RE: Bad Reference Semantics in PIDs Controller.

From: Aleksa Sarai
Date: Sun Aug 23 2015 - 08:24:43 EST


It turns out that, actually, the can_attach(), cancel_attach() and
attach() code is broken -- we're incrementing a ref on the old_css of
a task in can_attach(). Then we decrement the ref on a *different* css
(because the task has been migrated). This is clearly a bad thing.
Should we make cgroup_migrate() deal with the accounting for us (by
getting it to grab a ref before can_attach() and dropping it after the
attach succeeds or fails?).

--
Aleksa Sarai (cyphar)
www.cyphar.com
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