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    SubjectRe: OOPS: reproducible in vfs_follow_link 2.4.9,2.4.10-pre4


    On Thu, 6 Sep 2001, Giacomo Catenazzi wrote:

    > Hello.
    >
    > Since yesterdey, every time I run a 2.4.9 or 2.4.10pre-4 without the
    > "devfs=nomount" I
    > have two oops + /usr, /home /boot not mounted (all (also /): ext2).

    Don't use devfs. One of the known bugs - devfs passes a string to
    vfs_follow_link() and doesn't care to preserve it until vfs_follow_link()
    is done.

    E.g. rmmod during the symlink traversal will end up with

    vfs_follow_link(nd, s)
    [working]
    [blocked on IO/allocation/whatever]
    rmmod
    ...
    kfree(s)
    ...
    [the first process wakes up and oopses on attempt to dereference s]

    There are other scenarios that end up freeing a string passed to
    vfs_follow_link() (or, for that matter, being busily copied to userland by
    readlink(2)). Basically, if devfs decides that symlink is gone - pray.
    If it's being accessed right now you are going to end up with oops.

    No idea why you've started triggering it only now - not enough
    details to say.

    And yes, Richard had been informed about that months ago. Sigh...

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