GitLab

To have uniform semantics across OSes, we call memset() in
DecommitSystemPages() on macOS. This is costly and potentially wasteful,
as this may bring back compressed/swpped out pages from disk, just to
call memset().

To avoid that, call mmap() on top of the existing mapping.

Bug: 1086388
Change-Id: Iedbf8d1b5d9882cc5e229765b80f95e9ee12a8de
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2238118Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Reviewed-by: Bartek Nowierski <bartekn@chromium.org>
Commit-Queue: Benoit L <lizeb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781898}