blocks assigned to the object pages.
- The global swhash_mtx is removed, trie is synchronized by the
corresponding object lock.
- The swp_pager_meta_free_all() function used during object
termination is optimized by only looking at the trie instead of
having to search whole hash for the swap blocks owned by the object.
- On swap_pager_swapoff(), instead of iterating over the swhash,
global object list have to be inspected. There, we have to ensure
that we do see valid trie content if we see that the object type is
swap.
Sizing of the swblk zone is same as for swblock zone, each swblk maps
SWAP_META_PAGES pages.
Proposed by: alc
Reviewed by: alc, markj (previous version)
Tested by: alc, pho (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 1 month
Differential revision: https://reviews.freebsd.org/D11435
Setting this flag allows us to skip pages removal from VM object queue
during object termination and to leave that for cdev_pg_dtor function.
Move pages removal code to separate function vm_object_terminate_pages()
as comments does not survive indentation.
This will be required for Intel SGX support where we will have to remove
pages from VM object manually.
Reviewed by: kib, alc
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D11688
vm_radix trie.
Existing vm_radix_init() function is renamed to vm_radix_zinit().
Inlines moved out of the _ headers.
Reviewed by: alc, markj (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D11661
Extend the ino_t, dev_t, nlink_t types to 64-bit ints. Modify
struct dirent layout to add d_off, increase the size of d_fileno
to 64-bits, increase the size of d_namlen to 16-bits, and change
the required alignment. Increase struct statfs f_mntfromname[] and
f_mntonname[] array length MNAMELEN to 1024.
ABI breakage is mitigated by providing compatibility using versioned
symbols, ingenious use of the existing padding in structures, and
by employing other tricks. Unfortunately, not everything can be
fixed, especially outside the base system. For instance, third-party
APIs which pass struct stat around are broken in backward and
forward incompatible ways.
Kinfo sysctl MIBs ABI is changed in backward-compatible way, but
there is no general mechanism to handle other sysctl MIBS which
return structures where the layout has changed. It was considered
that the breakage is either in the management interfaces, where we
usually allow ABI slip, or is not important.
Struct xvnode changed layout, no compat shims are provided.
For struct xtty, dev_t tty device member was reduced to uint32_t.
It was decided that keeping ABI compat in this case is more useful
than reporting 64-bit dev_t, for the sake of pstat.
Update note: strictly follow the instructions in UPDATING. Build
and install the new kernel with COMPAT_FREEBSD11 option enabled,
then reboot, and only then install new world.
Credits: The 64-bit inode project, also known as ino64, started life
many years ago as a project by Gleb Kurtsou (gleb). Kirk McKusick
(mckusick) then picked up and updated the patch, and acted as a
flag-waver. Feedback, suggestions, and discussions were carried
by Ed Maste (emaste), John Baldwin (jhb), Jilles Tjoelker (jilles),
and Rick Macklem (rmacklem). Kris Moore (kris) performed an initial
ports investigation followed by an exp-run by Antoine Brodin (antoine).
Essential and all-embracing testing was done by Peter Holm (pho).
The heavy lifting of coordinating all these efforts and bringing the
project to completion were done by Konstantin Belousov (kib).
Sponsored by: The FreeBSD Foundation (emaste, kib)
Differential revision: https://reviews.freebsd.org/D10439
in place. To do per-cpu stats, convert all fields that previously were
maintained in the vmmeters that sit in pcpus to counter(9).
- Since some vmmeter stats may be touched at very early stages of boot,
before we have set up UMA and we can do counter_u64_alloc(), provide an
early counter mechanism:
o Leave one spare uint64_t in struct pcpu, named pc_early_dummy_counter.
o Point counter(9) fields of vmmeter to pcpu[0].pc_early_dummy_counter,
so that at early stages of boot, before counters are allocated we already
point to a counter that can be safely written to.
o For sparc64 that required a whole dummy pcpu[MAXCPU] array.
Further related changes:
- Don't include vmmeter.h into pcpu.h.
- vm.stats.vm.v_swappgsout and vm.stats.vm.v_swappgsin changed to 64-bit,
to match kernel representation.
- struct vmmeter hidden under _KERNEL, and only vmstat(1) is an exclusion.
This is based on benno@'s 4-year old patch:
https://lists.freebsd.org/pipermail/freebsd-arch/2013-July/014471.html
Reviewed by: kib, gallatin, marius, lidl
Differential Revision: https://reviews.freebsd.org/D10156
reviewing all uses of OFF_TO_IDX(), I observed that
vm_object_page_noreuse() is requiring an exclusive lock on the object
when, in fact, a shared lock suffices.
Reviewed by: kib, markj
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D10011
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.
Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96
We can iterate over consecutive resident pages in the top-level object
using the object's page list rather than by performing lookups in the
object radix tree. This extends one of the optimizations in r312208 to the
case where a shadow chain is present.
Suggested by: alc
Reviewed by: alc, kib (previous version)
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D9282
vm_object_madvise() is frequently used to apply advice to a contiguous
set of pages in an object with no backing object. Optimize this case by
skipping non-resident subranges in constant time, and by iterating over
resident pages using the object memq, thus avoiding radix tree lookups on
each page index in the specified range.
While here, move MADV_WILLNEED handling to vm_page_advise(), and rename the
"advise" parameter to vm_object_madvise() to "advice."
Reviewed by: alc, kib
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D9098
As noted in the removed comment, it is possible and not prohibitively
costly to look up the swap blocks for the given page index. Implement
a swap_pager_find_least() function to do that, and use it to iterate
simultaneously over both backing object page queue and swap
allocations when looking for shadowed pages.
Testing shows that number of new succesful scans, enabled by this
addition, is small but non-zero. When worked out, the change both
further reduces the depth of the shadow object chain, and frees unused
but allocated swap and memory.
Suggested and reviewed by: alc
Tested by: pho (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
independent layer of the virtual memory system. Update some of the nearby
comments to eliminate redundancy and improve clarity.
In vm/vm_reserv.c, do not use hyphens after adverbs ending in -ly per
The Chicago Manual of Style.
Update the comment in vm/vm_page.h defining the four types of page queues to
reflect the elimination of PG_CACHED pages and the introduction of the
laundry queue.
Reviewed by: kib, markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D8752
called to allocate a new page of radix trie nodes, there could be a call to
vm_radix_remove() on the same trie (of PG_CACHED pages) as the in-progress
vm_radix_insert(). With the removal of PG_CACHED pages, we can simplify
vm_radix_insert() and vm_radix_remove() by removing the flags on the root of
the trie that were used to detect this case and the code for restarting
vm_radix_insert() when it happened.
Reviewed by: kib, markj
Tested by: pho
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D8664
not remove user-space visible fields from vm_cnt or all of the references to
cached pages from comments. Those changes will come later.)
Reviewed by: kib, markj
Tested by: pho
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D8497
pages, specificially, dirty pages that have passed once through the inactive
queue. A new, dedicated thread is responsible for both deciding when to
launder pages and actually laundering them. The new policy uses the
relative sizes of the inactive and laundry queues to determine whether to
launder pages at a given point in time. In general, this leads to more
intelligent swapping behavior, since the laundry thread will avoid pageouts
when the marginal benefit of doing so is low. Previously, without a
dedicated queue for dirty pages, the page daemon didn't have the information
to determine whether pageout provides any benefit to the system. Thus, the
previous policy often resulted in small but steadily increasing amounts of
swap usage when the system is under memory pressure, even when the inactive
queue consisted mostly of clean pages. This change addresses that issue,
and also paves the way for some future virtual memory system improvements by
removing the last source of object-cached clean pages, i.e., PG_CACHE pages.
The new laundry thread sleeps while waiting for a request from the page
daemon thread(s). A request is raised by setting the variable
vm_laundry_request and waking the laundry thread. We request launderings
for two reasons: to try and balance the inactive and laundry queue sizes
("background laundering"), and to quickly make up for a shortage of free
pages and clean inactive pages ("shortfall laundering"). When background
laundering is requested, the laundry thread computes the number of page
daemon wakeups that have taken place since the last laundering. If this
number is large enough relative to the ratio of the laundry and (global)
inactive queue sizes, we will launder vm_background_launder_target pages at
vm_background_launder_rate KB/s. Otherwise, the laundry thread goes back
to sleep without doing any work. When scanning the laundry queue during
background laundering, reactivated pages are counted towards the laundry
thread's target.
In contrast, shortfall laundering is requested when an inactive queue scan
fails to meet its target. In this case, the laundry thread attempts to
launder enough pages to meet v_free_target within 0.5s, which is the
inactive queue scan period.
A laundry request can be latched while another is currently being
serviced. In particular, a shortfall request will immediately preempt a
background laundering.
This change also redefines the meaning of vm_cnt.v_reactivated and removes
the functions vm_page_cache() and vm_page_try_to_cache(). The new meaning
of vm_cnt.v_reactivated now better reflects its name. It represents the
number of inactive or laundry pages that are returned to the active queue
on account of a reference.
In collaboration with: markj
Reviewed by: kib
Tested by: pho
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D8302
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
if vnode is VMIO. For VMIO vnodes, set BO_DEAD in vm_object_terminate().
The vnode_destroy_object(), when calling into vm_object_terminate(),
must be able to flush buffers. BO_DEAD purpose is to quickly destroy
buffers on write when the underlying vnode is not operable any more
(one example is the devfs node after geom is gone). Setting BO_DEAD
for reclaiming vnode before object is terminated is premature, and
results in unability to flush buffers with live SU dependencies from
vinvalbuf() in vm_object_terminate().
Reported by: David Cross <dcrosstech@gmail.com>
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
swap_pager_copy() might unlock the object, which allows the parallel
collapse to execute. Besides destroying the object, it also might
move the reference from parent to the backing object, firing the
assertion ref_count == 1.
Collapses are prevented by bumping paging_in_progress counters on both
the object and its backing object.
Reported by: cem
Tested by: pho (previous version)
Reviewed by: alc
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
X-Differential revision: https://reviews.freebsd.org/D6085
intention of the POSIX IEEE Std 1003.1TM-2008/Cor 1-2013.
A robust mutex is guaranteed to be cleared by the system upon either
thread or process owner termination while the mutex is held. The next
mutex locker is then notified about inconsistent mutex state and can
execute (or abandon) corrective actions.
The patch mostly consists of small changes here and there, adding
neccessary checks for the inconsistent and abandoned conditions into
existing paths. Additionally, the thread exit handler was extended to
iterate over the userspace-maintained list of owned robust mutexes,
unlocking and marking as terminated each of them.
The list of owned robust mutexes cannot be maintained atomically
synchronous with the mutex lock state (it is possible in kernel, but
is too expensive). Instead, for the duration of lock or unlock
operation, the current mutex is remembered in a special slot that is
also checked by the kernel at thread termination.
Kernel must be aware about the per-thread location of the heads of
robust mutex lists and the current active mutex slot. When a thread
touches a robust mutex for the first time, a new umtx op syscall is
issued which informs about location of lists heads.
The umtx sleep queues for PP and PI mutexes are split between
non-robust and robust.
Somewhat unrelated changes in the patch:
1. Style.
2. The fix for proper tdfind() call use in umtxq_sleep_pi() for shared
pi mutexes.
3. Removal of the userspace struct pthread_mutex m_owner field.
4. The sysctl kern.ipc.umtx_vnode_persistent is added, which controls
the lifetime of the shared mutex associated with a vnode' page.
Reviewed by: jilles (previous version, supposedly the objection was fixed)
Discussed with: brooks, Martin Simmons <martin@lispworks.com> (some aspects)
Tested by: pho
Sponsored by: The FreeBSD Foundation
breaking the ABI. Special value is stored in the lock pointer to
indicate shared lock, and offline page in the shared memory is
allocated to store the actual lock.
Reviewed by: vangyzen (previous version)
Discussed with: deischen, emaste, jhb, rwatson,
Martin Simmons <martin@lispworks.com>
Tested by: pho
Sponsored by: The FreeBSD Foundation
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
These two functions were largely unrelated, they just used the same same
loop logic to walk through a backing object's memq. Pull out the
all_shadowed test as its own function and eliminate
OBSC_TEST_ALL_SHADOWED. Rename vm_object_backing_scan to
vm_object_collapse_scan.
No functional change.
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D4335
invalid (busy) page supposedly inserted by the vm_fault(), in the
OBSC_COLLAPSE_NOWAIT case. As a continuation to r221714, fix a case
when invalid page is found by the object scan in OBSC_COLLAPSE_WAIT
case as well. But, since this is waitable scan, we should wait for
the termination of the busy state and restart from the beginning of
the backing object' page queue. [*]
Do not free the shadow page swap space when the parent page is
invalid, otherwise this action potentially corrupts user data.
Combine all instances of the collapse scan sleep code fragments into
the new helper vm_object_backing_scan_wait().
Improve style compliance and comments. Change the return type of
vm_object_backing_scan() to bool.
Initial submission by: cem, https://reviews.freebsd.org/D4103 [*]
Reviewed by: alc, cem
Tested by: cem
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D4146
of POSIX_FADV_DONTNEED so that it causes the backing pages to be moved to
the head of the inactive queue instead of being cached.
This affects the implementation of POSIX_FADV_NOREUSE as well, since it
works by applying POSIX_FADV_DONTNEED to file ranges after they have been
read or written. At that point the corresponding buffers may still be
dirty, so the previous implementation would coalesce successive ranges and
apply POSIX_FADV_DONTNEED to the result, ensuring that pages backing the
dirty buffers would eventually be cached. To preserve this behaviour in an
efficient manner, this change adds a new buf flag, B_NOREUSE, which causes
the pages backing a VMIO buf to be placed at the head of the inactive queue
when the buf is released. POSIX_FADV_NOREUSE then works by setting this
flag in bufs that underlie the specified range.
Reviewed by: alc, kib
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D3726
Assume that a vnode is mapped shared and mlocked(), and then the vnode
is truncated, or truncated and then again extended past the mapping
point EOF. Truncation removes the pages past the truncation point,
and if pages are later created at this range, they are not properly
mapped into the mlocked region, and their wiring count is wrong.
The revert leaves the invalidated but wired pages on the object queue,
which means that the pages are found by vm_object_unwire() when the
mapped range is munlock()ed, and reused by the buffer cache when the
vnode is extended again.
The changes in r173708 were required since then vm_map_unwire() looked
at the page tables to find the page to unwire. This is no longer
needed with the vm_object_unwire() introduction, which follows the
objects shadow chain.
Also eliminate OBJPR_NOTWIRED flag for vm_object_page_remove(), which
is now redundand, we do not remove wired pages.
Reported by: trasz, Dmitry Sivachenko <trtrmitya@gmail.com>
Suggested and reviewed by: alc
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
in the requested array, then it is responsible for disposition of previous
page and is responsible for updating the entry in the requested array.
Now consumers of KPI do not need to re-lookup the pages after call to
vm_pager_get_pages().
Reviewed by: kib
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
When providing memory map information to userland, populate the vnode pointer
for tmpfs files. Set the memory mapping to appear as a vnode type, to match
FreeBSD 9 behavior.
This fixes the use of tmpfs files with the dtrace pid provider,
procstat -v, procfs, linprocfs, pmc (pmcstat), and ptrace (PT_VM_ENTRY).
Submitted by: Eric Badger <eric@badgerio.us> (initial revision)
Obtained from: Dell Inc.
PR: 198431
MFC after: 2 weeks
Reviewed by: jhb
Approved by: kib (mentor)
examined via 'vmstat -o'. It can be used to determine which files are
using physical pages of memory and how much each is using.
Differential Revision: https://reviews.freebsd.org/D2277
Reviewed by: alc, kib
MFC after: 2 weeks
Sponsored by: Norse Corp, Inc. (forward porting to HEAD/10)
This is ok since objects come from a NOFREE zone and allows objects to
be locked while traversing the object list without triggering a LOR.
Ensure that objects on the list are marked DEAD while free or stillborn,
and that they have a refcount of zero. This required updating most of
the pagers to explicitly mark an object as dead when deallocating it.
(Only the vnode pager did this previously.)
Differential Revision: https://reviews.freebsd.org/D2423
Reviewed by: alc, kib (earlier version)
MFC after: 2 weeks
Sponsored by: Norse Corp, Inc.
to UFS, perform updates during syncer scans, which in particular means
that tmpfs now performs scan on sync. Also, this means that a mtime
update may be delayed up to 30 seconds after the write.
The vm_object' OBJ_TMPFS_DIRTY flag for tmpfs swap object is similar
to the OBJ_MIGHTBEDIRTY flag for the vnode object, it indicates that
object could have been dirtied. Adapt fast page fault handler and
vm_object_set_writeable_dirty() to handle OBJ_TMPFS_NODE same as
OBJT_VNODE.
Reported by: Ronald Klop <ronald-lists@klop.ws>
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
vp->v_vflag without taking vnode lock and without bypass. We do know
that vp is the lowest level in the stack, since the pointer is
obtained from the object' handle. Stale VV_TEXT flag read can only
happen if parallel execve() is performed and not yet activated the
image, since process takes reference for text mapping. In this case,
the execve() code manages the VV_TEXT flag on its own already.
It was observed that otherwise read-only sendfile(2) requires
exclusive vnode lock and contending on it on some loads for VV_TEXT
handling.
Reported by: glebius, scottl
Tested by: glebius, pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
underlying physical pages are mapped by the pmap. If, for example, the
application has performed an mprotect(..., PROT_NONE) on any part of the
wired region, then those pages will no longer be mapped by the pmap.
So, using the pmap to lookup the wired pages in order to unwire them
doesn't always work, and when it doesn't work wired pages are leaked.
To avoid the leak, introduce and use a new function vm_object_unwire()
that locates the wired pages by traversing the object and its backing
objects.
At the same time, switch from using pmap_change_wiring() to the recently
introduced function pmap_unwire() for unwiring the region's mappings.
pmap_unwire() is faster, because it operates a range of virtual addresses
rather than a single virtual page at a time. Moreover, by operating on
a range, it is superpage friendly. It doesn't waste time performing
unnecessary demotions.
Reported by: markj
Reviewed by: kib
Tested by: pho, jmg (arm)
Sponsored by: EMC / Isilon Storage Division
and tmpfs object cannot shadow. In other words, tmpfs vm object is
always at the bottom of the shadow chain.
Reported and tested by: bdrewery
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
vnode for the tmpfs node owning this object. The flag is currently
used for two purposes. First, it allows to correctly handle VV_TEXT
for tmpfs vnode when the ref count on the object is decremented to 1,
similar to vnode_pager_dealloc() for regular filesystems. Second, it
prevents some operations, which are done on OBJT_SWAP vm objects
backing user anonymous memory, but are incorrect for the object owned
by tmpfs node.
The second kind of use of the OBJ_TMPFS flag is incorrect, since the
vnode might be reclaimed, which clears the flag, but vm object
operations must still be disallowed.
Introduce one more flag, OBJ_TMPFS_NODE, which is permanently set on
the object for VREG tmpfs node, and used instead of OBJ_TMPFS to test
whether vm object collapse and similar actions should be disabled.
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
To reduce the diff struct pcu.cnt field was not renamed, so
PCPU_OP(cnt.field) is still used. pc_cnt and pcpu are also used in
kvm(3) and vmstat(8). The goal was to not affect externally used KPI.
Bump __FreeBSD_version_ in case some out-of-tree module/code relies on the
the global cnt variable.
Exp-run revealed no ports using it directly.
No objection from: arch@
Sponsored by: EMC / Isilon Storage Division
a call of pager_swap_freespace() was moved around, now leading to freeing
the incorrect page because of the pindex changes after vm_page_rename().
Get back to use the correct pindex when destroying the swap space.
Sponsored by: EMC / Isilon storage division
Reported by: avg
Tested by: pho
MFC after: 7 days
coalesce would extend the object to keep pages for the anonymous
mapping created by the process. The pages has no relations to the
tmpfs file content which could be written into the corresponding
range, causing anonymous mapping and file content aliasing and
subsequent corruption.
Another lesser problem created by coalescing is over-accounting on the
tmpfs node destruction, since the object size is substracted from the
total count of the pages owned by the tmpfs mount.
Reported and tested by: bdrewery
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
pmap_remove_all(). Not doing the drain allows the pmap_enter() to
proceed in parallel, making the pmap_remove_all() effects void.
The race results in an invalidated page mapped wired by usermode.
Reported and tested by: pho
Reviewed by: alc
Sponsored by: The FreeBSD Foundation
Approved by: re (glebius)
The flag was mandatory since r209792, where vm_page_grab(9) was
changed to only support the alloc retry semantic.
Suggested and reviewed by: alc
Sponsored by: The FreeBSD Foundation
for nodes used in vm_radix.
On architectures supporting direct mapping, also avoid to pre-allocate
the KVA for such nodes.
In order to do so make the operations derived from vm_radix_insert()
to fail and handle all the deriving failure of those.
vm_radix-wise introduce a new function called vm_radix_replace(),
which can replace a leaf node, already present, with a new one,
and take into account the possibility, during vm_radix_insert()
allocation, that the operations on the radix trie can recurse.
This means that if operations in vm_radix_insert() recursed
vm_radix_insert() will start from scratch again.
Sponsored by: EMC / Isilon storage division
Reviewed by: alc (older version)
Reviewed by: jeff
Tested by: pho, scottl
Unify the 2 concept into a real, minimal, sxlock where the shared
acquisition represent the soft busy and the exclusive acquisition
represent the hard busy.
The old VPO_WANTED mechanism becames the hard-path for this new lock
and it becomes per-page rather than per-object.
The vm_object lock becames an interlock for this functionality:
it can be held in both read or write mode.
However, if the vm_object lock is held in read mode while acquiring
or releasing the busy state, the thread owner cannot make any
assumption on the busy state unless it is also busying it.
Also:
- Add a new flag to directly shared busy pages while vm_page_alloc
and vm_page_grab are being executed. This will be very helpful
once these functions happen under a read object lock.
- Move the swapping sleep into its own per-object flag
The KPI is heavilly changed this is why the version is bumped.
It is very likely that some VM ports users will need to change
their own code.
Sponsored by: EMC / Isilon storage division
Discussed with: alc
Reviewed by: jeff, kib
Tested by: gavin, bapt (older version)
Tested by: pho, scottl
