how do exit and _exit affect mmapped memory?

[Dmitry Goncharov]

Good morning,

A program uses glibc on linux. The program uses mmap with flag MAP_SHARED.
The program never calls munmap or msync.
Is there a guarantee that the contents of the mapped memory will be stored to
the file when the program calls exit?
Is there such a guarantee if the program calls _exit or is killed by a signal?
Does calling munmap give such a guarantee?
Thanks.

regards, Dmitry