21 Dec
2020
21 Dec
'20
6:03 p.m.
Hello,
On Sat, Dec 19, 2020 at 09:08:55PM -0800, Andy Lutomirski wrote:
On Sat, Dec 19, 2020 at 6:49 PM Andrea Arcangeli aarcange@redhat.com wrote:
The ptes are changed always with the PT lock, in fact there's no problem with the PTE updates. The only difference with mprotect runtime is that the mmap_lock is taken for reading. And the effect contested for this change doesn't affect the PTE, but supposedly the tlb flushing deferral.
Can you point me at where the lock ends up being taken in this path?
pte_offset_map_lock in change_pte_range, as in mprotect, no difference.
As I suspected on my follow up, the bug described wasn't there, but I'll look at the new theory posted.
Thanks, Andrea