314129 2026-05-05 15:34:25 -0700 Only update page main frame's process in ProvisionalPageProxy::didCommitLoadForFrame when committing the main frame itself 2026-05-06 14:34:28 -0700 1 1 1 Unclassified WebKit New Bugs WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 basuke basuke webkit-bug-importer oldest_to_newest 2207818 0 basuke 2026-05-05 15:34:25 -0700 In ProvisionalPageProxy::didCommitLoadForFrame, the code assigns the provisional page's FrameProcess to the underlying page's main frame when the frame process has changed: bool frameProcessChanged = m_frameProcess.ptr() != pageMainFrameProcess.ptr(); if (frameProcessChanged) pageMainFrame->setProcess(m_frameProcess); This assignment is only correct when the provisional commit is for the page's main frame itself. Under Site Isolation, a provisional page may commit for a different frame (e.g., during a multi-process BFCache restoration), in which case overwriting the page main frame's FrameProcess with the provisional's FrameProcess is incorrect — it leaves the real main frame pointing to the wrong process. Guard the setProcess call with 'pageMainFrame == m_mainFrame' so we only update the process when the provisional owns the page main frame. In paths where the provisional is for the main frame (the common case), this is a no-op. Prep patch for rdar://173743733 (multi-process BFCache restoration under Site Isolation). 2207862 1 basuke 2026-05-05 16:43:17 -0700 <rdar://problem/176305054> 2207864 2 basuke 2026-05-05 16:43:38 -0700 Pull request: https://github.com/WebKit/WebKit/pull/64310 2208289 3 ews-feeder 2026-05-06 14:34:26 -0700 Committed 312737@main (64bbad66316c): <https://commits.webkit.org/312737@main> Reviewed commits have been landed. Closing PR #64310 and removing active labels.