On Fri, Nov 18, 2011 at 10:55:35AM -0800, Tejun Heo wrote: > Percpu allocator recorded the cpus which map to the first and last > units in pcpu_first/last_unit_cpu respectively and used them to > determine the address range of a chunk - e.g. it assumed that the > first unit has the lowest address in a chunk while the last unit has > the highest address. > > This simply isn't true. Groups in a chunk can have arbitrary positive > or negative offsets from the previous one and there is no guarantee > that the first unit occupies the lowest offset while the last one the > highest. > > Fix it by actually comparing unit offsets to determine cpus occupying > the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu > to pcpu_low/high_unit_cpu to avoid confusion. > > The chunk address range is used to flush cache on vmalloc area > map/unmap and decide whether a given address is in the first chunk by > per_cpu_ptr_to_phys() and the bug was discovered by invalid > per_cpu_ptr_to_phys() translation for crash_note. > > Kudos to Dave Young for tracking down the problem. > > Signed-off-by: Tejun Heo <tj at kernel.org> > Reported-by: WANG Cong <xiyou.wangcong at gmail.com> > Reported-by: Dave Young <dyoung at redhat.com> > LKML-Reference: <4EC21F67.10905 at redhat.com> > Cc: stable @kernel.org BTW, waiting for Tested-by. If someone gives me that, I'll push it through percpu/for-fixes. Thanks. -- tejun
