From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=217.140.110.172 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793175985; b=I4bhuiILejRvF9p6o0olMdSeUVeLplgiSTKmmWjTmoSm1xShr6yt1meJrYQ8Yk9oeYjY BpHIHsj2dpdyl3/7nloG1EzaDJd3RLVUG5DrHShDoARdo91XvEW9CJS1tTJ2i6mfQw1FY JNY2i4nmksrUGjZMXjFlAopWhRZmvOdxBHs62r1NsMji+IwdhleW7iAILG5JljQKCb8MQ HU2mwKGtSDvoIRql1niRjtHG9wzrzHSTXP71KOiw3p17QqxVn2Px9DqpRVnZVXDNutdu2 W+69ypwMbifw/6SbiyxU50mIdgfa0yvYMWgM2fVDuOH9sXwYaejnVqjkzS9POYuJmrA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793175985; h=DMARC-Filter:Received:Received:DKIM-Signature:Message-ID:Date: MIME-Version:User-Agent:Subject:To:Cc:References:Content-Language: From:In-Reply-To:Content-Type:Content-Transfer-Encoding; bh=ZqxvUOYEnw6epSxNJkOsH/iPXoP3tG6fnt6qx+16CDI=; b=xR08YIlINIyx9n6iviYAr0GT0jyVNObbLlClWR1WUs43VQ/dmN5JoOW/Ff4gY0yLRR7/ yc7Z6deHY50vpEzbd2jT1wSfZmYi3GOCTHeoXQEJHWIexW5GIV4zx0ZEFUMXfJxU+h98D qusKCNs5DKI66rERqh1ESUlw/cukSNeGdZ/TinR2JTqGK6vUioW9qnhbQdqBF1t3wNk+l rs0a6vDFtj+HFYeyxTk+JqVI8c/Qu6ndlj+3omhG0m3GS+ws43sD2+Wk2/FBM7ltrnc5F 9WvItF2zWBNlf2RWvcb+gi4IpBqktue/19K+Ih6lYopAbTvZXPJVnamXHrY0se1M8uw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=tK8FPKJ7; arc=none smtp.remote-ip=217.140.110.172 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 80E5E606A31D; Wed, 28 Oct 2026 08:26:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 80E5E606A31D Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=tK8FPKJ7 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 70C092ECB; Wed, 28 Oct 2026 01:26:19 -0700 (PDT) Received: from [10.163.164.200] (unknown [10.163.164.200]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7FA7C3F7B4; Wed, 28 Oct 2026 01:26:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1793175982; bh=/EbjTDVkdW0F57Y0gRKQi9v+oLhQOt+D3xEeKM70nII=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=tK8FPKJ775LMj/HKo8mObMmx6qKh5HiYiCirC0X5N+Uj94ZXLcgBO0gJmsuhWRb4A Le1KG8SJsaJkW/YAWbL9G7bsI6/KPkhwkETh7gUgwJbaEDX8Eg/t78/F2JU1nNSeDl jDJpfCYMNVh0lVMDuVYpKwlU4CCZEtAy7DaSDSSM= Message-ID: <50f426ea-7477-4fb4-a520-0d7fe4b84c37@arm.com> Date: Wed, 28 Oct 2026 13:55:59 +0530 X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 14/46] mm/huge_memory: fix zapping migration entries for device-private THPs To: "David Hildenbrand (Arm)" , Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Chris Mason , stable@vger.kernel.org References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-14-6f74bec9a5bb@kernel.org> Content-Language: en-US From: Dev Jain In-Reply-To: <20261027-fixes_core-v1-14-6f74bec9a5bb@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 27/10/26 4:47 am, David Hildenbrand (Arm) wrote: > From: Chris Mason > > A PMD migration entry can refer to a device-private folio. > zap_huge_pmd_folio() checks the folio type instead of the entry type, > so it treats such a migration entry as a device-private entry. > > Installing the migration entry already removed the reverse mapping and > dropped the mapping reference. Zapping it must not repeat those > operations. Concurrent MADV_DONTNEED during migration back to system > memory can trigger this. > > Check the PMD entry type using pmd_is_device_private_entry(). > > Fix generated by an LLM and sent by Chris Mason in private. > > Fixes: 368076f52ebe ("mm/huge_memory: add device-private THP support to PMD operations") > Cc: stable@vger.kernel.org > Signed-off-by: Chris Mason > [ david: simplify description ] > Signed-off-by: David Hildenbrand (Arm) > --- Matches zap_nonpresent_ptes. Reviewed-by: Dev Jain > mm/huge_memory.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index eda020dd6e33f..1b50cc2b35351 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2493,7 +2493,7 @@ static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) > static void zap_huge_pmd_folio(struct mm_struct *mm, struct vm_area_struct *vma, > pmd_t pmdval, struct folio *folio, bool is_present) > { > - const bool is_device_private = folio_is_device_private(folio); > + const bool is_device_private = !is_present && pmd_is_device_private_entry(pmdval); > > /* Transfer young+dirty while the folio is still mapped. */ > if (is_present && !folio_test_anon(folio)) { >