Messages in this thread | | | From | Linus Torvalds <> | Date | Fri, 2 Nov 2018 10:15:56 -0700 | Subject | Re: [PULL] vhost: cleanups and fixes |
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On Fri, Nov 2, 2018 at 10:10 AM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > Don't you take over the VM with "use_mm()" when you do the copies? So > yes, it's a kernel thread, but it has a user VM, and though that > should have the user limits.
Oooh. *Just* as I sent this, I realized that "use_mm()" doesn't update the thread addr_limit.
That actually looks like a bug to me - although one that you've apparently been aware of and worked around.
Wouldn't it be nicer to just make "use_mm()" do
set_fs(USER_DS);
instead? And undo it on unuse_mm()?
And, in fact, maybe we should default kernel threads to have a zero address limit, so that they can't do any user accesses at all without doing this?
Adding Al to the cc, because I think he's been looking at set_fs() in general.
Linus
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