It detects both: buffer underflows and buffer overflows bugs at runtime
(on free(9) and realloc(9)) and prints backtraces from where memory was
allocated and from where it was freed.
Tested by: kris
of physical RAM instead of the bottom was a sound idea, but the implementation
left a lot to be desired. Scans would spend considerable time looking at
pages that are above of the address range given by the caller, and multiple
calls (like what happens in busdma) would spend more time on top of that
rescanning the same pages over and over.
Solve this, at least for now, with two simple optimizations. The first is
to not bother scanning high ordered pages that are outside of the provided
address range. Second is to cache the page index from the last successful
operation so that subsequent scans don't have to restart from the top. This
is conditional on the numpages argument being the same or greater between
calls.
MFC After: 2 weeks
The difference between WITNESS_CHECK() and WITNESS_WARN() is that
WITNESS_CHECK() should be used in the places that the return value of
witness_warn() is checked, whereas WITNESS_WARN() should be used in places
where the return value is ignored. Specifically, in a kernel without
WITNESS enabled, WITNESS_WARN() evaluates to an empty string where as
WITNESS_CHECK evaluates to 0. I also updated the one place that was
checking the return value of WITNESS_WARN() to use WITNESS_CHECK.
they are. They should be NULL at this point, except if we're coming from
swapdev_strategy().
It should only affect the case where we're swapping directly on a file over
NFS.
the resident page count matches the object size. We know it fully backs
its parent in this case.
Reviewed by: acl, tegge
Sponsored by: Isilon Systems, Inc.
statement. Specifically, a break statement that previously broke out of
the enclosing switch was not changed. Consequently, the enclosing loop
terminated prematurely.
This could result in "vm_page_insert: page already inserted" panics.
Submitted by: tegge
- provide an interface (macros) to the page coloring part of the VM system,
this allows to try different coloring algorithms without the need to
touch every file [1]
- make the page queue tuning values readable: sysctl vm.stats.pagequeue
- autotuning of the page coloring values based upon the cache size instead
of options in the kernel config (disabling of the page coloring as a
kernel option is still possible)
MD changes:
- detection of the cache size: only IA32 and AMD64 (untested) contains
cache size detection code, every other arch just comes with a dummy
function (this results in the use of default values like it was the
case without the autotuning of the page coloring)
- print some more info on Intel CPU's (like we do on AMD and Transmeta
CPU's)
Note to AMD owners (IA32 and AMD64): please run "sysctl vm.stats.pagequeue"
and report if the cache* values are zero (= bug in the cache detection code)
or not.
Based upon work by: Chad David <davidc@acns.ab.ca> [1]
Reviewed by: alc, arch (in 2004)
Discussed with: alc, Chad David, arch (in 2004)
- Provide tunable vm.memguard.desc, so one can specify memory type without
changing the code and recompiling the kernel.
- Allow to use memguard for kernel modules by providing sysctl
vm.memguard.desc, which can be changed to short description of memory
type before module is loaded.
- Move as much memguard code as possible to memguard.c.
- Add sysctl node vm.memguard. and move memguard-specific sysctl there.
- Add malloc_desc2type() function for finding memory type based on its
short description (ks_shortdesc field).
- Memory type can be changed (via vm.memguard.desc sysctl) only if it
doesn't exist (will be loaded later) or when no memory is allocated yet.
If there is allocated memory for the given memory type, return EBUSY.
- Implement two ways of memory types comparsion and make safer/slower the
default.
ephemeral mappings that are used as the source for three copy
operations from kernel space to user space. There are two reasons for
making this change: (1) Under heavy load exec_map can fill up causing
vm_map_find() to fail. When it fails, the nascent process is aborted
(SIGABRT). Whereas, this reimplementation using sf_buf_alloc()
sleeps. (2) Although it is possible to sleep on vm_map_find()'s
failure until address space becomes available (see kmem_alloc_wait()),
using sf_buf_alloc() is faster. Furthermore, the reimplementation
uses a CPU private mapping, avoiding a TLB shootdown on
multiprocessors.
Problem uncovered by: kris@
Reviewed by: tegge@
MFC after: 3 weeks
reclamation synchronously from get_pv_entry() instead of
asynchronously as part of the page daemon. Additionally, limit the
reclamation to inactive pages unless allocation from the PV entry zone
or reclamation from the inactive queue fails. Previously, reclamation
destroyed mappings to both inactive and active pages. get_pv_entry()
still, however, wakes up the page daemon when reclamation occurs. The
reason being that the page daemon may move some pages from the active
queue to the inactive queue, making some new pages available to future
reclamations.
Print the "reclaiming PV entries" message at most once per minute, but
don't stop printing it after the fifth time. This way, we do not give
the impression that the problem has gone away.
Reviewed by: tegge
by the zero-copy sockets method, and written to before the transmission
completes, we need to destroy all of the existing mappings to the page,
not just the one that we fault on. Otherwise, the mappings will no longer
be to the same page and changes made through one of the mappings will not
be visible through the others.
Observed by: tegge
If a copy-on-write fault occurs on the page, the new copy should inherit
a part of the original page's wire count.
Submitted by: tegge
MFC after: 1 week
- Prefer '_' to ' ', as it results in more easily parsed results in
memory monitoring tools such as vmstat.
- Remove punctuation that is incompatible with using memory type names
as file names, such as '/' characters.
- Disambiguate some collisions by adding subsystem prefixes to some
memory types.
- Generally prefer lower case to upper case.
- If the same type is defined in multiple architecture directories,
attempt to use the same name in additional cases.
Not all instances were caught in this change, so more work is required to
finish this conversion. Similar changes are required for UMA zone names.
vm_object_backing_scan() was not written to handle. Specifically, a wired
page within a backing object that is shadowed by a page within the shadow
object. Handle this state by removing the wired page from the backing
object. The wired page will be freed by socow_iodone().
Stop masking errors: If a page is being freed by vm_object_backing_scan(),
assert that it is no longer mapped rather than quietly destroying any
mappings.
Tested by: Harald Schmalzbauer
Before this change a copy operation with cp(1) would not update the
file access times.
According to the POSIX mmap(2) documentation: the st_atime field
of the mapped file may be marked for update at any time between the
mmap() call and the corresponding munmap() call. The initial read
or write reference to a mapped region shall cause the file's st_atime
field to be marked for update if it has not already been marked for
update.
I'm not sure this is the right thing to do, but at least I don't panic
anymore when swapping on a NFS file without using md(4).
X-MFC after: proper review
UMA boot pages.
Disable recursion on the general UMA lock now that startup_alloc() no
longer uses it.
Eliminate the variable uma_boot_free. It serves no purpose.
Note: This change eliminates a lock-order reversal between a system
map mutex and the UMA lock. See
http://sources.zabbadoz.net/freebsd/lor.html#109 for details.
MFC after: 3 days
vm_pager_init() is run before required nswbuf variable has been set
to correct value. This caused system to run with single pbuf available
for vnode_pager. Handle both cluster_pbuf_freecnt and vnode_pbuf_freecnt
variable in the same way.
Reported by: ade
Obtained from: alc
MFC after: 2 days
due to the vm object being locked.
When a process writes large amounts of data to a file, the vm object associated
with that file can contain most of the physical pages on the machine. If the
process is preempted while holding the lock on the vm object, pagedaemon would
be able to move very few pages from PQ_INACTIVE to PQ_CACHE or from PQ_ACTIVE
to PQ_INACTIVE, resulting in unlimited cleaning of dirty pages belonging to
other vm objects.
Temporarily unlock the page queues lock while locking vm objects to avoid lock
order violation. Detect and handle relevant page queue changes.
This change depends on both the lock portion of struct vm_object and normal
struct vm_page being type stable.
Reviewed by: alc
as opt_vmpage.h will not be available to user space library builds. A
similar existing check is present for KLD_MODULE for similar reasons.
MFC after: 3 days
