Messages in this thread | | | Date | Fri, 07 Sep 2012 18:59:40 -0400 | From | KOSAKI Motohiro <> | Subject | Re: [PATCH 3/5] mempolicy: fix a race in shared_policy_replace() |
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First off, thank you very much for reworking this for me. I haven't got a chance to get a test machine for this.
> shared_policy_replace() use of sp_alloc() is unsafe. 1) sp_node cannot > be dereferenced if sp->lock is not held and 2) another thread can modify > sp_node between spin_unlock for allocating a new sp node and next spin_lock. > The bug was introduced before 2.6.12-rc2. > > Kosaki's original patch for this problem was to allocate an sp node and policy > within shared_policy_replace and initialise it when the lock is reacquired. I > was not keen on this approach because it partially duplicates sp_alloc(). As > the paths were sp->lock is taken are not that performance critical this > patch converts sp->lock to sp->mutex so it can sleep when calling sp_alloc().
Looks make sense.
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
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