Joel Fernandes (Google) b53b0b9d9a pidfd: add polling support ... This patch adds polling support to pidfd. Android low memory killer (LMK) needs to know when a process dies once it is sent the kill signal. It does so by checking for the existence of /proc/pid which is both racy and slow. For example, if a PID is reused between when LMK sends a kill signal and checks for existence of the PID, since the wrong PID is now possibly checked for existence. Using the polling support, LMK will be able to get notified when a process exists in race-free and fast way, and allows the LMK to do other things (such as by polling on other fds) while awaiting the process being killed to die. For notification to polling processes, we follow the same existing mechanism in the kernel used when the parent of the task group is to be notified of a child's death (do_notify_parent). This is precisely when the tasks waiting on a poll of pidfd are also awakened in this patch. We have decided to include the waitqueue in struct pid for the following reasons: 1. The wait queue has to survive for the lifetime of the poll. Including it in task_struct would not be option in this case because the task can be reaped and destroyed before the poll returns. 2. By including the struct pid for the waitqueue means that during de_thread(), the new thread group leader automatically gets the new waitqueue/pid even though its task_struct is different. Appropriate test cases are added in the second patch to provide coverage of all the cases the patch is handling. Cc: Andy Lutomirski <luto@amacapital.net> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Daniel Colascione <dancol@google.com> Cc: Jann Horn <jannh@google.com> Cc: Tim Murray <timmurray@google.com> Cc: Jonathan Kowalski <bl0pbl33p@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Kees Cook <keescook@chromium.org> Cc: David Howells <dhowells@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: kernel-team@android.com Reviewed-by: Oleg Nesterov <oleg@redhat.com> Co-developed-by: Daniel Colascione <dancol@google.com> Signed-off-by: Daniel Colascione <dancol@google.com> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Christian Brauner <christian@brauner.io>		2019-06-28 12:17:55 +02:00
..
bpf	bpf: fix undefined behavior in narrow load handling	2019-05-13 02:05:50 +02:00
cgroup	kernel/sched/psi.c: expose pressure metrics on root cgroup	2019-05-14 19:52:48 -07:00
configs	kvm_config: add CONFIG_VIRTIO_MENU	2018-10-24 20:55:56 -04:00
debug	kdb: Fix bound check compiler warning	2019-05-14 13:44:24 +01:00
dma	DMA mapping updates for 5.2	2019-05-09 08:40:55 -07:00
events	mm/mmu_notifier: use correct mmu_notifier events for each invalidation	2019-05-14 09:47:49 -07:00
gcov	gcov: clang support	2019-05-14 19:52:51 -07:00
irq	Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2019-05-19 10:58:45 -07:00
livepatch	The major changes in this tracing update includes:	2019-05-15 16:05:47 -07:00
locking	locking/rwsem: Prevent decrement of reader count before increment	2019-05-07 08:46:46 +02:00
power	Power management updates for 5.2-rc1	2019-05-06 19:40:31 -07:00
printk	panic: add an option to replay all the printk message in buffer	2019-05-18 15:52:26 -07:00
rcu	The major changes in this tracing update includes:	2019-05-15 16:05:47 -07:00
sched	kernel/sched/psi.c: expose pressure metrics on root cgroup	2019-05-14 19:52:48 -07:00
time	Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2019-05-16 11:00:20 -07:00
trace	The major changes in this tracing update includes:	2019-05-15 16:05:47 -07:00
.gitignore	Provide in-kernel headers to make extending kernel easier	2019-04-29 16:48:03 +02:00
Kconfig.freezer	…
Kconfig.hz	…
Kconfig.locks	Remove Mysterious Macro Intended to Obscure Weird Behaviours (mmiowb())	2019-05-06 16:57:52 -07:00
Kconfig.preempt	kconfig: warn no new line at end of file	2018-12-15 17:44:35 +09:00
Makefile	kernel/Makefile: don't assume that kernel/gen_ikh_data.sh is executable	2019-05-14 19:52:47 -07:00
acct.c	acct_on(): don't mess with freeze protection	2019-04-04 21:04:13 -04:00
async.c	treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively	2019-04-09 14:19:06 +02:00
audit.c	audit: connect LOGIN record to its syscall record	2019-03-20 20:57:48 -04:00
audit.h	audit_compare_dname_path(): switch to const struct qstr *	2019-04-28 20:33:43 -04:00
audit_fsnotify.c	audit_compare_dname_path(): switch to const struct qstr *	2019-04-28 20:33:43 -04:00
audit_tree.c	fsnotify: switch send_to_group() and ->handle_event to const struct qstr *	2019-04-26 13:51:03 -04:00
audit_watch.c	audit_compare_dname_path(): switch to const struct qstr *	2019-04-28 20:33:43 -04:00
auditfilter.c	Merge branch 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2019-05-07 20:03:32 -07:00
auditsc.c	Merge branch 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2019-05-07 20:03:32 -07:00
backtracetest.c	backtrace-test: Simplify stack trace handling	2019-04-29 12:37:47 +02:00
bounds.c	kbuild: fix kernel/bounds.c 'W=1' warning	2018-10-31 08:54:14 -07:00
capability.c	LSM: add SafeSetID module that gates setid calls	2019-01-25 11:22:43 -08:00
compat.c	kernel/compat.c: mark expected switch fall-throughs	2019-05-15 08:16:14 -07:00
configs.c	kernel/configs: use .incbin directive to embed config_data.gz	2019-03-07 18:32:02 -08:00
context_tracking.c	…
cpu.c	Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2019-05-06 14:50:46 -07:00
cpu_pm.c	…
crash_core.c	kexec: export PG_offline to VMCOREINFO	2019-03-05 21:07:14 -08:00
crash_dump.c	…
cred.c	SELinux: Remove cred security blob poisoning	2019-01-08 13:18:44 -08:00
delayacct.c	delayacct: track delays from thrashing cache pages	2018-10-26 16:26:32 -07:00
dma.c	…
elfcore.c	…
exec_domain.c	…
exit.c	mm: change mm_update_next_owner() to update mm->owner with WRITE_ONCE	2019-05-14 19:52:47 -07:00
extable.c	…
fail_function.c	treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively	2019-04-09 14:19:06 +02:00
fork.c	pidfd: add polling support	2019-06-28 12:17:55 +02:00
freezer.c	…
futex.c	mm/gup: change GUP fast to use flags rather than a write 'bool'	2019-05-14 09:47:46 -07:00
gen_ikh_data.sh	Provide in-kernel headers to make extending kernel easier	2019-04-29 16:48:03 +02:00
groups.c	…
hung_task.c	kernel/hung_task.c: Use continuously blocked time when reporting.	2019-03-07 18:31:59 -08:00
iomem.c	mm/resource: Use resource_overlaps() to simplify region_intersects()	2019-04-19 12:59:36 +02:00
irq_work.c	irq_work: Do not raise an IPI when queueing work on the local CPU	2019-04-18 14:07:52 +02:00
jump_label.c	locking/static_key: Don't take sleeping locks in __static_key_slow_dec_deferred()	2019-04-29 08:29:21 +02:00
kallsyms.c	bpf: Add module name [bpf] to ksymbols for bpf programs	2019-01-21 17:38:56 -03:00
kcmp.c	…
kcov.c	kcov: convert kcov.refcount to refcount_t	2019-03-07 18:32:02 -08:00
kexec.c	…
kexec_core.c	power/suspend: Add function to disable secondaries for suspend	2019-05-03 19:42:41 +02:00
kexec_file.c	mm: memblock: make keeping memblock memory opt-in rather than opt-out	2019-05-14 09:47:50 -07:00
kexec_internal.h	…
kheaders.c	Provide in-kernel headers to make extending kernel easier	2019-04-29 16:48:03 +02:00
kmod.c	…
kprobes.c	kprobes: Fix error check when reusing optimized probes	2019-04-16 09:38:16 +02:00
ksysfs.c	…
kthread.c	include/: refactor headers to allow kthread.h inclusion in psi_types.h	2019-05-14 19:52:48 -07:00
latencytop.c	kernel/latencytop.c: rename clear_all_latency_tracing to clear_tsk_latency_tracing	2019-05-14 19:52:49 -07:00
memremap.c	kernel/memremap.c: remove the unused device_private_entry_fault() export	2019-05-14 09:47:51 -07:00
module-internal.h	kallsyms: store type information in its own array	2019-03-28 15:00:37 +01:00
module.c	Modules updates for v5.2	2019-05-14 10:55:54 -07:00
module_signing.c	modsign: use all trusted keys to verify module signature	2018-11-07 14:41:41 +01:00
notifier.c	kernel/notifier.c: double register detection	2019-05-14 19:52:49 -07:00
nsproxy.c	…
padata.c	padata: Replace padata_attr_type default_attrs field with groups	2019-04-25 22:06:11 +02:00
panic.c	panic: add an option to replay all the printk message in buffer	2019-05-18 15:52:26 -07:00
params.c	…
pid.c	pidfd: add polling support	2019-06-28 12:17:55 +02:00
pid_namespace.c	signal: Use group_send_sig_info to kill all processes in a pid namespace	2018-09-16 16:08:25 +02:00
profile.c	mm: remove include/linux/bootmem.h	2018-10-31 08:54:16 -07:00
ptrace.c	ptrace: take into account saved_sigmask in PTRACE{GET,SET}SIGMASK	2019-03-29 10:01:37 -07:00
range.c	…
reboot.c	panic/reboot: allow specifying reboot_mode for panic only	2019-05-14 19:52:51 -07:00
relay.c	Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2019-03-12 13:27:20 -07:00
resource.c	mm/resource: Use resource_overlaps() to simplify region_intersects()	2019-04-19 12:59:36 +02:00
rseq.c	rseq: Remove superfluous rseq_len from task_struct	2019-04-19 12:39:32 +02:00
seccomp.c	audit/stable-5.2 PR 20190507	2019-05-07 19:06:04 -07:00
signal.c	pidfd: add polling support	2019-06-28 12:17:55 +02:00
smp.c	cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM	2019-01-30 19:27:00 +01:00
smpboot.c	…
smpboot.h	…
softirq.c	softirq: Remove tasklet_hrtimer	2019-03-22 14:36:02 +01:00
stackleak.c	stackleak: Mark stackleak_track_stack() as notrace	2018-12-05 19:31:44 -08:00
stacktrace.c	stacktrace: Provide common infrastructure	2019-04-29 12:37:57 +02:00
stop_machine.c	treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively	2019-04-09 14:19:06 +02:00
sys.c	kernel/sys.c: prctl: fix false positive in validate_prctl_map()	2019-05-14 09:47:44 -07:00
sys_ni.c	signal: support CLONE_PIDFD with pidfd_send_signal	2019-05-07 14:31:03 +02:00
sysctl.c	kernel/sysctl.c: fix proc_do_large_bitmap for large input buffers	2019-05-14 19:52:51 -07:00
sysctl_binary.c	kernel/sysctl: add panic_print into sysctl	2019-01-04 13:13:47 -08:00
task_work.c	…
taskstats.c	genetlink: optionally validate strictly/dumps	2019-04-27 17:07:22 -04:00
test_kprobes.c	…
torture.c	torture: Don't try to offline the last CPU	2019-03-26 14:42:53 -07:00
tracepoint.c	tracing: Replace synchronize_sched() and call_rcu_sched()	2018-11-27 09:21:41 -08:00
tsacct.c	…
ucount.c	…
uid16.c	…
uid16.h	…
umh.c	umh: add exit routine for UMH process	2019-01-11 18:05:40 -08:00
up.c	smp,cpumask: introduce on_each_cpu_cond_mask	2018-10-09 16:51:11 +02:00
user-return-notifier.c	…
user.c	kernel/user.c: clean up some leftover code	2019-05-14 19:52:49 -07:00
user_namespace.c	userns: also map extents in the reverse map to kernel IDs	2018-11-07 23:51:16 -06:00
utsname.c	…
utsname_sysctl.c	…
watchdog.c	watchdog: Fix typo in comment	2019-04-18 14:05:51 +02:00
watchdog_hld.c	kernel/watchdog_hld.c: hard lockup message should end with a newline	2019-04-19 09:46:05 -07:00
workqueue.c	Merge branch 'for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq	2019-05-09 13:48:52 -07:00
workqueue_internal.h	sched/core, workqueues: Distangle worker accounting from rq lock	2019-04-16 16:55:15 +02:00