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    SubjectRe: nfsd changes for 2.6.37
    On Tue, Oct 26, 2010 at 06:11:56PM -0400, J. Bruce Fields wrote:
    > On Tue, Oct 26, 2010 at 05:44:41PM -0400, J. Bruce Fields wrote:
    > > On Tue, Oct 26, 2010 at 02:37:26PM -0700, Linus Torvalds wrote:
    > > > On Tue, Oct 26, 2010 at 2:24 PM, J. Bruce Fields <bfields@fieldses.org> wrote:
    > > > >
    > > > > I did a couple connectathon runs just now with no obvious ill effects
    > > > > except for some sleep-within-spinlock warnings in the lease code.
    > > >
    > > > Hmm. Those sleep-within-spinlock warnings are very likely serious
    > > > bugs.
    > >
    > > Yeah, didn't mean to belittle them.
    > >
    > > > Can you quote the whole warning with stack trace?
    > >
    > > It's just obvious allocations in setlease:
    > >
    > > BUG: sleeping function called from invalid context at mm/slab.c:3101
    > > in_atomic(): 1, irqs_disabled(): 0, pid: 4345, name: lease_tests
    > > 1 lock held by lease_tests/4345:
    > > #0: (file_lock_lock){+.+.+.}, at: [<ffffffff81128be5>] lock_flocks+0x15/0x20
    > > Pid: 4345, comm: lease_tests Not tainted 2.6.36-05858-gbd5e20b #1028
    > > Call Trace:
    > > [<ffffffff8103141d>] __might_sleep+0x10d/0x140
    > > [<ffffffff810e3ad3>] kmem_cache_alloc+0x1f3/0x230
    > > [<ffffffff8112a4d2>] generic_setlease+0x112/0x2c0
    > > [<ffffffff8112a6b5>] __vfs_setlease+0x35/0x40
    > > [<ffffffff8112acfe>] fcntl_setlease+0xce/0x180
    > > [<ffffffff810f7c2e>] sys_fcntl+0x2fe/0x630
    > > [<ffffffff81961999>] ? trace_hardirqs_on_thunk+0x3a/0x3f
    > > [<ffffffff81002658>] system_call_fastpath+0x16/0x1b
    > >
    > > I'm testing a patch.
    >
    > This works for me.
    >
    > I'm not saying it's correct, but it does at least pass my dumb tests
    > without complaining.

    I can't think of any more missing locking, though I did notice this on a
    quick look.

    --b.

    commit fc42117585672abd3cbf247dd311869233d1606a
    Author: J. Bruce Fields <bfields@redhat.com>
    Date: Tue Oct 26 18:25:30 2010 -0400

    fix nlmsvc_notify_blocked locking

    Signed-off-by: J. Bruce Fields <bfields@redhat.com>

    diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
    index 6f1ef00..c462d34 100644
    --- a/fs/lockd/svclock.c
    +++ b/fs/lockd/svclock.c
    @@ -700,14 +700,16 @@ nlmsvc_notify_blocked(struct file_lock *fl)
    struct nlm_block *block;

    dprintk("lockd: VFS unblock notification for block %p\n", fl);
    + spin_lock(&nlm_blocked_lock);
    list_for_each_entry(block, &nlm_blocked, b_list) {
    if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
    - nlmsvc_insert_block(block, 0);
    + nlmsvc_insert_block_locked(block, 0);
    + spin_unlock(&nlm_blocked_lock);
    svc_wake_up(block->b_daemon);
    return;
    }
    }
    -
    + spin_unlock(&nlm_blocked_lock);
    printk(KERN_WARNING "lockd: notification for unknown block!\n");
    }


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