On Monday, August 28, 2017, Nicolas Pitre wrote:

OK I moved the lock promotion right at the beginning _before_ validating
the split point. Also got a reference on the file to make sure that
hasn't changed too.

quoted

While we are at it, what happens if you mmap 120Kb, then munmap() the

middle

quoted

40Kb.  Leaving two 40Kb VMAs with 40Kb gap between them, that is.  Will

your

quoted

->vm_private_data be correct for both?

It wouldn't, but I now changed it to contain absolute values so now it
will. And if the split point lands in the hole then the code just
readjusts the pgoff at the beginning of the remaining part.

Here's the revised patch:

For whatever it's worth, as soon as I moved to 4.13-rc7,
CONFIG_CRAMFS_PHYSMEM=y crashes my XIP_KERNEL system before it can even 
get to any console output.

(both the old patch and the new patch)

If CONFIG_CRAMFS_PHYSMEM is not set, my XIP system boots fine.

However, if I boot -rc7 as a uImage, the new patch works just as good as
the old patch.

(mounting after boot, or booting with rootfstype=cramfs_physmem)


I guess I'll have to figure out what happened between -rc4 and -rc7.
Damn!


Chris