Re: [syzbot] [mm?] KCSAN: data-race in try_to_migrate_one / zap_page_range_single

[Ignacio Encinas Rubio]

Hello!

This seems like a recurrent complaint from KCSAN (other examples are
[1], [2]). 

>From what I understand looking at the source code, imprecise reporting 
of the maximum resident set size is considered to be acceptable.

Annotating `hiwater_rss` as `__data_racy` [3] should make KCSAN happy. 
Would this be an acceptable change? Another possibility would be making 
the update from `update_hiwater_rss` atomic, but it doesn't seem worth 
the potential slowdown.

Let me know if my proposal works for you.

Thanks!

[1] https://syzkaller.appspot.com/bug?extid=73d65fc86d6338db5990
[2] https://syzkaller.appspot.com/bug?extid=31cd52ba68feee156393
[3] https://docs.kernel.org/dev-tools/kcsan.html#selective-analysis