Messages in this thread | | | Date | Tue, 25 Aug 2015 12:00:54 +1000 | Subject | Re: [PATCH 1/2] cgroup: get a ref to source csses when migrating | From | Aleksa Sarai <> |
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> Have you verified that the scenario you're describing can actually > happen? AFAICS, cgroup_migrate_add_src() already does the pinning.
Hmmm. Looking at it, group_migrate_add_src() does grab a ref on the css_set which contains the css, and the comments mention that grabbing a ref on the css_set will stop the css from being dropped. I must've misunderstood one of your previous emails (where you said that such code was not safe in the ->can_fork(), ->cancel_fork() and ->fork()) path.
You also mentioned that depending on the css_set's ref being bumped to protect the contained csses is "sort of implementation detail. It can be implemented in different ways." Which made me think that depending on that is not a good idea.
But if it's safe to depend on the cgroup_migrate_add_src() pinning the ref on the css_set, I'll drop this patch and fix up the other one accordingly.
-- Aleksa Sarai (cyphar) www.cyphar.com
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