Im working on a simple project that shares a memory segment between a user
processand a kernel module. I'm having some problems with shm_map and there
doesn't seem to be much info on it.
Im not sure what happened to the memory when the user process that creates it
terminates. I have some questions.
1) Does the kernel mapping keep the segment from being garbage collected when
the use process that creates it terminated? I've experienced shm_unmap() panic
when tryingto unmap a segment
scenario:
User process Maps SegmentKernel maps it with shm_map()User Process
TerminatesKernel tries to shm_unmap() and it panics.
2) Is there a way for the kernel process to know when the user process has
goneaway? A ref count?
3) Does a SHM_ANON segment persist as long as the kernel has it mapped, or
doesit get garbage collected when the creating user process terminates?
4) When using a named segment, can the kernel "reuse" a mapping for a new
userprocess?
Example:
User process creates shm segment with path /fooKernel Maps shm segment with
shm_map()User process terminates.User process runs again, opening segment /foo
Does the kernel need to re-map, or is the original mapping valid?
Thanks!Laurie
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