Will Deacon
8682c2e2cc
locking/futex: Allow low-level atomic operations to return -EAGAIN ...
commit 6b4f4bc9cb22875f97023984a625386f0c7cc1c0 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>
[bwh: Backported to 4.9: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-30 14:41:42 +02:00
bpf: Check for integer overflow when using roundup_pow_of_two()
2021-02-23 13:59:16 +01:00
config: android: enable CONFIG_SECCOMP
2016-10-11 15:06:32 -07:00
kdb: Make memory allocations more robust
2021-03-03 17:44:31 +01:00
perf/core: Fix race in the perf_mmap_close() function
2020-11-18 18:26:31 +01:00
gcov: add support for GCC 10.1
2020-09-23 08:46:14 +02:00
genirq: Disable interrupts for force threaded handlers
2021-03-24 10:59:26 +01:00
livepatch/module: make TAINT_LIVEPATCH module-specific
2016-08-26 14:42:08 +02:00
futex: Handle early deadlock return correctly
2021-03-30 14:41:42 +02:00
PM: hibernate: remove the bogus call to get_gendisk() in software_resume()
2020-10-29 09:05:43 +01:00
printk: fix deadlock when kernel panic
2021-03-07 11:25:56 +01:00
rcuperf: Fix cleanup path for invalid perf_type strings
2019-05-31 06:48:30 -07:00
sched/fair: handle case of task_h_load() returning 0
2020-07-22 09:10:54 +02:00
kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data()
2021-03-24 10:59:25 +01:00
tracing: Check length before giving out the filter buffer
2021-02-23 13:59:15 +01:00
kernel/acct.c: fix the acct->needcheck check in check_free_space()
2018-01-10 09:29:51 +01:00
kernel/async.c: revert "async: simplify lowest_in_progress()"
2018-02-17 13:21:18 +01:00
audit: check the length of userspace generated audit records
2020-05-02 17:23:12 +02:00
Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit
2016-07-29 17:54:17 -07:00
audit: CONFIG_CHANGE don't log internal bookkeeping as an event
2020-10-01 20:40:07 +02:00
audit: fix error handling in audit_data_to_entry()
2020-03-11 07:53:05 +01:00
audit: print empty EXECVE args
2019-11-28 18:28:55 +01:00
kbuild: fix kernel/bounds.c 'W=1' warning
2018-11-13 11:16:57 -08:00
ptrace: Capture the ptracer's creds not PT_PTRACE_CAP
2017-01-06 10:40:13 +01:00
cgroup: add missing skcd->no_refcnt check in cgroup_sk_clone()
2020-08-21 11:01:56 +02:00
cgroup: pids: use atomic64_t for pids->limit
2019-12-21 10:42:02 +01:00
kernel/cpu: add arch override for clear_tasks_mm_cpumask() mm handling
2020-12-29 13:44:50 +01:00
kernel/cpu_pm: Fix uninitted local in cpu_pm
2020-06-20 10:24:21 +02:00
sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs
2017-10-12 11:51:25 +02:00
memcg: account security cred as well to kmemcg
2020-01-12 11:24:13 +01:00
futex: Mark the begin of futex exit explicitly
2021-02-03 23:19:49 +01:00
kernel/extable.c: mark core_kernel_text notrace
2017-07-21 07:42:21 +02:00
futex: Split futex_mm_release() for exit/exec
2021-02-03 23:19:49 +01:00
freezer, oom: check TIF_MEMDIE on the correct task
2016-07-28 16:07:41 -07:00
locking/futex: Allow low-level atomic operations to return -EAGAIN
2021-03-30 14:41:42 +02:00
kernel: make groups_sort calling a responsibility group_info allocators
2018-01-10 09:29:52 +01:00
kernel: hung_task.c: disable on suspend
2019-04-20 09:07:52 +02:00
jump_label: Invoke jump_label_test() via early_initcall()
2017-12-14 09:28:24 +01:00
kcov: ensure irq code sees a valid area
2018-08-03 07:55:12 +02:00
kexec: allow architectures to override boot mapping
2016-08-02 19:35:27 -04:00
objtool, x86: Add several functions and files to the objtool whitelist
2018-06-05 10:28:57 +02:00
kexec: fix double-free when failing to relocate the purgatory
2016-09-01 17:52:01 -07:00
usermodehelper: reset umask to default before executing user process
2020-10-14 09:48:14 +02:00
kretprobe: Avoid re-registration of the same kretprobe earlier
2021-02-10 09:09:25 +01:00
kexec: add a kexec_crash_loaded() function
2016-08-02 19:35:30 -04:00
kthread_worker: prevent queuing delayed work from timer_fn when it is being canceled
2020-11-10 10:24:02 +01:00
elfcore: fix building with clang
2021-02-10 09:09:25 +01:00
Fix: Disable sys_membarrier when nohz_full is enabled
2017-03-12 06:41:45 +01:00
mm, devm_memremap_pages: kill mapping "System RAM" support
2019-01-13 10:03:51 +01:00
module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols
2021-03-03 17:44:44 +01:00
x86/mm: split vmalloc_sync_all()
2020-04-02 17:20:26 +02:00
padata: purge get_cpu and reorder_via_wq from padata_do_serial
2020-05-27 16:41:53 +02:00
panic: ensure preemption is disabled during panic()
2019-10-17 13:42:25 -07:00
pidns: disable pid allocation if pid_ns_prepare_proc() is failed in alloc_pid()
2018-04-13 19:47:53 +02:00
signal/pid_namespace: Fix reboot_pid_ns to use send_sig not force_sig
2019-08-04 09:33:16 +02:00
profile: Convert to hotplug state machine
2016-07-15 10:41:42 +02:00
ptrace: Fix ->ptracer_cred handling for PTRACE_TRACEME
2019-07-10 09:55:45 +02:00
reboot: fix overflow parsing reboot cpu number
2020-11-18 18:26:32 +01:00
kernel/relay.c: fix memleak on destroy relay channel
2020-08-26 10:29:03 +02:00
resource: fix integer overflow at reallocation
2018-04-24 09:34:09 +02:00
seccomp: Add missing return in non-void function
2021-03-03 17:44:43 +01:00
signal: Extend exec_id to 64bits
2020-04-24 07:58:54 +02:00
cpu/hotplug: Fix SMT supported evaluation
2018-08-15 18:14:53 +02:00
kthread/smpboot: do not park in kthread_create_on_cpu()
2016-10-11 15:06:33 -07:00
Mark HI and TASKLET softirq synchronous
2018-08-15 18:14:42 +02:00
stacktrace, lockdep: Fix address, newline ugliness
2017-02-14 15:25:42 -08:00
stop_machine: Use raw spinlocks
2018-08-03 07:55:24 +02:00
kernel/sys.c: avoid copying possible padding bytes in copy_to_user
2020-10-01 20:40:04 +02:00
x86/pkeys: Fix pkeys build breakage for some non-x86 arches
2016-09-13 14:41:36 +02:00
sched/rt: Show the 'sched_rr_timeslice' SCHED_RR timeslice tuning knob in milliseconds
2020-07-09 09:35:55 +02:00
kernel/sysctl_binary.c: use generic UUID library
2016-05-20 17:58:30 -07:00
task_work: use READ_ONCE/lockless_dereference, avoid pi_lock if !task_works
2016-08-02 19:35:02 -04:00
taskstats: fix data-race
2020-01-12 11:24:12 +01:00
torture: Convert torture_shutdown() to hrtimer
2016-08-22 10:01:49 -07:00
tracepoint: Do not fail unregistering a probe due to memory failure
2021-03-03 17:44:38 +01:00
kernel/ucount.c: mark user_header with kmemleak_ignore()
2017-06-17 06:41:51 +02:00
kernel: make groups_sort calling a responsibility group_info allocators
2018-01-10 09:29:52 +01:00
smp: Add function to execute a function synchronously on a CPU
2016-09-05 13:52:39 +02:00
userns: move user access out of the mutex
2018-09-09 20:01:24 +02:00
Merge branch 'nsfs-ioctls' into HEAD
2016-09-22 20:00:36 -05:00
sys: don't hold uts_sem while accessing userspace memory
2018-09-09 20:01:24 +02:00
kernel/watchdog: prevent false hardlockup on overloaded system
2017-06-17 06:41:57 +02:00
kernel/watchdog: prevent false hardlockup on overloaded system
2017-06-17 06:41:57 +02:00
workqueue: Kick a worker based on the actual activation of delayed works
2021-01-12 19:49:01 +01:00
workqueue: Fix NULL pointer dereference
2017-11-15 15:53:17 +01:00
8682c2e2cc