bad: scheduling while atomic!

[Russell King <rmk@arm.linux.org.uk>]

I'm seeing tonnes of this with UP preempt in 2.5.71.  The following is
just one case which I've been able to track down:

bad: scheduling while atomic! (00000250 0 8 mtdblockd)
[<c02372d0>] (schedule+0x0/0x490) from [<c0335fd0>] (mtd_blktrans_thread+0x220/0x258)
 r7 = 00000000  r6 = C0109FBC  r5 = C0108000  r4 = C0109FB8
[<c0335db0>] (mtd_blktrans_thread+0x0/0x258) from [<c0224554>] (kernel_thread+0x40/0x48)
bad: scheduling while atomic! (00000251 0 8 mtdblockd)
[<c02372d0>] (schedule+0x0/0x490) from [<c0335fd0>] (mtd_blktrans_thread+0x220/0x258)
 r7 = 00000000  r6 = C0109FBC  r5 = C0108000  r4 = C0109FB8
[<c0335db0>] (mtd_blktrans_thread+0x0/0x258) from [<c0224554>] (kernel_thread+0x40/0x48)
bad: scheduling while atomic! (00000252 0 8 mtdblockd)
[<c02372d0>] (schedule+0x0/0x490) from [<c0335fd0>] (mtd_blktrans_thread+0x220/0x258)
 r7 = 00000000  r6 = C0109FBC  r5 = C0108000  r4 = C0109FB8
[<c0335db0>] (mtd_blktrans_thread+0x0/0x258) from [<c0224554>] (kernel_thread+0x40/0x48)

(The extra numbers are: preempt_count, kernel_locked, pid and comm).

This instance seems to be caused by the following code in
drivers/mtd/mtd_blkdevs.c:

         while (!tr->blkcore_priv->exiting) {
                 spin_lock_irq(rq->queue_lock);
 ...
                 spin_unlock_irq(rq->queue_lock);
 ...
                 spin_lock_irq(rq->queue_lock);
 ...
         }

It would be useful if we could balance the spin_locks with the
spin_unlocks. 8)

-- 
Russell King (rmk@arm.linux.org.uk)                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html