killed by OOM. When killed process waits for a page allocation, try to
satisfy the request as fast as possible.
This removes the often encountered deadlock, where OOM continously
selects the same victim process, that sleeps uninterruptibly waiting
for a page. The killed process may still sleep if page cannot be
obtained immediately, but testing has shown that system has much
higher chance to survive in OOM situation with the patch.
In collaboration with: pho
Reviewed by: alc
MFC after: 4 weeks
Enhanced process coredump routines.
This brings in the following features:
1) Limit number of cores per process via the %I coredump formatter.
Example:
if corefilename is set to %N.%I.core AND num_cores = 3, then
if a process "rpd" cores, then the corefile will be named
"rpd.0.core", however if it cores again, then the kernel will
generate "rpd.1.core" until we hit the limit of "num_cores".
this is useful to get several corefiles, but also prevent filling
the machine with corefiles.
2) Encode machine hostname in core dump name via %H.
3) Compress coredumps, useful for embedded platforms with limited space.
A sysctl kern.compress_user_cores is made available if turned on.
To enable compressed coredumps, the following config options need to be set:
options COMPRESS_USER_CORES
device zlib # brings in the zlib requirements.
device gzio # brings in the kernel vnode gzip output module.
4) Eventhandlers are fired to indicate coredumps in progress.
5) The imgact sv_coredump routine has grown a flag to pass in more
state, currently this is used only for passing a flag down to compress
the coredump or not.
Note that the gzio facility can be used for generic output of gzip'd
streams via vnodes.
Obtained from: Juniper Networks
Reviewed by: kan
stopped and debugger may modify or drop the signal. After the changes to
keep process-targeted signals on the process sigqueue, another thread
may note the old signal on the queue and act before the thread removes
changed or dropped signal from the process queue. Since process is
traced, it usually gets stopped. Or, if the same signal is delivered
while process was stopped, the thread may erronously remove it,
intending to remove the original signal.
Remove the signal from the queue before notifying the debugger. Restore
the siginfo to the head of sigqueue when signal is allowed to be
delivered to the debugee, using newly introduced KSI_HEAD ksiginfo_t
flag. This preserves required order of delivery. Always restore the
unchanged signal on the curthread sigqueue, not to the process queue,
since the thread is about to get it anyway, because sigmask cannot be
changed.
Handle failure of reinserting the siginfo into the queue by falling
back to sq_kill method, calling sigqueue_add with NULL ksi.
If debugger changed the signal to be delivered, use sigqueue_add()
with NULL ksi instead of only setting sq_signals bit.
Reported by: Gardner Bell <gbell72 rogers com>
Analyzed and first version of fix by: Tijl Coosemans <tijl coosemans org>
PR: 142757
Reviewed by: davidxu
MFC after: 2 weeks
to fail due to lack of resources to queue siginfo. Add KSI_SIGQ flag
that allows sigqueue_add() to fail while trying to allocate memory for
new siginfo. When the flag is not set, behaviour is the same as for
KSI_TRAP: if memory cannot be allocated, set bit in sq_kill. KSI_TRAP is
kept to preserve KBI.
Add SI_KERNEL si_code, to be used in siginfo.si_code when signal is
generated by kernel. Deliver siginfo when signal is generated by kill(2)
family of syscalls (SI_USER with properly filled si_uid and si_pid), or
by kernel (SI_KERNEL, mostly job control or SIGIO). Since KSI_SIGQ flag
is not set for the ksi, low memory condition cause old behaviour.
Keep psignal(9) KBI intact, but modify it to generate SI_KERNEL
si_code. Pgsignal(9) and gsignal(9) now take ksi explicitely. Add
pksignal(9) that behaves like psignal but takes ksi, and ddb kill
command implemented as pksignal(..., ksi = NULL) to not do allocation
while in debugger.
While there, remove some register specifiers and use ANSI C prototypes.
Reviewed by: davidxu
MFC after: 1 month
sure that a signal was delivered to the thread before returning from
syscall. Signal delivery puts new return frame on the user stack, and
modifies trap frame to enter signal handler. As a consequence, syscall
return code sets EINTR as error return for signal frame, instead of the
syscall return.
Also, for ia64, due to different registers layout for those two kind of
frames, usermode sigsegfaulted when returned from signal handler.
Use newly-introduced cpu_set_syscall_retval(9) to set syscall result,
and return EJUSTRETURN from kern_sigsuspend() to prevent syscall return
code from modifying this frame [1].
Another issue is that pending SIGCONT might be cancelled by SIGSTOP,
causing postsig() not to deliver any catched signal [2]. Modify
postsig() to return 1 if signal was posted, and 0 otherwise, and use
this in the kern_sigsuspend loop.
Proposed by: marcel [1]
Noted by: davidxu [2]
Reviewed by: marcel, davidxu
MFC after: 1 month
lock and curproc->p_sigacts->ps_mtx. Reschedule_signals may need to have
ps_mtx locked to decide and wakeup a thread, causing recursion on the
mutex.
Inform kern_sigprocmask() and reschedule_signals() about lock state
of the ps_mtx by new flag SIGPROCMASK_PS_LOCKED to avoid recursion.
Reported and tested by: keramida
MFC after: 1 month
while in kernel mode, and later changing signal mask to block the
signal, was fixed for sigprocmask(2) and ptread_exit(3). The same race
exists for sigreturn(2), setcontext(2) and swapcontext(2) syscalls.
Use kern_sigprocmask() instead of direct manipulation of td_sigmask to
reschedule newly blocked signals, closing the race.
Reviewed by: davidxu
Tested by: pho
MFC after: 1 month
kern_sigprocmask() to properly notify other possible candidate threads
for signal delivery.
Since sigsuspend() shall only return to usermode after a signal was
delivered, do cursig/postsig loop immediately after waiting for
signal, repeating the wait if wakeup was spurious due to race with
other thread fetching signal from the process queue before us. Add
thread_suspend_check() call to allow the thread to be stopped or killed
while in loop.
Modify last argument of kern_sigprocmask() from boolean to flags,
allowing the function to be called with locked proc. Convertion of the
callers that supplied 1 to the old argument will be done in the next
commit, and due to SIGPROCMASK_OLD value equial to 1, code is formally
correct in between.
Reviewed by: davidxu
Tested by: pho
MFC after: 1 month
not blocking the signal, signal is placed on the thread sigqueue. If
the selected thread is in kernel executing thr_exit() or sigprocmask()
syscalls, then signal might be not delivered to usermode for arbitrary
amount of time, and for exiting thread it is lost.
Put process-directed signals to the process queue unconditionally,
selecting the thread to deliver the signal only by the thread returning
to usermode, since only then the thread can handle delivery of signal
reliably. For exiting thread or thread that has blocked some signals,
check whether the newly blocked signal is queued for the process, and
try to find a thread to wakeup for delivery, in reschedule_signal(). For
exiting thread, assume that all signals are blocked.
Change cursig() and postsig() to look both into the thread and process
signal queues. When there is a signal that thread returning to usermode
could consume, TDF_NEEDSIGCHK flag is not neccessary set now. Do
unlocked read of p_siglist and p_pendingcnt to check for queued signals.
Note that thread that has a signal unblocked might get spurious wakeup
and EINTR from the interruptible system call now, due to the possibility
of being selected by reschedule_signals(), while other thread returned
to usermode earlier and removed the signal from process queue. This
should not cause compliance issues, since the thread has not blocked a
signal and thus should be ready to receive it anyway.
Reported by: Justin Teller <justin.teller gmail com>
Reviewed by: davidxu, jilles
MFC after: 1 month
PCATCH, to indicate that thread shall not be stopped upon receipt of
SIGSTOP until it reaches the kernel->usermode boundary.
Also change thread_single(SINGLE_NO_EXIT) to only stop threads at
the user boundary unconditionally.
Tested by: pho
Reviewed by: jhb
Approved by: re (kensmith)
specific macros for each audit argument type. This makes it easier to
follow call-graphs, especially for automated analysis tools (such as
fxr).
In MFC, we should leave the existing AUDIT_ARG() macros as they may be
used by third-party kernel modules.
Suggested by: brooks
Approved by: re (kib)
Obtained from: TrustedBSD Project
MFC after: 1 week
vn_open_cred invocations shall not audit namei path.
In particular, specify VN_OPEN_NOAUDIT for dotdot lookup performed by
default implementation of vop_vptocnp, and for the open done for core
file. vn_fullpath is called from the audit code, and vn_open there need
to disable audit to avoid infinite recursion. Core file is created on
return to user mode, that, in particular, happens during syscall return.
The creation of the core file is audited by direct calls, and we do not
want to overwrite audit information for syscall.
Reported, reviewed and tested by: rwatson
the removal of NQNFS, but was left in in case it was required for NFSv4.
Since our new NFSv4 client and server can't use it for their
requirements, GC the old mechanism, as well as other unused lease-
related code and interfaces.
Due to its impact on kernel programming and binary interfaces, this
change should not be MFC'd.
Proposed by: jeff
Reviewed by: jeff
Discussed with: rmacklem, zach loafman @ isilon
kern_time.c:
- Unused variable `p'.
kern_thr.c:
- Variable `error' is always caught immediately, so no reason to
initialize it. There is no way that error != 0 at the end of
create_thread().
kern_sig.c:
- Unused variable `code'.
kern_synch.c:
- `rval' is always assigned in all different cases.
kern_rwlock.c:
- `v' is always overwritten with RW_UNLOCKED further on.
kern_malloc.c:
- `size' is always initialized with the proper value before being used.
kern_exit.c:
- `error' is always caught and returned immediately. abort2() never
returns a non-zero value.
kern_exec.c:
- `len' is always assigned inside the if-statement right below it.
tty_info.c:
- `td' is always overwritten by FOREACH_THREAD_IN_PROC().
Found by: LLVM's scan-build
unnecessary, the normal process lock and thread lock are enough. The
spin lock is still needed for process and thread exiting to mimic
single sched_lock.
this eliminates some problems of locking, e.g, a thread lock is needed
but can not be used at that time. Only the process lock is needed now
for new field.
routine wakes up proc0 so that proc0 can swap the thread back in.
Historically, this has been done by waking up proc0 directly from
setrunnable() itself via a wakeup(). When waking up a sleeping thread
that was swapped out (the usual case when waking proc0 since only sleeping
threads are eligible to be swapped out), this resulted in a bit of
recursion (e.g. wakeup() -> setrunnable() -> wakeup()).
With sleep queues having separate locks in 6.x and later, this caused a
spin lock LOR (sleepq lock -> sched_lock/thread lock -> sleepq lock).
An attempt was made to fix this in 7.0 by making the proc0 wakeup use
the ithread mechanism for doing the wakeup. However, this required
grabbing proc0's thread lock to perform the wakeup. If proc0 was asleep
elsewhere in the kernel (e.g. waiting for disk I/O), then this degenerated
into the same LOR since the thread lock would be some other sleepq lock.
Fix this by deferring the wakeup of the swapper until after the sleepq
lock held by the upper layer has been locked. The setrunnable() routine
now returns a boolean value to indicate whether or not proc0 needs to be
woken up. The end result is that consumers of the sleepq API such as
*sleep/wakeup, condition variables, sx locks, and lockmgr, have to wakeup
proc0 if they get a non-zero return value from sleepq_abort(),
sleepq_broadcast(), or sleepq_signal().
Discussed with: jeff
Glanced at by: sam
Tested by: Jurgen Weber jurgen - ish com au
MFC after: 2 weeks
to enter thread_suspend_check().
- Set TDF_ASTPENDING along with TDF_NEEDSUSPCHK so we can move the
thread_suspend_check() to ast() rather than userret().
- Check TDF_NEEDSUSPCHK in the sleepq_catch_signals() optimization so
that we don't miss a suspend request. If this is set use the
expensive signal path.
- Set NEEDSUSPCHK when creating a new thread in thr in case the
creating thread is due to be suspended as well but has not yet.
Reviewed by: davidxu (Authored original patch)
requiring the per-process spinlock to only requiring the process lock.
- Reflect these changes in the proc.h documentation and consumers throughout
the kernel. This is a substantial reduction in locking cost for these
fields and was made possible by recent changes to threading support.
While the KSE project was quite successful in bringing threading to
FreeBSD, the M:N approach taken by the kse library was never developed
to its full potential. Backwards compatibility will be provided via
libmap.conf for dynamically linked binaries and static binaries will
be broken.
process lock leading to a hang. This bug was introduced in
kern_sig.c:1.351, when the call to expand_name() was moved earlier
bit this particular error case was not updated.
conjuction with 'thread' argument passing which is always curthread.
Remove the unuseful extra-argument and pass explicitly curthread to lower
layer functions, when necessary.
KPI results broken by this change, which should affect several ports, so
version bumping and manpage update will be further committed.
Tested by: kris, pho, Diego Sardina <siarodx at gmail dot com>
Remove this argument and pass curthread directly to underlying
VOP_LOCK1() VFS method. This modify makes the code cleaner and in
particular remove an annoying dependence helping next lockmgr() cleanup.
KPI results, obviously, changed.
Manpage and FreeBSD_version will be updated through further commits.
As a side note, would be valuable to say that next commits will address
a similar cleanup about VFS methods, in particular vop_lock1 and
vop_unlock.
Tested by: Diego Sardina <siarodx at gmail dot com>,
Andrea Di Pasquale <whyx dot it at gmail dot com>
silent NULL pointer dereference in the i386 and sparc64 pmap_pinit()
when the kmem_alloc_nofault() failed to allocate address space. Both
functions now return error instead of panicing or dereferencing NULL.
As consequence, vmspace_exec() and vmspace_unshare() returns the errno
int. struct vmspace arg was added to vm_forkproc() to avoid dealing
with failed allocation when most of the fork1() job is already done.
The kernel stack for the thread is now set up in the thread_alloc(),
that itself may return NULL. Also, allocation of the first process
thread is performed in the fork1() to properly deal with stack
allocation failure. proc_linkup() is separated into proc_linkup()
called from fork1(), and proc_linkup0(), that is used to set up the
kernel process (was known as swapper).
In collaboration with: Peter Holm
Reviewed by: jhb
This change introduces audit_proc_coredump() which is called by coredump(9)
to create an audit record for the coredump event. When a process
dumps a core, it could be security relevant. It could be an indicator that
a stack within the process has been overflowed with an incorrectly constructed
malicious payload or a number of other events.
The record that is generated looks like this:
header,111,10,process dumped core,0,Thu Oct 25 19:36:29 2007, + 179 msec
argument,0,0xb,signal
path,/usr/home/csjp/test.core
subject,csjp,csjp,staff,csjp,staff,1101,1095,50457,10.37.129.2
return,success,1
trailer,111
- We allocate a completely new record to make sure we arent clobbering
the audit data associated with the syscall that produced the core
(assuming the core is being generated in response to SIGABRT and not
an invalid memory access).
- Shuffle around expand_name() so we can use the coredump name at the very
beginning of the coredump call. Make sure we free the storage referenced
by "name" if we need to bail out early.
- Audit both successful and failed coredump creation efforts
Obtained from: TrustedBSD Project
Reviewed by: rwatson
MFC after: 1 month
audit it at the beginning of the syscall. This fixes a problem
where the user supplies an invalid process ID which is > 0 which
results in the PID argument not being audited.
Obtained from: TrustedBSD Project
MFC after: 1 week
- Use thread_lock() rather than sched_lock for per-thread scheduling
sychronization.
- Use the per-process spinlock rather than the sched_lock for per-process
scheduling synchronization.
- Move some common code into thread_suspend_switch() to handle the
mechanics of suspending a thread. The locking here is incredibly
convoluted and should be simplified.
Tested by: kris, current@
Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc.
Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
td_ru. This removes the requirement for per-process synchronization in
statclock() and mi_switch(). This was previously supported by
sched_lock which is going away. All modifications to rusage are now
done in the context of the owning thread. reads proceed without locks.
- Aggregate exiting threads rusage in thread_exit() such that the exiting
thread's rusage is not lost.
- Provide a new routine, rufetch() to fetch an aggregate of all rusage
structures from all threads in a process. This routine must be used
in any place requiring a rusage from a process prior to it's exit. The
exited process's rusage is still available via p_ru.
- Aggregate tick statistics only on demand via rufetch() or when a thread
exits. Tick statistics are kept in the thread and protected by sched_lock
until it exits.
Initial patch by: attilio
Reviewed by: attilio, bde (some objections), arch (mostly silent)
Change the VOP_OPEN(), vn_open() vnode operation and d_fdopen() cdev operation
argument from being file descriptor index into the pointer to struct file.
Proposed and reviewed by: jhb
Reviewed by: daichi (unionfs)
Approved by: re (kensmith)
- Remove also "MP SAFE" after prior "MPSAFE" pass. (suggested by bde)
- Remove extra blank lines in some cases.
- Add extra blank lines in some cases.
- Remove no-op comments consisting solely of the function name, the word
"syscall", or the system call name.
- Add punctuation.
- Re-wrap some comments.
system calls now enter without Giant held, and then in some cases, acquire
Giant explicitly.
Remove a number of other MPSAFE annotations in the credential code and
tweak one or two other adjacent comments.
