tree 07fe8d2d072d4d143c4edf4fea01ddcaff37840f
parent b343ae51c116dffaef07a8596661774c12212b66
author David S. Miller <davem@davemloft.net> 1285050292 -0700
committer David S. Miller <davem@davemloft.net> 1285050292 -0700

sparc64: Fix race in signal instruction flushing.

If another cpu does a very wide munmap() on the signal frame area,
it can tear down the page table hierarchy from underneath us.

Borrow an idea from the 64-bit fault path's get_user_insn(), and
disable cross call interrupts during the page table traversal
to lock them in place while we operate.

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>