[PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk
sebastian.capella at linaro.org
Fri Feb 21 23:37:14 EST 2014
Quoting Sebastian Capella (2014-02-21 15:59:11)
> - Cyril Chemparathy as his email is bouncing back to me.
> Quoting Sebastian Capella (2014-02-21 10:39:56)
> > Quoting Lorenzo Pieralisi (2014-02-20 08:27:55)
> > > > > > + cpu_switch_mm(idmap_pgd, &init_mm);
> [ ... ]
> > I can try removing it and seeing if there are side effects.
> FYI, It's definitely hanging with this removed, still looking.
I see when we reach this call, the 1st level page table @ TTBR0 is located
at different memory locations each run (expected). If we omit the
cpu_switch_mm we're corrupting the page table causing the observed
intermittent failures. I believe these match the corruption you expected.
The reason this doesn't happen when I leave the call is that idmap_pgd
is always at the same memory location. I expect this is because it's
allocated during init. I've seen the same address 50/50 times for
idmap_pgd. I don't think it is correct to rely on this behavior.
Would it be appropriate to use the swapper_pg_dir directly in place
- I do not see any modification to the swapper_pg_dir contents in the
code that would change from init time.
- swapper_pg_dir is always at the same offset.
Ideally we should have no issue with overwriting it with identical data.
I've run a couple hundred test loops using swapper_pg_dir and so far
there are no failures.
More information about the linux-arm-kernel