On 32 bit x86, the linear mapping contains a subset of physical memory, so kmap() may need to map the frame by allocating highmem memory and manipulating page tables.
“Once, yes. Twice, no way. Thrice?”
，这一点在wps中也有详细论述
波莉·托因比系《卫报》专栏作家
2026-03-26 11:00:00