[Bug 458201] Re: kernel stacktrace on volume detach in kvm guest

[Stefan Bader]

It seems this is a problem in the symbios scsi driver which looks like
being present in the same form upstream.

[  271.732918]  [<ffffffff8139a109>] __sym_mfree_dma+0x69/0x100

This function disables interrupts to take a spinlock. Then calls
functions to free resources which will emit the warning when called with
interrupts disabled.

void __sym_mfree_dma(m_pool_ident_t dev_dmat, void *m, int size, char *name)
{
        unsigned long flags;
        m_pool_p mp;

        spin_lock_irqsave(&sym53c8xx_lock, flags);
        mp = ___get_dma_pool(dev_dmat);
        if (!mp)
                goto out;
        __sym_mfree(mp, m, size, name);
#ifdef  SYM_MEM_FREE_UNUSED
        if (!mp->nump)
                ___del_dma_pool(mp);
#endif
 out:
        spin_unlock_irqrestore(&sym53c8xx_lock, flags);
}

Not sure whether the spinunlock might be simply moved up a bit. That
might need some discussion with upstream and or testing. But the bug
task could be moved to kernel. I guess the QEMU task can only be set to
invalid.

** Also affects: linux (Ubuntu)
   Importance: Undecided
       Status: New

** Changed in: linux (Ubuntu)
   Importance: Undecided => Low

** Changed in: linux (Ubuntu)
       Status: New => Triaged

-- 
kernel stacktrace on volume detach in kvm guest
https://bugs.launchpad.net/bugs/458201
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