of device pager in the pagers list by handle is now synchronized with
its removal from the list, and dev_pager_mtx is put before vm object
lock in lock order. Dispose the dev_pager_sx lock, since dev_pager_mtx
now covers the same block.
Noted by: kensmith
Reviewed by: alc
Approved by: re (kensmith)
vm_object_terminate() on a device-backed object at the same time that
another processor, call it Pa, is performing dev_pager_alloc() on the
same device. The problem is that vm_pager_object_lookup() should not be
allowed to return a doomed object, i.e., an object with OBJ_DEAD set,
but it does. In detail, the unfortunate sequence of events is: Pt in
vm_object_terminate() holds the doomed object's lock and sets OBJ_DEAD
on the object. Pa in dev_pager_alloc() holds dev_pager_sx and calls
vm_pager_object_lookup(), which returns the doomed object. Next, Pa
calls vm_object_reference(), which requires the doomed object's lock, so
Pa waits for Pt to release the doomed object's lock. Pt proceeds to the
point in vm_object_terminate() where it releases the doomed object's
lock. Pa is now able to complete vm_object_reference() because it can
now complete the acquisition of the doomed object's lock. So, now the
doomed object has a reference count of one! Pa releases dev_pager_sx
and returns the doomed object from dev_pager_alloc(). Pt now acquires
dev_pager_mtx, removes the doomed object from dev_pager_object_list,
releases dev_pager_mtx, and finally calls uma_zfree with the doomed
object. However, the doomed object is still in use by Pa.
Repeating my key point, vm_pager_object_lookup() must not return a
doomed object. Moreover, the test for the object's state, i.e.,
doomed or not, and the increment of the object's reference count
should be carried out atomically.
Reviewed by: kib
Approved by: re (kensmith)
MFC after: 3 weeks
d_mmap methods. prep_cdevsw() already installs the shims that
acquire/drop Giant for the methods of a driver that specified the
D_NEEDGIANT flag.
Reviewed by: alc
Approved by: re (kensmith)
should be set to VM_PAGE_BITS_ALL before returning, to ensure that
neither vm_pager_get_pages nor vm_fault calls vm_page_zero_invalid
after dev_pager_getpages has returned.
Submitted by: tegge
a long-time bug: vm_pager_get_pages() assumes that m[reqpage] contains a
valid page upon return from pgo_getpages(). In the case of the device
pager this page has been freed and replaced by a fake page. The fake page
is properly inserted into the vm object but m[reqpage] is left pointing
to a freed page. For now, update m[reqpage] to point to the fake page.
Submitted by: tegge
where physical addresses larger than virtual addresses, such as i386s
with PAE.
- Use this to represent physical addresses in the MI vm system and in the
i386 pmap code. This also changes the paddr parameter to d_mmap_t.
- Fix printf formats to handle physical addresses >4G in the i386 memory
detection code, and due to kvtop returning vm_paddr_t instead of u_long.
Note that this is a name change only; vm_paddr_t is still the same as
vm_offset_t on all currently supported platforms.
Sponsored by: DARPA, Network Associates Laboratories
Discussed with: re, phk (cdevsw change)
- Get rid of the useless atop() / pmap_phys_address() detour. The
device mmap handlers must now give back the physical address
without atop()'ing it.
- Don't borrow the physical address of the mapping in the returned
int. Now we properly pass a vm_offset_t * and expect it to be
filled by the mmap handler when the mapping was successful. The
mmap handler must now return 0 when successful, any other value
is considered as an error. Previously, returning -1 was the only
way to fail. This change thus accidentally fixes some devices
which were bogusly returning errno constants which would have been
considered as addresses by the device pager.
- Garbage collect the poorly named pmap_phys_address() now that it's
no longer used.
- Convert all the d_mmap_t consumers to the new API.
I'm still not sure wheter we need a __FreeBSD_version bump for this,
since and we didn't guarantee API/ABI stability until 5.1-RELEASE.
Discussed with: alc, phk, jake
Reviewed by: peter
Compile-tested on: LINT (i386), GENERIC (alpha and sparc64)
Runtime-tested on: i386
64-bit file sizes. This step simply addresses the remaining overflows,
and does attempt to optimise performance. The details are:
o Use a 64-bit type for the vm_object `size' and the size argument
to vm_object_allocate().
o Use the correct type for index variables in dev_pager_getpages(),
vm_object_page_clean() and vm_object_page_remove().
o Avoid an overflow in the i386 pmap_object_init_pt().
with the acquisition and release of Giant. (Annotate as MPSAFE.)
o Reorder the sanity checks in dev_pager_alloc() to reduce
the time that Giant is held.
most cases NULL is passed, but in some cases such as network driver locks
(which use the MTX_NETWORK_LOCK macro) and UMA zone locks, a name is used.
Tested on: i386, alpha, sparc64
(this commit is just the first stage). Also add various GIANT_ macros to
formalize the removal of Giant, making it easy to test in a more piecemeal
fashion. These macros will allow us to test fine-grained locks to a degree
before removing Giant, and also after, and to remove Giant in a piecemeal
fashion via sysctl's on those subsystems which the authors believe can
operate without Giant.
other "system" header files.
Also help the deprecation of lockmgr.h by making it a sub-include of
sys/lock.h and removing sys/lockmgr.h form kernel .c files.
Sort sys/*.h includes where possible in affected files.
OK'ed by: bde (with reservations)
Protect pager object list manipulation with a mutex.
It doesn't look possible to combine them under a single sx lock because
creation may block and we can't have the object list manipulation block
on anything other than a mutex because of interrupt requests.
Merge the contents (less some trivial bordering the silly comments)
of <vm/vm_prot.h> and <vm/vm_inherit.h> into <vm/vm.h>. This puts
the #defines for the vm_inherit_t and vm_prot_t types next to their
typedefs.
This paves the road for the commit to follow shortly: change
useracc() to use VM_PROT_{READ|WRITE} rather than B_{READ|WRITE}
as argument.
udev_t in the kernel but still called dev_t in userland.
Provide functions to manipulate both types:
major() umajor()
minor() uminor()
makedev() umakedev()
dev2udev() udev2dev()
For now they're functions, they will become in-line functions
after one of the next two steps in this process.
Return major/minor/makedev to macro-hood for userland.
Register a name in cdevsw[] for the "filedescriptor" driver.
In the kernel the udev_t appears in places where we have the
major/minor number combination, (ie: a potential device: we
may not have the driver nor the device), like in inodes, vattr,
cdevsw registration and so on, whereas the dev_t appears where
we carry around a reference to a actual device.
In the future the cdevsw and the aliased-from vnode will be hung
directly from the dev_t, along with up to two softc pointers for
the device driver and a few houskeeping bits. This will essentially
replace the current "alias" check code (same buck, bigger bang).
A little stunt has been provided to try to catch places where the
wrong type is being used (dev_t vs udev_t), if you see something
not working, #undef DEVT_FASCIST in kern/kern_conf.c and see if
it makes a difference. If it does, please try to track it down
(many hands make light work) or at least try to reproduce it
as simply as possible, and describe how to do that.
Without DEVT_FASCIST I belive this patch is a no-op.
Stylistic/posixoid comments about the userland view of the <sys/*.h>
files welcome now, from userland they now contain the end result.
Next planned step: make all dev_t's refer to the same devsw[] which
means convert BLK's to CHR's at the perimeter of the vnodes and
other places where they enter the game (bootdev, mknod, sysctl).
Made a new (inline) function devsw(dev_t dev) and substituted it.
Changed to the BDEV variant to this format as well: bdevsw(dev_t dev)
DEVFS will eventually benefit from this change too.
values. The 'int' return value for the procedure was never used and
not well defined in any case when there are mixed errors on pages, so
it has been removed. vm_pager_put_pages() and associated vm_pager
functions now return void.
changes to the VM system to support the new swapper, VM bug
fixes, several VM optimizations, and some additional revamping of the
VM code. The specific bug fixes will be documented with additional
forced commits. This commit is somewhat rough in regards to code
cleanup issues.
Reviewed by: "John S. Dyson" <root@dyson.iquest.net>, "David Greenman" <dg@root.com>
truncated to 32 bits.
* Change the calling convention of the device mmap entry point to
pass a vm_offset_t instead of an int for the offset allowing
devices with a larger memory map than (1<<32) to be supported
on the alpha (/dev/mem is one such).
These changes are required to allow the X server to mmap the various
I/O regions used for device port and memory access on the alpha.
