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    SubjectRe: [PATCH] Make GFP_DMA allocations w/o ZONE_DMA emit a warning instead of failing
    On Fri, 10 Jun 2011, Russell King - ARM Linux wrote:

    > > > > Should one submit a patch adding a warning to GFP_DMA allocations
    > > > > w/o ZONE_DMA, or the idea of the original patch is wrong?
    > > >
    > > > Linus was far from impressed by the original commit, saying:
    > > > | Using GFP_DMA is reasonable in a driver - on platforms where that
    > > > | matters, it should allocate from the DMA zone, on platforms where it
    > > > | doesn't matter it should be a no-op.
    > > >
    > > > So no, not even a warning.
    > > >
    > >
    > > Any words of wisdom for users with CONFIG_ZONE_DMA=n that actually use
    > > drivers where they need GFP_DMA? The page allocator should just silently
    > > return memory from anywhere?
    > See Linus' reply. I quote again "on platforms where it doesn't matter it
    > should be a no-op". If _you_ have a problem with that _you_ need to
    > discuss it with _Linus_, not me. I'm not going to be a middle-man sitting
    > between two people with different opinions.

    We're talking about two different things. Linus is saying that if GFP_DMA
    should be a no-op if the hardware doesn't require DMA memory because the
    kernel was correctly compiled without CONFIG_ZONE_DMA. I'm asking about a
    kernel that was incorrectly compiled without CONFIG_ZONE_DMA and now we're
    returning memory from anywhere even though we actually require GFP_DMA.

    If you don't want to form an opinion of your own, then I have no problem
    cc'ing Linus on it. I don't think he'd object to a

    #ifndef CONFIG_ZONE_DMA
    WARN_ON_ONCE(1, "%s (%d): allocating DMA memory without DMA support -- "
    "enable CONFIG_ZONE_DMA if needed.\n",
    current->comm, current->pid);

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      Last update: 2011-06-11 00:03    [W:0.125 / U:4.552 seconds]
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