Messages in this thread | | | Date | Wed, 6 Jun 2012 20:37:20 -0400 | From | Konrad Rzeszutek Wilk <> | Subject | Re: frontswap: is frontswap_init called from swapoff safe? |
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On Tue, Jun 05, 2012 at 07:41:52AM -0300, Cesar Eduardo Barros wrote: > I was looking at the swapfile.c parts of the recently-merged > frontswap, and noticed that frontswap_init can be called from > swapoff when try_to_unuse fails. > > This looks odd to me. Whether it is safe or not depends on what > frontswap_ops.init does, but the comment for __frontswap_init > ("Called when a swap device is swapon'd") and the function name > itself seem to imply it should be called only for swapon, not when > relinking the swap_info after a failed swapoff.
<nods> > > In particular, if frontswap_ops.init assumes the swap map is empty, > it would break, since as far as I know when try_to_unuse fails there > are still pages in the swap.
Let me look at this - can't do it this week - but will get back to you shortly. > > (By the way, the comment above enable_swap_info at sys_swapoff needs > to be updated to also explain why reading p->frontswap_map outside > the lock is safe at that point, like it does for p->prio and > p->swap_map.) > > -- > Cesar Eduardo Barros > cesarb@cesarb.net > cesar.barros@gmail.com
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