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    SubjectRe: [EXT4 set 5][PATCH 1/1] expand inode i_extra_isize to support features in larger inode
    On Tue, 10 Jul 2007 16:32:47 -0700 Andrew Morton <> wrote:

    > > + brelse(bh);
    > > + up_write(&EXT4_I(inode)->xattr_sem);
    > > + return error;
    > > +}
    > > +
    > We're doing GFP_KERNEL memory allocations while holding xattr_sem. This
    > can cause the VM to reenter the filesystem, perhaps taking i_mutex and/or
    > i_truncate_sem and/or journal_start() (I forget whether this still
    > happens). Have we checked whether this can occur and if so, whether we are
    > OK from a lock ranking POV? Bear in mind that journalled-data mode is more
    > complex in this regard.

    I notice that everyone carefully avoided addressing this ;)

    Oh well, hopefully people are testing with lockdep enabled. As long
    as the fs is put under extreme memory pressure, most bugs should be reported.

    Except lockdep doesn't know about journal_start(), which has ranking
    requirements similar to a semaphore. Nor does it know about lock_page().
    We already have hard-to-hit but deadlockable bugs in this area.

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      Last update: 2007-07-13 11:09    [W:0.021 / U:53.020 seconds]
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