RFR: 8315548: G1: Document why VM_G1CollectForAllocation::doit() may allocate without completing a GC [v2]

[Ivan Walulya]

> Hi all,
> 
> Please review this trivial change to add a comment explaining why we attempt to allocate at a VM_G1CollectForAllocation safepoint before triggering garbage collection.
> 
> Thanks,
> Ivan

Ivan Walulya has updated the pull request incrementally with one additional commit since the last revision:

  Thomas Review

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15559/files
  - new: https://git.openjdk.org/jdk/pull/15559/files/d9e926f3..7de8dea9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15559&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15559&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/15559.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15559/head:pull/15559

PR: https://git.openjdk.org/jdk/pull/15559