Atomic from interrupts (which implicitly includes RTOS task switching, which uses SysTick).
Does't have to be atomic from DMA (which I know historically, old days, could optionally use what they used to call cycle stealing).
My question re DMA was in the opposite direction: can a 32F4 perform a DMA write or read, n words, which is atomic from interrupts? I have used DMAs which could do this.