Pull drm fixes from Dave Airlie:
 "Only two sets of drivers fixes: one rcar-du lvds regression fix, and a
  group of fixes for vmwgfx"

* tag 'drm-fixes-for-v4.17-rc7' of git://people.freedesktop.org/~airlied/linux:
  drm/vmwgfx: Schedule an fb dirty update after resume
  drm/vmwgfx: Fix host logging / guestinfo reading error paths
  drm/vmwgfx: Fix 32-bit VMW_PORT_HB_[IN|OUT] macros
  drm: rcar-du: lvds: Fix crash in .atomic_check when disabling connector

Pull sound fixes from Takashi Iwai:
 "Two fixes:

   - a timer pause event notification was garbled upon the recent
     hardening work; corrected now

   - HD-audio runtime PM regression fix due to the incorrect return
     type"

* tag 'sound-4.17-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda - Fix runtime PM
  ALSA: timer: Fix pause event notification

Three fixes for vmwgfx. Two are cc'd stable and fix host logging and its
error paths on 32-bit VMs. One is a fix for a hibernate flaw
introduced with the 4.17 merge window.

* 'vmwgfx-fixes-4.17' of git://people.freedesktop.org/~thomash/linux:
  drm/vmwgfx: Schedule an fb dirty update after resume
  drm/vmwgfx: Fix host logging / guestinfo reading error paths
  drm/vmwgfx: Fix 32-bit VMW_PORT_HB_[IN|OUT] macros

Merge branch 'stable/for-linus-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb

Pull swiotlb fix from Konrad Rzeszutek Wilk:
 "One single fix in here: under Xen the DMA32 heap (in the hypervisor)
  would end up looking like swiss cheese.

  The reason being that for every coherent DMA allocation we didn't do
  the proper hypercall to tell Xen to return the page back to the DMA32
  heap. End result was (eventually) no DMA32 space if you (for example)
  continously unloaded and loaded modules"

* 'stable/for-linus-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb:
  xen-swiotlb: fix the check condition for xen_swiotlb_free_coherent

Pull rdma fixes from Jason Gunthorpe:
 "This is pretty much just the usual array of smallish driver bugs.

   - remove bouncing addresses from the MAINTAINERS file

   - kernel oops and bad error handling fixes for hfi, i40iw, cxgb4, and
     hns drivers

   - various small LOC behavioral/operational bugs in mlx5, hns, qedr
     and i40iw drivers

   - two fixes for patches already sent during the merge window

   - a long-standing bug related to not decreasing the pinned pages
     count in the right MM was found and fixed"

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (28 commits)
  RDMA/hns: Move the location for initializing tmp_len
  RDMA/hns: Bugfix for cq record db for kernel
  IB/uverbs: Fix uverbs_attr_get_obj
  RDMA/qedr: Fix doorbell bar mapping for dpi > 1
  IB/umem: Use the correct mm during ib_umem_release
  iw_cxgb4: Fix an error handling path in 'c4iw_get_dma_mr()'
  RDMA/i40iw: Avoid panic when reading back the IRQ affinity hint
  RDMA/i40iw: Avoid reference leaks when processing the AEQ
  RDMA/i40iw: Avoid panic when objects are being created and destroyed
  RDMA/hns: Fix the bug with NULL pointer
  RDMA/hns: Set NULL for __internal_mr
  RDMA/hns: Enable inner_pa_vld filed of mpt
  RDMA/hns: Set desc_dma_addr for zero when free cmq desc
  RDMA/hns: Fix the bug with rq sge
  RDMA/hns: Not support qp transition from reset to reset for hip06
  RDMA/hns: Add return operation when configured global param fail
  RDMA/hns: Update convert function of endian format
  RDMA/hns: Load the RoCE dirver automatically
  RDMA/hns: Bugfix for rq record db for kernel
  RDMA/hns: Add rq inline flags judgement
  ...

Pull btrfs fix from David Sterba:
 "A one-liner that prevents leaking an internal error value 1 out of the
  ftruncate syscall.

  This has been observed in practice. The steps to reproduce make a
  common pattern (open/write/fync/ftruncate) but also need the
  application to not check only for negative values and happens only for
  compressed inlined files.

  The conditions are narrow but as this could break userspace I think
  it's better to merge it now and not wait for the merge window"

* tag 'for-4.17-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Btrfs: fix error handling in btrfs_truncate()

Before commit 3b5b899c ("ALSA: hda: Make use of core codec functions
to sync power state"), hda_set_power_state() returned the response to
the Get Power State verb, a 32-bit unsigned integer whose expected value
is 0x233 after transitioning a codec to D3, and 0x0 after transitioning
it to D0.

The response value is significant because hda_codec_runtime_suspend()
does not clear the codec's bit in the codec_powered bitmask unless the
AC_PWRST_CLK_STOP_OK bit (0x200) is set in the response value.  That in
turn prevents the HDA controller from runtime suspending because
azx_runtime_idle() checks that the codec_powered bitmask is zero.

Since commit 3b5b899c, hda_set_power_state() only returns 0x0 or
0x1, thereby breaking runtime PM for any HDA controller.  That's because
an inline function introduced by the commit returns a bool instead of a
32-bit unsigned int.  The change was likely erroneous and resulted from
copying and pasting snd_hda_check_power_state(), which is immediately
preceding the newly introduced inline function.  Fix it.

Link: https://bugs.freedesktop.org/show_bug.cgi?id=106597
Fixes: 3b5b899c ("ALSA: hda: Make use of core codec functions to sync power state")
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Abhijeet Kumar <abhijeet.kumar@intel.com>
Reported-and-tested-by: Gunnar Krüger <taijian@posteo.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

This reverts the following commits that change CMA design in MM.

 3d2054ad ("ARM: CMA: avoid double mapping to the CMA area if CONFIG_HIGHMEM=y")

 1d47a3ec ("mm/cma: remove ALLOC_CMA")

 bad8c6c0 ("mm/cma: manage the memory of the CMA area by using the ZONE_MOVABLE")

Ville reported a following error on i386.

  Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
  microcode: microcode updated early to revision 0x4, date = 2013-06-28
  Initializing CPU#0
  Initializing HighMem for node 0 (000377fe:00118000)
  Initializing Movable for node 0 (00000001:00118000)
  BUG: Bad page state in process swapper  pfn:377fe
  page:f53effc0 count:0 mapcount:-127 mapping:00000000 index:0x0
  flags: 0x80000000()
  raw: 80000000 00000000 00000000 ffffff80 00000000 00000100 00000200 00000001
  page dumped because: nonzero mapcount
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted 4.17.0-rc5-elk+ #145
  Hardware name: Dell Inc. Latitude E5410/03VXMC, BIOS A15 07/11/2013
  Call Trace:
   dump_stack+0x60/0x96
   bad_page+0x9a/0x100
   free_pages_check_bad+0x3f/0x60
   free_pcppages_bulk+0x29d/0x5b0
   free_unref_page_commit+0x84/0xb0
   free_unref_page+0x3e/0x70
   __free_pages+0x1d/0x20
   free_highmem_page+0x19/0x40
   add_highpages_with_active_regions+0xab/0xeb
   set_highmem_pages_init+0x66/0x73
   mem_init+0x1b/0x1d7
   start_kernel+0x17a/0x363
   i386_start_kernel+0x95/0x99
   startup_32_smp+0x164/0x168

The reason for this error is that the span of MOVABLE_ZONE is extended
to whole node span for future CMA initialization, and, normal memory is
wrongly freed here.  I submitted the fix and it seems to work, but,
another problem happened.

It's so late time to fix the later problem so I decide to reverting the
series.
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Laura Abbott <labbott@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull libata fixes from Tejun Heo:
 "Nothing too interesting.  Four patches to update the blacklist and
  add a controller ID"

* 'for-4.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata:
  ahci: Add PCI ID for Cannon Lake PCH-LP AHCI
  libata: blacklist Micron 500IT SSD with MU01 firmware
  libata: Apply NOLPM quirk for SAMSUNG PM830 CXM13D1Q.
  libata: Blacklist some Sandisk SSDs for NCQ

Pull block fixes from Jens Axboe:
 "Two fixes that should go into this release:

   - a loop writeback error clearing fix from Jeff

   - the sr sense fix from myself"

* tag 'for-linus-20180524' of git://git.kernel.dk/linux-block:
  loop: clear wb_err in bd_inode when detaching backing file
  sr: pass down correctly sized SCSI sense buffer

Pull power management fix from Rafael Wysocki:
 "Fix a regression from the 4.15 cycle that caused the system suspend
  and resume overhead to increase on many systems and triggered more
  serious problems on some of them (Rafael Wysocki)"

* tag 'pm-4.17-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM / core: Fix direct_complete handling for devices with no callbacks

This one should be using the default LPM policy for mobile chipsets so
add the PCI ID to the driver list of supported revices.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org

Jun Wu at Facebook reported that an internal service was seeing a return
value of 1 from ftruncate() on Btrfs in some cases. This is coming from
the NEED_TRUNCATE_BLOCK return value from btrfs_truncate_inode_items().

btrfs_truncate() uses two variables for error handling, ret and err.
When btrfs_truncate_inode_items() returns non-zero, we set err to the
return value. However, NEED_TRUNCATE_BLOCK is not an error. Make sure we
only set err if ret is an error (i.e., negative).

To reproduce the issue: mount a filesystem with -o compress-force=zstd
and the following program will encounter return value of 1 from
ftruncate:

int main(void) {
        char buf[256] = { 0 };
        int ret;
        int fd;

        fd = open("test", O_CREAT | O_WRONLY | O_TRUNC, 0666);
        if (fd == -1) {
                perror("open");
                return EXIT_FAILURE;
        }

        if (write(fd, buf, sizeof(buf)) != sizeof(buf)) {
                perror("write");
                close(fd);
                return EXIT_FAILURE;
        }

        if (fsync(fd) == -1) {
                perror("fsync");
                close(fd);
                return EXIT_FAILURE;
        }

        ret = ftruncate(fd, 128);
        if (ret) {
                printf("ftruncate() returned %d\n", ret);
                close(fd);
                return EXIT_FAILURE;
        }

        close(fd);
        return EXIT_SUCCESS;
}

Fixes: ddfae63c ("btrfs: move btrfs_truncate_block out of trans handle")
CC: stable@vger.kernel.org # 4.15+
Reported-by: Jun Wu <quark@fb.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

When posted work request, it need to compute the length of
all sges of every wr and fill it into the msg_len field of
send wqe. Thus, While posting multiple wr,
tmp_len should be reinitialized to zero.

Fixes: 8b9b8d14 ("RDMA/hns: Fix the endian problem for hns")
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

When use cq record db for kernel, it needs to set the hr_cq->db_en
to 1 and configure the dma address of record cq db of qp context.

Fixes: 86188a88 ("RDMA/hns: Support cq record doorbell for kernel space")
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

The err pointer comes from uverbs_attr_get, not from the uobject member,
which does not store an ERR_PTR.

Fixes: be934cca ("IB/uverbs: Add device memory registration ioctl support")
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>

Each user_context receives a separate dpi value and thus a different
address on the doorbell bar. The qedr_mmap function needs to validate
the address and map the doorbell bar accordingly.
The current implementation always checked against dpi=0 doorbell range
leading to a wrong mapping for doorbell bar. (It entered an else case
that mapped the address differently). qedr_mmap should only be used
for doorbells, so the else was actually wrong in the first place.
This only has an affect on arm architecture and not an issue on a
x86 based architecture.
This lead to doorbells not occurring on arm based systems and left
applications that use more than one dpi (or several applications
run simultaneously ) to hang.

Fixes: ac1b36e5 ("qedr: Add support for user context verbs")
Signed-off-by: Ariel Elior <Ariel.Elior@cavium.com>
Signed-off-by: Michal Kalderon <Michal.Kalderon@cavium.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

Pull MFD fix from Lee Jones:
 "A single cros_ec_spi fix correcting the handling for long-running
  commands"

* tag 'mfd-fixes-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd:
  mfd: cros_ec: Retry commands when EC is known to be busy

Pull alpha fixes from Matt Turner:
 "A few small changes for alpha"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha:
  alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering #2
  alpha: simplify get_arch_dma_ops
  alpha: use dma_direct_ops for jensen

We have had problems displaying fbdev after a resume and as a
workaround we have had to call vmw_fb_refresh(). This has had
a number of unwanted side-effects. The root of the problem was,
however that the coalesced fbdev dirty region was not empty on
the first dirty_mark() after a resume, so a flush was never
scheduled.

Fix this by force scheduling an fbdev flush after resume, and
remove the workaround.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>

The error paths were leaking opened channels.
Fix by using dedicated error paths.

Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>

Depending on whether the kernel is compiled with frame-pointer or not,
the temporary memory location used for the bp parameter in these macros
is referenced relative to the stack pointer or the frame pointer.
Hence we can never reference that parameter when we've modified either
the stack pointer or the frame pointer, because then the compiler would
generate an incorrect stack reference.

Fix this by pushing the temporary memory parameter on a known location on
the stack before modifying the stack- and frame pointers.

Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>

Commit 001dde94 ("mfd: cros ec: spi: Fix "in progress" error
signaling") pointed out some bad code, but its analysis and conclusion
was not 100% correct.

It *is* correct that we should not propagate result==EC_RES_IN_PROGRESS
for transport errors, because this has a special meaning -- that we
should follow up with EC_CMD_GET_COMMS_STATUS until the EC is no longer
busy. This is definitely the wrong thing for many commands, because
among other problems, EC_CMD_GET_COMMS_STATUS doesn't actually retrieve
any RX data from the EC, so commands that expected some data back will
instead start processing junk.

For such commands, the right answer is to either propagate the error
(and return that error to the caller) or resend the original command
(*not* EC_CMD_GET_COMMS_STATUS).

Unfortunately, commit 001dde94 forgets a crucial point: that for
some long-running operations, the EC physically cannot respond to
commands any more. For example, with EC_CMD_FLASH_ERASE, the EC may be
re-flashing its own code regions, so it can't respond to SPI interrupts.
Instead, the EC prepares us ahead of time for being busy for a "long"
time, and fills its hardware buffer with EC_SPI_PAST_END. Thus, we
expect to see several "transport" errors (or, messages filled with
EC_SPI_PAST_END). So we should really translate that to a retryable
error (-EAGAIN) and continue sending EC_CMD_GET_COMMS_STATUS until we
get a ready status.

IOW, it is actually important to treat some of these "junk" values as
retryable errors.

Together with commit 001dde94, this resolves bugs like the
following:

1. EC_CMD_FLASH_ERASE now works again (with commit 001dde94, we
   would abort the first time we saw EC_SPI_PAST_END)
2. Before commit 001dde94, transport errors (e.g.,
   EC_SPI_RX_BAD_DATA) seen in other commands (e.g.,
   EC_CMD_RTC_GET_VALUE) used to yield junk data in the RX buffer; they
   will now yield -EAGAIN return values, and tools like 'hwclock' will
   simply fail instead of retrieving and re-programming undefined time
   values

Fixes: 001dde94 ("mfd: cros ec: spi: Fix "in progress" error signaling")
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

memory-barriers.txt has been updated with the following requirement.

"When using writel(), a prior wmb() is not needed to guarantee that the
cache coherent memory writes have completed before writing to the MMIO
region."

Current writeX() and iowriteX() implementations on alpha are not
satisfying this requirement as the barrier is after the register write.

Move mb() in writeX() and iowriteX() functions to guarantee that HW
observes memory changes before performing register operations.
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Matt Turner <mattst88@gmail.com>

Remove the dma_ops indirection.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matt Turner <mattst88@gmail.com>

The generic dma_direct implementation does the same thing as the alpha
pci-noop implementation, just with more bells and whistles.  And unlike
the current code it at least has a theoretical chance to actually compile.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matt Turner <mattst88@gmail.com>

Commit 08810a41 (PM / core: Add NEVER_SKIP and SMART_PREPARE
driver flags) inadvertently prevented the power.direct_complete flag
from being set for devices without PM callbacks and with disabled
runtime PM which also prevents power.direct_complete from being set
for their parents.  That led to problems including a resume crash on
HP ZBook 14u.

Restore the previous behavior by causing power.direct_complete to be
set for those devices again, but do that in a more direct way to
avoid overlooking that case in the future.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=199693
Fixes: 08810a41 (PM / core: Add NEVER_SKIP and SMART_PREPARE driver flags)
Reported-by: Thomas Martitz <kugel@rockbox.org>
Tested-by: Thomas Martitz <kugel@rockbox.org>
Cc: 4.15+ <stable@vger.kernel.org> # 4.15+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Johan Hovold <johan@kernel.org>

On some CPUs we can prevent a vulnerability related to store-to-load
forwarding by preventing store forwarding between privilege domains,
by inserting a barrier in kernel entry and exit paths.

This is known to be the case on at least Power7, Power8 and Power9
powerpc CPUs.

Barriers must be inserted generally before the first load after moving
to a higher privilege, and after the last store before moving to a
lower privilege, HV and PR privilege transitions must be protected.

Barriers are added as patch sections, with all kernel/hypervisor entry
points patched, and the exit points to lower privilge levels patched
similarly to the RFI flush patching.

Firmware advertisement is not implemented yet, so CPU flush types
are hard coded.

Thanks to Michal Suchánek for bug fixes and review.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michal Suchánek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Single regression fix for rcar-du lvds

* 'drm/du/fixes' of git://linuxtv.org/pinchartl/media:
  drm: rcar-du: lvds: Fix crash in .atomic_check when disabling connector

Pull SCSI fixes from James Bottomley:
 "Two driver fixes (zfcp and target core), one information leak in sg
  and one build clean up"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: sg: allocate with __GFP_ZERO in sg_build_indirect()
  scsi: core: clean up generated file scsi_devinfo_tbl.c
  scsi: target: tcmu: fix error resetting qfull_time_out to default
  scsi: zfcp: fix infinite iteration on ERP ready list

Pull vfs fixes from Al Viro:
 "Assorted fixes all over the place"

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  aio: fix io_destroy(2) vs. lookup_ioctx() race
  ext2: fix a block leak
  nfsd: vfs_mkdir() might succeed leaving dentry negative unhashed
  cachefiles: vfs_mkdir() might succeed leaving dentry negative unhashed
  unfuck sysfs_mount()
  kernfs: deal with kernfs_fill_super() failures
  cramfs: Fix IS_ENABLED typo
  befs_lookup(): use d_splice_alias()
  affs_lookup: switch to d_splice_alias()
  affs_lookup(): close a race with affs_remove_link()
  fix breakage caused by d_find_alias() semantics change
  fs: don't scan the inode cache before SB_BORN is set
  do d_instantiate/unlock_new_inode combinations safely
  iov_iter: fix memory leak in pipe_get_pages_alloc()
  iov_iter: fix return type of __pipe_get_pages()

When a loop block device encounters a writeback error, that error will
get propagated to the bd_inode's wb_err field. If we then detach the
backing file from it, attach another and fsync it, we'll get back the
writeback error that we had from the previous backing file.

This is a bit of a grey area as POSIX doesn't cover loop devices, but it
is somewhat counterintuitive.

If we detach a backing file from the loopdev while there are still
unreported errors, take it as a sign that we're no longer interested in
the previous file, and clear out the wb_err in the loop blockdev.
Reported-and-Tested-by: Theodore Y. Ts'o <tytso@mit.edu>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

kill_ioctx() used to have an explicit RCU delay between removing the
reference from ->ioctx_table and percpu_ref_kill() dropping the refcount.
At some point that delay had been removed, on the theory that
percpu_ref_kill() itself contained an RCU delay.  Unfortunately, that was
the wrong kind of RCU delay and it didn't care about rcu_read_lock() used
by lookup_ioctx().  As the result, we could get ctx freed right under
lookup_ioctx().  Tejun has fixed that in a6d7cff4 ("fs/aio: Add explicit
RCU grace period when freeing kioctx"); however, that fix is not enough.

Suppose io_destroy() from one thread races with e.g. io_setup() from another;
CPU1 removes the reference from current->mm->ioctx_table[...] just as CPU2
has picked it (under rcu_read_lock()).  Then CPU1 proceeds to drop the
refcount, getting it to 0 and triggering a call of free_ioctx_users(),
which proceeds to drop the secondary refcount and once that reaches zero
calls free_ioctx_reqs().  That does
        INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
        queue_rcu_work(system_wq, &ctx->free_rwork);
and schedules freeing the whole thing after RCU delay.

In the meanwhile CPU2 has gotten around to percpu_ref_get(), bumping the
refcount from 0 to 1 and returned the reference to io_setup().

Tejun's fix (that queue_rcu_work() in there) guarantees that ctx won't get
freed until after percpu_ref_get().  Sure, we'd increment the counter before
ctx can be freed.  Now we are out of rcu_read_lock() and there's nothing to
stop freeing of the whole thing.  Unfortunately, CPU2 assumes that since it
has grabbed the reference, ctx is *NOT* going away until it gets around to
dropping that reference.

The fix is obvious - use percpu_ref_tryget_live() and treat failure as miss.
It's not costlier than what we currently do in normal case, it's safe to
call since freeing *is* delayed and it closes the race window - either
lookup_ioctx() comes before percpu_ref_kill() (in which case ctx->users
won't reach 0 until the caller of lookup_ioctx() drops it) or lookup_ioctx()
fails, ctx->users is unaffected and caller of lookup_ioctx() doesn't see
the object in question at all.

Cc: stable@kernel.org
Fixes: a6d7cff4 "fs/aio: Add explicit RCU grace period when freeing kioctx"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

open file, unlink it, then use ioctl(2) to make it immutable or
append only.  Now close it and watch the blocks *not* freed...

Immutable/append-only checks belong in ->setattr().
Note: the bug is old and backport to anything prior to 737f2e93
("ext2: convert to use the new truncate convention") will need
these checks lifted into ext2_setattr().

Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

That can (and does, on some filesystems) happen - ->mkdir() (and thus
vfs_mkdir()) can legitimately leave its argument negative and just
unhash it, counting upon the lookup to pick the object we'd created
next time we try to look at that name.

Some vfs_mkdir() callers forget about that possibility...
Acked-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

That can (and does, on some filesystems) happen - ->mkdir() (and thus
vfs_mkdir()) can legitimately leave its argument negative and just
unhash it, counting upon the lookup to pick the object we'd created
next time we try to look at that name.

Some vfs_mkdir() callers forget about that possibility...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

new_sb is left uninitialized in case of early failures in kernfs_mount_ns(),
and while IS_ERR(root) is true in all such cases, using IS_ERR(root) || !new_sb
is not a solution - IS_ERR(root) is true in some cases when new_sb is true.

Make sure new_sb is initialized (and matches the reality) in all cases and
fix the condition for dropping kobj reference - we want it done precisely
in those situations where the reference has not been transferred into a new
super_block instance.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

make sure that info->node is initialized early, so that kernfs_kill_sb()
can list_del() it safely.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

There's an extra C here...

Fixes: 99c18ce5 ("cramfs: direct memory access support")
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

RTFS(Documentation/filesystems/nfs/Exporting) if you try to make
something exportable.

Fixes: ac632f5b "befs: add NFS export support"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>