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    SubjectRe: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c - bisected
    On Tue, Aug 26, 2008 at 04:51:52PM -0700, Linus Torvalds wrote:
    > On Wed, 27 Aug 2008, Adrian Bunk wrote:
    > > >
    > > > We're much better off with a 1% code-size reduction than forcing big
    > > > stacks on people. The 4kB stack option is also a good way of saying "if it
    > > > works with this, then 8kB is certainly safe".
    > >
    > > You implicitely assume both would solve the same problem.
    > I'm just saying that your logic doesn't hold water.
    > If we can save kernel stack usage, then a 1% increase in kernel size is
    > more than worth it.

    From some tests the size increase seems to become bigger for smaller
    kernels, but I don't have any really good data.

    An interesting question is why most of our architectures for embedded
    devices only offer bigger stacks:

    The only architectures offering a 4kB stacks option are:
    - m68knommu
    - sh
    - 32bit x86

    The following architectures that are used in embedded devices
    always use 8kB stacks (or bigger) in your tree:
    - arm
    - avr32
    - blackfin
    - cris
    - frv
    - h8300
    - m32r
    - m68k
    - mips
    - mn10300 (has an #ifdef CONFIG_4KSTACKS but no kconfig option)
    - powerpc
    - xtensa

    > > While 4kB stacks are something we anyway never got 100% working
    > What? Don't be silly.
    > Linux _historically_ always used 4kB stacks.
    > No, they are likely not usable on x86-64, but dammit, they should be more
    > than usable on x86-32 still.

    When did we get callpaths like like nfs+xfs+md+scsi reliably
    working with 4kB stacks on x86-32?

    > Linus



    "Is there not promise of rain?" Ling Tan asked suddenly out
    of the darkness. There had been need of rain for many days.
    "Only a promise," Lao Er said.
    Pearl S. Buck - Dragon Seed

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