Messages in this thread | | | Date | Mon, 4 Jun 2012 07:26:04 +0100 | From | Al Viro <> | Subject | Re: Question about do_mmap changes |
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On Mon, Jun 04, 2012 at 12:29:45AM -0500, Larry Finger wrote: > Al, > > In commit e3fc629d7bb70848fbf479688a66d4e76dff46ac in 3.5-rc1, you > change do_mmap() to static, and use do_mmap_pgoff() instaed. The > VirtualBox kernel module calls do_mmap(), and no longer compiles. I > fixed the compile problem with the patch [snip] > I am not quite sure why do_munmap() is undefined as the symbol is > exported; however, should do_mmap_pgoff() be exported?
a) you'd better make very certain that you are holding ->mmap_sem on current->mm; I couldn't verify that.
b) as for rtR0MemObjLinuxDoMmap(), I would suggest pulling down_write()/ up_write() on ->mmap_sem into the function, collapsing them down into do_mmap() turning it into vm_mmap(). Oh, and probably breaking wrists to whoever had come up with that function name, but that's a matter of taste. Some prefer kneecaps.
c) WTF is MY_DO_MUNMAP() and are you guaranteed that you are doing that to current->mm and not to something else? If not, you have a big problem; if yes, convert to vm_munmap().
Again, doing mmap/munmap to some random process' mm is a bloody bad idea; there's a shitload of races in that area.
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