On Mon, Mar 10, 2014 at 10:01:58PM -0700, Andrew Morton wrote:
> On Tue, 11 Mar 2014 00:51:09 -0400 Dave Jones <[email protected]> wrote:
>
> > On Mon, Mar 10, 2014 at 09:46:12PM -0700, Andrew Morton wrote:
> > > On Mon, 10 Mar 2014 20:13:40 -0700 Andrew Morton
> > <[email protected]> wrote:
> > >
> > > > > Anyone ? I'm hitting this trace on an almost daily basis, which is
> > a pain
> > > > > while trying to reproduce a different bug..
> > > >
> > > > Damn, I thought we'd fixed that but it seems not. Cc's added.
> > > >
> > > > Guys, what stops the migration target page from coming unlocked in
> > > > parallel with zap_pte_range()'s call to migration_entry_to_page()?
> > >
> > > page_table_lock, sort-of. At least, transitions of is_migration_entry()
> > > and page_locked() happen under ptl.
> > >
> > > I don't see any holes in regular migration. Do you know if this is
> > > reproducible with CONFIG_NUMA_BALANCING=n or CONFIG_NUMA=n?
> >
> > CONFIG_NUMA_BALANCING was n already btw, so I'll do a NUMA=n run.
>
> There probably isn't much point unless trinity is using
> sys_move_pages(). Is it?
Trinity will do every syscall an arch has.
In the test case I have so far, I've narrowed it down to the vm group of
syscalls
(so running with '-g vm' will do anything that I deemed 'vm'. Including..
sys_move_pages)
I'll try to narrow it down further tomorrow.
> If so it would be interesting to disable
> trinity's move_pages calls and see if it still fails.
Ok, I'll try that first.
> Grasping at straws here, trying to reduce the amount of code to look at :(
*nod*, it's not helped by the fact that the trace happens at process exit time
which could be considerably later after the syscall that buggers everything up
has happened.
Dave
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