Operating system swapping process

Question

Please help me explaining this in simpler words:

If we were to swap out process P1 and swap in process P2, the
I/O operation might then attempt to use memory that now belongs to process
P2. There are two main solutions to this problem: never swap a process with
pending I/O, or execute I/O operations only into operating-system buffers.
Transfers between operating-system buffers and process memory then occur
only when the process is swapped in. Note that this double buffering itself
adds overhead.

Comments

@manisha11

they are telling about, what problem could occur in  time of context switching. If suppose, we are doing SRTF operation and in middle we r doing IO operation, then which problem could occur- they explained that one. 

Is these line from Galvin?

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@srestha yes but "

Transfers between operating-system buffers and process memory then occur
only when the process is swapped in. Note that this double buffering itself
adds overhead.???

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chk this : https://cs.stackexchange.com/questions/89767/why-cant-oses-swap-out-processes-that-are-waiting-for-i-o

yes, it is double buffering because I think, 2 process working on memory same time