Maks Verver wrote:

It seems that probles is caused by shared mapping between kernel space and user
space. We have page mapped as executable in user space and at the same time the same
page is mapped in kernel space as writable (row 2 and 4 in table above). I am pretty
sure that kernel mapping is from buffer space and the buffer was created to read .text
segment from file to memory. I think that instead of turning off cache for user entries it is enough just to
write-back and invalidate cache for kernel entry, assuming that code is already in buffer.

In row 1 of table there is only one writable and executable kernel entry and I
think it may be something allocated via kmem_alloc_wait() and it shouldn't not cause any
trouble.

In row 3 we have only one executable and writable user entry and it also
shouldn't be a problem. I think that user stack is mapped as readable, writable and executable
so maybe it was page from stack.

grzesiek