Messages in this thread | | | Date | Thu, 13 Oct 2005 03:13:47 -0700 | From | Chris Wright <> | Subject | Re: [PATCH] New System call unshare (try 2) |
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* Jamie Lokier (jamie@shareable.org) wrote: > Janak Desai wrote: > > Don't allow sighand unsharing if not unsharing vm > > Why not? It's permitted to clone with unshared sighand and shared vm, > and it's useful too.
I think that one's just backwards. Although I do question how useful it is to unshare sighand. Sharing vm is pretty intimate ;-)
> It's the combination shared sighand + unshared vm which is not > allowed by clone - so I think that's what you should refuse. > > > Don't allow vm unsharing if task cloned with CLONE_THREAD > > It would be better to do what clone does, and say "don't allow sighand > unsharing if task cloned with CLONE_THREAD". This is because > CLONE_THREAD tasks must have shared signals.
Yes, I agree.
> In combination with the rule above for sighand (my rule, not yours), > that implies "don't allow vm unsharing.." as a consequence. > > > Don't allow vm unsharing if the task is performing async io > > Why not? > > Async ios are tied to an mm (see lookup_ioctx in fs/aio.c), which may > be shared among tasks. I see no reason why the async ios can't > continue and be waited in on in other tasks that may be using the old mm.
My concern was the case where there are no other tasks. But I don't think that's an issue other than having the aio effect of setting up aio then exiting.
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