In some cases, it may be useful to provide a way to skip a number
of bytes in a vringh_kiov.

Let's implement vringh_kiov_advance() for this purpose, reusing the
code from vringh_iov_xfer().
We replace that code calling the new vringh_kiov_advance().
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-6-sgarzare@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

riov and wiov can be reused with subsequent calls of vringh_getdesc_*().

Let's add a paragraph in the documentation of these functions to better
explain when riov and wiov need to be cleaned up.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-5-sgarzare@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

__vringh_iov() overwrites the contents of riov and wiov, in fact it
resets the 'i' and 'used' fields, but also the 'consumed' field should
be reset to avoid an inconsistent state.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-4-sgarzare@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

Usually iotlb accesses are synchronized with a spinlock.
Let's request it as a new parameter in vringh_set_iotlb() and
hold it when we navigate the iotlb in iotlb_translate() to avoid
race conditions with any new additions/deletions of ranges from
the ioltb.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-3-sgarzare@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

The identical mapping used until now created issues when mapping
different virtual pages with the same physical address.
To solve this issue, we can use the iova module, to handle the IOVA
allocation.
For simplicity we use an IOVA allocator with byte granularity.

We add two new functions, vdpasim_map_range() and vdpasim_unmap_range(),
to handle the IOVA allocation and the registration into the IOMMU/IOTLB.
These functions are used by dma_map_ops callbacks.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-2-sgarzare@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

This commit deduces the VIRTIO device ID of a probed
device from its pdev device ids.
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Link: https://lore.kernel.org/r/20210317094933.16417-8-lingshan.zhu@intel.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

vDPA requres VIRTIO_F_ACCESS_PLATFORM as a must, this commit
examines this when set features.
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210317094933.16417-7-lingshan.zhu@intel.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

This commit would read and store device feature
bits when probe.

rename ifcvf_get_features() to ifcvf_get_hw_features(),
it reads and stores features of the probed device.

new ifcvf_get_features() simply returns stored
feature bits.
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210317094933.16417-6-lingshan.zhu@intel.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

This commit removes the version number string, using kernel
version is enough.
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210317094933.16417-5-lingshan.zhu@intel.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

IFCVF driver probes multiple types of devices now,
to distinguish the original device driven by IFCVF
from others, it is renamed as "N3000".
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210317094933.16417-4-lingshan.zhu@intel.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

This commit enabled Intel FPGA SmartNIC C5000X-PL virtio-net
for vDPA
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210317094933.16417-3-lingshan.zhu@intel.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

In this commit, ifcvf_get_vendor_id() will return
a device specific vendor id of the probed pci device
than a hard code.
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210317094933.16417-2-lingshan.zhu@intel.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

The virtqueue doorbell is usually implemented via registeres but we
don't provide the necessary vma->flags like VM_PFNMAP. This may cause
several issues e.g when userspace tries to map the doorbell via vhost
IOTLB, kernel may panic due to the page is not backed by page
structure. This patch fixes this by setting the necessary
vm_flags. With this patch, try to map doorbell via IOTLB will fail
with bad address.

Cc: stable@vger.kernel.org
Fixes: ddd89d0a ("vhost_vdpa: support doorbell mapping via mmap")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210413091557.29008-1-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

This patch reports the per vq doorbell location and size to vDPA
bus. Userspace can then map the doorbell via mmap() via vhost-vDPA bus
driver.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210415073147.19331-8-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>

Sometimes it might be useful to report the capability physical
address. One example is to report the physical address of the doorbell
in order to be mapped by userspace.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210415073147.19331-7-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

No user now and the capability should not be setup
externally. Instead, every access to the capability should be done via
virtio_pci_modern_device.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210415073147.19331-6-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>

All users (both virtio-pci library and vp_vdpa driver) has been
switched to use vp_modern_map_vq_notify(). So there's no need to
export the low level helper of vp_modern_get_queue_notify_off().
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210415073147.19331-5-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>

This patch switches to use vp_vdpa to use vp_modern_map_notify().
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210415073147.19331-4-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>

This patch switch to use vp_modern_map_notify() for virtio-pci
library.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210415073147.19331-3-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>

This patch factors out the logic of vq notify area mapping. Following
patches will switch to use this common helpers for both virtio_pci
library and virtio-pci vDPA driver.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210415073147.19331-2-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>

Not all virtio_net devices support the ctrl queue feature. Thus, there
is no need to allocate unused resources.
Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Link: https://lore.kernel.org/r/20210502093319.61313-1-mgurtovoy@nvidia.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

Typo: compation --> compaction
Signed-off-by: Liu Xiang <liu.xiang@zlingsmart.com>
Link: https://lore.kernel.org/r/20210327031710.16151-1-liu.xiang@zlingsmart.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>

Follow comment style mentioned in the Writing kernel-doc document [1].

Following warnings are fixed.

$ scripts/kernel-doc -v -none drivers/vdpa/vdpa.c
drivers/vdpa/vdpa.c:67: info: Scanning doc for __vdpa_alloc_device
drivers/vdpa/vdpa.c:84: warning: No description found for return value of '__vdpa_alloc_device'
drivers/vdpa/vdpa.c:153: info: Scanning doc for _vdpa_register_device
drivers/vdpa/vdpa.c:163: warning: No description found for return value of '_vdpa_register_device'
drivers/vdpa/vdpa.c:172: info: Scanning doc for vdpa_register_device
drivers/vdpa/vdpa.c:180: warning: No description found for return value of 'vdpa_register_device'
drivers/vdpa/vdpa.c:191: info: Scanning doc for _vdpa_unregister_device
drivers/vdpa/vdpa.c:205: info: Scanning doc for vdpa_unregister_device
drivers/vdpa/vdpa.c:217: info: Scanning doc for __vdpa_register_driver
drivers/vdpa/vdpa.c:224: warning: No description found for return value of '__vdpa_register_driver'
drivers/vdpa/vdpa.c:233: info: Scanning doc for vdpa_unregister_driver
drivers/vdpa/vdpa.c:243: info: Scanning doc for vdpa_mgmtdev_register
drivers/vdpa/vdpa.c:250: warning: No description found for return value of 'vdpa_mgmtdev_register'

After the fix:

scripts/kernel-doc -v -none drivers/vdpa/vdpa.c
drivers/vdpa/vdpa.c:67: info: Scanning doc for __vdpa_alloc_device
drivers/vdpa/vdpa.c:153: info: Scanning doc for _vdpa_register_device
drivers/vdpa/vdpa.c:172: info: Scanning doc for vdpa_register_device
drivers/vdpa/vdpa.c:191: info: Scanning doc for _vdpa_unregister_device
drivers/vdpa/vdpa.c:205: info: Scanning doc for vdpa_unregister_device
drivers/vdpa/vdpa.c:217: info: Scanning doc for __vdpa_register_driver
drivers/vdpa/vdpa.c:233: info: Scanning doc for vdpa_unregister_driver
drivers/vdpa/vdpa.c:243: info: Scanning doc for vdpa_mgmtdev_register

[1] https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.htmlSigned-off-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20210406170457.98481-3-parav@nvidia.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

Follow comment style mentioned in the Writing kernel-doc document [1].

Following warnings are fixed.
$ scripts/kernel-doc -v -none include/linux/vdpa.h
include/linux/vdpa.h:11: warning: missing initial short description on line:
 * vDPA callback definition.
include/linux/vdpa.h:11: info: Scanning doc for vDPA
include/linux/vdpa.h:15: warning: cannot understand function prototype: 'struct vdpa_callback '
include/linux/vdpa.h:21: warning: missing initial short description on line:
 * vDPA notification area
include/linux/vdpa.h:21: info: Scanning doc for vDPA
include/linux/vdpa.h:25: warning: cannot understand function prototype: 'struct vdpa_notification_area '
include/linux/vdpa.h:31: warning: missing initial short description on line:
 * vDPA vq_state definition
include/linux/vdpa.h:31: info: Scanning doc for vDPA
include/linux/vdpa.h:34: warning: cannot understand function prototype: 'struct vdpa_vq_state '
include/linux/vdpa.h:41: info: Scanning doc for vDPA device
include/linux/vdpa.h:51: warning: cannot understand function prototype: 'struct vdpa_device '
include/linux/vdpa.h:62: info: Scanning doc for vDPA IOVA range
include/linux/vdpa.h:66: warning: cannot understand function prototype: 'struct vdpa_iova_range '
include/linux/vdpa.h:72: info: Scanning doc for vDPA_config_ops
include/linux/vdpa.h:203: warning: cannot understand function prototype: 'struct vdpa_config_ops '
include/linux/vdpa.h:270: info: Scanning doc for vdpa_driver
include/linux/vdpa.h:275: warning: cannot understand function prototype: 'struct vdpa_driver '
include/linux/vdpa.h:347: info: Scanning doc for vdpa_mgmtdev_ops
include/linux/vdpa.h:360: warning: cannot understand function prototype: 'struct vdpa_mgmtdev_ops '

After this fix:

scripts/kernel-doc -v -none include/linux/vdpa.h
include/linux/vdpa.h:11: info: Scanning doc for struct vdpa_calllback
include/linux/vdpa.h:21: info: Scanning doc for struct vdpa_notification_area
include/linux/vdpa.h:31: info: Scanning doc for struct vdpa_vq_state
include/linux/vdpa.h:41: info: Scanning doc for struct vdpa_device
include/linux/vdpa.h:62: info: Scanning doc for struct vdpa_iova_range
include/linux/vdpa.h:72: info: Scanning doc for struct vdpa_config_ops
include/linux/vdpa.h:270: info: Scanning doc for struct vdpa_driver
include/linux/vdpa.h:347: info: Scanning doc for struct vdpa_mgmtdev_ops

[1] https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.htmlSigned-off-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20210406170457.98481-2-parav@nvidia.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

Allow to control vdpa device creation and destruction using the vdpa
management tool.

Examples:
1. List the management devices
$ vdpa mgmtdev show
pci/0000:3b:00.1:
  supported_classes net

2. Create vdpa instance
$ vdpa dev add mgmtdev pci/0000:3b:00.1 name vdpa0

3. Show vdpa devices
$ vdpa dev show
vdpa0: type network mgmtdev pci/0000:3b:00.1 vendor_id 5555 max_vqs 16 \
max_vq_size 256
Signed-off-by: Eli Cohen <elic@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210408091320.4600-1-elic@nvidia.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

This patch introduce a vDPA driver for virtio-pci device. It bridges
the virtio-pci control command to the vDPA bus. This will be used for
features prototyping and testing.

Note that get/restore virtqueue state is not supported which needs
extension on the virtio specification.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210223061905.422659-4-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

Merge tag 'perf-tools-fixes-for-v5.12-2021-04-25' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux

Pull perf tools fixes from Arnaldo Carvalho de Melo:

 - Fix potential NULL pointer dereference in the auxtrace option parser

 - Fix access to PID in an array when setting a PID filter in 'perf ftrace'

 - Fix error return code in the 'perf data' tool and in maps__clone(),
   found using a static analysis tool from Huawei

* tag 'perf-tools-fixes-for-v5.12-2021-04-25' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux:
  perf map: Fix error return code in maps__clone()
  perf ftrace: Fix access to pid in array when setting a pid filter
  perf auxtrace: Fix potential NULL pointer dereference
  perf data: Fix error return code in perf_data__create_dir()

Pull x86 perf fixes from Borislav Petkov:

 - Fix Broadwell Xeon's stepping in the PEBS isolation table of CPUs

 - Fix a panic when initializing perf uncore machinery on Haswell and
   Broadwell servers

* tag 'perf_urgent_for_v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/kvm: Fix Broadwell Xeon stepping in isolation_ucodes[]
  perf/x86/intel/uncore: Remove uncore extra PCI dev HSWEP_PCI_PCU_3

Pull locking fix from Borislav Petkov:
 "Fix ordering in the queued writer lock's slowpath"

* tag 'locking_urgent_for_v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/qrwlock: Fix ordering in queued_write_lock_slowpath()

Pull scheduler fix from Borislav Petkov:
 "Fix a typo in a macro ifdeffery"

* tag 'sched_urgent_for_v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  preempt/dynamic: Fix typo in macro conditional statement

Pull x86 fix from Borislav Petkov:
 "Fix an out-of-bounds memory access when setting up a crash kernel with
  kexec"

* tag 'x86_urgent_for_v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/crash: Fix crash_setup_memmap_entries() out-of-bounds access

Pull kvm fix from Paolo Bonzini:
 "Fix SRCU bug introduced in the merge window"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86/xen: Take srcu lock when accessing kvm_memslots()

This reverts commit 0c85a7e8.

The games with 'rm' are on (two separate instances) of a local variable,
and make no difference.

Quoting Aditya Pakki:
 "I was the author of the patch and it was the cause of the giant UMN
  revert.

  The patch is garbage and I was unaware of the steps involved in
  retracting it. I *believed* the maintainers would pull it, given it
  was already under Greg's list. The patch does not introduce any bugs
  but is pointless and is stupid. I accept my incompetence and for not
  requesting a revert earlier."

Link: https://lwn.net/Articles/854319/Requested-by: Aditya Pakki <pakki001@umn.edu>
Cc: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull pin control fixes from Linus Walleij:
 "Late pin control fixes, would have been in the main pull request
  normally but hey I got lucky and we got another week to polish up
  v5.12 so here we go.

  One driver fix and one making the core debugfs work:

   - Fix the number of pins in the community of the Intel Lewisburg SoC

   - Show pin numbers for controllers with base = 0 in the new debugfs
     feature"

* tag 'pinctrl-v5.12-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: core: Show pin numbers for the controllers with base = 0
  pinctrl: lewisburg: Update number of pins in community

Merge misc fixes from Andrew Morton:
 "5 patches.

  Subsystems affected by this patch series: coda, overlayfs, and
  mm (pagecache and memcg)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  tools/cgroup/slabinfo.py: updated to work on current kernel
  mm/filemap: fix mapping_seek_hole_data on THP & 32-bit
  mm/filemap: fix find_lock_entries hang on 32-bit THP
  ovl: fix reference counting in ovl_mmap error path
  coda: fix reference counting in coda_file_mmap error path

Pull block fix from Jens Axboe:
 "A single fix for a behavioral regression in this series, when
  re-reading the partition table with partitions open"

* tag 'block-5.12-2021-04-23' of git://git.kernel.dk/linux-block:
  block: return -EBUSY when there are open partitions in blkdev_reread_part

slabinfo.py script does not work with actual kernel version.

First, it was unable to recognise SLUB susbsytem, and when I specified
it manually it failed again with

  AttributeError: 'struct page' has no member 'obj_cgroups'

.. and then again with

  File "tools/cgroup/memcg_slabinfo.py", line 221, in main
    memcg.kmem_caches.address_of_(),
  AttributeError: 'struct mem_cgroup' has no member 'kmem_caches'

Link: https://lkml.kernel.org/r/cec1a75e-43b4-3d64-2084-d9f98fda037f@virtuozzo.comSigned-off-by: Vasily Averin <vvs@virtuozzo.com>
Tested-by: Roman Gushchin <guro@fb.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

No problem on 64-bit, or without huge pages, but xfstests generic/285
and other SEEK_HOLE/SEEK_DATA tests have regressed on huge tmpfs, and on
32-bit architectures, with the new mapping_seek_hole_data().  Several
different bugs turned out to need fixing.

u64 cast to stop losing bits when converting unsigned long to loff_t
(and let's use shifts throughout, rather than mixed with * and /).

Use round_up() when advancing pos, to stop assuming that pos was already
THP-aligned when advancing it by THP-size.  (This use of round_up()
assumes that any THP has THP-aligned index: true at present and true
going forward, but could be recoded to avoid the assumption.)

Use xas_set() when iterating away from a THP, so that xa_index stays in
synch with start, instead of drifting away to return bogus offset.

Check start against end to avoid wrapping 32-bit xa_index to 0 (and to
handle these additional cases, seek_data or not, it's easier to break
the loop than goto: so rearrange exit from the function).

[hughd@google.com: remove unneeded u64 casts, per Matthew]
  Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2104221347240.1170@eggly.anvils

Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2104211737410.3299@eggly.anvils
Fixes: 41139aa4 ("mm/filemap: add mapping_seek_hole_data")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

No problem on 64-bit, or without huge pages, but xfstests generic/308
hung uninterruptibly on 32-bit huge tmpfs.

Since commit 0cc3b0ec ("Clarify (and fix) in 4.13 MAX_LFS_FILESIZE
macros"), MAX_LFS_FILESIZE is only a PAGE_SIZE away from wrapping 32-bit
xa_index to 0, so the new find_lock_entries() has to be extra careful
when handling a THP.

Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2104211735430.3299@eggly.anvils
Fixes: 5c211ba2 ("mm: add and use find_lock_entries")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>