forked from Minki/linux
f731a8e89f
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
|
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|---|---|---|
| .. | ||
| boot | ||
| configs | ||
| include | ||
| kernel | ||
| lib | ||
| mm | ||
| oprofile | ||
| plat-axs10x | ||
| plat-eznps | ||
| plat-hsdk | ||
| plat-sim | ||
| plat-tb10x | ||
| Kbuild | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||