Commits
Vineet Gupta committed 96af7d92d8d
ARC: show_regs: lockdep: re-enable preemption [ Upstream commit f731a8e89f8c78985707c626680f3e24c7a60772 ] signal handling core calls show_regs() with preemption disabled which on ARC takes mmap_sem for mm/vma access, causing lockdep splat. | [ARCLinux]# ./segv-null-ptr | potentially unexpected fatal signal 11. | BUG: sleeping function called from invalid context at kernel/fork.c:1011 | in_atomic(): 1, irqs_disabled(): 0, pid: 70, name: segv-null-ptr | no locks held by segv-null-ptr/70. | CPU: 0 PID: 70 Comm: segv-null-ptr Not tainted 4.18.0+ #69 | | Stack Trace: | arc_unwind_core+0xcc/0x100 | ___might_sleep+0x17a/0x190 | mmput+0x16/0xb8 | show_regs+0x52/0x310 | get_signal+0x5ee/0x610 | do_signal+0x2c/0x218 | resume_user_mode_begin+0x90/0xd8 Workaround by re-enabling preemption temporarily. Note that the preemption disabling in core code around show_regs() was introduced by commit 3a9f84d354ce ("signals, debug: fix BUG: using smp_processor_id() in preemptible code in print_fatal_signal()") to silence a differnt lockdep seen on x86 bakc in 2009. Cc: <stable@vger.kernel.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Sasha Levin <sashal@kernel.org>