From c2ff4764e03e7a8d758352f4aceb8fe1be6ac971 Mon Sep 17 00:00:00 2001 From: Zeng Heng Date: Thu, 21 May 2026 15:30:11 +0800 Subject: [PATCH] arm64: tlb: Flush walk cache when unsharing PMD tables When huge_pmd_unshare() is called to unshare a PMD table, the tlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true but the aarch64 tlb_flush() only checked tlb->freed_tables to determine whether to use TLBF_NONE (vae1is, invalidates walk cache) or TLBF_NOWALKCACHE (vale1is, leaf-only). This caused the stale PMD page table entry to remain in the walk cache after unshare, potentially leading to incorrect page table walks. Fix by including unshared_tables in the check, so that when unsharing tables, TLBF_NONE is used and the walk cache is properly invalidated. Here is the detailed distinction between vae1is and vale1is: | Instruction Combination | Actual Invalidation Scope | | ------------------------ | --------------------------------------------------| | `VAE1IS` + TTL=`0` | All entries at all levels (full invalidation) | | `VAE1IS` + TTL=`2` (L2) | Non-leaf at Level 0/1 + leaf at Level 2 | | `VALE1IS` + TTL=`0` | Leaf entries at all levels (non-leaf not cleared) | | `VALE1IS` + TTL=`2` (L2) | Leaf entry at Level 2 only | Signed-off-by: Zeng Heng Fixes: 8ce720d5bd91 ("mm/hugetlb: fix excessive IPI broadcasts when unsharing PMD tables using mmu_gather") Cc: Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/tlb.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h index 10869d7731b8..751bd57bc3ba 100644 --- a/arch/arm64/include/asm/tlb.h +++ b/arch/arm64/include/asm/tlb.h @@ -53,7 +53,8 @@ static inline int tlb_get_level(struct mmu_gather *tlb) static inline void tlb_flush(struct mmu_gather *tlb) { struct vm_area_struct vma = TLB_FLUSH_VMA(tlb->mm, 0); - tlbf_t flags = tlb->freed_tables ? TLBF_NONE : TLBF_NOWALKCACHE; + tlbf_t flags = (tlb->freed_tables || tlb->unshared_tables) ? + TLBF_NONE : TLBF_NOWALKCACHE; unsigned long stride = tlb_get_unmap_size(tlb); int tlb_level = tlb_get_level(tlb);