linux-kernel - [PATCH AUTOSEL 5.15 23/41] tlb: hugetlb: Add more sizes to tlb_remove_huge_tlb

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Message-Id: <20220412004656.350101-23-sashal@kernel.org>
Date:   Mon, 11 Apr 2022 20:46:35 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Steve Capper <steve.capper@....com>,
        David Hildenbrand <david@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Sasha Levin <sashal@...nel.org>,
        aneesh.kumar@...ux.ibm.com, npiggin@...il.com,
        linux-arch@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH AUTOSEL 5.15 23/41] tlb: hugetlb: Add more sizes to tlb_remove_huge_tlb_entry

From: Steve Capper <steve.capper@....com>

[ Upstream commit 697a1d44af8ba0477ee729e632f4ade37999249a ]

tlb_remove_huge_tlb_entry only considers PMD_SIZE and PUD_SIZE when
updating the mmu_gather structure.

Unfortunately on arm64 there are two additional huge page sizes that
need to be covered: CONT_PTE_SIZE and CONT_PMD_SIZE. Where an end-user
attempts to employ contiguous huge pages, a VM_BUG_ON can be experienced
due to the fact that the tlb structure hasn't been correctly updated by
the relevant tlb_flush_p.._range() call from tlb_remove_huge_tlb_entry.

This patch adds inequality logic to the generic implementation of
tlb_remove_huge_tlb_entry s.t. CONT_PTE_SIZE and CONT_PMD_SIZE are
effectively covered on arm64. Also, as well as ptes, pmds and puds;
p4ds are now considered too.

Reported-by: David Hildenbrand <david@...hat.com>
Suggested-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Anshuman Khandual <anshuman.khandual@....com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Link: https://lore.kernel.org/linux-mm/811c5c8e-b3a2-85d2-049c-717f17c3a03a@redhat.com/
Signed-off-by: Steve Capper <steve.capper@....com>
Acked-by: David Hildenbrand <david@...hat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>
Reviewed-by: Catalin Marinas <catalin.marinas@....com>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lore.kernel.org/r/20220330112543.863-1-steve.capper@arm.com
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/asm-generic/tlb.h | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 2c68a545ffa7..71942a1c642d 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -565,10 +565,14 @@ static inline void tlb_flush_p4d_range(struct mmu_gather *tlb,
 #define tlb_remove_huge_tlb_entry(h, tlb, ptep, address)	\
 	do {							\
 		unsigned long _sz = huge_page_size(h);		\
-		if (_sz == PMD_SIZE)				\
-			tlb_flush_pmd_range(tlb, address, _sz);	\
-		else if (_sz == PUD_SIZE)			\
+		if (_sz >= P4D_SIZE)				\
+			tlb_flush_p4d_range(tlb, address, _sz);	\
+		else if (_sz >= PUD_SIZE)			\
 			tlb_flush_pud_range(tlb, address, _sz);	\
+		else if (_sz >= PMD_SIZE)			\
+			tlb_flush_pmd_range(tlb, address, _sz);	\
+		else						\
+			tlb_flush_pte_range(tlb, address, _sz);	\
 		__tlb_remove_tlb_entry(tlb, ptep, address);	\
 	} while (0)
 
-- 
2.35.1