From d3eb70ead6474ec16f976fcacf10a7a890a95bd3 Mon Sep 17 00:00:00 2001 From: Pingfan Liu Date: Fri, 12 Nov 2021 13:22:14 +0800 Subject: [PATCH] arm64: mm: Fix VM_BUG_ON(mm != &init_mm) for trans_pgd trans_pgd_create_copy() can hit "VM_BUG_ON(mm != &init_mm)" in the function pmd_populate_kernel(). This is the combined consequence of commit 5de59884ac0e ("arm64: trans_pgd: pass NULL instead of init_mm to *_populate functions"), which replaced &init_mm with NULL and commit 59511cfd08f3 ("arm64: mm: use XN table mapping attributes for user/kernel mappings"), which introduced the VM_BUG_ON. Since the former sounds reasonable, it is better to work on the later. From the perspective of trans_pgd, two groups of functions are considered in the later one: pmd_populate_kernel() mm == NULL should be fixed, else it hits VM_BUG_ON() p?d_populate() mm == NULL means PXN, that is OK, since trans_pgd only copies a linear map, no execution will happen on the map. So it is good enough to just relax VM_BUG_ON() to disregard mm == NULL Fixes: 59511cfd08f3 ("arm64: mm: use XN table mapping attributes for user/kernel mappings") Signed-off-by: Pingfan Liu Cc: # 5.13.x Cc: Ard Biesheuvel Cc: James Morse Cc: Matthias Brugger Reviewed-by: Catalin Marinas Reviewed-by: Pasha Tatashin Link: https://lore.kernel.org/r/20211112052214.9086-1-kernelfans@gmail.com Signed-off-by: Will Deacon --- arch/arm64/include/asm/pgalloc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h index 8433a2058eb1..237224484d0f 100644 --- a/arch/arm64/include/asm/pgalloc.h +++ b/arch/arm64/include/asm/pgalloc.h @@ -76,7 +76,7 @@ static inline void __pmd_populate(pmd_t *pmdp, phys_addr_t ptep, static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmdp, pte_t *ptep) { - VM_BUG_ON(mm != &init_mm); + VM_BUG_ON(mm && mm != &init_mm); __pmd_populate(pmdp, __pa(ptep), PMD_TYPE_TABLE | PMD_TABLE_UXN); } -- 2.39.5