rseq: Prevent hard lockup on granted time slice extension

Browse source

__exit_to_user_mode_loop() invokes rseq_grant_timeslice_extension() with
interrupts enabled. If the extension is granted it invokes
hrtimer_rearm_deferred_tif() to ensure that a pending deferred hrtimer
rearm is handled before exiting to user space.

Though this invokes __hrtimer_rearm_deferred() which expects to be invoked
with interrupts disabled as it takes hrtimer_cpu_base::lock with
raw_spin_lock(). That's a livelock waiting to happen and caught by lockdep:

    WARNING: ./include/linux/hrtimer_rearm.h:17 at irqentry_exit, CPU#1: slice_test
    WARNING: inconsistent lock state
    inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.

Prevent this by disabling interrupts around the invocation of
hrtimer_rearm_deferred_tif() in rseq_grant_timeslice_extension().

[ tglx: Massaged change log ]

Fixes: 15dd3a9488 ("hrtimer: Push reprogramming timers into the interrupt return path")
Signed-off-by: Niels Pressel <npressel@ethz.ch>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260802124423.51616-1-npressel@ethz.ch

...

This commit is contained in:

Niels Pressel 2026-08-02 14:44:23 +02:00 • committed by Thomas Gleixner

parent 075b74841b

commit ada54c2ba6

1 changed files with 1 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

1

include/linux/rseq_entry.h

View file