Messages in this thread | | | Date | Sat, 11 Jun 2011 09:46:40 +0900 | Subject | Re: [PATCH] [BUGFIX] update mm->owner even if no next owner. | From | Hiroyuki Kamezawa <> |
| |
2011/6/11 Hugh Dickins <hughd@google.com>: > On Fri, 10 Jun 2011, KAMEZAWA Hiroyuki wrote: >> >> I think this can be a fix. > > Sorry, I think not: I've not digested your rationale, > but three things stand out: > > 1. Why has this only just started happening? I may not have run that > test on 3.0-rc1, but surely I ran it for hours with 2.6.39; > maybe not with khugepaged, but certainly with ksmd. > Not sure. I pointed this just by review because I found "charge" in khugepaged is out of mmap_sem now.
> 2. Your hunk below: >> - if (!mm_need_new_owner(mm, p)) >> + if (!mm_need_new_owner(mm, p)) { >> + rcu_assign_pointer(mm->owner, NULL); > is now setting mm->owner to NULL at times when we were sure it did not > need updating before (task is not the owner): you're damaging mm->owner. > Ah, yes. It's my mistake.
> 3. There's a patch from Andrea in 3.0-rc1 which looks very likely to be > relevant, 692e0b35427a "mm: thp: optimize memcg charge in khugepaged". > I'll try reproducing without that tonight (I crashed in 20 minutes > this morning, so it's not too hard). >
Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |