[scudo] Reflect the allowed values for M_DECAY_TIME on Android

[ChiaHungDuan]

No description provided.

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: None (ChiaHungDuan)

Changes

On Android, this interval constraint was used to avoid increasing the memory pressure by a long interval. Now the memory footprint is managed better and we always do a M_PURGE call before changing the interval. It's better to remove this legacy constraint.

---

Full diff: https://github.com/llvm/llvm-project/pull/89114.diff

1 Files Affected:

• (modified) compiler-rt/lib/scudo/standalone/wrappers_c.inc (-8)

diff --git a/compiler-rt/lib/scudo/standalone/wrappers_c.inc b/compiler-rt/lib/scudo/standalone/wrappers_c.inc
index 21d5b7add51275..28374548e39076 100644
--- a/compiler-rt/lib/scudo/standalone/wrappers_c.inc
+++ b/compiler-rt/lib/scudo/standalone/wrappers_c.inc
@@ -251,14 +251,6 @@ INTERFACE WEAK int SCUDO_PREFIX(mallopt)(int param, int value) {
       // M_PURGE call so that we can minimize the impact of any unreleased pages
       // introduced by interval transition.
       SCUDO_ALLOCATOR.releaseToOS(scudo::ReleaseToOS::Force);
-
-      if (value == 0) {
-        // Will set the release values to their minimum values.
-        value = INT32_MIN;
-      } else {
-        // Will set the release values to their maximum values.
-        value = INT32_MAX;
-      }
     }
 
     SCUDO_ALLOCATOR.setOption(scudo::Option::ReleaseInterval,

[ChiaHungDuan]

Based on the values allowed on Android, we may need to convert the values (-1, 0, 1) to ms, i.e., multiply 1000. But after reviewing few use cases of M_DECAY_TIME, I think we may still need to do some value mapping here. Will upload a new one.

[cferris1000]

Should this check be value > 0? That more closely matches what it did before.

[ChiaHungDuan]

I'm thinking instead of ">=", maybe we can assert the range of values? given that only three values are valid. (And the description also says 0 and 1 are only allowed numbers)

[cferris1000]

That would be fine with me. We sanitize the values when coming through Android anyway, so verifying a -1, 0, or 1 is probably a better way to do this.

[ChiaHungDuan]

Done. CHECK added.

[cferris1000]

LGTM.