This is OBJT_SWAP pager, specialized for tmpfs. Right now, both swap pager
and generic vm code have to explicitly handle swap objects which are tmpfs
vnode v_object, in the special ways. Replace (almost) all such places with
proper methods.
Since VM still needs a notion of the 'swap object', regardless of its
use, add yet another type-classification flag OBJ_SWAP. Set it in
vm_object_allocate() where other type-class flags are set.
This change almost completely eliminates the knowledge of tmpfs from VM,
and opens a way to make OBJT_SWAP_TMPFS loadable from tmpfs.ko.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D30070
This eliminates the staircase of conditions in vm_map_entry_set_vnode_text().
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D30070
This prevents a situation where other thread modifies map entries
permissions between setting max_prot, then relocking, then setting prot,
confusing the operation outcome. E.g. you can get an error that is not
possible if operation is performed atomic.
Also enable setting rwx for max_prot even if map does not allow to set
effective rwx protection.
Reviewed by: brooks, markj (previous version)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D28117
It is checked in vm_map_insert() and vm_map_protect() that PROT_WRITE |
PROT_EXEC are never specified together, if vm_map has MAP_WX flag set.
FreeBSD control flag allows specific binary to request WX exempt, and
there are per ABI boolean sysctls kern.elf{32,64}.allow_wx to enable/
disable globally.
Reviewed by: emaste, jhb
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D28050
On platforms without a direct map[*], vm_map_insert() may in rare
situations need to allocate a kernel map entry in order to allocate
kernel map entries. This poses a problem similar to the one solved for
vmem boundary tags by vmem_bt_alloc(). In fact the kernel map case is a
bit more complicated since we must allocate entries with the kernel map
locked, whereas vmem can recurse into itself because boundary tags are
allocated up-front.
The solution is to add a custom slab allocator for kmapentzone which
allocates KVA directly from kernel_map, bypassing the kmem_* layer.
This avoids mutual recursion with the vmem btag allocator. Then, when
vm_map_insert() allocates a new kernel map entry, it avoids triggering
allocation of a new slab with M_NOVM until after the insertion is
complete. Instead, vm_map_insert() allocates from the reserve and sets
a flag in kernel_map to trigger re-population of the reserve just before
the map is unlocked. This places an implicit upper bound on the number
of kernel map entries that may be allocated before the kernel map lock
is released, but in general a bound of 1 suffices.
[*] This also comes up on amd64 with UMA_MD_SMALL_ALLOC undefined, a
configuration required by some kernel sanitizers.
Discussed with: kib, rlibby
Reported by: andrew
Tested by: pho (i386 and amd64 with !UMA_MD_SMALL_ALLOC)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D26851
This is mostly mechanical except for vmspace_exit(). There, use the new
refcount_release_if_last() to avoid switching to vmspace0 unless other
processes are sharing the vmspace. In that case, upon switching to
vmspace0 we can unconditionally release the reference.
Remove the volatile qualifier from vm_refcnt now that accesses are
protected using refcount(9) KPIs.
Reviewed by: alc, kib, mmel
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D27057
The entries and their clip boundaries must be aligned on supported
superpages sizes from pagesizes[]. vm_map operations return Mach
error KERN_INVALID_ARGUMENT, which is usually translated to EINVAL, if
it would require clip not at the boundary.
In other words, entries force preserving virtual addresses superpage
properties.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D24652
Today, the zone is only used to allocate a trio of kernel maps: the
kernel map itself, and the exec and pipe submaps. Maps for user
processes are dynamically allocated but are embedded in the vmspace
structure, which is allocated from its own zone. Make the
aforementioned kernel maps statically allocated and get rid of the zone.
While here, remove a stale comment above vmspace_alloc() and change the
names of locks initialized in vm_map_init() to match vmspace_zinit().
Reported by: alc
Reviewed by: alc, kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D26052
In the most common case (fork+execve) this doesn't matter, but further
attempts to apply entropy would fail in (e.g.) a pre-fork server.
Reported by: Alfredo Mazzinghi
Reviewed by: kib, markj
Obtained from: CheriBSD
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D25966
All vm_object_page_remove() callers, except
linux_invalidate_mapping_pages() in the LinuxKPI, free swap space when
removing a range of pages from an object. The LinuxKPI case appears to
be an unintentional omission that could result in leaked swap blocks, so
unconditionally free swap space in vm_object_page_remove() to protect
against similar bugs in the future.
Reviewed by: alc, kib
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D25329
Functions which take untrusted user ranges must validate against the
bounds of the map, and also check for wraparound. Instead of having the
same logic duplicated in a number of places, add a function to check.
Reviewed by: dougm, kib
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D25328
an inline function vm_map_lookup_clip_start that invokes them both and
use it in places that invoke both. Drop a couple of local variables
made unnecessary by this function.
Reviewed by: markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D22987
A submap can only be created from an entry spanning the entire request
range. In particular, if vm_map_lookup_entry() returns false or the
returned entry contains "end".
Since the only use of submaps in FreeBSD is for the static pipe and
execve argument KVA maps, this has no functional effect.
Github PR: https://github.com/freebsd/freebsd/pull/420
Submitted by: Wuyang Chung <wuyang.chung1@gmail.com> (original)
Reviewed by: dougm, kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D23299
Filesystems which want to use it in limited capacity can employ the
VOP_UNLOCK_FLAGS macro.
Reviewed by: kib (previous version)
Differential Revision: https://reviews.freebsd.org/D21427
entry in the vm_map, making invariants related to the max_free entry
field invalid. Move the clipping work into vm_map_entry_link, so that
linking is okay when the new entry clips a current entry, and the
vm_map doesn't have to be briefly corrupted. Change assertions and
conditions in SPLAY_{LEFT,RIGHT}_STEP since the max_free invariants
can now be trusted in all cases.
Tested by: pho
Reviewed by: alc
Differential Revision: https://reviews.freebsd.org/D22897
In r355270 by me, vm_object_shadow() was changed to handle the
reference counting for the shared case, but the extra reference that
was done in vmspace_fork() for the shared/need_copy case was not
removed.
Submitted by: jeff
require the object lock to synchronize collapse. Other swap objects such
as tmpfs do not.
Reported by: mjg
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D22747
space. Where the vm_map tree now has null pointers, store pointers to
next and previous entries in right and left fields, making the binary
tree threaded. Have the predecessor and successor functions compute
what the prev and next fields previously stored.
Reviewed by: markj, kib (previous version)
Tested by: pho (previous version)
Differential Revision: https://reviews.freebsd.org/D21964
Suppose that the map entry is wired, so that we later assign
fault_type = entry->protection. Suppose further that we jump back to
RetryLookup. Then fault_type will no longer contain the original
fault protection mask, but instead that of the wired entry.
Submitted by: Wuyang Chung <wuyang.chung1@gmail.com>
Reviewed by: kib
MFC after: 3 days
Github PR: https://github.com/freebsd/freebsd/pull/419
Differential Revision: https://reviews.freebsd.org/D22683
If the starting pindex is equal to object->size, there is nothing to do.
This was harmless since the rest of vm_map_pmap_enter() has no effect
when psize == 0.
Submitted by: Wuyang Chung <wuyang.chung1@gmail.com>
Reviewed by: alc, dougm, kib
MFC after: 1 week
Github PR: https://github.com/freebsd/freebsd/pull/417
Differential Revision: https://reviews.freebsd.org/D22678
The handle value is stable for all shadow objects in the inheritance
chain. This allows to avoid descending the shadow chain to get to the
bottom of it in vm_map_entry_set_vnode_text(), and eliminate
corresponding object relocking which appeared to be contending.
Change vm_object_allocate_anon() and vm_object_shadow() to handle more
of the cred/charge initialization for the new shadow object, in
addition to set up the handle.
Reported by: jeff
Reviewed by: alc (previous version), jeff (previous version)
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differrential revision: https://reviews.freebsd.org/D22541
broken in r355082. Reduce some locking in nearby related object type
checks.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D22565
(e.g. root->left = NULL) to affect the behavior of that function. This
change stops that data manipulation, and instead calls a pair of
functions, one for the left direction and the other for the right,
with the function called depending whether or not we currently null
the root child in that direction to control the behavior of
vm_map_splay_merge.
Reviewed by: kib
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D22589
'entry'. Where 'entry' is used to identify the starting point for
iteration, use 'first_entry'. These are the naming conventions used in
most of the vm_map.c code. Where VM_MAP_ENTRY_FOREACH can be used, do
so. Squeeze a few lines to fit in 80 columns. Where lines are being
modified for these reasons, look to remove style(9) violations.
Reviewed by: alc, markj
Differential Revision: https://reviews.freebsd.org/D22458
Note that the change in vm_object_collapse() is arguably a correctness
fix. We must not collapse into content-identity carrying objects.
Reviewed by: jeff
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D22467
entry, when that entry has been seen already, keep the
already-looked-up value in a variable and use that instead of looking
it up again.
Approved by: alc, markj (earlier version), kib (earlier version)
Differential Revision: https://reviews.freebsd.org/D22348
reudundant complicated checks and additional locking required only for
anonymous memory. Introduce vm_object_allocate_anon() to create these
objects. DEFAULT and SWAP objects now have the correct settings for
non-anonymous consumers and so individual consumers need not modify the
default flags to create super-pages and avoid ONEMAPPING/NOSPLIT.
Reviewed by: alc, dougm, kib, markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D22119
entries are stabilized, repeatedly verifies the same entry. Check each
entry in turn.
Reviewed by: kib (code only), alc
Tested by: pho
MFC after: 7 days
Differential Revision: https://reviews.freebsd.org/D22405
around entry->{next,prev} when those are used for ordered list
traversal, and use those wrapper functions everywhere. Where the next
field is used for maintaining a stack of deferred operations, #define
defer_next to make that different usage clearer, and then use the
'right' pointer instead of 'next' for that purpose.
Approved by: markj
Tested by: pho (as part of a larger patch)
Differential Revision: https://reviews.freebsd.org/D22347
consistency checking slows performance dramatically. This change
reduces the number of assertions checked by completely walking the
vm_map tree only when the write-lock is released, and only then if the
number of modifications to the tree since the last walk exceeds the
number of tree nodes.
Reviewed by: alc, kib
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D22163
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_map_free_{left,right} rather than re-implementing them. Use the
VM_MAP_FOREACH macro where applicable. Fix some indentation.
Suggested by: kib (in a comment on D21964)
Tested by: pho (as part of D21964)
Differential Revision: https://reviews.freebsd.org/D22011
