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    SubjectRe: [PATCH] regression: vmalloc easily fail.
    On Tue, Oct 28, 2008 at 08:55:13PM -0200, Glauber Costa wrote:
    > Commit db64fe02258f1507e13fe5212a989922323685ce broke
    > KVM (the symptom) for me. The cause is that vmalloc
    > allocations fail, despite of the fact that /proc/meminfo
    > shows plenty of vmalloc space available.
    >
    > After some investigation, it seems to me that the current
    > way to compute the next addr in the rb-tree transversal
    > leaves a spare page between each allocation. After a few
    > allocations, regardless of their size, we run out of vmalloc
    > space.

    Right... that was to add a guard page like the old vmalloc allocator.
    vmallocs still add their extra page too, so most of them will have
    a 2 page guard area, but I didn't think this would hurt significantly.

    I'm not against the patch, but I wonder exactly what is filling it up
    and how? (can you look at the vmalloc proc function to find out?)

    >
    > Signed-off-by: Glauber Costa <glommer@redhat.com>
    > Cc: Jeremy Fitzhardinge <jeremy@goop.org>
    > Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
    > ---
    > mm/vmalloc.c | 2 +-
    > 1 files changed, 1 insertions(+), 1 deletions(-)
    >
    > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
    > index 0365369..a33b0d1 100644
    > --- a/mm/vmalloc.c
    > +++ b/mm/vmalloc.c
    > @@ -363,7 +363,7 @@ retry:
    > }
    >
    > while (addr + size >= first->va_start && addr + size <= vend) {
    > - addr = ALIGN(first->va_end + PAGE_SIZE, align);
    > + addr = ALIGN(first->va_end, align);
    >
    > n = rb_next(&first->rb_node);
    > if (n)
    > --
    > 1.5.6.5


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