[jdk17u] RFR: 8275426: PretouchTask num_chunks calculation can overflow

[Aleksey Shipilev]

On Thu, 18 Nov 2021 11:26:48 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Unclean backport to fix the overflow in pretouch code. There is a reproducer for x86_32.
> 
> The backport does not apply cleanly, because `pretouch_gang` was renamed to `pretouch_workers` later.
> @kimbarrett, please ack this version.
> 
> Additional testing:
>  - [x] Linux x86_32 reproducer
>  - [x] Linux x86_64 fastdebug `tier1`
>  - [x] Linux x86_32 fastdebug `tier1`

Got the push approval.

-------------

PR: https://git.openjdk.java.net/jdk17u/pull/286