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 D9ABC3AEF2E; Mon, 27 Apr 2026 09:02:56 +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=1777280576; cv=none; b=u+z/XBOhRad8VrX4MPHs/s6xEm78dn1Lm65pfc9wWX92SMJKEz0inBZ79Jp6Y1WGGuUshewcWlsJCllFHbyNIxPMNFC45ASsQ6ZZ6SV9FdrrOv3j6oTpn3LjR4eMYBj3qp8Pk9uachLnlbKa//0LmMA98mkaoXb/Hwe6c59uMkU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777280576; c=relaxed/simple; bh=wy/P39pQu9CaZ8geWArqNl3zzbwhV+vR+8sJLe05890=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=U2jDVjpZneJhScQk6DgRVnbuDHd8ACtYYEDXZn0jYENUr0eAi6V1TG/3aYcpvSHv5szWdKSqgF2/QR9s06ECRWj4ZmNQ6sHFEdklad9hnh2ZBfJrrhDuEomTq+Q8HnCt7Cy336kX20ZmzsQFIP8XRND1v2XJA8VAX7oIQGnGfKY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=R7OC+bA9; 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="R7OC+bA9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1ADDC2BCB8; Mon, 27 Apr 2026 09:02:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777280576; bh=wy/P39pQu9CaZ8geWArqNl3zzbwhV+vR+8sJLe05890=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=R7OC+bA99ctkDyeRAb0p7Lgp2eukG7MR2xNPuMwyaYvUtoSOole8/rtRG50kNqGgg qwCzQ4prrx3lS75jyF70qfCYRg24/RsNKGyLNAJQehTk8TxxFqVJpXKvnM2DNQn2Pz TsKcQQITzo+ejHHF5etfd7/QVHr7Q9KdzJOyA28sTKll7Xe5suu5sylKc3NEQmOsLl UybVepF43lh5cxDUpcW0E7OzYK9MKD5almH+qNP1ANsXefb9KHU98ExrQUqUrHWKJH dalubLruZlmy9oNt78mDSnLPsbw5t/oocDg2uv9qFalsyscYLElLE75eIGRY1iB7hd KH6GIgM4UrbHg== Message-ID: <69c4c12c-7cdc-4a17-9eb7-6fb1a61f9834@kernel.org> Date: Mon, 27 Apr 2026 11:02:50 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/page_vma_mapped_walk: add missing pgtable entry accessors To: Alexander Gordeev , Andrew Morton , Lorenzo Stoakes Cc: Gerald Schaefer , Heiko Carstens , Vasily Gorbik , linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260427052000.196402-1-agordeev@linux.ibm.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 On 4/27/26 07:20, Alexander Gordeev wrote: > Convert pgtable direct entry dereferences to the corresponding > pXdp_get() accessors. Use ptep_get_lockless() variant for PTE > reads when no lock is taken. > > Signed-off-by: Alexander Gordeev > --- > mm/page_vma_mapped.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c > index b38a1d00c971..a4520bb10d2a 100644 > --- a/mm/page_vma_mapped.c > +++ b/mm/page_vma_mapped.c > @@ -41,7 +41,7 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw, pmd_t *pmdvalp, > if (!pvmw->pte) > return false; > > - ptent = ptep_get(pvmw->pte); > + ptent = ptep_get_lockless(pvmw->pte); > > if (pte_none(ptent)) { > return false; > @@ -219,17 +219,17 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) > restart: > do { > pgd = pgd_offset(mm, pvmw->address); > - if (!pgd_present(*pgd)) { > + if (!pgd_present(pgdp_get(pgd))) { > step_forward(pvmw, PGDIR_SIZE); > continue; > } > p4d = p4d_offset(pgd, pvmw->address); > - if (!p4d_present(*p4d)) { > + if (!p4d_present(p4dp_get(p4d))) { > step_forward(pvmw, P4D_SIZE); > continue; > } > pud = pud_offset(p4d, pvmw->address); > - if (!pud_present(*pud)) { > + if (!pud_present(pudp_get(pud))) { > step_forward(pvmw, PUD_SIZE); > continue; Wasn't there a problem with folded page tables, where we would no longer be able to optimize out the folded page table accesses? I thought we discussed ways to resolve that. Let me dig ... -- Cheers, David