tree ec9ae51837c8f25a84322b58e8f50b077d37e580
parent 594a7208962ee2c0ddf10c4b6bd5f5989b84e174
author Kostya Kortchinsky <kostyak@google.com> 1583262991 -0800
committer Copybara-Service <copybara-worker@google.com> 1598597847 -0700

[scudo][standalone] Do not fill 32b regions at once

Summary:
For the 32b primary, whenever we created a region, we would fill it
all at once (eg: create all the transfer batches for all the blocks
in that region). This wasn't ideal as all the potential blocks in
a newly created region might not be consummed right away, and it was
using extra memory (and release cycles) to keep all those free
blocks.

So now we keep track of the current region for a given class, and
how filled it is, carving out at most `MaxNumBatches` worth of
blocks at a time.

Additionally, lower `MaxNumBatches` on Android from 8 to 4. This
lowers the randomness of blocks, which isn't ideal for security, but
keeps things more clumped up for PSS/RSS accounting purposes.

Subscribers: #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D75551

GitOrigin-RevId: a0e86420ae72e4dc38c3a341943d4f14139e1e4b