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Thu, 07 May 2026 18:37:48 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-bcac02c82a3sm12614666b.13.2026.05.07.18.37.46 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 07 May 2026 18:37:47 -0700 (PDT) From: Wei Yang To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, riel@surriel.com, liam@infradead.org, vbabka@kernel.org, harry@kernel.org, jannh@google.com, sj@kernel.org, ziy@nvidia.com, balbirs@nvidia.com Cc: linux-mm@kvack.org, Wei Yang , Lorenzo Stoakes , stable@vger.kernel.org Subject: [PATCH] mm/page_vma_mapped: revalidate and do proper check before return device-private pmd Date: Fri, 8 May 2026 01:37:28 +0000 Message-Id: <20260508013728.21285-1-richard.weiyang@gmail.com> X-Mailer: git-send-email 2.11.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: For pmd_trans_huge() and pmd_is_migration_entry(), we does following before return the pmd entry: * re-validate pmd entry * check PVMW_MIGRATION * check_pmd() * handle on pte level if split under us But for device-private pmd, we just return after pmd_lock(). This may lead to inproper situation. This patch fixes commit 65edfda6f3f2 ("mm/rmap: extend rmap and migration support device-private entries") by following the same pattern as pmd_trans_huge() and pmd_is_migration_entry(). Fixes: 65edfda6f3f2 ("mm/rmap: extend rmap and migration support device-private entries") Signed-off-by: Wei Yang Cc: David Hildenbrand Cc: Balbir Singh Cc: SeongJae Park Cc: Zi Yan Cc: Lorenzo Stoakes Cc: --- mm/page_vma_mapped.c | 34 +++++++++++++++++++++++----------- 1 file changed, 23 insertions(+), 11 deletions(-) diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index a4d52fdb3056..5d337ea43019 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -269,21 +269,33 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) spin_unlock(pvmw->ptl); pvmw->ptl = NULL; } else if (!pmd_present(pmde)) { - const softleaf_t entry = softleaf_from_pmd(pmde); + softleaf_t entry = softleaf_from_pmd(pmde); if (softleaf_is_device_private(entry)) { pvmw->ptl = pmd_lock(mm, pvmw->pmd); - return true; - } - - if ((pvmw->flags & PVMW_SYNC) && - thp_vma_suitable_order(vma, pvmw->address, - PMD_ORDER) && - (pvmw->nr_pages >= HPAGE_PMD_NR)) - sync_with_folio_pmd_zap(mm, pvmw->pmd); + entry = softleaf_from_pmd(*pvmw->pmd); + + if (softleaf_is_device_private(entry)) { + if (pvmw->flags & PVMW_MIGRATION) + return not_found(pvmw); + if (!check_pmd(softleaf_to_pfn(entry), pvmw)) + return not_found(pvmw); + return true; + } - step_forward(pvmw, PMD_SIZE); - continue; + /* THP pmd was split under us: handle on pte level */ + spin_unlock(pvmw->ptl); + pvmw->ptl = NULL; + } else { + if ((pvmw->flags & PVMW_SYNC) && + thp_vma_suitable_order(vma, pvmw->address, + PMD_ORDER) && + (pvmw->nr_pages >= HPAGE_PMD_NR)) + sync_with_folio_pmd_zap(mm, pvmw->pmd); + + step_forward(pvmw, PMD_SIZE); + continue; + } } if (!map_pte(pvmw, &pmde, &ptl)) { if (!pvmw->pte) -- 2.34.1