From: Tejun Heo Date: Tue, 21 Sep 2010 05:57:19 +0000 (+0200) Subject: percpu: fix pcpu_last_unit_cpu X-Git-Tag: v2.6.36-rc6~54^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=46b30ea9bc3698bc1d1e6fd726c9601d46fa0a91;p=pandora-kernel.git percpu: fix pcpu_last_unit_cpu pcpu_first/last_unit_cpu are used to track which cpu has the first and last units assigned. This in turn is used to determine the span of a chunk for man/unmap cache flushes and whether an address belongs to the first chunk or not in per_cpu_ptr_to_phys(). When the number of possible CPUs isn't power of two, a chunk may contain unassigned units towards the end of a chunk. The logic to determine pcpu_last_unit_cpu was incorrect when there was an unused unit at the end of a chunk. It failed to ignore the unused unit and assigned the unused marker NR_CPUS to pcpu_last_unit_cpu. This was discovered through kdump failure which was caused by malfunctioning per_cpu_ptr_to_phys() on a kvm setup with 50 possible CPUs by CAI Qian. Signed-off-by: Tejun Heo Reported-by: CAI Qian Cc: stable@kernel.org --- Reading git-diff-tree failed