Will Deacon d2045151af locking/futex: Allow low-level atomic operations to return -EAGAIN ... commit 6b4f4bc9cb upstream. Some futex() operations, including FUTEX_WAKE_OP, require the kernel to perform an atomic read-modify-write of the futex word via the userspace mapping. These operations are implemented by each architecture in arch_futex_atomic_op_inuser() and futex_atomic_cmpxchg_inatomic(), which are called in atomic context with the relevant hash bucket locks held. Although these routines may return -EFAULT in response to a page fault generated when accessing userspace, they are expected to succeed (i.e. return 0) in all other cases. This poses a problem for architectures that do not provide bounded forward progress guarantees or fairness of contended atomic operations and can lead to starvation in some cases. In these problematic scenarios, we must return back to the core futex code so that we can drop the hash bucket locks and reschedule if necessary, much like we do in the case of a page fault. Allow architectures to return -EAGAIN from their implementations of arch_futex_atomic_op_inuser() and futex_atomic_cmpxchg_inatomic(), which will cause the core futex code to reschedule if necessary and return back to the architecture code later on. Cc: <stable@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2019-05-10 17:53:15 +02:00
..
bpf	bpf: fix sanitation rewrite in case of non-pointers	2019-04-20 09:15:09 +02:00
cgroup	cgroup/pids: turn cgroup_subsys->free() into cgroup_subsys->release() to fix the accounting	2019-04-05 22:31:37 +02:00
configs	ANDROID: binder: add hwbinder,vndbinder to BINDER_DEVICES.	2017-08-22 18:43:23 -07:00
debug	kdb: Don't back trace on a cpu that didn't round up	2019-02-12 19:46:09 +01:00
events	perf/core: Restore mmap record type correctly	2019-04-20 09:14:59 +02:00
gcov	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
irq	genirq: Prevent use-after-free and work list corruption	2019-05-10 17:53:13 +02:00
livepatch	livepatch: Validate module/old func name length	2018-09-09 19:55:58 +02:00
locking	Revert "locking/lockdep: Add debug_locks check in __lock_downgrade()"	2019-04-27 09:35:42 +02:00
power	PM / sleep: wakeup: Fix build error caused by missing SRCU support	2018-09-09 19:55:58 +02:00
printk	printk: Wake klogd when passing console_lock owner	2018-12-17 09:28:55 +01:00
rcu	rcu: Do RCU GP kthread self-wakeup from softirq and interrupt	2019-03-23 14:35:30 +01:00
sched	sched/deadline: Correctly handle active 0-lag timers	2019-05-02 09:40:32 +02:00
time	alarmtimer: Return correct remaining time	2019-04-17 08:37:52 +02:00
trace	fs: prevent page refcount overflow in pipe_buf_get	2019-05-04 09:15:18 +02:00
.gitignore
acct.c	kernel/acct.c: fix the acct->needcheck check in check_free_space()	2018-01-10 09:31:17 +01:00
async.c	kernel/async.c: revert "async: simplify lowest_in_progress()"	2018-02-16 20:23:05 +01:00
audit.c	audit: return on memory error to avoid null pointer dereference	2018-05-30 07:52:39 +02:00
audit.h	ipc: mqueue: Replace timespec with timespec64	2017-09-03 20:21:24 -04:00
audit_fsnotify.c
audit_tree.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
audit_watch.c	audit: fix use-after-free in audit_add_watch	2018-09-26 08:38:09 +02:00
auditfilter.c	audit: allow not equal op for audit by executable	2018-08-03 07:50:39 +02:00
auditsc.c	audit: fix potential null dereference 'context->module.name'	2018-08-06 16:20:49 +02:00
backtracetest.c
bounds.c	kbuild: fix kernel/bounds.c 'W=1' warning	2018-11-13 11:15:08 -08:00
capability.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
compat.c	compat: fix 4-byte infoleak via uninitialized struct field	2018-05-16 10:10:26 +02:00
configs.c
context_tracking.c
cpu.c	cpu/hotplug: Mute hotplug lockdep during init	2019-04-05 22:31:38 +02:00
cpu_pm.c
crash_core.c	kdump: write correct address of mem_section into vmcoreinfo	2018-01-17 09:45:27 +01:00
crash_dump.c
cred.c
delayacct.c	delayacct: Use raw_spinlocks	2018-08-03 07:50:38 +02:00
dma.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
elfcore.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
exec_domain.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
exit.c	cgroup/pids: turn cgroup_subsys->free() into cgroup_subsys->release() to fix the accounting	2019-04-05 22:31:37 +02:00
extable.c	extable: Enable RCU if it is not watching in kernel_text_address()	2017-09-23 16:50:20 -04:00
fork.c	fork: record start_time late	2019-01-13 10:01:02 +01:00
freezer.c
futex.c	locking/futex: Allow low-level atomic operations to return -EAGAIN	2019-05-10 17:53:15 +02:00
futex_compat.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
groups.c	kernel: make groups_sort calling a responsibility group_info allocators	2017-12-20 10:10:18 +01:00
hung_task.c	kernel: hung_task.c: disable on suspend	2019-04-20 09:15:05 +02:00
irq_work.c
jump_label.c	sched/core: Fix cpu.max vs. cpuhotplug deadlock	2018-12-05 19:41:17 +01:00
kallsyms.c
kcmp.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c	kcov: ensure irq code sees a valid area	2018-08-03 07:50:22 +02:00
kexec.c
kexec_core.c
kexec_file.c
kexec_internal.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
kmod.c	kmod: move #ifdef CONFIG_MODULES wrapper to Makefile	2017-09-08 18:26:51 -07:00
kprobes.c	kprobes: Fix error check when reusing optimized probes	2019-04-27 09:35:38 +02:00
ksysfs.c
kthread.c	kthread, tracing: Don't expose half-written comm when creating kthreads	2018-08-03 07:50:21 +02:00
latencytop.c
Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
memremap.c	mm, devm_memremap_pages: kill mapping "System RAM" support	2019-01-13 10:01:02 +01:00
module-internal.h
module.c	kobject: return error code if writing /sys/.../uevent fails	2019-02-12 19:46:02 +01:00
module_signing.c
notifier.c
nsproxy.c
padata.c
panic.c	panic: avoid deadlocks in re-entrant console drivers	2018-12-29 13:39:10 +01:00
params.c	kernel/params.c: improve STANDARD_PARAM_DEF readability	2017-10-03 17:54:26 -07:00
pid.c	pids: make task_tgid_nr_ns() safe	2017-08-21 12:47:31 -07:00
pid_namespace.c
profile.c
ptrace.c	ptrace: take into account saved_sigmask in PTRACE{GET,SET}SIGMASK	2019-05-04 09:15:22 +02:00
range.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
reboot.c
relay.c	relay: check return of create_buf_file() properly	2019-03-13 14:03:20 -07:00
resource.c	resource: fix integer overflow at reallocation	2018-04-24 09:36:22 +02:00
seccomp.c	seccomp: Move speculation migitation control to arch code	2018-05-22 18:54:04 +02:00
signal.c	signal: Restore the stop PTRACE_EVENT_EXIT	2019-02-20 10:20:54 +01:00
smp.c	cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM	2019-02-12 19:46:13 +01:00
smpboot.c	watchdog/core, powerpc: Lock cpus across reconfiguration	2017-10-04 10:53:54 +02:00
smpboot.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
softirq.c	Mark HI and TASKLET softirq synchronous	2018-08-15 18:12:47 +02:00
stacktrace.c
stop_machine.c	stop_machine: Atomically queue and wake stopper threads	2018-09-05 09:26:36 +02:00
sys.c	sys: don't hold uts_sem while accessing userspace memory	2018-09-09 19:56:00 +02:00
sys_ni.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
sysctl.c	kernel/sysctl.c: fix out-of-bounds access when setting file-max	2019-04-27 09:35:42 +02:00
sysctl_binary.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
task_work.c	locking/barriers: Convert users of lockless_dereference() to READ_ONCE()	2017-12-25 14:26:21 +01:00
taskstats.c
test_kprobes.c
torture.c
tracepoint.c	tracepoint: Do not warn on ENOMEM	2018-05-09 09:51:50 +02:00
tsacct.c
ucount.c
uid16.c	kernel: make groups_sort calling a responsibility group_info allocators	2017-12-20 10:10:18 +01:00
umh.c	kmod: split out umh code into its own file	2017-09-08 18:26:50 -07:00
up.c	smp: Avoid using two cache lines for struct call_single_data	2017-08-29 15:14:38 +02:00
user-return-notifier.c
user.c
user_namespace.c	userns: move user access out of the mutex	2018-09-09 19:56:00 +02:00
utsname.c
utsname_sysctl.c	sys: don't hold uts_sem while accessing userspace memory	2018-09-09 19:56:00 +02:00
watchdog.c	watchdog: Mark watchdog touch functions as notrace	2018-09-05 09:26:42 +02:00
watchdog_hld.c	watchdog: Mark watchdog touch functions as notrace	2018-09-05 09:26:42 +02:00
workqueue.c	watchdog: Mark watchdog touch functions as notrace	2018-09-05 09:26:42 +02:00
workqueue_internal.h	Merge branch 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq	2017-11-06 12:26:49 -08:00