Fix a bug in the device pager code that can trigger an assertion
in devfs if a particular race condition is hit in the device pager
code.

This was a side effect of change 227530 which changed the de

Fix a bug in the device pager code that can trigger an assertion
in devfs if a particular race condition is hit in the device pager
code.

This was a side effect of change 227530 which changed the device
pager interface to call a new destructor routine for the cdev.
That destructor routine, old_dev_pager_dtor(), takes a VM object
handle.

The object handle is cast to a struct cdev *, and passed into
dev_rel().

That works in most cases, except the case in cdev_pager_allocate()
where there is a race condition between two threads allocating an
object backed by the same device. The loser of the race
deallocates its object at the end of the function.

The problem is that before inserting the object into the
dev_pager_object_list, the object's handle is changed from the
struct cdev pointer to the object's own address. This is to avoid
conflicts with the winner of the race, which already inserted an
object in the list with a handle that is a pointer to the same cdev
structure.

The object is then passed to vm_object_deallocate(), and eventually
makes its way down to old_dev_pager_dtor(). That function passes
the handle pointer (which is actually a VM object, not a struct
cdev as usual) into dev_rel(). dev_rel() decrements the reference
count in the assumed struct cdev (which happens to be 0), and
that triggers the assertion in dev_rel() that the reference count
is greater than or equal to 0.

The fix is to add a cdev pointer to the VM object, and use that
pointer when calling the cdev_pg_dtor() routine.

vm_object.h: Add a struct cdev pointer to the VM object
structure.

device_pager.c: In cdev_pager_allocate(), populate the new cdev
pointer.

In dev_pager_dealloc(), use the new cdev pointer
when calling the object's cdev_pg_dtor() routine.

Reviewed by: kib
Sponsored by: Spectra Logic Corporation
MFC after: 1 week

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MFC

MFC @ r241285

IFC @ r243164

Move the declaration of vm_phys_paddr_to_vm_page() from vm/vm_page.h
to vm/vm_phys.h, where it belongs.

Requested and reviewed by: alc
MFC after: 2 weeks

IFC @ r242684

Sync from head

Merge head r233826 through r239173.

After the PHYS_TO_VM_PAGE() function was de-inlined, the main reason
to pull vm_param.h was removed. Other big dependency of vm_page.h on
vm_param.h are PA_LOCK* definitions, which are only needed f

After the PHYS_TO_VM_PAGE() function was de-inlined, the main reason
to pull vm_param.h was removed. Other big dependency of vm_page.h on
vm_param.h are PA_LOCK* definitions, which are only needed for
in-kernel code, because modules use KBI-safe functions to lock the
pages.

Stop including vm_param.h into vm_page.h. Include vm_param.h
explicitely for the kernel code which needs it.

Suggested and reviewed by: alc
MFC after: 2 weeks

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IFC @ r238370

IFC @ r236291.
Diff reductions to the enclosure driver made in r235911.

Merge head r233826 through r236168.

Do not double-reference the found vm object in cdev_pager_lookup().
vm_pager_object_lookup() already referenced the object.

Note that there is no in-tree consumers of cdev_pager_lookup(). The
only k

Do not double-reference the found vm object in cdev_pager_lookup().
vm_pager_object_lookup() already referenced the object.

Note that there is no in-tree consumers of cdev_pager_lookup(). The
only known user of the function is i915 gem driver, which is not yet
imported. This should make the KPI change minor.

Submitted by: avg
MFC after: 1 week

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MFC

Add new pager type, OBJT_MGTDEVICE. It provides the device pager
which carries fictitous managed pages. In particular, the consumers of
the new object type can remove all mappings of the device page

Add new pager type, OBJT_MGTDEVICE. It provides the device pager
which carries fictitous managed pages. In particular, the consumers of
the new object type can remove all mappings of the device page with
pmap_remove_all().

The range of physical addresses used for fake page allocation shall be
registered with vm_phys_fictitious_reg_range() interface to allow the
PHYS_TO_VM_PAGE() to work in pmap.

Most likely, only i386 and amd64 pmaps can handle fictitious managed
pages right now.

Sponsored by: The FreeBSD Foundation
Reviewed by: alc
MFC after: 1 month

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IFC @230489 (pending review).

IFC @ r227804

Pull in the virtio drivers from head.

Update the device pager interface, while keeping the compatibility
layer for old KPI and KBI. New interface should be used together with
d_mmap_single cdevsw method.

Device pager can be allocated w

Update the device pager interface, while keeping the compatibility
layer for old KPI and KBI. New interface should be used together with
d_mmap_single cdevsw method.

Device pager can be allocated with the cdev_pager_allocate(9)
function, which takes struct cdev_pager_ops, containing
constructor/destructor and page fault handler methods supplied by
driver.

Constructor and destructor, called at the pager allocation and
deallocation time, allow the driver to handle per-object private data.

The pager handler is called to handle page fault on the vm map entry
backed by the driver pager. Driver shall return either the vm_page_t
which should be mapped, or error code (which does not cause kernel
panic anymore). The page handler interface has a placeholder to
specify the access mode causing the fault, but currently PROT_READ is
always passed there.

Sponsored by: The FreeBSD Foundation
Reviewed by: alc
MFC after: 1 month

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IFC @ r225592

sys/dev/bvm/bvm_console.c - move up to the new alt-break order.

Integrate FreeBSD/head into projects/zfsd/head as of SVN revision 224870.

Fix a race in the device pager allocation. If another thread won and
allocated the device pager for the given handle, then the object
fictitious pages list and the object membership in the global obj

Fix a race in the device pager allocation. If another thread won and
allocated the device pager for the given handle, then the object
fictitious pages list and the object membership in the global object
list still need to be initialized. Otherwise, dev_pager_dealloc() will
traverse uninitialized pointers.

Reported and tested by: pho
Reviewed by: jhb
Approved by: re (kensmith)
MFC after: 1 week

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IFC @ r224187

Integrate from Head into ZFSD feature branch as of revision r224141.

Handle a race between device_pager and devsw in a more graceful manner:
return an error code rather than panic the kernel.

Sponsored by: Sandvine Incorporated
Reviewed by: kib
Tested by: pho
MFC aft

Handle a race between device_pager and devsw in a more graceful manner:
return an error code rather than panic the kernel.

Sponsored by: Sandvine Incorporated
Reviewed by: kib
Tested by: pho
MFC after: 2 weeks

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Merge svn+ssh://svn.freebsd.org/base/head@219553