From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1B0E1393DE2 for ; Wed, 13 May 2026 19:25:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778700354; cv=none; b=MZDiEnoRbnNXBPghoEEBifueRCRHc2PFOmARI7WQtPKwiH6zYENWi6Fx0iarXQ9RYd7Gi0sZemUSOgm33kirFCHuAc2OIUHb3X7hPPZKox6tPO3NSHLW7riztF5FCgcfyj0J7bRjGzVKpp/jhtcz+0YSR7lZ/3UITmj8rixN2qU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778700354; c=relaxed/simple; bh=dcHEedjcbYTa5ji+5U3BtpK3fMkNmMQxYIMOByi+CyQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=DZHsm+uNRZ6yQR3c9b9DXxiegBvcjGsvfKuGl5aJLCdVvPyOZiYI2xItIK1z9cH2HsZYh1lOfKgyY1JQQLf1hch4K7jpXNL1RM4iH9dDPfVhbI9qH57cxPOQO4CEQGg3X2XpHXPPleyR33K1/LnMkTbxNIpXJ53gTCmQ5SjBHQE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tHkXzZsp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tHkXzZsp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8B34C19425; Wed, 13 May 2026 19:25:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778700353; bh=dcHEedjcbYTa5ji+5U3BtpK3fMkNmMQxYIMOByi+CyQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=tHkXzZspy1pC3ShHZU8mgjSCvF2w5H8Z92G8Y/mWeEPsw2OPZlCNEhGu1C3N9DyBE np57+GVHz7TxM0Y5NR0O0Zrxcnrc8GC+1VXGdIRhJKpxff4NPicmJmYJzS/d6si0kz DeIHLUFmRWGYkvHFOOuHzqiztC4vsGi60JMHKH8OP1QFfXs8TgPgRnOVQS15NwxcwF Zx82scCGcLq+IsyC6VnesVfsvEH7qrQWAz04PsiBgSykZ63t7DeV7VusdxS5dTf8jT BYFJnNOR3Q8tW+qQpqnjPoriaYQZ7VFKO+Z/HvSMPYrVzXYl3ecjmcz8noJMvvHxzY sU+gCehLSL0Ug== Message-ID: Date: Wed, 13 May 2026 21:25:42 +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 04/13] mm/huge_memory: move softleaf_to_folio() inside migration branch To: Usama Arif , Andrew Morton , chrisl@kernel.org, kasong@tencent.com, ljs@kernel.org, ziy@nvidia.com Cc: bhe@redhat.com, willy@infradead.org, youngjun.park@lge.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, alex@ghiti.fr, kas@kernel.org, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, npache@redhat.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, Vlastimil Babka , lance.yang@linux.dev, linux-kernel@vger.kernel.org, nphamcs@gmail.com, shikemeng@huaweicloud.com, kernel-team@meta.com References: <20260427100553.2754667-1-usama.arif@linux.dev> <20260427100553.2754667-5-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 4/27/26 12:01, Usama Arif wrote: > change_non_present_huge_pmd() calls softleaf_to_folio() unconditionally > at the top of the function. softleaf_to_folio() extracts a PFN from > the entry and converts it to a folio pointer, which is only meaningful > for migration and device_private entries that encode a real PFN. > > A swap entry encodes a swap offset instead, so softleaf_to_folio() > would produce a bogus pointer and crash on mprotect() when a PMD swap > entry is present. > > Move the call into the migration_write branch where the folio is > actually used, so the function is safe for any non-present PMD type. > > 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 49da0746b8ca..d82a19b5e276 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2619,11 +2619,12 @@ static void change_non_present_huge_pmd(struct mm_struct *mm, > bool uffd_wp_resolve) > { > softleaf_t entry = softleaf_from_pmd(*pmd); > - const struct folio *folio = softleaf_to_folio(entry); > pmd_t newpmd; > > VM_WARN_ON(!pmd_is_valid_softleaf(*pmd)); > if (softleaf_is_migration_write(entry)) { > + const struct folio *folio = softleaf_to_folio(entry); > + > /* > * A protection check is difficult so > * just be safe and disable write Right, and the folio is only required on that path Acked-by: David Hildenbrand (Arm) -- Cheers, David