From: Oleg Nesterov <oleg@redhat.com>
Date: Mon, 21 Apr 2014 13:26:01 +0000 (+0200)
Subject: KVM: async_pf: mm->mm_users can not pin apf->mm
X-Git-Tag: v3.2.60~57
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0e40d9cf4b9c34971ab42afbe2cb52fa0c6f0cd1;p=pandora-kernel.git

KVM: async_pf: mm->mm_users can not pin apf->mm

commit 41c22f626254b9dc0376928cae009e73d1b6a49a upstream.

get_user_pages(mm) is simply wrong if mm->mm_users == 0 and exit_mmap/etc
was already called (or is in progress), mm->mm_count can only pin mm->pgd
and mm_struct itself.

Change kvm_setup_async_pf/async_pf_execute to inc/dec mm->mm_users.

kvm_create_vm/kvm_destroy_vm play with ->mm_count too but this case looks
fine at first glance, it seems that this ->mm is only used to verify that
current->mm == kvm->mm.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

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