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    Subject[PATCH rc5-mm1 1/3] mm-have-zonelist: fix memcg ooms
    Memcgroups up against their limit were OOMing unjustifiably on x86_32
    with highmem: pages ripe for freeing were not being found.

    It's because the zonelist changes in vmscan.c now derive zone from gfp_mask,
    and the gfp mask being passed into try_to_free_mem_cgroup_pages is atuned
    to allocating a struct page_cgroup (__GFP_HIGHMEM masked off), whereas here
    we need to be scanning highmem zones.

    Frankenstein a gfp_mask from GFP_HIGHUSER_MOVABLE and the mask passed in.

    Signed-off-by: Hugh Dickins <hugh@veritas.com>
    ---
    Same error was in -rc3-mm1, sorry for not sending fix in time for -rc5-mm1.
    The error comes 1 or 4 patches earlier, but this patch atop 2.6.25-rc5-mm1
    fits best just after
    mm-have-zonelist-contains-structs-with-both-a-zone-pointer-and-zone_idx.patch

    I've other GFP masking fixes or cleanups to come another day: this fixes
    just one clear bug, peculiar to the -mm tree, orthogonal to the rest.
    But two little do_try_to_free_pages cleanups follow on from this...

    mm/vmscan.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    --- 2.6.25-rc5-mm1/mm/vmscan.c 2008-03-11 14:19:36.000000000 +0000
    +++ linux/mm/vmscan.c 2008-03-11 20:09:05.000000000 +0000
    @@ -1444,7 +1444,6 @@ unsigned long try_to_free_mem_cgroup_pag
    gfp_t gfp_mask)
    {
    struct scan_control sc = {
    - .gfp_mask = gfp_mask,
    .may_writepage = !laptop_mode,
    .may_swap = 1,
    .swap_cluster_max = SWAP_CLUSTER_MAX,
    @@ -1454,9 +1453,10 @@ unsigned long try_to_free_mem_cgroup_pag
    .isolate_pages = mem_cgroup_isolate_pages,
    };
    struct zonelist *zonelist;
    - int target_zone = gfp_zonelist(GFP_HIGHUSER_MOVABLE);

    - zonelist = &NODE_DATA(numa_node_id())->node_zonelists[target_zone];
    + sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
    + (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
    + zonelist = NODE_DATA(numa_node_id())->node_zonelists;
    if (do_try_to_free_pages(zonelist, sc.gfp_mask, &sc))
    return 1;
    return 0;

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