274266 – REGRESSION (278815@main): [ MacOS iOS Debug ] TestWebKitAPI.AdvancedPrivacyProtections.AddNoiseToWebAudioAPIs is a consistent failure

Jay Stfleur

Reported 2024-05-16 10:31:06 PDT

Description: TestWebKitAPI.AdvancedPrivacyProtections.AddNoiseToWebAudioAPIs Is a consistent failure o n Ventura+ and iOS after changes one 278817@main Buildbot URL: https://build.webkit.org/#/builders/949/builds/2901/steps/19/logs/stdio History: https://results.webkit.org/?suite=api-tests&test=TestWebKitAPI.AdvancedPrivacyProtections.AddNoiseToWebAudioAPIs&style=debug

Radar WebKit Bug Importer

Comment 1 2024-05-16 10:31:32 PDT

<rdar://problem/128209071>

Diego Pino

Comment 2 2024-05-17 01:18:40 PDT

According to: https://results.webkit.org/?suite=api-tests&test=TestWebKitAPI.AdvancedPrivacyProtections.AddNoiseToWebAudioAPIs&style=debug The test passed in 278812@main, but failed in 278817@main. The chart doesn't show test results for the interval: [278813@main, 278816@main]. Exploring that range, the changeset 278815@main seems more related to this test regression. https://github.com/WebKit/WebKit/commit/775bac300c8b006803ba1d5c2f7bf28a0f77bc69

Wenson Hsieh

Comment 3 2024-05-17 07:58:17 PDT

Oh, I see — this is hitting a debug-only assertion that we shouldn't be fast-mallocing, seemingly because: 1. The noise injection mechanism now allocates some amount of memory in the process of mapping all equal values to the same noisy value. 2. There's some logic in web audio code that uses `ForbidMallocUseForCurrentThreadScope` to enforce no allocations, for performance reasons. Since this codepath is only triggered for private browsing and we already take a slight performance hit for noise injection before these mitigations, I think it's safe to deploy a `DisableMallocRestrictionsForCurrentThreadScope` here to suppress the debug assertion.

Wenson Hsieh

Comment 4 2024-05-17 07:58:17 PDT Comment hidden (obsolete)

Oh, I see — this is hitting a debug-only assertion that we shouldn't be fast-mallocing, seemingly because: 1. The noise injection mechanism now allocates some amount of memory in the process of mapping all equal values to the same noisy value. 2. There's some logic in web audio code that uses `ForbidMallocUseForCurrentThreadScope` to enforce no allocations, for performance reasons. Since this codepath is only triggered for private browsing and we already take a slight performance hit for noise injection before these mitigations, I think it's safe to deploy a `DisableMallocRestrictionsForCurrentThreadScope` here to suppress the debug assertion.

Wenson Hsieh

Comment 5 2024-05-17 09:29:23 PDT

Pull request: https://github.com/WebKit/WebKit/pull/28715

Wenson Hsieh

Comment 6 2024-05-17 15:17:28 PDT Comment hidden (obsolete)

Pull request: https://github.com/WebKit/WebKit/pull/28741

EWS

Comment 7 2024-05-17 20:45:16 PDT

Committed 278945@main (1e5a82de122e): <https://commits.webkit.org/278945@main> Reviewed commits have been landed. Closing PR #28715 and removing active labels.