On Thu, 2009-06-18 at 00:37 -0400, Lee Schermerhorn wrote: > On Wed, 2009-06-17 at 09:45 +0200, Stefan Lankes wrote: > > > I've placed the last rebased version in : > > > > > > http://free.linux.hp.com/~lts/Patches/PageMigration/2.6.28-rc4-mmotm- > > > 081110/ > > > > > > > OK! I will try to reconstruct the problem. > > Stefan: > > Today I rebased the migrate on fault patches to 2.6.30-mmotm-090612... > [along with my shared policy series atop which they sit in my tree]. > Patches reside in: > > http://free.linux.hp.com/~lts/Patches/PageMigration/2.6.30-mmotm-090612-1220/ > I have updated the migrate-on-fault tarball in the above location to fix part of the problems I was seeing. See below. > > I did a quick test. I'm afraid the patches have suffered some "bit rot" > vis a vis mainline/mmotm over the past several months. Two possibly > related issues: > > 1) lazy migration doesn't seem to work. Looks like > mbind(<some-policy>+MPOL_MF_MOVE+MPOL_MF_LAZY) is not unmapping the > pages so, of course, migrate on fault won't work. I suspect the > reference count handling has changed since I last tried this. [Note one > of the patch conflicts was in the MPOL_MF_LAZY addition to the mbind > flag definitions in mempolicy.h and I may have botched the resolution > thereof.] > > 2) When the pages get freed on exit/unmap, they are still PageLocked() > and free_pages_check()/bad_page() bugs out with bad page state. > > Note: This is independent of memcg--i.e., happens whether or not memcg > configured. > <snip> OK. Found time to look at this. Turns out I hadn't tested since trylock_page() was introduced. I did a one-for-one replacement of the old API [TestSetPageLocked()], not noticing that the sense of the return was inverted. Thus, I was bailing out of the migrate_pages_unmap_only() loop with the page locked, thinking someone else had locked it and would take care of it. Since the page wasn't unmapped from the page table[s], of course it wouldn't migrate on fault--wouldn't even fault! Fixed this. Now: lazy migration works w/ or w/o memcg configured, but NOT with the swap resource controller configured. I'll look at that as time permits. Lee -- To unsubscribe from this list: send the line "unsubscribe linux-numa" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
