proc: Remove kernel stack swapping support, part 6

- Remove most checks of the P_INMEM flag.
- Some uses remain since a few userspace tools, e.g., ps(1) and top(1)
expect the flag to be set. Thes

proc: Remove kernel stack swapping support, part 6

- Remove most checks of the P_INMEM flag.
- Some uses remain since a few userspace tools, e.g., ps(1) and top(1)
expect the flag to be set. These can be cleaned up but the code has
most likely been copy-pasted elsewhere and while linger for a long
time.

Tested by: pho
Reviewed by: alc, imp, kib
Differential Revision: https://reviews.freebsd.org/D46117

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kern_racct.c: Don't compile if RACCT undefined

Just skip compiling this file if RACCT isn't defined. This allows to
skip including headers that no code uses at all, and also to remove the
whole fil

kern_racct.c: Don't compile if RACCT undefined

Just skip compiling this file if RACCT isn't defined. This allows to
skip including headers that no code uses at all, and also to remove the
whole file's #ifdef/#endif bracketing.

Reviewed by: markj
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation

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sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

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AST: rework

Make most AST handlers dynamically registered. This allows to have
subsystem-specific handler source located in the subsystem files,
instead of making subr_trap.c aware of it. For inst

AST: rework

Make most AST handlers dynamically registered. This allows to have
subsystem-specific handler source located in the subsystem files,
instead of making subr_trap.c aware of it. For instance, signal
delivery code on return to userspace is now moved to kern_sig.c.

Also, it allows to have some handlers designated as the cleanup (kclear)
type, which are called both at AST and on thread/process exit. For
instance, ast(), exit1(), and NFS server no longer need to be aware
about UFS softdep processing.

The dynamic registration also allows third-party modules to register AST
handlers if needed. There is one caveat with loadable modules: the
code does not make any effort to ensure that the module is not unloaded
before all threads processed through AST handler in it. In fact, this
is already present behavior for hwpmc.ko and ufs.ko. I do not think it
is worth the efforts and the runtime overhead to try to fix it.

Reviewed by: markj
Tested by: emaste (arm64), pho
Discussed with: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D35888

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sysent: Get rid of bogus sys/sysent.h include.

Where appropriate hide sysent.h under proper condition.

MFC after: 2 weeks

kern_racct: Fix a typo in a source code comment

- s/maxumum/maximum/

MFC after: 3 days

umtx: Split umtx.h on two counterparts.

To prevent umtx.h polluting by future changes split it on two headers:
umtx.h - ABI header for userspace;
umtxvar.h - the kernel staff.

While here fix umtx_k

umtx: Split umtx.h on two counterparts.

To prevent umtx.h polluting by future changes split it on two headers:
umtx.h - ABI header for userspace;
umtxvar.h - the kernel staff.

While here fix umtx_key_match style.

Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D31248
MFC after: 2 weeks

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Use atomic loads/stores when updating td->td_state

KCSAN complains about racy accesses in the locking code. Those races are
fine since they are inside a TD_SET_RUNNING() loop that expects the value

Use atomic loads/stores when updating td->td_state

KCSAN complains about racy accesses in the locking code. Those races are
fine since they are inside a TD_SET_RUNNING() loop that expects the value
to be changed by another CPU.

Use relaxed atomic stores/loads to indicate that this variable can be
written/read by multiple CPUs at the same time. This will also prevent
the compiler from doing unexpected re-ordering.

Reported by: GENERIC-KCSAN
Test Plan: KCSAN no longer complains, kernel still runs fine.
Reviewed By: markj, mjg (earlier version)
Differential Revision: https://reviews.freebsd.org/D28569

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Drop "All rights reserved" from all my stuff. This includes
Foundation copyrights, approved by emaste@. It does not include
files which carry other people's copyrights; if you're one
of those peopl

Drop "All rights reserved" from all my stuff. This includes
Foundation copyrights, approved by emaste@. It does not include
files which carry other people's copyrights; if you're one
of those people, feel free to make similar change.

Reviewed by: emaste, imp, gbe (manpages)
Differential Revision: https://reviews.freebsd.org/D26980

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Move racct/rctl throttling from userret() to ast(). There's no reason
for it to sit in the syscall fast path.

Reviewed by: kib
MFC after: 2 weeks
Sponsored by: DARPA
Differential Revision: https://

Move racct/rctl throttling from userret() to ast(). There's no reason
for it to sit in the syscall fast path.

Reviewed by: kib
MFC after: 2 weeks
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D26368

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kern: clean up empty lines in .c and .h files

Merge ^/head r358269 through r358399.

Mark more nodes as CTLFLAG_MPSAFE or CTLFLAG_NEEDGIANT (17 of many)

r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly mark

Mark more nodes as CTLFLAG_MPSAFE or CTLFLAG_NEEDGIANT (17 of many)

r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked).
Use it in preparation for a general review of all nodes.

This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.

Mark all obvious cases as MPSAFE. All entries that haven't been marked
as MPSAFE before are by default marked as NEEDGIANT

Approved by: kib (mentor, blanket)
Commented by: kib, gallatin, melifaro
Differential Revision: https://reviews.freebsd.org/D23718

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Merge ^/head r351317 through r351731.

proc: eliminate the zombproc list

It is not needed by anything in the kernel and it slightly drives up contention
on both proctree and allproc locks.

Reviewed by: kib
Sponsored by: The FreeBSD Foun

proc: eliminate the zombproc list

It is not needed by anything in the kernel and it slightly drives up contention
on both proctree and allproc locks.

Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21447

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Merge ^/head r340918 through r341763.

racct: add RACCT_ENABLED macro and racct_set_unlocked

This allows to remove PROC_LOCK/UNLOCK pairs spread thorought the kernel
only used to appease racct_set.

Sponsored by: The FreeBSD Foundation

Convert racct_enable to bool and annotate as __read_frequently

Sponsored by: The FreeBSD Foundation

Deinline racct throttling out of syscall exit path.

racct is not enabled by default and even when it is enabled processes are
typically not throttled. The order of checks is left unchanged since
rac

Deinline racct throttling out of syscall exit path.

racct is not enabled by default and even when it is enabled processes are
typically not throttled. The order of checks is left unchanged since
racct_enable will be annotated as __read_frequently, while checking for the
flag in the processes would probably require an extra fetch.

Sponsored by: The FreeBSD Foundation

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proc: create a dedicated lock for zombproc to ligthen the load on allproc_lock

waitpid always takes proctree to evaluate the list, but only takes allproc
if it can reap. With this patch allproc is n

proc: create a dedicated lock for zombproc to ligthen the load on allproc_lock

waitpid always takes proctree to evaluate the list, but only takes allproc
if it can reap. With this patch allproc is no longer taken, which helps during
poudriere -j 128.

Discussed with: kib
Sponsored by: The FreeBSD Foundation

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Merge ^/head r340427 through r340868.

fork: remove avoidable proc lock/unlock pair

We don't have to access the process after making it runnable, so there
is no need to hold it either.

Sponsored by: The FreeBSD Foundation

call racct_proc_ucred_changed() under the proc lock

The lock is required to ensure that the switch to the new credentials
and the transfer of the process's accounting data from the old
credentials t

call racct_proc_ucred_changed() under the proc lock

The lock is required to ensure that the switch to the new credentials
and the transfer of the process's accounting data from the old
credentials to the new ones is done atomically. Otherwise, some updates
may be applied to the new credentials and then additionally transferred
from the old credentials if the updates happen after proc_set_cred() and
before racct_proc_ucred_changed().

The problem is especially pronounced for RACCT_RSS because
- there is a strict accounting for this resource (it's reclaimable)
- it's updated asynchronously by the vm daemon
- it's updated by setting an absolute value instead of applying a delta

I had to remove a call to rctl_proc_ucred_changed() from
racct_proc_ucred_changed() and make all callers of latter call the
former as well. The reason is that rctl_proc_ucred_changed, as it is
implemented now, cannot be called while holding the proc lock, so the
lock is dropped after calling racct_proc_ucred_changed. Additionally,
I've added calls to crhold / crfree around the rctl call, because
without the proc lock there is no gurantee that the new credentials,
owned by the process, will stay stable. That does not eliminate a
possibility that the credentials passed to the rctl will get stale.
Ideally, rctl_proc_ucred_changed should be able to work under the proc
lock.

Many thanks to kib for pointing out the above problems.

PR: 222027
Discussed with: kib
No comment: trasz
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D15048

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