kmap_atomic/kunmap_atomic_核心功能

/* *drivers/md/raid5-cache.c *r5l_write_stripe */for (i = 0; i < sh->disks; i++) {void *addr;if (!test_bit(R5_Wantwrite, &sh->dev[i].flags))continue;write_disks++;/* checksum is already calculated in last run */if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))continue;addr = kmap_atomic(sh->dev[i].page);sh->dev[i].log_checksum = crc32c_le(log->uuid_checksum, addr, PAGE_SIZE);kunmap_atomic(addr);}

出現了kmap_atomic(sh->dev[i].page)和kunmap_atomic(addr)，臨時記憶體映射，記憶體的一段空間，映射給物理頁面，使用完臨時映射後應該及時釋放