RESOLVED FIXED313657
[Site Isolation] Enable same-site BFCache with cross-site iframes 
https://bugs.webkit.org/show_bug.cgi?id=313657
Summary [Site Isolation] Enable same-site BFCache with cross-site iframes
Basuke Suzuki
Reported 2026-04-29 08:53:22 PDT
Step 2 of same-site BFCache under Site Isolation. Step 1 (bug 313615) enabled in-process BFCache for same-site navigations when the page has no cross-site iframes. This bug covers the remaining case: pages WITH cross-site iframes. The challenge is that in-process BFCache (driven by FrameLoader in the WebProcess) does not coordinate with iframe processes. Cross-site iframe content lives in separate processes that need to be suspended/restored. Approach: When the WebProcess caches a page with cross-site iframes, it notifies the UIProcess via a new IPC. The UIProcess then calls the existing suspendSubframeProcesses() to coordinate iframe process suspension using the existing SetSubframesSuspended IPC. On restore, the reverse path unsuspends iframe processes. This completes same-site BFCache support under Site Isolation. rdar://175857874
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Radar WebKit Bug Importer
Comment 1 2026-05-06 08:54:12 PDT
<rdar://problem/176368842>
Basuke Suzuki
Comment 2 2026-05-12 08:36:07 PDT
Pull request: https://github.com/WebKit/WebKit/pull/64762
EWS
Comment 3 2026-05-28 09:40:56 PDT
Committed 314050@main (444bd55f4300): <https://commits.webkit.org/314050@main> Reviewed commits have been landed. Closing PR #64762 and removing active labels.
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