From 975ca3986bec8ebd6d8b45f4a7f77c730e424ac4 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Thu, 8 Jun 2023 12:35:09 -0700 Subject: [PATCH] x86: allow get_locked_pte() to fail In rare transient cases, not yet made possible, pte_offset_map() and pte_offset_map_lock() may not find a page table: handle appropriately. Link: https://lkml.kernel.org/r/b7fa8547-4f28-ec82-9893-1b2eb58e40b4@google.com Signed-off-by: Hugh Dickins Cc: Alexander Gordeev Cc: Alexandre Ghiti Cc: Aneesh Kumar K.V Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Chris Zankel Cc: Claudio Imbrenda Cc: David Hildenbrand Cc: "David S. Miller" Cc: Geert Uytterhoeven Cc: Greg Ungerer Cc: Heiko Carstens Cc: Helge Deller Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: John David Anglin Cc: John Paul Adrian Glaubitz Cc: Kirill A. Shutemov Cc: Matthew Wilcox (Oracle) Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Simek Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Palmer Dabbelt Cc: Peter Zijlstra Cc: Qi Zheng Cc: Russell King Cc: Suren Baghdasaryan Cc: Thomas Bogendoerfer Cc: Thomas Gleixner Cc: Will Deacon Signed-off-by: Andrew Morton --- arch/x86/kernel/ldt.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c index 525876e7b9f4..adc67f98819a 100644 --- a/arch/x86/kernel/ldt.c +++ b/arch/x86/kernel/ldt.c @@ -367,8 +367,10 @@ static void unmap_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt) va = (unsigned long)ldt_slot_va(ldt->slot) + offset; ptep = get_locked_pte(mm, va, &ptl); - pte_clear(mm, va, ptep); - pte_unmap_unlock(ptep, ptl); + if (!WARN_ON_ONCE(!ptep)) { + pte_clear(mm, va, ptep); + pte_unmap_unlock(ptep, ptl); + } } va = (unsigned long)ldt_slot_va(ldt->slot);