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    SubjectRe: -mm merge plans for 2.6.26 (memcgroup)
    On Sun, 20 Apr 2008, Andrew Morton wrote:
    >
    > These can be found at
    > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.25/2.6.25-mm1

    A couple of comments on memcgroup patches in your
    high-priority initial section (I've not studied further yet)
    > Merge, and backport to 2.6.25.x

    > disable-the-memory-controller-by-default-v3.patch
    > disable-the-memory-controller-by-default-v3-fix.patch

    If those are to go in, then the sooner the better, yes.

    But though I argued for cgroup_disable=memory (or some such),
    I think myself that taking it even further now (requiring an
    additional cgroup_enable=memory at boottime to get the memcg
    stuff you chose with CGROUP_MEM_RES_CTLR=y at build time) is
    confusing overkill, just messing around.

    Others think differently. A compromise would be to improve the
    helptext for CGROUP_MEM_RES_CTLR (some of it is presently nonsense,
    isn't it? Certainly there's a significant overhead, but it's the
    32-bit struct page not the 64-bit which then suffers from crossing
    cacheline boundaries). Not much point in mentioning
    cgroup_disable=memory if those patches go in, but needs to say
    cgroup_enable=memory bootoption also needed.

    > memcgroup-check-and-initialize-page-cgroup-in-memmap_init_zone.patch

    No, it was a good find from Shi, but you were right to think the patch
    fishy, and Kame put in lots of work (thank you!) to identify the actual
    culprit: he and Mel are discussing what the actual fix should be; and
    we might want to choose a different fix for stable than for 2.6.26.

    I think you should drop that memmap_init_zone patch: the cgroup
    pointer is not the only field we assume is zeroed, both flags and
    mapping can cause trouble if they were not originally zeroed.
    Re-zero the whole struct page? No, far better to fix the
    root of the corruption, that Kame and Mel are working on.

    Hugh


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