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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8ffd5bbb1e1sm102900876d6.22.2026.07.12.05.39.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 12 Jul 2026 05:39:18 -0700 (PDT) Date: Sun, 12 Jul 2026 08:39:13 -0400 From: Gregory Price To: Usama Arif Cc: Andrew Morton , apopple@nvidia.com, balbirs@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, david@kernel.org, dev.jain@arm.com, jannh@google.com, joshua.hahnjy@gmail.com, lance.yang@linux.dev, liam@infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ljs@kernel.org, matthew.brost@intel.com, npache@redhat.com, rakie.kim@sk.com, ryan.roberts@arm.com, vbabka@kernel.org, ying.huang@linux.alibaba.com, ziy@nvidia.com, shakeel.butt@linux.dev, hannes@cmpxchg.org, sashiko-bot , stable@vger.kernel.org Subject: Re: [PATCH v3 1/3] mm/mempolicy: skip non-present PMDs when queueing folios Message-ID: References: <20260710105557.1987433-1-usama.arif@linux.dev> <20260710105557.1987433-2-usama.arif@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260710105557.1987433-2-usama.arif@linux.dev> X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 2C88B40004 X-Stat-Signature: 3kydthcys5uc5y7m5kuitnj5cnpoagyg X-HE-Tag: 1783859960-506961 X-HE-Meta: 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 JHs8XQ5W 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jul 10, 2026 at 03:55:21AM -0700, Usama Arif wrote: > queue_folios_pmd() is called under pmd_trans_huge_lock(), whose > pmd_is_huge() check returns true for any non-present, non-none PMD > softleaf. Passing such a PMD to pmd_folio() treats the softleaf encoding > as a hardware PFN and can return a bogus folio pointer. > > Mirror queue_folios_pte_range(): handle non-present entries before > looking up a folio. Keep migration entries counted as failures, but skip > other non-present PMDs such as device-private entries. > > Potential trigger: an HMM-based GPU driver migrates an anonymous THP > folio to device memory via migrate_vma_pages(), leaving a device-private > PMD. Userspace then calls mbind(), migrate_pages() or > set_mempolicy_home_node() on that range. > > Reported-by: sashiko-bot > Link: https://sashiko.dev/#/patchset/20260703173903.3789516-1-usama.arif%40linux.dev?part=6 > Fixes: 368076f52ebe ("mm/huge_memory: add device-private THP support to PMD operations") > Cc: > Reviewed-by: Joshua Hahn > Reviewed-by: Zi Yan > Acked-by: David Hildenbrand (Arm) > Signed-off-by: Usama Arif Reviewed-by: Gregory Price