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    SubjectRe: [bug] SLOB crash, 2.6.24-rc2
    On Wed, Nov 14, 2007 at 03:10:13PM -0800, David Miller wrote:
    > From: Matt Mackall <mpm@selenic.com>
    > Date: Wed, 14 Nov 2007 16:53:36 -0600
    >
    > > He hit the bug using SLOB and there are no kmem (or any other) caches
    > > in SLOB.
    >
    > That's unfortunate, is there any user tracking facility at
    > all?

    No, the usual strategy for debugging problems -outside- SLOB is to
    switch to another allocator with more extensive debugging facilities.

    It is of course possible to add redzoning, last user, etc., but there
    aren't many advantages to implementing these in SLOB compared to
    switching allocators, unless the bug disappears in those other
    allocators. In the case of random pointer fandango, such bugs are
    likely to disappear when you turn on debugging anyway.

    The most likely thing you'll hit in SLOB vs SLUB/SLAB is that SLOB
    doesn't hand back power-of-two allocations for kmalloc. Instead, it
    has 2-byte granularity on most machines. So small pointer overruns on
    kmalloced objects will be somewhat more visible in SLOB than
    SLAB/SLUB. I don't think SLAB/SLUB debugging can detect overruns
    inside the not-requested-but-still-allocated region of objects.

    I've implemented redzoning and various other debugging checks for
    earlier versions of SLOB to find problems -in- the allocator, but
    those won't apply to current SLOB (which can be considered v2).

    --
    Mathematics is the supreme nostalgia of our time.
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