From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 68502C43327 for ; Thu, 2 Jul 2026 15:32:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=K6BXeY1SuXwf6XNLIwmaGIUYMIBQYDCncKaEEO6QK5o=; b=UHQC0XbS+dSPuEsKQyBrNcboTe UJg8xLSY2Ql5WwaPDTSVQ4MPkJy+25HYiir1DRjz28CTkMBlzLaPVNadI2PsdXjSBz3CAE9uIljV6 EAL6MEXF+sKlQWQeHvG2+DjEk5nRbrjsfh6VlkKv77baUtvCjV7AnTlR9kVj2WskgNgp6b91u9uxX +uUWowpLCp+LyHMTewtH1j2Nq2o8Tiofrdf55/AoaeSnajPAFf2bgkaQimzSLj3wjDbdsdEjerMVc Ndwed6Ggqh/vAUoIeuDKvEfQnfK1M5V5SxtTeS94HIiXmk7crG4H2uUMfNwg+1bor4snFhXliGvER 0grgdb9Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wfJP3-00000004p2y-0ToK; Thu, 02 Jul 2026 15:32:37 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wfJP2-00000004p2U-1Zh4 for linux-arm-kernel@lists.infradead.org; Thu, 02 Jul 2026 15:32:36 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id CD853601EC; Thu, 2 Jul 2026 15:32:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9271B1F000E9; Thu, 2 Jul 2026 15:32:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783006355; bh=K6BXeY1SuXwf6XNLIwmaGIUYMIBQYDCncKaEEO6QK5o=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=RrfHMTc6WpFqBIjgT3gKXJn9UOPoDGOmQjbssocbfy19iPWhzvzZOmDc2uft1nTM/ G4mcZQYbMHXOrHseVJCkoj98KH/X/o931BKZVuGiz0o8Sx08jvdPQC00UZ01xGkDe0 ANjXIGZ1epVEZa/j/Wi5/7tIdg3oTErIEWdOWc+QRX0pwGPIq40tRn1qFM7FYFQXAY zHmSlxTopOz0AVxljNc3xjqdmrClnJqiS3j5wBtfJ8Wu0IrfTdc0iUeT+sEnWbwR2S iMJSwCbMr6porAjAWR31wA7EQRiBrXaHFYTaVgyinEnl24OpPzs/7aTh/Q2g3PTBmX HzG8A1gFURwlg== Message-ID: <00d6e0fb-dcba-45d5-98c0-f5ed81604ca0@kernel.org> Date: Thu, 2 Jul 2026 17:32:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/6] mm/rmap: use huge_ptep_get() in try_to_unmap_one() To: Dev Jain , muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org Cc: riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, kas@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcampbell@nvidia.com, apopple@nvidia.com, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, j-nomura@ce.jp.nec.com, nao.horiguchi@gmail.com, ak@linux.intel.com, mel@csn.ul.ie, pfalcato@suse.de, jpoimboe@kernel.org, dave.hansen@intel.com, tglx@kernel.org, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, stable@vger.kernel.org References: <20260702051341.126509-1-dev.jain@arm.com> <20260702051341.126509-3-dev.jain@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 7/2/26 07:13, Dev Jain wrote: > try_to_unmap_one() handles hugetlb folios when memory failure needs > to replace a poisoned hugetlb mapping with a hwpoison entry. In that > case page_vma_mapped_walk() returns the pte pointer to the hugetlb folio > in pvmw.pte, but the code reads it with ptep_get(). > > On arches which provide their own huge_ptep_get() to dereference a huge > pte pointer, accessing via ptep_get() would cause pte_pfn(), pte_present() > etc to misbehave. > > It is not clear whether this has a trivially visible effect to userspace. > > Just use huge_ptep_get() for dereferencing a huge pte pointer. > > Fixes: c7ab0d2fdc84 ("mm: convert try_to_unmap_one() to use page_vma_mapped_walk()") > Cc: stable@vger.kernel.org > Reported-by: David Hildenbrand > Signed-off-by: Dev Jain > --- > include/linux/hugetlb.h | 3 +++ > mm/rmap.c | 16 ++++++++++------ > 2 files changed, 13 insertions(+), 6 deletions(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 2abaf99321e90..fdb7bdf7645c5 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -1261,6 +1261,9 @@ static inline void hugetlb_count_sub(long l, struct mm_struct *mm) > { > } > > +pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, > + pte_t *ptep); Two tabs, or just in a single line. If others prefer a stub, I don't care. This here is shortest to let the linker bail out. > + > static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, > unsigned long addr, pte_t *ptep) > { > diff --git a/mm/rmap.c b/mm/rmap.c > index 1c77d5dc06e9f..aa8a254efaecc 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -2095,11 +2095,16 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, > /* Unexpected PMD-mapped THP? */ > VM_BUG_ON_FOLIO(!pvmw.pte, folio); > > - /* > - * Handle PFN swap PTEs, such as device-exclusive ones, that > - * actually map pages. > - */ That comment now actually belongs above the pte_present() check below. -- Cheers, David