From 3998dc50ebdc127ae79b10992856fb76debc2005 Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Thu, 15 Sep 2022 16:25:19 +0200 Subject: [PATCH] mm: Fix TLB flush for not-first PFNMAP mappings in unmap_region() This is a stable-specific patch. I botched the stable-specific rewrite of commit b67fbebd4cf98 ("mmu_gather: Force tlb-flush VM_PFNMAP vmas"): As Hugh pointed out, unmap_region() actually operates on a list of VMAs, and the variable "vma" merely points to the first VMA in that list. So if we want to check whether any of the VMAs we're operating on is PFNMAP or MIXEDMAP, we have to iterate through the list and check each VMA. Signed-off-by: Jann Horn Signed-off-by: Greg Kroah-Hartman --- mm/mmap.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index cd1d2680ac58..5c2c7651ca29 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2638,6 +2638,7 @@ static void unmap_region(struct mm_struct *mm, { struct vm_area_struct *next = vma_next(mm, prev); struct mmu_gather tlb; + struct vm_area_struct *cur_vma; lru_add_drain(); tlb_gather_mmu(&tlb, mm); @@ -2652,8 +2653,12 @@ static void unmap_region(struct mm_struct *mm, * concurrent flush in this region has to be coming through the rmap, * and we synchronize against that using the rmap lock. */ - if ((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) != 0) - tlb_flush_mmu(&tlb); + for (cur_vma = vma; cur_vma; cur_vma = cur_vma->vm_next) { + if ((cur_vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) != 0) { + tlb_flush_mmu(&tlb); + break; + } + } free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, next ? next->vm_start : USER_PGTABLES_CEILING);