Hi, Pu, Thanks for updating the series. But even if it just update the signed-off-by, please update the version.
Also, can you check the Sashiko's comments? https://sashiko.dev/#/patchset/20260706083636.159883-1-hupu%40transsion.com Thank you, On Mon, 6 Jul 2026 08:36:46 +0000 Pu Hu <[email protected]> wrote: > From: Pu Hu <[email protected]> > > This series fixes two arm64 kprobes issues observed when running > simpleperf with preemptirq tracepoints and dwarf callchains while a > kprobe is active on a frequently executed kernel function. > > The crash happens in the kprobe debug exception path. While a kprobe is > preparing or executing its XOL single-step instruction, perf/trace code > can run in the same window. That code may either take a fault of its own > or hit another kprobe. > > Patch 1 makes kprobe_fault_handler() handle a fault in > KPROBE_HIT_SS/KPROBE_REENTER only when the faulting PC points at the > current kprobe's XOL instruction. Otherwise the fault is left to the > normal fault handling path. > > Patch 2 allows a kprobe hit in KPROBE_HIT_SS to be handled as a > recoverable one-level reentry. Only a hit while already in > KPROBE_REENTER remains unrecoverable. > > Patch 3 adds a kprobes selftest which registers a kprobe on a frequently > executed filemap fault path and drives repeated file-backed page faults > from userspace. This provides a smaller reproducer for validating the > fault handling fix. > > This follows the same logic as the existing x86 fixes: > 6381c24cd6d5 ("kprobes/x86: Fix page-fault handling logic") > 6a5022a56ac3 ("kprobes/x86: Allow to handle reentered kprobe on > single-stepping") > > Reproducer: > > simpleperf record -p <pid> -f 10000 \ > -e preemptirq:preempt_disable \ > -e preemptirq:preempt_enable \ > --duration 9 --call-graph dwarf \ > -o /data/local/tmp/perf.data > > The new selftest can be built from tools/testing/selftests/kprobe/ and > used to exercise the page fault handling path with the test kprobe > module loaded. > > Before this series, the crash reproduced frequently. With both patches > applied, it was no longer reproduced in our testing. > > > Pu Hu (3): > arm64: kprobes: Do not handle non-XOL faults as kprobe faults > arm64: kprobes: Allow reentering kprobes while single-stepping > selftests/kprobes: Add kprobe stress test for page fault handling > > arch/arm64/kernel/probes/kprobes.c | 22 +++- > tools/testing/selftests/kprobe/.gitignore | 2 + > tools/testing/selftests/kprobe/Makefile | 75 +++++++++++++ > tools/testing/selftests/kprobe/fault_stress.c | 105 ++++++++++++++++++ > .../selftests/kprobe/kprobe_folio_stress.c | 70 ++++++++++++ > 5 files changed, 273 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/kprobe/.gitignore > create mode 100644 tools/testing/selftests/kprobe/Makefile > create mode 100644 tools/testing/selftests/kprobe/fault_stress.c > create mode 100644 tools/testing/selftests/kprobe/kprobe_folio_stress.c > > -- > 2.43.0 > -- Masami Hiramatsu (Google) <[email protected]>
