[PATCH] D68471: [scudo][standalone] Correct releaseToOS behavior

[Matt Morehouse via Phabricator via llvm-commits]

morehouse accepted this revision.
morehouse added inline comments.
This revision is now accepted and ready to land.


================
Comment at: lib/scudo/standalone/tests/primary_test.cpp:195
+// test for an error in how the release criteria were computed.
+template <typename Primary> static void testReleaseToOS() {
+  auto Deleter = [](Primary *P) {
----------------
cryptoad wrote:
> morehouse wrote:
> > Does this test the two cases mentioned in the description?
> > 
> >   - `< 1` page in use, `> 1` page in free list (should release)
> >   - `< 1` page in free list (shouldn't release)
> > 
> > 
> > 
> > 
> Indeed, this tests the aforementioned first case, **not** the second one.
> I don't think I have a way to test that from here. One of the indicators being `LastReleaseAtNs` being updated (without released bytes), and it's not accessible.
> I'll see if I can toy with the prototype some more to bubble the information up the chain, unless you have an idea.
> 
> 
Is there a way to glean unmapped/released bytes from `GlobalStats`?  If not, it seems like something worth adding to Scudo's telemetry.

I also see there's already a `printStats` method.  Perhaps we could modify it to print into a buffer where we could extract the released metadata.


Repository:
  rCRT Compiler Runtime

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  https://reviews.llvm.org/D68471/new/

https://reviews.llvm.org/D68471