On Tue, 22 Mar 2005, David S. Miller wrote: > On Tue, 22 Mar 2005 19:36:46 +0000 (GMT) > Hugh Dickins <[EMAIL PROTECTED]> wrote: > > > I notice that although both i386 and sparc64 use pgtable-nopud.h, the > > i386 pud_clear does nothing at all and the sparc64 pud_clear resets to 0. > > This was a dead end. I386 doesn't do anything with pud_clear() in > order to work around a chip erratum. > > IA64 does clear in pud_clear() just like sparc64.
My mind kept flipping back and forth on whether it was pud_clear(). I agree, I can't see that it's the issue now. > I think it's the floor/ceiling stuff. > > At that pud_clear(), we do it if floor-->ceiling (after masking) > covers the whole PUD. Not whether start/end do, which is what > the code sort of does right now. Not an explanation I understood ;) > "start" and "end" say which specific entries we might be purging. Yes. > "floor" and "ceiling" say that once that purging is done, the > extent of the potential address space freed. Well, they specify the limits beyond which we cannot free, because there's other stuff still making use of addresses beyond. > I cooked up a quick patch that changes the logic to: > > floor &= PUD_MASK; > ceiling &= PUD_MASK; > if (floor - 1 >= ceiling - 1) > return; That can't be right. In exit_mmap, for example, floor will be 0 throughout, and the condition will be true for all values of ceiling. > pmd = pmd_offset(pud, start); > pud_clear(pud); > pmd_free_tlb(tlb, pmd); > > and things start to basically work. Because none of your higher level tables are being freed at all: eventually you'll run out of memory. I still can't see what's wrong with the code that's already there. My brain is seizing up, I'm taking a break. Hugh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
