Date: Mon, 08 Dec 2025 18:09:13 +0000 From: Austin Shafer <ashafer@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 452b92fadae1 - stable/15 - linuxkpi: gracefully handle page lookup failure in lkpi_vmf_insert_pfn_prot_locked Message-ID: <69371449.cb52.3c135d9c@gitrepo.freebsd.org>
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The branch stable/15 has been updated by ashafer: URL: https://cgit.FreeBSD.org/src/commit/?id=452b92fadae16e30f815203863bb9dd92ddff762 commit 452b92fadae16e30f815203863bb9dd92ddff762 Author: Austin Shafer <ashafer@FreeBSD.org> AuthorDate: 2025-10-28 18:08:01 +0000 Commit: Austin Shafer <ashafer@FreeBSD.org> CommitDate: 2025-12-08 18:08:32 +0000 linuxkpi: gracefully handle page lookup failure in lkpi_vmf_insert_pfn_prot_locked Currently lkpi_vmf_insert_pfn_prot_locked will check the page iter to find a usage of the page. If no page was found, it continues on to try using PHYS_TO_VM_PAGE() to get a page. Currently it does not check if a valid page was found before passing it to vm_page_busy_acquire, which can cause a kernel page fault as vm_page_busy_acquire expects a valid page pointer. This can easily be triggered while starting KDE6 in wayland mode, which many users have been reporting. With this change plasma6 starts properly in wayland mode. Sponsored by: NVIDIA PR: 288565 Reviewed by: markj, kbowling (mentor) Differential Revision: https://reviews.freebsd.org/D53412 (cherry picked from commit 03b214a35db1ebdc7575cad8d695c65daf2817bf) --- sys/compat/linuxkpi/common/src/linux_page.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/sys/compat/linuxkpi/common/src/linux_page.c b/sys/compat/linuxkpi/common/src/linux_page.c index a71a708c1bd8..2b2827579cba 100644 --- a/sys/compat/linuxkpi/common/src/linux_page.c +++ b/sys/compat/linuxkpi/common/src/linux_page.c @@ -345,6 +345,10 @@ retry: page = vm_page_grab_iter(vm_obj, pindex, VM_ALLOC_NOCREAT, &pages); if (page == NULL) { page = PHYS_TO_VM_PAGE(IDX_TO_OFF(pfn)); + if (page == NULL) { + pctrie_iter_reset(&pages); + return (VM_FAULT_SIGBUS); + } if (!vm_page_busy_acquire(page, VM_ALLOC_WAITFAIL)) { pctrie_iter_reset(&pages); goto retry;
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