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    SubjectRe: [PATCH 3/3] seq_file: convert seq buffer to vmalloc
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    On Thu, 2011-09-22 at 14:07 -0700, Joe Perches wrote:
    > On Thu, 2011-09-22 at 13:57 -0700, Colin Cross wrote:
    > > seq_files are often used for debugging. When things are going wrong
    > > due to failed physically contiguous allocations, the exponentially
    > > growing physically contiguous allocations in seq_read can make things
    > > worse. There is no need for physically contiguous memory, so switch
    > > to virtually contiguous memory instead.
    >
    > vmalloc's are relatively expensive.

    And very limited on certain archs..

    > Perhaps use kmalloc when appropriate instead?
    >
    > []
    > > - /* don't ask for more than the kmalloc() max size */
    > > - if (size > KMALLOC_MAX_SIZE)
    > > - size = KMALLOC_MAX_SIZE;
    > > -
    > > - buf = kmalloc(size, GFP_KERNEL);
    > > + buf = vmalloc(size);
    > > if (!buf)
    > > return -ENOMEM;
    >
    > if (size > KMALLOC_MAX_SIZE)
    > buf = vmalloc(size, GFP_KERNEL)
    > else
    > buf = kmalloc(size, GFP_KERNEL)

    There's wrappers for this stuff IIRC, that said all this is a horrible
    idea. Just avoid the situation instead of coping with it.


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