On 11/22/2011 05:10 AM, Tejun Heo wrote: > 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. Tested-by: Dave Young <dyoung at redhat.com> > > Thanks. > -- Thanks Dave
