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| author | Karl Mehltretter <kmehltretter@gmail.com> | 2026-07-24 08:05:31 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@armlinux.org.uk> | 2026-08-05 16:14:44 +0100 |
| commit | 8a58a41100ea377e978d99600ec24a9bd0273662 (patch) | |
| tree | 5b3d2d4917b602747ca9a3d00884d322b709c68d | |
| parent | 8ed9bff906cf8036531d1559f10e82733a52b41f (diff) | |
| download | linux-8a58a41100ea377e978d99600ec24a9bd0273662.tar.gz linux-8a58a41100ea377e978d99600ec24a9bd0273662.zip | |
ARM: 9483/1: select HAVE_POSIX_CPU_TIMERS_TASK_WORK
Commit c6e61c06d606 ("ARM: 9463/1: Allow to enable RT") enabled PREEMPT_RT
on ARM but did not select HAVE_POSIX_CPU_TIMERS_TASK_WORK. This leaves
CONFIG_POSIX_CPU_TIMERS_TASK_WORK disabled, so CPU timers expire in hard
IRQ context.
On PREEMPT_RT this makes run_posix_cpu_timers() take the sleeping
sighand->siglock:
BUG: sleeping function called from invalid context at spinlock_rt.c:48
rt_spin_lock from lock_task_sighand
lock_task_sighand from run_posix_cpu_timers
run_posix_cpu_timers from update_process_times
ARM handles TIF_NOTIFY_RESUME on all return-to-user paths, including v7-M.
ARM32 KVM host support was removed by commit 541ad0150ca4 ("arm: Remove
32bit KVM host support"), so the select need not be conditional on KVM.
Select it to defer POSIX CPU timer expiry to task context.
Reproduced with setrlimit(RLIMIT_CPU, ...) and a busy loop. The same path
is used by setitimer(ITIMER_PROF or ITIMER_VIRTUAL) and POSIX CPU timers
created with timer_create().
Assisted-by: Claude:claude-fable-5
Fixes: c6e61c06d606 ("ARM: 9463/1: Allow to enable RT")
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
| -rw-r--r-- | arch/arm/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index b8aa3fcce107..bcb53bc9b931 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -133,6 +133,7 @@ config ARM select HAVE_PERF_EVENTS select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP + select HAVE_POSIX_CPU_TIMERS_TASK_WORK select MMU_GATHER_RCU_TABLE_FREE if SMP && ARM_LPAE select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_RSEQ |