x86/mm: Use mm_alloc() in poking_init()

stable inclusion
from stable-v5.10.189
commit 6ee042fd240fb669f4637f8cd89899b15911e5df
category: bugfix
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I8LVBS
CVE: N/A
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6ee042fd240fb669f4637f8cd89899b15911e5df



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Intel-SIG: commit 6ee042fd240f ("x86/mm: Use mm_alloc() in poking_init()")
Backport x86 related patches from 5.10.189 upstream

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commit 3f4c8211 upstream.

Instead of duplicating init_mm, allocate a fresh mm. The advantage is
that mm_alloc() has much simpler dependencies. Additionally it makes
more conceptual sense, init_mm has no (and must not have) user state
to duplicate.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221025201057.816175235@infradead.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Aichun Shi <aichun.shi@intel.com>