Commit Graph

3445 Commits

Author SHA1 Message Date
Gleb Smirnoff
cfcae3f86f Remove UMA_ZONE_REFCNT feature, now unused.
Blessed by:	jeff
2016-03-01 00:33:32 +00:00
Konstantin Belousov
1bdbd70599 Implement process-shared locks support for libthr.so.3, without
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
2016-02-28 17:52:33 +00:00
Gleb Smirnoff
b28cc462ad Include sys/_task.h into uma_int.h, so that taskqueue.h isn't a
requirement for uma_int.h.

Suggested by:	jhb
2016-02-09 20:22:35 +00:00
Mark Johnston
3f38e13073 Plug a vm_page leak introduced in r292373.
Reported by:	vangyzen
2016-02-05 19:35:53 +00:00
Gleb Smirnoff
e60b2fcbeb Redo r292484. Embed task(9) into zone, so that uz_maxaction is called
in a context that can sleep, allowing consumers of the KPI to run their
drain routines without any extra measures.

Discussed with:	jtl
2016-02-03 23:30:17 +00:00
Gleb Smirnoff
9542ea7b80 Move uma_dbg_alloc() and uma_dbg_free() into uma_core.c, which allows
to make uma_dbg.h not depend on uma_int.h, which allows to uninclude
uma_int.h from the mbuf(9) allocator.
2016-02-03 22:02:36 +00:00
Konstantin Belousov
ba7c64d17b Typo in comment. 2016-01-24 13:38:41 +00:00
John Baldwin
8a4dc40ff4 Various cleanups to the main function for AIO kernel processes:
- Pull the vmspace logic out into helper functions and reduce duplication.
  Operations on the vmspace are all isolated to vm_map.c, but it now exports
  a new 'vmspace_switch_aio' for use by AIO kernel processes.
- When an AIO kernel process wants to exit, break out of the main loop and
  perform cleanup after the loop end.  This reduces a lot of indentation and
  allows cleanup to more closely mirror setup actions before the loop starts.
- Convert a DIAGNOSTIC to KASSERT().
- Replace mycp with more typical 'p'.

Reviewed by:	kib
Sponsored by:	Chelsio Communications
Differential Revision:	https://reviews.freebsd.org/D4990
2016-01-19 21:37:51 +00:00
Alan Cox
477bffbe4d A fix to r292469: Iterate over the physical segments in descending rather
than ascending order in vm_phys_alloc_contig() so that, for example, a
sequence of contigmalloc(low=0, high=4GB) calls doesn't exhaust the supply
of low physical memory resulting in a later contigmalloc(low=0, high=1MB)
failure.

Reported by:	cy
Tested by:	cy
Sponsored by:	EMC / Isilon Storage Division
2016-01-16 04:41:40 +00:00
Adrian Chadd
54de56f3b2 Fix the domain iterator to not try the first-touch / fixed domain
more than once when doing round-robin.

This lead to a panic because the iterator was trying the same domain
twice and not trying one of the other domains.

Reported by: pho
Tested by: pho
2016-01-10 17:53:43 +00:00
Konstantin Belousov
ff64a90ed9 Add missed relpbuf() for a smallfs page-in.
Reported by:	Shawn Webb
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
2015-12-27 14:42:39 +00:00
Jonathan T. Looney
54503a13d8 Add a safety net to reclaim mbufs when one of the mbuf zones become
exhausted.

It is possible for a bug in the code (or, theoretically, even unusual
network conditions) to exhaust all possible mbufs or mbuf clusters.
When this occurs, things can grind to a halt fairly quickly. However,
we currently do not call mb_reclaim() unless the entire system is
experiencing a low-memory condition.

While it is best to try to prevent exhaustion of one of the mbuf zones,
it would also be useful to have a mechanism to attempt to recover from
these situations by freeing "expendable" mbufs.

This patch makes two changes:

a) The patch adds a generic API to the UMA zone allocator to set a
function that should be called when an allocation fails because the
zone limit has been reached. Because of the way this function can be
called, it really should do minimal work.

b) The patch uses this API to try to free mbufs when an allocation
fails from one of the mbuf zones because the zone limit has been
reached. The function schedules a callout to run mb_reclaim().

Differential Revision:	https://reviews.freebsd.org/D3864
Reviewed by:	gnn
Comments by:	rrs, glebius
MFC after:	2 weeks
Sponsored by:	Juniper Networks
2015-12-20 02:05:33 +00:00
Alan Cox
c869e67208 Introduce a new mechanism for relocating virtual pages to a new physical
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
2015-12-19 18:42:50 +00:00
Conrad Meyer
8170d6e52b vm_page_replace: add wrapper to KASSERT about old page
It turns out the callers of vm_page_replace know exactly which page they are
replacing and would like to assert about it.  Change those from hard panics to
KASSERTs, and provide them with a wrapper so they don't have to deal with
warnings from an INVARIANTS-dependent dead store of the return value of
vm_page_replace.

Submitted by:	Ryan Libby <rlibby@gmail.com>
Reviewed by:	alc, kib (earlier version)
Sponsored by:	EMC / Isilon Storage Division
Differential Revision:	https://reviews.freebsd.org/D4497
2015-12-17 17:48:57 +00:00
Conrad Meyer
dc62d55929 vm_page.h: page busy macro fixups
Minor changes to:
  - delete extraneous trailing semicolons from macro definitions, and
  - correct spelling of "busying" in panic messages

Submitted by:	Ryan Libby <rlibby@gmail.com>
Reviewed by:	alc, kib
Sponsored by:	EMC / Isilon Storage Division
Differential Revision:	https://reviews.freebsd.org/D4577
2015-12-16 23:23:12 +00:00
Gleb Smirnoff
b0cd20172d A change to KPI of vm_pager_get_pages() and underlying VOP_GETPAGES().
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
2015-12-16 21:30:45 +00:00
Mark Johnston
d9e2e68d38 Don't make assertions about td_critnest when the scheduler is stopped.
A panicking thread always executes with a critical section held, so any
attempt to allocate or free memory while dumping will otherwise cause a
second panic. This can occur, for example, if xpt_polled_action() completes
non-dump I/O that was pending at the time of the panic. The fact that this
can occur is itself a bug, but asserting in this case does little but
reduce the reliability of kernel dumps.

Suggested by:	kib
Reported by:	pho
2015-12-11 20:05:07 +00:00
Conrad Meyer
5e09bdc821 vm_page_replace: remove redundant radix lookup
Remove redundant lookup of the old page from vm_page_replace.  Verification
that the old page exists is already done by vm_radix_replace.

Submitted by:	Ryan Libby <rlibby@gmail.com>
Reviewed by:	alc, kib
Sponsored by:	EMC / Isilon Storage Division
Follow-up to:	https://reviews.freebsd.org/D4326
Differential Revision:	https://reviews.freebsd.org/D4471
2015-12-10 22:57:27 +00:00
Conrad Meyer
6fee422ed5 vm_fault_hold: handle vm_page_rename failure
On vm_page_rename failure, fix a missing object unlock and a double free of
a page.

First remove the old page, then rename into other page into first_object,
then free the old page.  This avoids the problem on rename failure.  This is
a little ugly but seems to be the most straightforward solution.

Tested with:
  $ sysctl debug.fail_point.uma_zalloc_arg="1%return"
  $ kyua test -k /usr/tests/sys/Kyuafile

Submitted by:	Ryan Libby <rlibby@gmail.com>
Reviewed by:	kib
Seen by:	alc
Sponsored by:	EMC / Isilon Storage Division
Differential Revision:	https://reviews.freebsd.org/D4326
2015-12-06 17:46:12 +00:00
Conrad Meyer
4cc8daf782 Pull vm_object_scan_all_shadowed out of vm_object_backing_scan
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
2015-12-03 17:21:10 +00:00
Konstantin Belousov
99a1570a25 r221714 fixed the situation when the collapse scan improperly handled
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
2015-12-01 09:06:09 +00:00
Konstantin Belousov
b89def80f5 Minor cleanup.
Systematically use ANSI C functions definitions.
Correct type of the flags argument to the dev_pager_putpages() function.
Use vm_pager_free_nonreq().

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-11-29 11:37:25 +00:00
Konstantin Belousov
2eb2f0d5e3 In vm_pageout_grow_cache(), do not re-try the inactive queue when
active queue scan initiated write.

Re-trying from the inactive queue when doing active scan makes the
loop never end if number of domains is greater than 1 and inactive or
active scan cannot reach the target.

Reported and tested by:	Andrew Gallatin <gallatin@netflix.com>
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2015-11-27 19:43:36 +00:00
Alan Cox
67b7e4345e Correct an error in vm_reserv_reclaim_contig(). In the highly unusual
case that the reservation contained "low", the starting position in the
popmap for the free page search was incorrectly calculated.  The most
likely (and visible) symptom of this error was the assertion failure,
"vm_reserv_reclaim_contig: pa is too low".
2015-11-26 19:12:18 +00:00
Konstantin Belousov
9af50b0126 Record proper commit message for r291157.
The r289895 revision did not accounted for the block containing the
requested page, when calculating the run of pages.  Include the pages
before/after the requested page, that fit into the reqblock, into the
calculation.

Noted by:	glebius
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-11-22 09:50:13 +00:00
Konstantin Belousov
4586820a07 Noted by: glebius
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-11-22 09:48:03 +00:00
Mark Johnston
7672ca059a Remove unneeded includes of opt_kdtrace.h.
As of r258541, KDTRACE_HOOKS is defined in opt_global.h, so opt_kdtrace.h
is not needed when defining SDT(9) probes.
2015-11-22 02:01:01 +00:00
Gleb Smirnoff
09c837b897 Remove remnants of the old NFS from vnode pager.
Reviewed by:	kib
Sponsored by:	Netflix
2015-11-20 23:52:27 +00:00
Jonathan T. Looney
1067a2ba68 Consistently enforce the restriction against calling malloc/free when in a
critical section.

uma_zalloc_arg()/uma_zalloc_free() may acquire a sleepable lock on the
zone. The malloc() family of functions may call uma_zalloc_arg() or
uma_zalloc_free().

The malloc(9) man page currently claims that free() will never sleep.
It also implies that the malloc() family of functions will not sleep
when called with M_NOWAIT. However, it is more correct to say that
these functions will not sleep indefinitely. Indeed, they may acquire
a sleepable lock. However, a developer may overlook this restriction
because the WITNESS check that catches attempts to call the malloc()
family of functions within a critical section is inconsistenly
applied.

This change clarifies the language of the malloc(9) man page to clarify
the restriction against calling the malloc() family of functions
while in a critical section or holding a spin lock. It also adds
KASSERTs at appropriate points to make the enforcement of this
restriction more consistent.

PR:		204633
Differential Revision:	https://reviews.freebsd.org/D4197
Reviewed by:	markj
Approved by:	gnn (mentor)
Sponsored by:	Juniper Networks
2015-11-19 14:04:53 +00:00
Konstantin Belousov
76386c7ecd Rework the test which raises OOM condition. Right now, the code
checks for the swap space consumption plus checks that the amount of
the free pages exceeds some limit, in case pagedeamon did not coped
with the page shortage in one of the late passes.  This is wrong
because it does not account for the presence of the reclamaible pages
in the queues which are not selectable for reclaim immediately.  E.g.,
on the swap-less systems, large active queue easily triggered OOM.

Instead, only raise OOM when pagedaemon is unable to produce a free
page in several back-to-back passes.  Track the failed passes per
pagedaemon thread.

The number of passes to trigger OOM was selected empirically and
tested both on small (32M-64M i386 VM) and large (32G amd64)
configurations.  If the specifics of the load require tuning, sysctl
vm.pageout_oom_seq sets the number of back-to-back passes which must
fail before OOM is raised.  Each pass takes 1/2 of seconds.  Less the
value, more sensible the pagedaemon is to the page shortage.

In future, some heuristic to calculate the value of the tunable might
be designed based on the system configuration and load.  But before it
can be done, the i/o system must be fixed to reliably time-out
pagedaemon writes, even if waiting for the memory to proceed.  Then,
code can account for the in-flight page-outs and postpone OOM until
all of them finished, which should reduce the need in tuning.  Right
now, ignoring the in-flight writes and the counter allows to break
deadlocks due to write path doing sleepable memory allocations.

Reported by:	Dmitry Sivachenko, bde, many others
Tested by:	pho, bde, tuexen (arm)
Reviewed by:	alc
Discussed with:	bde, imp
Sponsored by:	The FreeBSD Foundation
MFC after:	3 weeks
2015-11-16 06:26:26 +00:00
Konstantin Belousov
3949873f7a Do not use vmspace_resident_count() for the OOM process selection.
Residency count track the number of pte entries installed into the
current pmap, which does not reflect the consumption of the physical
memory by the address map.  Due to several mechanisms like pv entries
reclamation, copy on write etc. the resident pte entries count may be
much less than the amount of physical memory kept by the process.

Provide the OOM-specific vm_pageout_oom_pagecount() function which
estimates the amount of reclamaible memory which could be stolen if
the process is killed.

Reported and tested by:	pho
Reviewed by:	alc
Comments text by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	3 weeks
2015-11-16 06:02:11 +00:00
Konstantin Belousov
b98acc0a1b VM daemon works in parallel with the pagedaemon threads, and, among
other actions, swaps out kernel stacks of the processes.  On the other
hand, currentl OOM logic which selects a process to kill in the
critical condition, skips process with swapped-out thread.  Under some
loads, this results in the big(gest) process being ignored by OOM.

Do not skip a process which has inhibited thread due to the swap-out,
in the OOM selection loop.  Note that killing such process requires
the thread stack page-in, but sometimes this is the only way to
recover.

Reported and tested by:	pho
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	3 weeks
2015-11-16 05:52:04 +00:00
John Baldwin
645743ea99 Export various helper variables describing the layout and size of
certain kernel structures for use by debuggers. This mostly aids
in examining cores from a kernel without debug symbols as a debugger
can infer these values if debug symbols are available.

One set of variables describes the layout of 'struct linker_file' to
walk the list of loaded kernel modules.

A second set of variables describes the layout of 'struct proc' and
'struct thread' to walk the list of processes in the kernel and the
threads in each process.

The 'pcb_size' variable is used to index into the stoppcbs[] array.

The 'vm_maxuser_address' is used to distinguish kernel virtual addresses
from user addresses. This doesn't have to be perfect, and
'vm_maxuser_address' is a cheap and simple way to differentiate kernel
pointers from simple values like TIDs and PIDs.

While here, annotate the fields in struct pcb used by kgdb on amd64
and i386 to note that their ABI should be preserved.  Annotations for
other platforms will be added in the future.

Reviewed by:	kib
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D3773
2015-11-12 22:00:59 +00:00
Mark Johnston
7e78597f04 Ensure that deactivated pages that are not expected to be reused are
reclaimed in FIFO order by the pagedaemon.  Previously we would enqueue
such pages at the head of the inactive queue, yielding a LIFO reclaim order.

Reviewed by:	alc
MFC after:	2 weeks
Sponsored by:	EMC / Isilon Storage Division
2015-11-08 01:36:18 +00:00
Konstantin Belousov
eac91e326a Reduce the amount of calls to VOP_BMAP() made from the local vnode
pager.  It is enough to execute VOP_BMAP() once to obtain both the
disk block address for the requested page, and the before/after limits
for the contiguous run.  The clipping of the vm_page_t array passed to
the vnode_pager_generic_getpages() and the disk address for the first
page in the clipped array can be deduced from the call results.

While there, remove some noise (like if (1) {...}) and adjust nearby
code.

Reviewed by:	alc
Discussed with:	glebius
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	3 weeks
2015-10-24 21:59:22 +00:00
Jason A. Harmening
7c989c156f Fix capitalization 2015-10-23 12:06:06 +00:00
Jason A. Harmening
a50730587b Remove unclear comment about address truncation in busdma. Add (hopefully much clearer) comment at declaration of PHYS_TO_VM_PAGE().
Noted by:	avg
2015-10-23 12:03:25 +00:00
Konstantin Belousov
69b8585e79 Only marker is guaranteed to be present on the queue after the relock
in vm_pageout_fallback_object_lock() and vm_pageout_page_lock().  The
check for the m->queue == queue assumes that the page does belong to a
queue.

Modify the 'unchanged' calculation bu dereferencing the marker tailq
pointers, which is known to belong to the queue.  Since for a page m
linked to the queue, m->queue must be equal to the queue index, assert
this instead of checking.

In collaboration with:	alc
Sponsored by:	The FreeBSD Foundation (kib)
MFC after:	2 weeks
2015-10-18 09:33:28 +00:00
Konstantin Belousov
8748f58cde Revert r289302, invalid pages can be queued, e.g. by vfs_vmio_unwire().
Found by:	alc
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
2015-10-15 19:07:38 +00:00
Konstantin Belousov
12a73f207a Invalid pages should not appear on the inactive queue. Change the
check into an assertion.

Reviewed by:	alc
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
2015-10-14 09:03:32 +00:00
Jeff Roberson
21fae96123 Parallelize the buffer cache and rewrite getnewbuf(). This results in a
8x performance improvement in a micro benchmark on a 4 socket machine.

 - Get buffer headers from a per-cpu uma cache that sits in from of the
   free queue.
 - Use a per-cpu quantum cache in vmem to eliminate contention for kva.
 - Use multiple clean queues according to buffer cache size to eliminate
   clean queue lock contention.
 - Introduce a bufspace daemon that attempts to prevent getnewbuf() callers
   from blocking or doing direct recycling.
 - Close some bufspace allocation races that could lead to endless
   recycling.
 - Further the transition to a more modern style of small functions grouped
   by prefix in order to improve growing complexity.

Sponsored by:	EMC / Isilon
Reviewed by:	kib
Tested by:	pho
2015-10-14 02:10:07 +00:00
Alan Cox
e595970add Exploit r288122 to avoid pointlessly enqueueing a page that is about to be
freed.

Submitted by:	kmacy
Differential Revision:	https://reviews.freebsd.org/D1674
2015-10-09 03:38:58 +00:00
Alan Cox
27e9ed8a5a Exploit r288122 to address a cosmetic issue. Pages belonging to either
the kernel or kmem object can't be paged out.  Since they can't be paged
out, they are never enqueued in a paging queue.  Nonetheless, passing
PQ_INACTIVE to vm_page_unwire() in kmem_unback() creates the appearance
that these pages are being enqueued in the inactive queue.  As of r288122,
we can avoid giving this false impression by passing PQ_NONE.

Submitted by:	kmacy
Differential Revision:	https://reviews.freebsd.org/D1674
2015-10-06 05:49:00 +00:00
Warner Losh
d635a37ffa Mark swap_pager_putpages static at its definition. It was already
static at its declaration. Remove needless swapdev_strategy forward
declaration.

MFC After: 3 days
2015-10-05 21:29:17 +00:00
Alan Cox
bc7275964c Reduce the scope of a variable to the only file where it is used. 2015-10-03 19:27:52 +00:00
Mark Johnston
3138cd3670 As a step towards the elimination of PG_CACHED pages, rework the handling
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
2015-09-30 23:06:29 +00:00
Alan Cox
9e829b2272 The conversion of kmem_alloc_attr() from operating on a vm map to a vmem
arena in r254025 introduced a bug in the case when an allocation is only
partially successful.  Specifically, the vm object lock was not being
acquired before freeing the allocated pages.  To address this bug, replace
the existing code by a call to kmem_unback().

Change the type of a variable in kmem_alloc_attr() so that an allocation
of two or more gigabytes won't fail.

Replace the error handling code in kmem_back() by a call to kmem_unback().

Reviewed by:	kib (an earlier version)
MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division
2015-09-26 22:57:10 +00:00
Alan Cox
087a613247 Exploit r288122 to address a cosmetic issue. Since the pages allocated
by noobj_alloc() don't belong to a vm object, they can't be paged out.
Since they can't be paged out, they are never enqueued in a paging queue.
Nonetheless, passing PQ_INACTIVE to vm_page_unwire() creates the appearance
that these pages are being enqueued in the inactive queue.  As of r288122,
we can avoid giving this false impression by passing PQ_NONE.

Submitted by:	kmacy
Differential Revision:	https://reviews.freebsd.org/D1674
2015-09-26 17:45:10 +00:00
Alan Cox
15aaea7892 Change vm_page_unwire() such that it (1) accepts PQ_NONE as the specified
queue and (2) returns a Boolean indicating whether the page's wire count
transitioned to zero.

Exploit this change in vfs_vmio_release() to avoid pointlessly enqueueing
a page that is about to be freed.

(An earlier version of this change was developed by attilio@ and kmacy@.
Any errors in this version are my own.)

Reviewed by:	kib
Sponsored by:	EMC / Isilon Storage Division
2015-09-22 18:16:52 +00:00
Alan Cox
d9347bca9a Correct a non-fatal error in vm_pageout_worker(). vm_pageout_worker()
should not assume that vm_pages_needed will remain set while it sleeps.
Other threads can clear vm_pages_needed by performing a sufficient
number of vm_page_free() calls, e.g., process termination.  The effect
of this error was that vm_pageout_worker() would free and/or launder
pages when, in fact, there was no shortage of free pages.

Rewrite a nearby comment to describe all of the possible cases and not
just the most common case.  The problem being that the comment made
the most common case seem like the only case.

Reviewed by:	kib
MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division
2015-09-20 19:20:03 +00:00