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The > unlock sequence is racy vs. clearing the list_pending_op pointer in the > tasks robust list head. To plug this race the kernel needs to know the > instruction window. As the VDSO is per MM the addresses are stored in > mm_struct::futex. > > Architectures which implement support for this have to update these > addresses when the VDSO is (re)mapped. > > Arguably this could be resolved by chasing mm->context->vdso->image, but > that that's architecture specific and requires to touch quite some cache > lines. Having it in mm::futex reduces the cache line impact and avoids > having yet another set of architecture specific functionality. > > Signed-off-by: Thomas Gleixner Reviewed-by: Mathieu Desnoyers -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com