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    SubjectRe: next-20081119: general protection fault: get_next_timer_interrupt()
    2008/11/25  <malahal@us.ibm.com>:
    > Jens Axboe [jens.axboe@oracle.com] wrote:
    >> On Mon, Nov 24 2008, malahal@us.ibm.com wrote:
    >> > Stephen Rothwell [sfr@canb.auug.org.au] wrote:
    >> > > > The block timer code calls del_timer(), should it call del_timer_sync()?
    >> > > > It is possible although unlikely that you are hitting del_timer_sync vs
    >> > > > del_timer problem in the block timeout code. Can only be seen on SMP
    >> > > > systems though!
    >> > >
    >> > > Is this still a problem in next-20081121? In that tree, the block commit
    >> > > "block: leave the request timeout timer running even on an empty list"
    >> > > was changed to add this:
    >> > >
    >> > > diff --git a/block/blk-core.c b/block/blk-core.c
    >> > > index 04267d6..44f547c 100644
    >> > > --- a/block/blk-core.c
    >> > > +++ b/block/blk-core.c
    >> > > @@ -391,6 +391,7 @@ EXPORT_SYMBOL(blk_stop_queue);
    >> > > void blk_sync_queue(struct request_queue *q)
    >> > > {
    >> > > del_timer_sync(&q->unplug_timer);
    >> > > + del_timer_sync(&q->timeout);
    >> > > kblockd_flush_work(&q->unplug_work);
    >> > > }
    >> > > EXPORT_SYMBOL(blk_sync_queue);
    >> >
    >> > I was looking at the Linux tree. Clearly same problem doesn't exist with
    >> > the above commit! I wonder why kblockd_flush_work() is called after the
    >> > del_timer_sync(). It makes sense to cancel the work and then shutdown
    >> > the timer(s). I doubt if you are running into this problem though.
    >>
    >> If the kernel tested doesn't include the above fix, it'll surely go
    >> boom. Can someone verify that this is the case?
    >
    > Just looked, next-20081119 doesn't have the above fix. It is included in
    > next-20081120. Also note that the above fix is only partially copied,
    > there is other part that removed deleting the timer when there are no
    > outstanding requests.
    >
    Yes, I can not reproduce it anymore on linux-next 1121 and newer. (I
    did not try 1120)
    It seems the fix works pretty good.
    Is it still needed and reasonable to investigate the problem on next-20081119?
    Unfortunately I do not have much time for it.

    All these problems have gone away on next-1125 except ODEBUG warning on HPET.


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