

     Disallows escapes to outside the starting dirfd's
     tree, using techniques such as ".." or absolute links. Absolute
     paths in openat(2) are also disallowed.

     Conceptually this flag is to ensure you "stay below" a certain
     point in the filesystem tree -- but this requires some additional
     to protect against various races that would allow escape using
     "..".

     Currently LOOKUP_BENEATH implies LOOKUP_NO_MAGICLINKS, because it
     can trivially beam you around the filesystem (breaking the
     protection). In future, there might be similar safety checks done
     as in LOOKUP_IN_ROOT, but that requires more discussion.

  In addition, two new flags are added that expand on the above ideas:

  LOOKUP_NO_SYMLINKS:

     Does what it says on the tin. No symlink resolution is allowed at
     all, including magic-links. Just as with LOOKUP_NO_MAGICLINKS this
     can still be used with NOFOLLOW to open an fd for the symlink as
     long as no parent path had a symlink component.

  LOOKUP_IN_ROOT:

     This is an extension of LOOKUP_BENEATH that, rather than blocking
     attempts to move past the root, forces all such movements to be
     scoped to the starting point. This provides chroot(2)-like
     protection but without the cost of a chroot(2) for each filesystem
     operation, as well as being safe against race attacks that
     chroot(2) is not.

     If a race is detected (as with LOOKUP_BENEATH) then an error is
     generated, and similar to LOOKUP_BENEATH it is not permitted to
     cross magic-links with LOOKUP_IN_ROOT.

     The primary need for this is from container runtimes, which
     currently need to do symlink scoping in userspace[7] when opening
     paths in a potentially malicious container.

     There is a long list of CVEs that could have bene mitigated by
     having RESOLVE_THIS_ROOT (such as CVE-2017-1002101,
     CVE-2017-1002102, CVE-2018-15664, and CVE-2019-5736, just to name a
     few).

  In order to make all of the above more usable, I'm working on
  libpathrs[8] which is a C-friendly library for safe path resolution.
  It features a userspace-emulated backend if the kernel doesn't support
  openat2(2). Hopefully we can get userspace to switch to using it, and
  thus get openat2(2) support for free once it's ready.

  Future work would include implementing things like
  RESOLVE_NO_AUTOMOUNT and possibly a RESOLVE_NO_REMOTE (to allow
  programs to be sure they don't hit DoSes though stale NFS handles)"

* 'work.openat2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  Documentation: path-lookup: include new LOOKUP flags
  selftests: add openat2(2) selftests
  open: introduce openat2(2) syscall
  namei: LOOKUP_{IN_ROOT,BENEATH}: permit limited ".." resolution
  namei: LOOKUP_IN_ROOT: chroot-like scoped resolution
  namei: LOOKUP_BENEATH: O_BENEATH-like scoped resolution
  namei: LOOKUP_NO_XDEV: block mountpoint crossing
  namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution
  namei: LOOKUP_NO_SYMLINKS: block symlink resolution
  namei: allow set_root() to produce errors
  namei: allow nd_jump_link() to produce errors
  nsfs: clean-up ns_get_path() signature to return int
  namei: only return -ECHILD from follow_dotdot_rcu()

Pull RCU warning removal from Paul McKenney:
 "A single commit that fixes an embarrassing bug discussed here:

      https://lore.kernel.org/lkml/20200125131425.GB16136@zn.tnic/

  which apparently also affects smaller systems"

[ This was sent to Ingo, but since I see the issue on the laptop I use for
  testing during the merge window, I'm doing the pull directly     - Linus ]

* 'urgent-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  rcu: Forgive slow expedited grace periods at boot time

Pull core fixes from Ingo Molnar:
 "Three objtool fixes, plus marking SFI as obsolete"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Skip samples subdirectory
  objtool: Fix ARCH=x86_64 build error
  objtool: Silence build output
  MAINTAINERS: Mark simple firmware interface (SFI) obsolete

Pull char/misc driver updates from Greg KH:
 "Here is the big char/misc/whatever driver changes for 5.6-rc1

  Included in here are loads of things from a variety of different
  driver subsystems:
   - soundwire updates
   - binder updates
   - nvmem updates
   - firmware drivers updates
   - extcon driver updates
   - various misc driver updates
   - fpga driver updates
   - interconnect subsystem and driver updates
   - bus driver updates
   - uio driver updates
   - mei driver updates
   - w1 driver cleanups
   - various other small driver updates

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'char-misc-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (86 commits)
  mei: me: add jasper point DID
  char: hpet: Use flexible-array member
  binder: fix log spam for existing debugfs file creation.
  mei: me: add comet point (lake) H device ids
  nvmem: add QTI SDAM driver
  dt-bindings: nvmem: add binding for QTI SPMI SDAM
  dt-bindings: imx-ocotp: Add i.MX8MP compatible
  dt-bindings: soundwire: fix example
  soundwire: cadence: fix kernel-doc parameter descriptions
  soundwire: intel: report slave_ids for each link to SOF driver
  siox: Use the correct style for SPDX License Identifier
  w1: omap-hdq: Simplify driver with PM runtime autosuspend
  firmware: stratix10-svc: Remove unneeded semicolon
  firmware: google: Probe for a GSMI handler in firmware
  firmware: google: Unregister driver_info on failure and exit in gsmi
  firmware: google: Release devices before unregistering the bus
  slimbus: qcom: add missed clk_disable_unprepare in remove
  slimbus: Use the correct style for SPDX License Identifier
  slimbus: qcom-ngd-ctrl: Use dma_request_chan() instead dma_request_slave_channel()
  dt-bindings: SLIMBus: add slim devices optional properties
  ...

Pull driver core updates from Greg KH:
 "Here is a small set of changes for 5.6-rc1 for the driver core and
  some firmware subsystem changes.

  Included in here are:
   - device.h splitup like you asked for months ago
   - devtmpfs minor cleanups
   - firmware core minor changes
   - debugfs fix for lockdown mode
   - kernfs cleanup fix
   - cpu topology minor fix

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'driver-core-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (22 commits)
  firmware: Rename FW_OPT_NOFALLBACK to FW_OPT_NOFALLBACK_SYSFS
  devtmpfs: factor out common tail of devtmpfs_{create,delete}_node
  devtmpfs: initify a bit
  devtmpfs: simplify initialization of mount_dev
  devtmpfs: factor out setup part of devtmpfsd()
  devtmpfs: fix theoretical stale pointer deref in devtmpfsd()
  driver core: platform: fix u32 greater or equal to zero comparison
  cpu-topology: Don't error on more than CONFIG_NR_CPUS CPUs in device tree
  debugfs: Return -EPERM when locked down
  driver core: Print device when resources present in really_probe()
  driver core: Fix test_async_driver_probe if NUMA is disabled
  driver core: platform: Prevent resouce overflow from causing infinite loops
  fs/kernfs/dir.c: Clean code by removing always true condition
  component: do not dereference opaque pointer in debugfs
  drivers/component: remove modular code
  debugfs: Fix warnings when building documentation
  device.h: move 'struct driver' stuff out to device/driver.h
  device.h: move 'struct class' stuff out to device/class.h
  device.h: move 'struct bus' stuff out to device/bus.h
  device.h: move dev_printk()-like functions to dev_printk.h
  ...

Pull staging and IIO updates from Greg KH:
 "Here is the big staging/iio driver patches for 5.6-rc1

  Included in here are:

   - lots of new IIO drivers and updates for that subsystem

   - the usual huge quantity of minor cleanups for staging drivers

   - removal of the following staging drivers:
       - isdn/avm
       - isdn/gigaset
       - isdn/hysdn
       - octeon-usb
       - octeon ethernet

  Overall we deleted far more lines than we added, removing over 40k of
  old and obsolete driver code.

  All of these changes have been in linux-next for a while with no
  reported issues"

* tag 'staging-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (353 commits)
  staging: most: usb: check for NULL device
  staging: next: configfs: fix release link
  staging: most: core: fix logging messages
  staging: most: core: remove container struct
  staging: most: remove struct device core driver
  staging: most: core: drop device reference
  staging: most: remove device from interface structure
  staging: comedi: drivers: fix spelling mistake "to" -> "too"
  staging: exfat: remove fs_func struct.
  staging: wilc1000: avoid mutex unlock without lock in wilc_wlan_handle_txq()
  staging: wilc1000: return zero on success and non-zero on function failure
  staging: axis-fifo: replace spinlock with mutex
  staging: wilc1000: remove unused code prior to throughput enhancement in SPI
  staging: wilc1000: added 'wilc_' prefix for 'struct assoc_resp' name
  staging: wilc1000: move firmware API struct's to separate header file
  staging: wilc1000: remove use of infinite loop conditions
  staging: kpc2000: rename variables with kpc namespace
  staging: vt6656: Remove memory buffer from vnt_download_firmware.
  staging: vt6656: Just check NEWRSR_DECRYPTOK for RX_FLAG_DECRYPTED.
  staging: vt6656: Use vnt_rx_tail struct for tail variables.
  ...

Pull tty/serial driver updates from Greg KH:
 "Here are the big set of tty and serial driver updates for 5.6-rc1

  Included in here are:
   - dummy_con cleanups (touches lots of arch code)
   - sysrq logic cleanups (touches lots of serial drivers)
   - samsung driver fixes (wasn't really being built)
   - conmakeshash move to tty subdir out of scripts
   - lots of small tty/serial driver updates

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (140 commits)
  tty: n_hdlc: Use flexible-array member and struct_size() helper
  tty: baudrate: SPARC supports few more baud rates
  tty: baudrate: Synchronise baud_table[] and baud_bits[]
  tty: serial: meson_uart: Add support for kernel debugger
  serial: imx: fix a race condition in receive path
  serial: 8250_bcm2835aux: Document struct bcm2835aux_data
  serial: 8250_...

Pull USB/Thunderbolt/PHY driver updates from Greg KH:
 "Here is the big USB and Thunderbolt and PHY driver updates for
  5.6-rc1.

  With the advent of USB4, "Thunderbolt" has really become USB4, so the
  renaming of the Kconfig option and starting to share subsystem code
  has begun, hence both subsystems coming in through the same tree here.

  PHY driver updates also touched USB drivers, so that is coming in
  through here as well.

  Major stuff included in here are:
   - USB 4 initial support added (i.e. Thunderbolt)
   - musb driver updates
   - USB gadget driver updates
   - PHY driver updates
   - USB PHY driver updates
   - lots of USB serial stuff fixed up
   - USB typec updates
   - USB-IP fixes
   - lots of other smaller USB driver updates

  All of these have been in linux-next for a while now (the usb-serial
  tree is already tested in linux-next on its own before merged into
  here), with no reported issues"

[ Removed an incorrect compile test enablement for PHY_EXYNOS5250_SATA
  that causes configuration warnings    - Linus ]

* tag 'usb-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (207 commits)
  Doc: ABI: add usb charger uevent
  usb: phy: show USB charger type for user
  usb: cdns3: fix spelling mistake and rework grammar in text
  usb: phy: phy-gpio-vbus-usb: Convert to GPIO descriptors
  USB: serial: cyberjack: fix spelling mistake "To" -> "Too"
  USB: serial: ir-usb: simplify endpoint check
  USB: serial: ir-usb: make set_termios synchronous
  USB: serial: ir-usb: fix IrLAP framing
  USB: serial: ir-usb: fix link-speed handling
  USB: serial: ir-usb: add missing endpoint sanity check
  usb: typec: fusb302: fix "op-sink-microwatt" default that was in mW
  usb: typec: wcove: fix "op-sink-microwatt" default that was in mW
  usb: dwc3: pci: add ID for the Intel Comet Lake -V variant
  usb: typec: tcpci: mask event interrupts when remove driver
  usb: host: xhci-tegra: set MODULE_FIRMWARE for tegra186
  usb: chipidea: add inline for ci_hdrc_host_driver_init if host is not defined
  usb: chipidea: handle single role for usb role class
  usb: musb: fix spelling mistake: "periperal" -> "peripheral"
  phy: ti: j721e-wiz: Fix build error without CONFIG_OF_ADDRESS
  USB: usbfs: Always unlink URBs in reverse order
  ...

Pull pin control updates from Linus Walleij:
 "This is the bulk of pin control changes, nothing too exciting about
  this.

  Some changes hit arch/sh and arch/arm but are well isolated and
  acknowledged by the respective arch maintainers.

  Core changes:

   - Dropped the chained IRQ setup callback into GPIOLIB as we got rid
     of the last users of that in this changeset.

  New drivers:

   - New driver for Ingenic X1830.

   - New driver for Freescale i.MX8MP.

  Driver enhancements:

   - Fix all remaining Intel drivers to pass their IRQ chips along with
     the GPIO chips.

   - Intel Baytrail allocates its irqchip dynamically.

   - Intel Lynxpoint is thoroughly rewritten and modernized.

   - Aspeed AST2600 pin muxing and configuration is much improved.

   - Qualcomm SC7180 functions are updated and wakeup interrupt map is
     provided.

   - A whole slew of Renesas SH-PFC cleanups and improvements.

   - Fix up the Intel DT bindings to use the generic YAML DT bindings
     schema (a first user of this)"

* tag 'pinctrl-v5.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl: (99 commits)
  pinctrl: madera: Remove extra blank line
  pinctrl: qcom: Don't lock around irq_set_irq_wake()
  pinctrl: mvebu: armada-37xx: use use platform api
  gpio: Drop the chained IRQ handler assign function
  pinctrl: freescale: Add i.MX8MP pinctrl driver support
  dt-bindings: imx: Add pinctrl binding doc for i.MX8MP
  pinctrl: tigerlake: Tiger Lake uses _HID enumeration
  pinctrl: sunrisepoint: Add Coffee Lake-S ACPI ID
  pinctrl: iproc: Use platform_get_irq_optional() to avoid error message
  pinctrl: dt-bindings: Fix some errors in the lgm and pinmux schema
  pinctrl: intel: Pass irqchip when adding gpiochip
  pinctrl: intel: Add GPIO <-> pin mapping ranges via callback
  pinctrl: baytrail: Replace WARN with dev_info_once when setting direct-irq pin to output
  pinctrl: baytrail: Do not clear IRQ flags on direct-irq enabled pins
  pinctrl: sunrisepoint: Add missing Interrupt Status register offset
  pinctrl: sh-pfc: Split R-Car H3 support in two independent drivers
  pinctrl: artpec6: fix __iomem on reg in set
  pinctrl: ingenic: Use devm_platform_ioremap_resource()
  pinctrl: ingenic: Factorize irq_set_type function
  pinctrl: ingenic: Remove duplicated ingenic_chip_info structures
  ...

Pull GPIO updates from Linus Walleij:
 "This is the bulk of GPIO changes for the v5.6 kernel cycle.

  This is a pretty calm cycle so far, nothing special going on really.
  Some more changes will come in from the irqchip and pin control trees.

  I also deleted an orphan include file for FMC that was dangling since
  subsystem was removed.

  Core changes:

   - Document the usecases for the kernelspace vs userspace handling of
     GPIOs.

   - Handle MSI (message signalled interrupts) properly in the core
     hierarchical irqdomain code.

   - Fix a rare race condition while initializing the descriptor array.

  New drivers:

   - Xylon LogiCVC GPIO driver.

   - WDC934x GPIO controller driver.

  Driver improvements:

   - Implemented suspend/resume in the Tegra driver.

   - MPC8xx edge detection fixup.

   - Properly convert ThunderX to use hierarchical irqdomain with
     GPIOLIB_IRQCHIP on top of the revert of the previous buggy
     switchover. This time it works (hopefully).

  Misc:

   - Drop a FMC remnant file <linux/ipmi-fru.h>

   - A slew of fixes"

* tag 'gpio-v5.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (48 commits)
  MAINTAINERS: Replace Tien Hock Loh as Altera PIO maintainer
  gpiolib: hold gpio devices lock until ->descs array is initialised
  gpio: aspeed-sgpio: fixed typos
  gpio: mvebu: clear irq in edge cause register before unmask edge irq
  gpiolib: Lower verbosity when allocating hierarchy irq
  gpiolib: Remove duplicated function gpio_do_set_config()
  gpio: Fix the no return statement warning
  gpio: wcd934x: Add support to wcd934x gpio controller
  gpiolib: remove set but not used variable 'config'
  gpio: vx855: fixed a typo
  gpio: mockup: sort headers alphabetically
  gpio: mockup: update the license tag
  gpio: Remove the unused flags
  gpiolib: Set lockdep class for hierarchical irq domains
  gpio: thunderx: Switch to GPIOLIB_IRQCHIP
  gpiolib: Add the support for the msi parent domain
  gpiolib: Add support for the irqdomain which doesn't use irq_fwspec as arg
  gpio: Add use guidance documentation
  dt-bindings: gpio: wcd934x: Add bindings for gpio
  gpio: altera: change to platform_get_irq_optional to avoid false-positive error
  ...

Pull security subsystem update from James Morris:
 "Just one minor fix this time"

* 'for-v5.6' of git://git.kernel.org:/pub/scm/linux/kernel/git/jmorris/linux-security:
  security: remove EARLY_LSM_COUNT which never used

Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull IMA updates from Mimi Zohar:
 "Two new features - measuring certificates and querying IMA for a file
  hash - and three bug fixes:

   - Measuring certificates is like the rest of IMA, based on policy,
     but requires loading a custom policy. Certificates loaded onto a
     keyring, for example during early boot, before a custom policy has
     been loaded, are queued and only processed after loading the custom
     policy.

   - IMA calculates and caches files hashes. Other kernel subsystems,
     and possibly kernel modules, are interested in accessing these
     cached file hashes.

  The bug fixes prevent classifying a file short read (e.g. shutdown) as
  an invalid file signature, add a missing blank when displaying the
  securityfs policy rules containing LSM labels, and, lastly, fix the
  handling of the IMA policy information for unknown LSM labels"

* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  IMA: Defined delayed workqueue to free the queued keys
  IMA: Call workqueue functions to measure queued keys
  IMA: Define workqueue for early boot key measurements
  IMA: pre-allocate buffer to hold keyrings string
  ima: ima/lsm policy rule loading logic bug fixes
  ima: add the ability to query the cached hash of a given file
  ima: Add a space after printing LSM rules for readability
  IMA: fix measuring asymmetric keys Kconfig
  IMA: Read keyrings= option from the IMA policy
  IMA: Add support to limit measuring keys
  KEYS: Call the IMA hook to measure keys
  IMA: Define an IMA hook to measure keys
  IMA: Add KEY_CHECK func to measure keys
  IMA: Check IMA policy flag
  ima: avoid appraise error for hash calc interrupt

Pull tomoyo update from Tetsuo Handa:
 "One 'int' -> 'atomic_t' conversion patch to suppress KCSAN's warning"

* tag 'tomoyo-pr-20200128' of git://git.osdn.net/gitroot/tomoyo/tomoyo-test1:
  tomoyo: Use atomic_t for statistics counter

Pull s390 updates from Vasily Gorbik:

 - Add clang 10 build support.

 - Fix BUG() implementation to contain precise bug address, which is
   relevant for kprobes.

 - Make ftraced function appear in a stacktrace.

 - Minor perf improvements and refactoring.

 - Possible deadlock and recovery fixes in pci code.

* tag 's390-5.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390: fix __EMIT_BUG() macro
  s390/ftrace: generate traced function stack frame
  s390: adjust -mpacked-stack support check for clang 10
  s390/jump_label: use "i" constraint for clang
  s390/cpum_sf: Use DIV_ROUND_UP
  s390/cpum_sf: Use kzalloc and minor changes
  s390/cpum_sf: Convert debug trace to common layout
  s390/pci: Fix possible deadlock in recover_store()
  s390/pci: Recover handle in clp_set_pci_fn()

Pull UML updates from Anton Ivanov:
 "I am sending this on behalf of Richard who is traveling.

  This contains the following changes for UML:

   - Fix for time travel mode

   - Disable CONFIG_CONSTRUCTORS again

   - A new command line option to have an non-raw serial line

   - Preparations to remove obsolete UML network drivers"

* tag 'for-linus-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: Fix time-travel=inf-cpu with xor/raid6
  Revert "um: Enable CONFIG_CONSTRUCTORS"
  um: Mark non-vector net transports as obsolete
  um: Add an option to make serial driver non-raw

Pull tracing fix from Steven Rostedt:
 "Kprobe events added 'ustring' to distinguish reading strings from
  kernel space or user space.

  But the creating of the event format file only checks for 'string' to
  display string formats. 'ustring' must also be handled"

* tag 'trace-v5.5-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing/kprobes: Have uname use __get_str() in print_fmt

For personalities previously registered via IORING_REGISTER_PERSONALITY,
allow any command to select them. This is done through setting
sqe->personality to the id returned from registration, and then flagging
sqe->flags with IOSQE_PERSONALITY.

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If an application wants to use a ring with different kinds of
credentials, it can register them upfront. We don't lookup credentials,
the credentials of the task calling IORING_REGISTER_PERSONALITY is used.

An 'id' is returned for the application to use in subsequent personality
support.

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If IORING_SETUP_ATTACH_WQ is set, it expects wq_fd in io_uring_params to
be a valid io_uring fd io-wq of which will be shared with the newly
created io_uring instance. If the flag is set but it can't share io-wq,
it fails.

This allows creation of "sibling" io_urings, where we prefer to keep the
SQ/CQ private, but want to share the async backend to minimize the amount
of overhead associated with having multiple rings that belong to the same
backend.

Reported-by: Jens Axboe <axboe@kernel.dk>
Reported-by: Daurnimator <quae@daurnimator.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Export a helper to attach to an existing io-wq, rather than setting up
a new one. This is doable now that we have reference counted io_wq's.

Reported-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We currently setup the io_wq with a static set of mm and creds. Even for
a single-use io-wq per io_uring, this is suboptimal as we have may have
multiple enters of the ring. For sharing the io-wq backend, it doesn't
work at all.

Switch to passing in the creds and mm when the work item is setup. This
means that async work is no longer deferred to the io_uring mm and creds,
it is done with the current mm and creds.

Flag this behavior with IORING_FEAT_CUR_PERSONALITY, so applications know
they can rely on the current personality (mm and creds) being the same
for direct issue and async issue.

Reviewed-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull thermal updates from Daniel Lezcano:

 - Depromote debug print on the db8500 platform (Linus Walleij)

 - Fix compilation warning when compiling with make W=1 (Amit Kucheria)

 - Code cleanup and refactoring, regmap conversion and add hwmon support
   on Qoriq (Andrey Smirnov)

 - Add an idle injection cpu cooling device and its documentation,
   rename the cpu_cooling device to cpufreq_cooling device (Daniel
   Lezcano)

 - Convert unexported functions to static, add the __init annotation in
   the thermal-of code and remove the pointless wrapper functions
   (Daniel Lezcano)

 - Fix register offset for Armada XP and register reset bit
   initialization (Zak Hays)

 - Enable hwmon on the rockchip (Stefan Schaeckeler)

 - Add the thermal sensor for the H6/H5/H3/A64/A83T/R40 sun8i platform
   and their device tree bindings, followed by a fix for the ths number
   and the sparse warnings (Yangtao Li)

 - Code cleansup for the sun8i and hwmon support (Yangtao Li)

 - Silent some messages which are misleading given the changes made in
   the previous version on generic-adc (Martin Blumenstingl)

 - Rename exynos to Exynos (Krzysztof Kozlowski)

 - Add the bcm2711 thermal driver with the device tree bindings (Stefan
   Wahren)

 - Use usleep_range() instead of udelay() as the call is always done in
   a sleep-able context (Geert Uytterhoeven)

 - Do code cleanup and re-organization to set the scene for a new
   process for the brcmstb (Florian Fainelli)

 - Fix bindings check issues on brcm (Stefan Wahren)

 - Add Jasper Lake support on int340x (Nivedita Swaminathan)

 - Add Comet Lake support on intel pch (Gayatri Kammela)

 - Fix unmatched pci_release_region() on x86 (Chuhong Yuan)

 - Remove temperature boundaries for rcar and rcar3 (Niklas Söderlund)

 - Fix return value to -ENODEV when thermal_zone_of_sensor_register() is
   called with the of-node is missing (Peter Mamonov)

 - Code cleanup, interrupt bouncing, and better support on stm32 (Pascal
   Paillet)

* tag 'thermal-v5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux: (66 commits)
  thermal: stm32: Fix low threshold interrupt flood
  thermal: stm32: Improve temperature computing
  thermal: stm32: Handle multiple trip points
  thermal: stm32: Disable interrupts at probe
  thermal: stm32: Rework sensor mode management
  thermal: stm32: Fix icifr register name
  thermal: of: Make thermal_zone_of_sensor_register return -ENODEV if a sensor OF node is missing
  thermal: rcar_gen3_thermal: Remove temperature bound
  thermal: rcar_thermal: Remove temperature bound
  thermal: intel: intel_pch_thermal: Add Comet Lake (CML) platform support
  thermal: intel: Fix unmatched pci_release_region
  thermal: int340x: processor_thermal: Add Jasper Lake support
  dt-bindings: brcm,avs-ro-thermal: Fix binding check issues
  thermal: brcmstb_thermal: Register different ops per process
  thermal: brcmstb_thermal: Restructure interrupt registration
  thermal: brcmstb_thermal: Add 16nm process thermal parameters
  dt-bindings: thermal: Define BCM7216 thermal sensor compatible
  thermal: brcmstb_thermal: Prepare to support a different process
  thermal: brcmstb_thermal: Do not use DT coefficients
  thermal: rcar_thermal: Use usleep_range() instead of udelay()
  ...