On Tue, Sep 13, 2022, Kirill A. Shutemov wrote: > On Tue, Sep 13, 2022 at 02:53:25PM +0000, Sean Christopherson wrote: > > > > Switching topics, what actually prevents mmapp() on the shim? I tried to follow, > > > > but I don't know these areas well enough. > > > > > > It has no f_op->mmap, so mmap() will fail with -ENODEV. See do_mmap(). > > > (I did not read the switch statement correctly at first. Note there are > > > two 'fallthrough' there.) > > > > Ah, validate_mmap_request(). Thought not implementing ->mmap() was the key, but > > couldn't find the actual check. > > validate_mmap_request() is in mm/nommu.c which is not relevant for real > computers. > > I was talking about this check: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/mmap.c#n1495 Hence the comment about 'fallthrough'. Thanks again!
