removed from objects including calls to free. Pages must not be xbusy
when freed and not on an object. Strengthen assertions to match these
expectations. In practice very little code had to change busy handling
to meet these rules but we can now make stronger guarantees to busy
holders and avoid conditionally dropping busy in free.
Refine vm_page_remove() and vm_page_replace() semantics now that we have
stronger guarantees about busy state. This removes redundant and
potentially problematic code that has proliferated.
Discussed with: markj
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D22822
Atomics are used for page busy and valid state when the shared busy is
held. The details of the locking protocol and valid and dirty
synchronization are in the updated vm_page.h comments.
Reviewed by: kib, markj
Tested by: pho
Sponsored by: Netflix, Intel
Differential Revision: https://reviews.freebsd.org/D21594
- VM_ALLOC_NOCREAT will grab without creating a page.
- vm_page_grab_valid() will grab and page in if necessary.
- vm_page_busy_acquire() automates some busy acquire loops.
Discussed with: alc, kib, markj
Tested by: pho (part of larger branch)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21546
races with page busy state. The object lock is still used as an interlock
to ensure that the identity stays valid. Most callers should use
vm_page_sleep_if_busy() to handle the locking particulars.
Reviewed by: alc, kib, markj
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21255
There are several mechanisms by which a vm_page reference is held,
preventing the page from being freed back to the page allocator. In
particular, holding the page's object lock is sufficient to prevent the
page from being freed; holding the busy lock or a wiring is sufficent as
well. These references are protected by the page lock, which must
therefore be acquired for many per-page operations. This results in
false sharing since the page locks are external to the vm_page
structures themselves and each lock protects multiple structures.
Transition to using an atomically updated per-page reference counter.
The object's reference is counted using a flag bit in the counter. A
second flag bit is used to atomically block new references via
pmap_extract_and_hold() while removing managed mappings of a page.
Thus, the reference count of a page is guaranteed not to increase if the
page is unbusied, unmapped, and the object's write lock is held. As
a consequence of this, the page lock no longer protects a page's
identity; operations which move pages between objects are now
synchronized solely by the objects' locks.
The vm_page_wire() and vm_page_unwire() KPIs are changed. The former
requires that either the object lock or the busy lock is held. The
latter no longer has a return value and may free the page if it releases
the last reference to that page. vm_page_unwire_noq() behaves the same
as before; the caller is responsible for checking its return value and
freeing or enqueuing the page as appropriate. vm_page_wire_mapped() is
introduced for use in pmap_extract_and_hold(). It fails if the page is
concurrently being unmapped, typically triggering a fallback to the
fault handler. vm_page_wire() no longer requires the page lock and
vm_page_unwire() now internally acquires the page lock when releasing
the last wiring of a page (since the page lock still protects a page's
queue state). In particular, synchronization details are no longer
leaked into the caller.
The change excises the page lock from several frequently executed code
paths. In particular, vm_object_terminate() no longer bounces between
page locks as it releases an object's pages, and direct I/O and
sendfile(SF_NOCACHE) completions no longer require the page lock. In
these latter cases we now get linear scalability in the common scenario
where different threads are operating on different files.
__FreeBSD_version is bumped. The DRM ports have been updated to
accomodate the KPI changes.
Reviewed by: jeff (earlier version)
Tested by: gallatin (earlier version), pho
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20486
Use it to indicate whether the page may be safely freed following
its removal from the object. Also change vm_page_remove() to assume
that the page's object pointer is non-NULL, and have callers perform
this check instead.
This is a step towards an implementation of an atomic reference counter
for each physical page structure.
Reviewed by: alc, dougm, kib
MFC after: 1 week
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20758
These calls are not the same in general: the former will dequeue the
page if it is enqueued, while the latter will just leave it alone. But,
all existing uses of the former apply to unmanaged pages, which are
never enqueued in the first place. No functional change intended.
Reviewed by: kib
MFC after: 1 week
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20470
This was enumerated with exhaustive search for sys/eventhandler.h includes,
cross-referenced against EVENTHANDLER_* usage with the comm(1) utility. Manual
checking was performed to avoid redundant includes in some drivers where a
common os_bsd.h (for example) included sys/eventhandler.h indirectly, but it is
possible some of these are redundant with driver-specific headers in ways I
didn't notice.
(These CUs did not show up as missing eventhandler.h in tinderbox.)
X-MFC-With: r347984
Revert r338177, r338176, r338175, r338174, r338172
After long consultations with re@, core members and mmacy, revert
these changes. Followup changes will be made to mark them as
deprecated and prent a message about where to find the up-to-date
driver. Followup commits will be made to make this clear in the
installer. Followup commits to reduce POLA in ways we're still
exploring.
It's anticipated that after the freeze, this will be removed in
13-current (with the residual of the drm2 code copied to
sys/arm/dev/drm2 for the TEGRA port's use w/o the intel or
radeon drivers).
Due to the impending freeze, there was no formal core vote for
this. I've been talking to different core members all day, as well as
Matt Macey and Glen Barber. Nobody is completely happy, all are
grudgingly going along with this. Work is in progress to mitigate
the negative effects as much as possible.
Requested by: re@ (gjb, rgrimes)
As discussed on the MLs drm2 conflicts with the ports' version and there
is no upstream for most if not all of drm. Both have been merged in to
a single port.
Users on powerpc, 32-bit hardware, or with GPUs predating Radeon
and i915 will need to install the graphics/drm-legacy-kmod. All
other users should be able to use one of the LinuxKPI-based ports:
graphics/drm-stable-kmod, graphics/drm-next-kmod, graphics/drm-devel-kmod.
MFC: never
Approved by: core@
Make vm_wait() take the vm_object argument which specifies the domain
set to wait for the min condition pass. If there is no object
associated with the wait, use curthread' policy domainset. The
mechanics of the wait in vm_wait() and vm_wait_domain() is supplied by
the new helper vm_wait_doms(), which directly takes the bitmask of the
domains to wait for passing min condition.
Eliminate pagedaemon_wait(). vm_domain_clear() handles the same
operations.
Eliminate VM_WAIT and VM_WAITPFAULT macros, the direct functions calls
are enough.
Eliminate several control state variables from vm_domain, unneeded
after the vm_wait() conversion.
Scetched and reviewed by: jeff
Tested by: pho
Sponsored by: The FreeBSD Foundation, Mellanox Technologies
Differential revision: https://reviews.freebsd.org/D14384
kern_yield(0) effectively causes the calling thread to be rescheduled
immediately since it resets the thread's priority to the highest possible
value. This can cause livelocks when the pattern
"while (!trylock()) kern_yield(0);" is used since the thread holding the
lock may linger on the runqueue for the CPU on which the looping thread is
running.
MFC after: 1 week
Suppose that we have an exclusively busy page, and a thread which can
accept shared-busy page. In this case, typical code waiting for the
page xbusy state to pass is
again:
VM_OBJECT_WLOCK(object);
...
if (vm_page_xbusied(m)) {
vm_page_lock(m);
VM_OBJECT_WUNLOCK(object); <---1
vm_page_busy_sleep(p, "vmopax");
goto again;
}
Suppose that the xbusy state owner locked the object, unbusied the
page and unlocked the object after we are at the line [1], but before we
executed the load of the busy_lock word in vm_page_busy_sleep(). If it
happens that there is still no waiters recorded for the busy state,
the xbusy owner did not acquired the page lock, so it proceeded.
More, suppose that some other thread happen to share-busy the page
after xbusy state was relinquished but before the m->busy_lock is read
in vm_page_busy_sleep(). Again, that thread only needs vm_object lock
to proceed. Then, vm_page_busy_sleep() reads busy_lock value equal to
the VPB_SHARERS_WORD(1).
In this case, all tests in vm_page_busy_sleep(9) pass and we are going
to sleep, despite the page being share-busied.
Update check for m->busy_lock == VPB_UNBUSIED in vm_page_busy_sleep(9)
to also accept shared-busy state if we only wait for the xbusy state to
pass.
Merge sequential if()s with the same 'then' clause in
vm_page_busy_sleep().
Note that the current code does not share-busy pages from parallel
threads, the only way to have more that one sbusy owner is right now
is to recurse.
Reported and tested by: pho (previous version)
Reviewed by: alc, markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D8196
pagers fault routines always return with a result page, be it the
proper and valid result page, or initially passed freshly allocated
placeholder. Do not free the passed in page until we are able to
provide the replacement, and do not assign NULL to *mres.
Reported and tested by: dumbbell
Reviewed by: royger (who also verified that Xen code is safe)
Sponsored by: The FreeBSD Foundation
address and use this mechanism when:
1. kmem_alloc_{attr,contig}() can't find suitable free pages in the physical
memory allocator's free page lists. This replaces the long-standing
approach of scanning the inactive and inactive queues, converting clean
pages into PG_CACHED pages and laundering dirty pages. In contrast, the
new mechanism does not use PG_CACHED pages nor does it trigger a large
number of I/O operations.
2. on 32-bit MIPS processors, uma_small_alloc() and the pmap can't find
free pages in the physical memory allocator's free page lists that are
covered by the direct map. Tested by: adrian
3. ttm_bo_global_init() and ttm_vm_page_alloc_dma32() can't find suitable
free pages in the physical memory allocator's free page lists.
In the coming months, I expect that this new mechanism will be applied in
other places. For example, balloon drivers should use relocation to
minimize fragmentation of the guest physical address space.
Make vm_phys_alloc_contig() a little smarter (and more efficient in some
cases). Specifically, use vm_phys_segs[] earlier to avoid scanning free
page lists that can't possibly contain suitable pages.
Reviewed by: kib, markj
Glanced at: jhb
Discussed with: jeff
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D4444
o With new KPI consumers can request contiguous ranges of pages, and
unlike before, all pages will be kept busied on return, like it was
done before with the 'reqpage' only. Now the reqpage goes away. With
new interface it is easier to implement code protected from race
conditions.
Such arrayed requests for now should be preceeded by a call to
vm_pager_haspage() to make sure that request is possible. This
could be improved later, making vm_pager_haspage() obsolete.
Strenghtening the promises on the business of the array of pages
allows us to remove such hacks as swp_pager_free_nrpage() and
vm_pager_free_nonreq().
o New KPI accepts two integer pointers that may optionally point at
values for read ahead and read behind, that a pager may do, if it
can. These pages are completely owned by pager, and not controlled
by the caller.
This shifts the UFS-specific readahead logic from vm_fault.c, which
should be file system agnostic, into vnode_pager.c. It also removes
one VOP_BMAP() request per hard fault.
Discussed with: kib, alc, jeff, scottl
Sponsored by: Nginx, Inc.
Sponsored by: Netflix
This change re-organizes code a little bit to extract common pieces
of ttm_alloc_new_pages() and ttm_get_pages() into dedicated functions.
Also, for requests without address restrictions regular vm_page_alloc()
is used.
Lastly, when vm_page_alloc_contig() fails we call VM_WAIT before calling
vm_pageout_grow_cache() to ensure that there is enough free pages at all.
Reviewed by: kib
MFC after: 15 days
This update brings few features:
o Support for the setmaster/dropmaster ioctls. For instance, they
are used to run multiple X servers simultaneously.
o Support for minor devices. The only user-visible change is a new
entry in /dev/dri but it is useless at the moment. This is a
first step to support render nodes [1].
The main benefit is to greatly reduce the diff with Linux (at the
expense of an unreadable commit diff). Hopefully, next upgrades will be
easier.
No updates were made to the drivers, beside adapting them to API
changes.
[1] https://en.wikipedia.org/wiki/Direct_Rendering_Manager#Render_nodes
Tested by: Many people
MFC after: 1 month
Relnotes: yes
in the radeonkms driver.
Note: In PCI mode virtual addresses on the graphics card that map to system
RAM are translated to physical addresses by the graphics card itself. In
AGP mode address translation is done by the AGP chipset so fictitious
addresses appear on the system bus. For the CPU cache management to work
correctly when the CPU accesses this memory it needs to use the same
fictitious addresses (and let the chipset translate them) instead of using
the physical addresses directly.
Reviewed by: kib
MFC after: 1 month
vm_phys_fictitious_to_vm_page should not be called directly, even when
operating on a range that has been registered using
vm_phys_fictitious_reg_range. PHYS_TO_VM_PAGE should be used instead
because on arches that use VM_PHYSSEG_DENSE the page might come
directly from vm_page_array.
Reported by: nwhitehorn
Tested by: nwhitehorn, David Mackay <davidm.jx8p@gmail.com>
Sponsored by: Citrix Systems R&D
the queue where to enqueue pages that are going to be unwired.
- Add stronger checks to the enqueue/dequeue for the pagequeues when
adding and removing pages to them.
Of course, for unmanaged pages the queue parameter of vm_page_unwire() will
be ignored, just as the active parameter today.
This makes adding new pagequeues quicker.
This change effectively modifies the KPI. __FreeBSD_version will be,
however, bumped just when the full cache of free pages will be
evicted.
Sponsored by: EMC / Isilon storage division
Reviewed by: alc
Tested by: pho
... for msleep/cv_*wait() return values, where wait_event*() is used
on Linux. ERESTARTSYS is the return code expected by callers when the
operation was interrupted.
For instance, this is the case of radeon_cs_ioctl() (radeon_cs.c): if
an error occurs, and the code isn't ERESTARTSYS (eg. EINTR), it logs an
error.
Note that ERESTARTSYS is defined as ERESTART, but this keeps callers'
code close to Linux.
Submitted by: avg@ (previous version)
Previously the code would just iterate over the whole tree as if it were
just a list.
Without this change I would observe X server becoming more and more
jerky over time.
MFC after: 5 days
shifts into the sign bit. Instead use (1U << 31) which gets the
expected result.
This fix is not ideal as it assumes a 32 bit int, but does fix the issue
for most cases.
A similar change was made in OpenBSD.
Discussed with: -arch, rdivacky
Reviewed by: cperciva
Add a new ttm_bo_release_mmap() function to unmap pages in a
vm_object_t. Pages are freed when the buffer object is later released.
This function is called in ttm_bo_unmap_virtual_locked(), replacing
Linux' unmap_mapping_range(). In particular this is called when a buffer
object is about to be moved, so that its mapping is invalidated.
However, we don't use this function in ttm_bo_vm_dtor(), because the
vm_object_t is already marked as OBJ_DEAD and the pages will be
unmapped.
Approved by: kib@
This fixes a crash where a SIGLALRM, heavily used by X.Org, would
interrupt the wait, causing the page fault to fail and the "Xorg"
process to receive a SIGSEGV.
Approved by: kib@
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Mon Jan 14 15:08:14 2013 +0100
drm/ttm: fix fence locking in ttm_buffer_object_transfer, 2nd try
This fixes up
commit e8e89622ed361c46bf90ba4828e685a8b603f7e5
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Tue Dec 18 22:25:11 2012 +0100
drm/ttm: fix fence locking in ttm_buffer_object_transfer
which leaves behind a might_sleep in atomic context, since the
fence_lock spinlock is held over a kmalloc(GFP_KERNEL) call. The fix
is to revert the above commit and only take the lock where we need it,
around the call to ->sync_obj_ref.
v2: Fixup things noticed by Maarten Lankhorst:
- Brown paper bag locking bug.
- No need for kzalloc if we clear the entire thing on the next line.
- check for bo->sync_obj (totally unlikely race, but still someone
else could have snuck in) and clear fbo->sync_obj if it's cleared
already.
Reported-by: Dave Airlie <airlied@gmail.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Approved by: kib@
Author: Dave Airlie <airlied@gmail.com>
Date: Wed Jan 16 15:58:34 2013 +1000
ttm: on move memory failure don't leave a node dangling
if we have a move notify callback, when moving fails, we call move notify
the opposite way around, however this ends up with *mem containing the mm_node
from the bo, which means we double free it. This is a follow on to the previous
fix.
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Approved by: kib@
Author: Dave Airlie <airlied@gmail.com>
Date: Wed Jan 16 14:25:44 2013 +1000
ttm: don't destroy old mm_node on memcpy failure
When we are using memcpy to move objects around, and we fail to memcpy
due to lack of memory to populate or failure to finish the copy, we don't
want to destroy the mm_node that has been copied into old_copy.
While working on a new kms driver that uses memcpy, if I overallocated bo's
up to the memory limits, and eviction failed, then machine would oops soon
after due to having an active bo with an already freed drm_mm embedded in it,
freeing it a second time didn't end well.
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Approved by: kib@
Author: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Date: Tue Jan 15 14:57:28 2013 +0100
drm/ttm: unexport ttm_bo_wait_unreserved
All legitimate users of this function outside ttm_bo.c are gone, now
it's only an implementation detail.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Approved by: kib@
Author: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Date: Tue Jan 15 14:57:10 2013 +0100
drm/ttm: use ttm_bo_reserve_slowpath_nolru in ttm_eu_reserve_buffers, v2
This requires re-use of the seqno, which increases fairness slightly.
Instead of spinning with a new seqno every time we keep the current one,
but still drop all other reservations we hold. Only when we succeed,
we try to get back our other reservations again.
This should increase fairness slightly as well.
Changes since v1:
- Increase val_seq before calling ttm_bo_reserve_slowpath_nolru and
retrying to take all entries to prevent a race.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Approved by: kib@
Author: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Date: Tue Jan 15 14:57:05 2013 +0100
drm/ttm: add ttm_bo_reserve_slowpath
Instead of dropping everything, waiting for the bo to be unreserved
and trying over, a better strategy would be to do a blocking wait.
This can be mapped a lot better to a mutex_lock-like call.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Approved by: kib@
Author: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Date: Tue Jan 15 14:56:48 2013 +0100
drm/ttm: cleanup ttm_eu_reserve_buffers handling
With the lru lock no longer required for protecting reservations we
can just do a ttm_bo_reserve_nolru on -EBUSY, and handle all errors
in a single path.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
