On Wed,  4 Aug 2021 16:20:10 +0800 zhangkui [off-list ref] wrote:

There is a usecase in Android that an app process's memory is swapped out
by process_madvise() with MADV_PAGEOUT, such as the memory is swapped to
zram or a backing device. When the process is scheduled to running, like
switch to foreground, multiple page faults may cause the app dropped
frames.
To reduce the problem, SMS can read-ahead memory of the process immediately
when the app switches to forground.
Calling process_madvise() with MADV_WILLNEED can meet this need.

This will require a small update to the process_madvise(2) manpage. 
Can you please send a patch?