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    SubjectRe: doublefault debugging (was Re: Linux v2.5.62 --- spontaneous reboots)

    On Thu, 20 Feb 2003, William Lee Irwin III wrote:
    >
    > You might want to grab aeb's fully non-recursive pathwalking if
    > you really want to cut back the stack to 4KB, as well as fixing
    > whatever stackblasting drivers are about.

    The path walking should really not be an issue. Each level of a symlink
    takes something like 64 bytes of stack on x86 (I checked it some time ago,
    maybe it's changed a bit), since the actual recursive part is very shallow
    indeed.

    And since we don't recurse deeper than 5 levels anyway, the symlink
    recursion ends up not being a real problem compared to a lot of other
    code (never mind the single functions with hundreds of bytes of stack
    space: just regular function calls 5 levels deep is quite normal).

    That fs recursion was not the problem even back in the days when the max
    stack depth was <3kB (4kB allocation, 1kB task_struct). It used to be 8
    levels deep or something, it was changed to 5 not because we ran out on
    x86, but because of those stupid sparc register windows (causing much
    bigger minimum function stack requirements than on x86).

    Linus

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