9 Aug
2022
9 Aug
'22
8:23 p.m.
On 09.08.22 22:20, Linus Torvalds wrote:
On Tue, Aug 9, 2022 at 1:14 PM Linus Torvalds torvalds@linux-foundation.org wrote:
But as there are two bits, I'm sure somebody ends up touching one and not the other.
Ugh. The nommu code certainly does odd things here. That just looks wrong.
And the hugetlb code does something horrible too, but never *sets* it, so it looks like some odd subset of VM_SHARED.
mm/mmap.c:do_mmap() contains the magic bit
switch (flags & MAP_TYPE) { case MAP_SHARED: ... case MAP_SHARED_VALIDATE: ... vm_flags |= VM_SHARED | VM_MAYSHARE; if (!(file->f_mode & FMODE_WRITE)) vm_flags &= ~(VM_MAYWRITE | VM_SHARED); fallthrough;
VM_SHARED semantics are confusing.
--
Thanks,
David / dhildenb