locking question: do_mmap(), do_munmap()

Manfred Spraul (manfreds@colorfullife.com)
Sat, 09 Oct 1999 14:48:55 +0200

which semaphores/spinlocks protect do_mmap() and do_munmap()?

do_mmap():
I wrote a test patch, and I found out that some (all?) callers call
lock_kernel(), but that mm->mmap_sem is _NOT ACQUIRED_. Eg
sys_uselib()-> do_load_elf_??() -> do_mmap().

do_munmap():
???? I think here is a race:
sys_munmap() doesn't call lock_kernel(), it only acquires mm->mmap_sem.
do_mmap() internally calls do_munmap(), ie with the kernel lock, but
without mm->mmap_sem.

What about adding debugging runtime checks to these function?
ie #defines which call down_trylock() and spin_trylock() and oops on
missing locks?
We could define them to "(void)0" before 2.4.

--
	Manfred


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