Manage process-related IDs with bitmaps

Currently unique pid allocation on fork often requires a full walk of
process, group, session lists to make sure it is not used by anything.
This has a side e

Manage process-related IDs with bitmaps

Currently unique pid allocation on fork often requires a full walk of
process, group, session lists to make sure it is not used by anything.
This has a side effect of requiring proctree to be held along with allproc,
which adds more contention in poudriere -j 128.

The patch below implements trivial bitmaps which gets rid of the problem.
Dedicated lock is introduced to manage IDs.

While here a bug was discovered: all processes would inherit reap id from
the first process spawned by init. This had a side effect of keeping the
ID used and when allocation rolls over to the beginning it keeps being
skipped.

The patch is loosely based on initial work by mjoras@.

Reviewed by: kib
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.

Revert "fork: fix use-after-free with vfork"

This unreliably breaks libc handling of vfork where forking succeded,
but execve did not.

vfork code in libc performs waitpid with WNOHANG in case of fa

Revert "fork: fix use-after-free with vfork"

This unreliably breaks libc handling of vfork where forking succeded,
but execve did not.

vfork code in libc performs waitpid with WNOHANG in case of failed exec.
With the fix exit codepath was waking up the parent before the child
fully transitioned to a zombie. Woken up parent would waitpid, which
could find a not-yet-zombie child and fail to reap it due to the WNOHANG
flag.

While removing the flag fixes the problem, it is not an option due to older
releases which would still suffer from the kernel change.

Revert the fix until a solution can be worked out.

Note that while use-after-free which gets back due to the revert is a real
bug, it's side-effects are limited due to the fact that struct proc memory
is never released by UMA.

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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

fork: fix use-after-free with vfork

The pointer to the child is stored without any reference held. Then it is
blindly used to wait until P_PPWAIT is cleared. However, if the child is
autoreaped it c

fork: fix use-after-free with vfork

The pointer to the child is stored without any reference held. Then it is
blindly used to wait until P_PPWAIT is cleared. However, if the child is
autoreaped it could have exited and get freed before the parent started
waiting.

Use the existing hold mechanism to mitigate the problem. Most common case
of doing exec remains unchanged. The corner case of doing exit performs
wake up before waiting for holds to clear.

Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D18295

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proc: implement pid hash locks and an iterator

forks, exits and waits are frequently stalled during poudriere -j 128 runs
due to killpg and process list exports performed for each package.

Both use

proc: implement pid hash locks and an iterator

forks, exits and waits are frequently stalled during poudriere -j 128 runs
due to killpg and process list exports performed for each package.

Both uses take the allproc lock. The latter case can be modified to iterate
over the hash with finer grained locking instead.

Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17817

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proc: always store parent pid in p_oppid

Doing so removes the dependency on proctree lock from sysctl process list
export which further reduces contention during poudriere -j 128 runs.

Reviewed by:

proc: always store parent pid in p_oppid

Doing so removes the dependency on proctree lock from sysctl process list
export which further reduces contention during poudriere -j 128 runs.

Reviewed by: kib (previous version)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17825

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fork: avoid endless wait with PTRACE_FORK and RFSTOPPED.

An RFSTOPPED thread can't clean TDB_STOPATFORK, which is done in the
fork_return() in its context, so parent is stuck forever. Triggered
whe

fork: avoid endless wait with PTRACE_FORK and RFSTOPPED.

An RFSTOPPED thread can't clean TDB_STOPATFORK, which is done in the
fork_return() in its context, so parent is stuck forever. Triggered
when trying to ptrace linux process. Instead of waiting for the new
thread to clear TDB_STOPATFORK, tag it as traced and reparent to the
debugger in do_fork(), and let it only notify the debugger when run.

Submitted by: Yanko Yankulov <yanko.yankulov@gmail.com>
Reviewed by: jhb
MFC after: 1 week
X-MFC-Note: keep p_dbgwait placeholder intact
Differential revision: https://reviews.freebsd.org/D15857

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Reduce contention on the proctree lock during heavy package build.

There is a proctree -> allproc ordering established.

Most of the time it is either xlock -> xlock or slock -> slock.

On fork howe

Reduce contention on the proctree lock during heavy package build.

There is a proctree -> allproc ordering established.

Most of the time it is either xlock -> xlock or slock -> slock.

On fork however there is a slock -> xlock pair which results in
pathological wait times due to threads keeping proctree held for
reading and all waiting on allproc. Switch this to xlock -> xlock.
Longer term fix would get rid of proctree in this place to begin with.
Right now it is necessary to walk the session/process group lists to
determine which id is free. The walk can be avoided e.g. with bitmaps.

The exit path used to have one place which dealt with allproc and
then with proctree. Move the allproc acquire into the section protected
by proctree. This reduces contention against threads waiting on proctree
in the fork codepath - the fork proctree holder does not have to wait
for allproc as often.

Finally, move tidhash manipulation outside of the area protected by
either of these locks. The removal from the hash was already unprotected.
There is no legitimate reason to look up thread ids for a process still
under construction.

This results in about 50% wait time reduction during -j 128 package build.

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Postpone sx_sunlock(&proctree_lock) on fork until after allproc is dropped.

There is a significant contention on the lock during -j 128 package build.
This change drops total wait time on this lock

Postpone sx_sunlock(&proctree_lock) on fork until after allproc is dropped.

There is a significant contention on the lock during -j 128 package build.
This change drops total wait time on this lock by 60%.

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Remove trailing whitespace.
No functional change.

Merge ^/head r327886 through r327930.

Implement 'domainset', a cpuset based NUMA policy mechanism. This allows
userspace to control NUMA policy administratively and programmatically.

Implement domainset based iterators in the page laye

Implement 'domainset', a cpuset based NUMA policy mechanism. This allows
userspace to control NUMA policy administratively and programmatically.

Implement domainset based iterators in the page layer.

Remove the now legacy numa_* syscalls.

Cleanup some header polution created by having seq.h in proc.h.

Reviewed by: markj, kib
Discussed with: alc
Tested by: pho
Sponsored by: Netflix, Dell/EMC Isilon
Differential Revision: https://reviews.freebsd.org/D13403

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Merge ^/head r325999 through r326131.

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

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Merge ^/head r325505 through r325662.

Introduce EVENTHANDLER_LIST and some users.

This introduces a facility to EVENTHANDLER(9) for explicitly defining a
reference to an event handler list. This is useful since previously all
invokers o

Introduce EVENTHANDLER_LIST and some users.

This introduces a facility to EVENTHANDLER(9) for explicitly defining a
reference to an event handler list. This is useful since previously all
invokers of events had to do a locked traversal of the global list of
event handler lists in order to find the appropriate event handler list.
By keeping a pointer to the appropriate list an invoker can avoid this
traversal completely. The pointer is initialized with SYSINIT(9) during
the eventhandler stage. Users registering interest in events do not need
to know if the event is backed by such a list, since the list is added
to the global list of lists. As with lists that are not pre-defined it
is safe to register for the events before the list has been created.

This converts the process_* and thread_* events to using the new
facility, as these are events whose locked traversals end up showing up
significantly in ports build workflows (and presumably other workflows
with many short lived threads/procs). It may be advantageous to convert
other events to using the new facility.

The el_flags field is now unused, but leave it be so that this revision
can be MFC'd.

Reviewed by: bdrewery, markj, mjg
Approved by: rstone (mentor)
In collaboration with: ian
MFC after: 4 weeks
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D12814

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MFhead@r323635

MFH @ r323558.

If the user tries to set kern.randompid to 1 (which is meaningless), set
it to a random value between 100 and 1123, rather than 0 as before.

Submitted by: Marie Helene Kvello-Aune <marieheleneka@gma

If the user tries to set kern.randompid to 1 (which is meaningless), set
it to a random value between 100 and 1123, rather than 0 as before.

Submitted by: Marie Helene Kvello-Aune <marieheleneka@gmail.com>
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D5336

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Merge ^/head r319801 through r320041.

Move struct syscall_args syscall arguments parameters container into
struct thread.

For all architectures, the syscall trap handlers have to allocate the
structure on the stack. The structure takes

Move struct syscall_args syscall arguments parameters container into
struct thread.

For all architectures, the syscall trap handlers have to allocate the
structure on the stack. The structure takes 88 bytes on 64bit arches
which is not negligible. Also, it cannot be easily found by other
code, which e.g. caused duplication of some members of the structure
to struct thread already. The change removes td_dbg_sc_code and
td_dbg_sc_nargs which were directly copied from syscall_args.

The structure is put into the copied on fork part of the struct thread
to make the syscall arguments information correct in the child after
fork.

This move will also allow several more uses shortly.

Reviewed by: jhb (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
X-Differential revision: https://reviews.freebsd.org/D11080

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Merge ^/head r316992 through r317215.

- Remove 'struct vmmeter' from 'struct pcpu', leaving only global vmmeter
in place. To do per-cpu stats, convert all fields that previously were
maintained in the vmmeters that sit in pcpus to c

- Remove 'struct vmmeter' from 'struct pcpu', leaving only global vmmeter
in place. To do per-cpu stats, convert all fields that previously were
maintained in the vmmeters that sit in pcpus to counter(9).
- Since some vmmeter stats may be touched at very early stages of boot,
before we have set up UMA and we can do counter_u64_alloc(), provide an
early counter mechanism:
o Leave one spare uint64_t in struct pcpu, named pc_early_dummy_counter.
o Point counter(9) fields of vmmeter to pcpu[0].pc_early_dummy_counter,
so that at early stages of boot, before counters are allocated we already
point to a counter that can be safely written to.
o For sparc64 that required a whole dummy pcpu[MAXCPU] array.

Further related changes:
- Don't include vmmeter.h into pcpu.h.
- vm.stats.vm.v_swappgsout and vm.stats.vm.v_swappgsin changed to 64-bit,
to match kernel representation.
- struct vmmeter hidden under _KERNEL, and only vmstat(1) is an exclusion.

This is based on benno@'s 4-year old patch:
https://lists.freebsd.org/pipermail/freebsd-arch/2013-July/014471.html

Reviewed by: kib, gallatin, marius, lidl
Differential Revision: https://reviews.freebsd.org/D10156

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