Al Viro <viro@xxxxxxxxxxxxxxxxxx> writes: > On Wed, Dec 08, 2021 at 02:25:24PM -0600, Eric W. Biederman wrote: >> There are two big uses of do_exit. The first is it's design use to be >> the guts of the exit(2) system call. The second use is to terminate >> a task after something catastrophic has happened like a NULL pointer >> in kernel code. >> >> Add a function make_task_dead that is initialy exactly the same as >> do_exit to cover the cases where do_exit is called to handle >> catastrophic failure. In time this can probably be reduced to just a >> light wrapper around do_task_dead. For now keep it exactly the same so >> that there will be no behavioral differences introducing this new >> concept. >> >> Replace all of the uses of do_exit that use it for catastraphic >> task cleanup with make_task_dead to make it clear what the code >> is doing. >> >> As part of this rename rewind_stack_do_exit >> rewind_stack_and_make_dead. > > Umm... What about .Linvalid_mask: in arch/xtensa/kernel/entry.S? > That's an obvious case for your make_task_dead(). Good catch. Being in assembly it did not have anything after the name do_exit so it hid from my regex "[^A-Za-z0-9_]do_exit[^A-Za-z0-9]". Thank you for finding that. Skimming the surrounding code it looks like Linvalid_mask can only be reached by buggy hardware or buggy kernel code. If userspace could trigger the condition it would be a candidate for force_exit_sig. I am a bit puzzled why die is not called, instead of die being handrolled there. xtensa folks any thoughts? If not I will queue up a minimal patch to replace do_exit with make_task_dead. Eric
