The icswx code introduced an A-B B-A deadlock:
CPU0 CPU1
---- ----
lock(&anon_vma->mutex);
lock(&mm->mmap_sem);
lock(&anon_vma->mutex);
lock(&mm->mmap_sem);
Instead of using the mmap_sem to keep mm_users constant, take the
page table spinlock.
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
8bdafa39a4