Date: Thu, 21 Sep 2006 10:04:12 +0200
To: linux-kernel@vger.kernel.org
Subject: munmap from inside kernel
From: "Andreas Block" <andreas.block@esd-electronics.com>
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Hi,

following scenario:
Two linux systems connected via PCI.
I'd like to write a driver, which allows to map memory from the remote  
system into local user space and vice versa.
This works quite well utilizing mmap and respective vma_ops.
I do have one problem though. When the buffer on the remote side gets  
destroyed, I'd like to remove the mappings from local user space into this  
buffer (I do prefer a segfaulting application over an application writing  
into "I don't know where").
Under kernel 2.4.x I used "do_munmap()" in protection of "mm->mmap_sem"  
and it seemed to work quite well for me.
Now using kernel 2.6.x (I tested 2.6.8 and 2.6.15) this seemingly doesn't  
work anymore, because I do end up with a crash, when trying to manually  
unmap the memory.

Is there any safe way to "trigger munmap()" from inside the kernel?

Best regards,
Andreas
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