From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CCEF9271464; Wed, 8 Jul 2026 13:12:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783516327; cv=none; b=DzRoBiP7yII2KNNFs+B4k6mfl9eBYqvaM35JHVF1bXeO6Wgm8tnICBgun9zSPDK1KmrmkvfgWzBU1lM+l9IsTpyp8HbDefasKxXhczde+y2Z+U3dZg10dlerGpcK2astKaJDwimGVAK2b7EqnNHADU21ThneQzkmmSBqxytFM+o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783516327; c=relaxed/simple; bh=SzXjE3q2spX06tS525dlI9mzedQrqWwffX1C55R7s/E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=n4So7zqYXSxTh0wh3fmpnux60HqKzi+Jj4yX4QhU7q5BWJ5cpYSy6ef7zI//FH4SQ4pVXxNg9owy8sPZaWjbuvUPsRAglX9rGH70teS2MCrytNn/GYx/AfuqHvuTVWXqFoGOYNQarGux9X6snralKcSFW90o+9nWNdUChqS7FAg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ncv/lTIr; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ncv/lTIr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE1851F000E9; Wed, 8 Jul 2026 13:11:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783516325; bh=2xoTJUVCMoAA0S9QwdA/2rHDyx2S8Uo8HqqZplJCTfU=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Ncv/lTIrZk4Eu47jjFa/0pc7PWzz9gHW0qPdQR1xTsVinQsfV+Mugp3a+N1Ojy74s 9wJNnFKACFz8xG3pH/rfJZgPXLJwuNZ3ID4sBDXjDcGUAe9r+ZG5/sJkqwP3lC8Pom ZkHwS4+W7mewk8oT/lyAvGr3B8tiAYH+9K8lRVGhRZfVsgBF7Cap1maGcEGAdQBpDC NdqkG0EC5hSnvTEw9m9RgxHm1sBxE8GLaAeGYpJeHWrB4tWMGumSe6YMliFRIIsluC Cd6RueppI/F9zAFEFDHXOQ4pOcOWpGjuibK2PMBnCDlv5alOXU1XJExf2dOQhwMcnM fBDxYxKevuGCg== Message-ID: <9450b10b-3340-4261-9a9c-3f95cea3fb65@kernel.org> Date: Wed, 8 Jul 2026 15:11:57 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/3] mm/huge_memory: skip device-private PMDs in madvise_free_huge_pmd To: Usama Arif , Andrew Morton , apopple@nvidia.com, balbirs@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, dev.jain@arm.com, gourry@gourry.net, 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 Cc: stable@vger.kernel.org References: <20260708122040.861335-1-usama.arif@linux.dev> <20260708122040.861335-4-usama.arif@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/8/26 14:20, Usama Arif wrote: > madvise_free_pte_range() checks pmd_trans_huge(*pmd) unlocked, then > madvise_free_huge_pmd() takes pmd_trans_huge_lock(). pmd_is_huge() > returns true for a device-private PMD, so orig_pmd can be device-private > and enter the !pmd_present() branch. > > Allow device-private PMDs in that non-present assertion and continue to > out before calling pmd_folio(). This keeps the assertion for unexpected > PMD softleafs while skipping device-private PMDs like other non-present > PMDs in this path. > > Potential trigger: an HMM-based GPU driver races with madvise(MADV_FREE): > migrate_vma_pages() flips the PMD to a device-private entry between the > caller's pmd_trans_huge() check and the callee's pmd_trans_huge_lock(). > > Fixes: 368076f52ebe ("mm/huge_memory: add device-private THP support to PMD operations") > Cc: > Reviewed-by: Joshua Hahn > Reviewed-by: Zi Yan > Reviewed-by: Balbir Singh > Signed-off-by: Usama Arif > --- > mm/huge_memory.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index c0892cc533a9..ddbdc83b4cae 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2298,7 +2298,8 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, > > if (unlikely(!pmd_present(orig_pmd))) { > VM_BUG_ON(thp_migration_supported() && > - !pmd_is_migration_entry(orig_pmd)); > + !pmd_is_migration_entry(orig_pmd) && > + !pmd_is_device_private_entry(orig_pmd)); Same comment as to #2. -- Cheers, David