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    SubjectRe: [patch 6/7 -mm] oom: avoid oom killer for lowmem allocations
    On 02/11/2010 04:19 AM, David Rientjes wrote:
    > On Wed, 10 Feb 2010, Rik van Riel wrote:
    >
    >>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
    >>> --- a/mm/page_alloc.c
    >>> +++ b/mm/page_alloc.c
    >>> @@ -1914,6 +1914,9 @@ rebalance:
    >>> * running out of options and have to consider going OOM
    >>> */
    >>> if (!did_some_progress) {
    >>> + /* The oom killer won't necessarily free lowmem */
    >>> + if (high_zoneidx< ZONE_NORMAL)
    >>> + goto nopage;
    >>> if ((gfp_mask& __GFP_FS)&& !(gfp_mask& __GFP_NORETRY)) {
    >>> if (oom_killer_disabled)
    >>> goto nopage;
    >>
    >> Are there architectures that only have one memory zone?
    >>
    >
    > It actually ends up not to matter because of how gfp_zone() is implemented
    > (and you can do it with mem= on architectures with larger ZONE_DMA zones
    > such as ia64). ZONE_NORMAL is always guaranteed to be defined regardless
    > of architecture or configuration because it's the default zone for memory
    > allocation unless specified by a bit in GFP_ZONEMASK, it doesn't matter
    > whether it actually has memory or not. high_zoneidx in this case is just
    > gfp_zone(gfp_flags) which always defaults to ZONE_NORMAL when one of the
    > GFP_ZONEMASK bits is not set. Thus, the only way to for the conditional
    > in this patch to be true is when __GFP_DMA, or __GFP_DMA32 for x86_64, is
    > passed to the page allocator and CONFIG_ZONE_DMA or CONFIG_ZONE_DMA32 is
    > enabled, respectively.

    Fair enough.

    Acked-by: Rik van Riel <riel@redhat.com>

    --
    All rights reversed.


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