Commit Graph

1319 Commits

Author SHA1 Message Date
Alexander Motin
49114ce463 MFV 286711: 6096 ZFS_SMB_ACL_RENAME needs to cleanup better
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Gordon Ross <gordon.w.ross@gmail.com>
Reviewed by: George Wilson <gwilson@zfsmail.com>
Approved by: Robert Mustacchi <rm@joyent.com>

illumos/illumos-gate@8f5190a540
2015-08-13 00:13:55 +00:00
Alexander Motin
3b1f51e911 MFV 286709:
6093 zfsctl_shares_lookup should only VN_RELE() on zfs_zget() success

Reviewed by: Gordon Ross <gwr@nexenta.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Dan McDonald <danmcd@omniti.com>

illumos/illumos-gate@0f92170f1e
2015-08-13 00:10:36 +00:00
Alexander Motin
0d0def87fe MFV 286707: 5959 clean up per-dataset feature count code
Reviewed by: Toomas Soome <tsoome@me.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>
Author: Matthew Ahrens <mahrens@delphix.com>

illumos/illumos-gate@ca0cc3918a

A ZFS feature flags (large blocks) tracks its refcounts as the number of
datasets that have ever used the feature. Several features of this type
are planned to be added (new checksum functions). This code should be made
common infrastructure rather than duplicating the code for each feature.
2015-08-12 23:59:17 +00:00
Alexander Motin
b696497df0 MFV r286704: 5960 zfs recv should prefetch indirect blocks
5925 zfs receive -o origin=

Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Author: Paul Dagnelie <pcd@delphix.com>

While running 'zfs recv' we noticed that every 128th 8K block required a
read. We were seeing that restore_write() was calling dmu_tx_hold_write()
and the indirect block was not cached. We should prefetch upcoming indirect
blocks to avoid having to go to disk and blocking the restore_write().

Allow an incremental send stream to be received as a clone, even if the
stream does not mark it as a clone.
2015-08-12 22:41:06 +00:00
Alexander Motin
d0687a01d7 MFV r284763: 5981 Deadlock in dmu_objset_find_dp
illumos/illumos-gate@1d3f896f54

https://www.illumos.org/issues/5981
  When dmu_objset_find_dp gets called with a read lock held, it fans out
  the work to the task queue. Each task in turn acquires its own read
  lock before calling the callback. If during this process anyone tries
  to a acquire a write lock, it will stall all read lock requests.Thus
  the tasks will never finish, the read lock of the caller will never
  get freed and the write lock never acquired.  deadlock.

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Arne Jansen <jansen@webgods.de>
2015-08-12 19:10:29 +00:00
Alexander Motin
101a6d4eac MFV r284762: 5269 zpool import slow
illumos/illumos-gate@12380e1e70

https://www.illumos.org/issues/5269
  When importing a pool (at boot or with zpool import) with many
  filesystem, the process can take minutes. It doesn't matter whether
  the pool has been exported cleanly or uncleanly.  The problem is that
  each dataset has its own log chain. On import, all datasets have to be
  checked if there are logs to replay.  The idea is to speed up this
  process by paralellizing it.

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Arne Jansen <jansen@webgods.de>
2015-08-12 18:47:30 +00:00
Alexander Motin
ebf527de10 MFV r286682: 5765 add support for estimating send stream size with
lzc_send_space when source is a bookmark

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com>
Approved by: Albert Lee <trisk@nexenta.com>
Author: Max Grossman <max.grossman@delphix.com>

illumos/illumos-gate@643da460c8
2015-08-12 18:23:08 +00:00
Alexander Motin
2d41b1006f MFV r286224: 5695 dmu_sync'ed holes do not retain birth time
illumos/illumos-gate@70163ac57e

https://www.illumos.org/issues/5695
  In dmu_sync_ready(), a hole block pointer will have it's logical size
  explicitly set as it's necessary for replay purposes. To "undo" this,
  dmu_sync_done() will zero out any hole that it finds. This becomes a
  problem when using the "hole_birth" feature, as this will also wipe out
  any birth time that might have happened to be set on the hole.
  ...
  As a fix, the logic to zero out a hole is only applied to old style
  holes with a birth time of zero. Holes created with the "hole_birth"
  feature enabled will have a non-zero birth time, and will be skipped
  (thus preserving the ltime, type, and level information as well).
  In addition, zdb was updated to also print the ltime, type, and level
  information for these new style holes. Previously, only the logical
  birth time would be printed.

Author: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>
2015-08-12 17:21:41 +00:00
Alexander Motin
ef00c83db1 Fix set of sign extension bugs in r286625. 2015-08-12 08:36:58 +00:00
Alexander Motin
b3fc966389 Fix assertion panic caused by combination of r286598 and TRIM. 2015-08-11 19:15:55 +00:00
Alexander Motin
3caed89878 Fix r286625 build on i386. 2015-08-11 12:38:01 +00:00
Alexander Motin
a3b3a9752c Fix minor mismerge in r286574. 2015-08-11 12:22:16 +00:00
Alexander Motin
c350858a50 MFV r277425:
5376 arc_kmem_reap_now() should not result in clearing arc_no_grow
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Reviewed by: Richard Elling <richard.elling@richardelling.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Matthew Ahrens <mahrens@delphix.com>

illumos/illumos-gate@2ec99e3e98
2015-08-11 10:39:19 +00:00
Alexander Motin
6be7d38913 Remove extra lock, that IMO only creates potential problems now. 2015-08-11 09:18:51 +00:00
Alexander Motin
1af86496cb MFV 286604: 5812 assertion failed in zrl_tryenter(): zr_owner==NULL
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: Will Andrews <will@freebsd.org>
Approved by: Gordon Ross <gwr@nexenta.com>
Author: Matthew Ahrens <mahrens@delphix.com>

illumos/illumos-gate@8df173054c
2015-08-10 21:36:51 +00:00
Alexander Motin
799f47828d MFV 286602: 5810 zdb should print details of bpobj
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Will Andrews <will@freebsd.org>
Reviewed by: Simon Klinkert <simon.klinkert@gmail.com>
Approved by: Gordon Ross <gwr@nexenta.com>
Author: Matthew Ahrens <mahrens@delphix.com>

illumos/illumos-gate@732885fca0
2015-08-10 21:32:40 +00:00
Alexander Motin
c70c15ffa9 MFV 286599: 5808 spa_check_logs is not necessary on readonly pools
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Simon Klinkert <simon.klinkert@gmail.com>
Reviewed by: Will Andrews <will@freebsd.org>
Approved by: Gordon Ross <gwr@nexenta.com>
Author: Matthew Ahrens <mahrens@delphix.com>

illumos/illumos-gate@23367a2f2c
2015-08-10 21:19:42 +00:00
Alexander Motin
f7bf11ab59 MFV 286597: 5701 zpool list reports incorrect "alloc" value for cache devices
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Alek Pinchuk <alek.pinchuk@nexenta.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Prakash Surya <prakash.surya@delphix.com>

illumos/illumos-gate@a52fc310ba
2015-08-10 21:13:59 +00:00
Alexander Motin
2e92f38b63 Local addition and mismerge fix for r286579. 2015-08-10 20:34:46 +00:00
Alexander Motin
de8b7ceff1 MFV 286588: 5820 verify failed in zio_done(): BP_EQUAL(bp, io_bp_orig)
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Approved by: Garrett D'Amore <garrett@damore.org>
Author: Matthew Ahrens <mahrens@delphix.com>

illumod/illumos-gate@34e8acef00
2015-08-10 19:38:07 +00:00
Alexander Motin
57f7c5acf5 MFV 286586: 5746 more checksumming in zfs send
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com>
Approved by: Albert Lee <trisk@omniti.com>
Author: Matthew Ahrens <mahrens@delphix.com>

illumos/illumos-gate@98110f08fa
2015-08-10 19:32:58 +00:00
Alexander Motin
9b4b955150 MFV r277430: 5313 Allow I/Os to be aggregated across ZIO priority classes
Reviewed by: Andriy Gapon <avg@FreeBSD.org>
Reviewed by: Will Andrews <willa@SpectraLogic.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Justin T. Gibbs <justing@spectralogic.com>

illumos/illumos-gate@fe319232d2
2015-08-10 12:39:10 +00:00
Alexander Motin
498b9d6c63 Fix r286574 build in user-space. 2015-08-10 12:25:26 +00:00
Alexander Motin
0702ce1a52 Fix r286570 build with debug. 2015-08-10 11:52:54 +00:00
Alexander Motin
83a6947e11 MFV r277428: 5056 ZFS deadlock on db_mtx and dn_holds
Reviewed by: Will Andrews <willa@spectralogic.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Justin Gibbs <justing@spectralogic.com>

illumos/illumos-gate@bc9014e6a8
2015-08-10 11:30:07 +00:00
Alexander Motin
f13e9e1470 MFV r277427: 5445 Add more visibility via arcstats; specifically
arc_state_t stats and differentiate between "data" and "metadata"

Reviewed by: Basil Crow <basil.crow@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Bayard Bell <bayard.bell@nexenta.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Prakash Surya <prakash.surya@delphix.com>

illumos/illumos-gate@4076b1bf41
2015-08-10 10:59:58 +00:00
Alexander Motin
c908dc6f4b MFV r277426: 5408 managing ZFS cache devices requires lots of RAM
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Don Brady <dev.fs.zfs@gmail.com>
Reviewed by: Josef 'Jeff' Sipek <josef.sipek@nexenta.com>
Approved by: Garrett D'Amore <garrett@damore.org>
Author: Chris Williamson <Chris.Williamson@delphix.com>

illumos/illumos-gate@89c86e3229

Currently, every buffer cached in the L2ARC is accompanied by a 240-byte
header in memory, leading to very high memory consumption when using very
large cache devices. These changes significantly reduce this overhead.

Currently:

L1-only header = 176 bytes
L1 + L2 or L2-only header = 176 bytes + 32 byte checksum + 32 byte l2hdr
    = 240 bytes

Memory-optimized:

L1-only header = 176 bytes
L1 + L2 header = 176 bytes + 32 byte checksum = 208 bytes
L2-only header = 96 bytes + 32 byte checksum = 128 bytes

So overall:

          Trunk  Optimized
        +-----------------+
L1-only | 176 B  | 176 B  | (same)
        +-----------------+
L1 & L2 | 240 B  | 208 B  | (saved 32 bytes)
        +-----------------+
L2-only | 240 B  | 128 B  | (saved 116 bytes)
        +-----------------+

For an average blocksize of 8KB, this means that for the L2ARC, the ratio
of metadata to data has gone down from about 2.92% to 1.56%.  For a
'storage optimized' EC2 instance with 1600GB of SSD and 60GB of RAM, this
means that we expect a completely full L2ARC to use (1600 GB * 0.0156) /
60GB = 41% of the available memory, down from 78%.
2015-08-10 10:34:23 +00:00
Alexander Motin
1838fc920f MFV 286555: Avoid 128K kmem allocations in mzap_upgrade()
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Approved by: Rich Lowe <richlowe@richlowe.net>

illumos/illumos-gate@be3e2ab906
2015-08-09 20:41:44 +00:00
Alexander Motin
475e2caa3d MFV 286553: 5769 Cast 'zfs bad bloc' to ULL for x86
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Richard PALO <richard@NetBSD.org>
Approved by: Dan McDonald <danmcd@omniti.com>

illumos/illumos-gate@8c76e0763b
2015-08-09 20:32:30 +00:00
Alexander Motin
a5a2e782be MFV 286550: 5694 traverse_prefetcher does not prefetch enough
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Josef 'Jeff' Sipek <josef.sipek@nexenta.com>
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com>
Approved by: Garrett D'Amore <garrett@damore.org>
Author: George Wilson <george.wilson@delphix.com>

illumos/illumos-gate@34d7ce052c
2015-08-09 20:23:35 +00:00
Alexander Motin
927211755b MFV 286548:
5693 ztest fails in dbuf_verify: buf[i] == 0, due to dedup and bp_override

Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Matthew Ahrens <mahrens@delphix.com>

illumos/illumos-gate@7f7ace3700
2015-08-09 20:08:38 +00:00
Alexander Motin
4ff9527edc MFV 286546:
5661 ZFS: "compression = on" should use lz4 if feature is enabled

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Reviewed by: Xin LI <delphij@freebsd.org>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Justin T. Gibbs <justing@spectralogic.com>

illumos/illumos-gate@db1741f555
2015-08-09 20:02:16 +00:00
Alexander Motin
9834135947 MFV 286544:
5630 stale bonus buffer in recycled dnode_t leads to data corruption

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Will Andrews <will@freebsd.org>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Justin T. Gibbs <justing@spectralogic.com>
2015-08-09 19:35:39 +00:00
Alexander Motin
07470009be MFV 286542: 5592 NULL pointer dereference in dsl_prop_notify_all_cb()
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Will Andrews <will@freebsd.org>
Approved by: Robert Mustacchi <rm@joyent.com>

illumos/illumos-gate@9d47dec048
2015-08-09 19:29:10 +00:00
Alexander Motin
1d367fea94 MFV 286540: 5531 NULL pointer dereference in dsl_prop_get_ds()
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Justin T. Gibbs <justing@spectralogic.com>

illumos/illumos-gate@e57a022b8f
2015-08-09 19:26:21 +00:00
Alexander Motin
c44a37d0b7 MFV 286538:
5562 ZFS sa_handle's violate kmem invariants, debug kernels panic on boot

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Robert Mustacchi <rm@fingolfin.org>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Rich Lowe <richlowe@richlowe.net>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Justin T. Gibbs <justing@spectralogic.com>

illumos/illumos-gate@0fda3cc5c1
2015-08-09 19:17:59 +00:00
Mark Johnston
1c9a705223 Remove a couple of unused fields from the FBT probe struct. 2015-08-03 17:39:36 +00:00
Steven Hartland
ebbc56ecd6 Fix KSTACK_PAGES check in ZFS module
The check introduced by r285946 failed to add the dependency on
opt_kstack_pages.h which meant the default value for the platform instead
of the customised options KSTACK_PAGES=X was being tested.

Also wrap in #ifdef __FreeBSD__ for portability.

MFC after:	3 days
Sponsored by:	Multiplay
2015-08-03 09:34:09 +00:00
Mark Johnston
48fcd357c4 Avoid dereferencing curthread->td_proc->p_cred in DTrace probe context.
When a process is exiting, there is a narrow window where p_cred may be
NULL while its threads are still executing. Specifically, the last thread
to exit a process sets the process state to PRS_ZOMBIE with the proc
spinlock held and then calls thread_exit(). thread_exit() drops the spin
lock, permitting the process to be reaped and thus causing its cred struct
to be released. However, the exiting thread may still cause DTrace probes
to fire by calling sched_throw(), resulting in a double fault if such a
probe enabling attempts to access the GID or UID DIF variables.

The thread's cred reference is not susceptible to this race since it is not
released until after the thread has exited.

MFC after:	1 week
2015-08-02 00:11:56 +00:00
Steven Hartland
1635369e99 Add warning about low KSTACK_PAGES for ZFS use
As ZFS requires a more kernel stack pages than is the default on some
architectures e.g. i386, warn if KSTACK_PAGES is less than
ZFS_MIN_KSTACK_PAGES (which is 4 at the time of writing).

MFC after:	3 days
Sponsored by:	Multiplay
2015-07-28 11:19:38 +00:00
Mark Johnston
d258fd1d98 Remove checks for a NULL return value from M_WAITOK allocations. 2015-07-21 23:44:36 +00:00
Ed Schouten
5a170c1b0e Add an API for easily creating userspace threads in kernelspace.
This change refactors the existing create_thread() function to be more
generic. It replaces almost all of its arguments by a callback that can
be used to extract the thread ID and copy it out to the right place, but
also to perform additional initialization steps, such as setting the
trapframe. This also makes the difference between thr_new() and
thr_create() more clear in my opinion.

This function is going to be used by the CloudABI compatibility layer.

It looks like the OpenSolaris compatibility framework already provides a
function called thread_create(). Rename this function to
do_thread_create() and use a macro to deal with the namespacing
conflict. A similar approach is already used for thread_exit().

MFC after:	1 month
2015-07-20 10:20:04 +00:00
Mark Johnston
32cd0147fa Implement the lockstat provider using SDT(9) instead of the custom provider
in lockstat.ko. This means that lockstat probes now have typed arguments and
will utilize SDT probe hot-patching support when it arrives.

Reviewed by:	gnn
Differential Revision:	https://reviews.freebsd.org/D2993
2015-07-19 22:14:09 +00:00
Mark Johnston
efe8b26b82 Modify lockstat_nsecs() to just return unless lockstat probes are actually
enabled. The cost of a timecounter read can be quite significant, and the
problem became more apparent after r284297, since that change resulted in
a call to lockstat_nsecs() for each acquisition of an rwlock read lock.

PR:		201642
Reviewed by:	avg
Tested by:	Jason Unovitch
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D3073
2015-07-18 00:22:00 +00:00
Konstantin Belousov
888e282ab4 When checking for the valid value of the frame pointer, verify that it
belongs to the kernel stack address range for the thread.  Right now,
code checks that new frame is not farther then KSTACK_PAGES pages from
the current frame, which allows the address to point past the top of
the stack.

Reviewed by:	andrew, emaste, markj
Differential revision:	https://reviews.freebsd.org/D3108
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2015-07-16 19:40:18 +00:00
Mateusz Guzik
752fc07d33 vfs: implement v_holdcnt/v_usecount manipulation using atomic ops
Transitions 0->1 and 1->0 (which decide e.g. on putting the vnode on the free
list) of either counter are still guarded with vnode interlock.

Reviewed by:	kib (earlier version)
Tested by:	pho
2015-07-16 13:57:05 +00:00
Mateusz Guzik
8a08cec166 Create a dedicated function for ensuring that cdir and rdir are populated.
Previously several places were doing it on its own, partially
incorrectly (e.g. without the filedesc locked) or even actively harmful
by populating jdir or assigning rootvnode without vrefing it.

Reviewed by:	kib
2015-07-11 16:22:48 +00:00
Mariusz Zaborski
306a82f8f4 Rename zfs nvpair files to not colidate with our nvlist.
PR:		201356
Approved by:	pjd (mentor)
2015-07-09 21:53:40 +00:00
Mateusz Guzik
f131759f54 fd: make 'rights' a manadatory argument to fget* functions 2015-07-05 19:05:16 +00:00
Konstantin Belousov
6fdfd88220 Use single instance of the identical INKERNEL() and PMC_IN_KERNEL()
macros on amd64 and i386.  Move the definition to machine/param.h.
kgdb defines INKERNEL() too, the conflict is resolved by renaming kgdb
version to PINKERNEL().

On i386, correct the lowest kernel address.  After the shared page was
introduced, USRSTACK no longer points to the last user address + 1 [*]

Submitted by:	Oliver Pinter [*]
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-07-02 14:37:21 +00:00