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16483f51c7
We can't be holding the mmap_sem while calling flush_cache_user_range because the flush can fault. If we fault on a user address, the page fault handler will try to take mmap_sem again. Since both places acquire the read lock, most of the time it succeeds. However, if another thread tries to acquire the write lock on the mmap_sem (e.g. mmap) in between the call to flush_cache_user_range and the fault, the down_read in do_page_fault will deadlock. Also, since we really can't be holding the mmap_sem while calling flush_cache_user_range AND vma is actually unused by the flush itself, get rid of vma as an argument. Change-Id: If55409bde41ad1060fa4fe7cbd4ac530d4d9a106 Signed-off-by: Dima Zavin <dima@android.com>