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    SubjectRe: [RFC PATCH 0/2] Fix up the NFS mmap code

    On Sat, 9 Jan 2010, Al Viro wrote:
    > Well, sure - it steps on i_mutex-before-mmmap_sem first from ls somewhere and
    > records the ordering for posterity. Then NFS steps into mmap() (on a
    > different inode) and gets conflicting ordering.

    Look closer: the inodes for directories and for non-directories have
    i_mutex in different lockdep classes.

    So that "on a different inode" thing should have made it a non-issue,
    since there is no actual chain back. There is "mmap_sem ->
    i_mutex_regular_file" (for mmap) and there is "i_mutex_directory ->
    mmap_sem" (for filldir), but that isn't an ABBA.

    The problem _seems_ to be (if I read Andi's chain correctly) that a
    directory hasn't gone through the i_mutex_dir_key change, so filldir ends
    up being counted against the default i_mutex_key.


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      Last update: 2010-01-09 03:25    [W:0.021 / U:10.136 seconds]
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