From nobody Sun Feb 8 09:10:24 2026 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6952F2F9985 for ; Tue, 20 Jan 2026 09:19:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768900776; cv=none; b=Qj4YIixvRzGj5ZLd3UQI0J3X01QI2QvLpD80Xk0op2r6VYiTcS2EPs01PF4y8duCJt3H28+4700n6JQNcbGYmfbD7dSQXsFEbXZBQdFmobH7O9y3XoK9lF0PHuWtSTCVTi4Q5v/tANRMF2d8VU9cVOZULSc7+urwJVDEMIJysmc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768900776; c=relaxed/simple; bh=PHSBhI8m1+DcVKrA3sW1DexLR5nKSBb/1XCqhctyF0Q=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=X06YH8PE2zdL0/8JchRGyhtWoIQU/PvuQ16Zem7AieZ9I0YYY7E7alI7T9uWUSMHno1gbNJWcq1bwk9iiExkd+6hULWdJVPj05Px/qIFs+9pRj0LGRrPZUvI+xt1GkEdryubt0guVqj8rumDNpWOdrkZX6vPUY+GxBHoP5yHSkU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--smostafa.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=TMC8Tria; arc=none smtp.client-ip=209.85.128.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--smostafa.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="TMC8Tria" Received: by mail-wm1-f74.google.com with SMTP id 5b1f17b1804b1-47d62cc05daso35497675e9.3 for ; Tue, 20 Jan 2026 01:19:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1768900773; x=1769505573; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=X0gVSCji/amPzVpAugMKA+gNQb8Vp/dW4y1DM63bYO0=; b=TMC8TriayohpgXeZqQmISsBrPaCOHIOAYbLbf1UoahMD6hZSLDdHkDIWmZxhNujbyf jIon9ivtqYZyAc//x2Vekbe12v8DYmTGa8veBxvtvSgwb2mr2KUzboKIY/o/LSiRNWzn 9WxJkTfk2XEh/uNgdtGqUSe6aIFBO363voS3+jjOufU6VwxTkbKwpDtNuvWnewVtuoyE CyrXO9KGuXZz2mevlm/OhEuWd/niO7+il+DLJT5TuZl/yrtsCiltUu7VKOE6dVl4ulqV 3kNkPAhhe6CWX6PvVdU3M+46o8sNCZ2BTOdNuvuAvhAMrgrC4FVf4q49B3k86oU4niGG X7TQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1768900773; x=1769505573; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=X0gVSCji/amPzVpAugMKA+gNQb8Vp/dW4y1DM63bYO0=; b=o8Ud5H1kV47423A7pK3aAcEll8iS3qKCJx75WXNs6zWndlV4aT6PfNnRHtf/HOgaOc HraIyZUaw5WhlGq3K8osjnCl1NfyRt5X540uMWfgUmnoNzn51DssSxUdvCsJV4JOEhlu KCJMh1xbaklc361AvBFcoPl4l0H69F9dsFJJejMNXqV5wIkZBcORvst0tJGUC0Ly7985 t0KMTS0bCFYbtMS6a2/gtlr3xD96m+AMVi8rzRPbhdXuIJvU/eDEs03rPYeAgjhnaYCt e4ZjHL0z8mxN4JVOUJ09Sn/NxUE0R0869bidiRWTsJYSfndp9jfQkORKDQx7sjHWfBR3 tAhA== X-Forwarded-Encrypted: i=1; AJvYcCWNgc2caNZ5Kj+BmuCv9X+rH1N4szITL1buswrQEaPFACnoGrPfO/BSCMKoCMvMWCZ8ervjT0nnI4ybZwc=@vger.kernel.org X-Gm-Message-State: AOJu0YzmcPfMyx0O5ooRA5zQKC3gc20ugEbt1x2w99c574nfX2NU9+ek B1XPNL/AGya77AjYiSbDq/BheZ6hXfOr/aAg7H7I9BbCpHwywG0cGZoEKVv56sjlLdVm/XLrxf4 6/J3HbviLtz8+wA== X-Received: from wrbgz21.prod.google.com ([2002:a05:6000:4815:b0:435:64f6:e987]) (user=smostafa job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:6099:b0:47e:e952:86ca with SMTP id 5b1f17b1804b1-4803e79b81dmr13478605e9.2.1768900772778; Tue, 20 Jan 2026 01:19:32 -0800 (PST) Date: Tue, 20 Jan 2026 09:19:25 +0000 In-Reply-To: <20260120091926.670155-1-smostafa@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260120091926.670155-1-smostafa@google.com> X-Mailer: git-send-email 2.52.0.457.g6b5491de43-goog Message-ID: <20260120091926.670155-2-smostafa@google.com> Subject: [PATCH v2 1/2] mm/page_ext: Add page_ext_get_from_phys() From: Mostafa Saleh To: linux-mm@kvack.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Cc: corbet@lwn.net, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, akpm@linux-foundation.org, vbabka@suse.cz, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, xiaqinxin@huawei.com, baolu.lu@linux.intel.com, rdunlap@infradead.org, Mostafa Saleh Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The IOMMU code operates on physical addresses which can be outside of system RAM. Add a new function page_ext_get_from_phys() to abstract the logic of checking the address and returning the page_ext. Signed-off-by: Mostafa Saleh Acked-by: Vlastimil Babka --- include/linux/page_ext.h | 6 ++++++ mm/page_ext.c | 23 +++++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h index 76c817162d2f..61e876e255e8 100644 --- a/include/linux/page_ext.h +++ b/include/linux/page_ext.h @@ -93,6 +93,7 @@ static inline bool page_ext_iter_next_fast_possible(unsig= ned long next_pfn) #endif =20 extern struct page_ext *page_ext_get(const struct page *page); +extern struct page_ext *page_ext_from_phys(phys_addr_t phys); extern void page_ext_put(struct page_ext *page_ext); extern struct page_ext *page_ext_lookup(unsigned long pfn); =20 @@ -215,6 +216,11 @@ static inline struct page_ext *page_ext_get(const stru= ct page *page) return NULL; } =20 +static inline struct page_ext *page_ext_from_phys(phys_addr_t phys) +{ + return NULL; +} + static inline void page_ext_put(struct page_ext *page_ext) { } diff --git a/mm/page_ext.c b/mm/page_ext.c index 297e4cd8ce90..e2e92bd27ebd 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -538,6 +538,29 @@ struct page_ext *page_ext_get(const struct page *page) return page_ext; } =20 +/** + * page_ext_from_phys() - Get the page_ext structure for a physical addres= s. + * @phys: The physical address to query. + * + * This function safely gets the `struct page_ext` associated with a given + * physical address. It performs validation to ensure the address correspo= nds + * to a valid, online struct page before attempting to access it. + * It returns NULL for MMIO, ZONE_DEVICE, holes and offline memory. + * + * Return: NULL if no page_ext exists for this physical address. + * Context: Any context. Caller may not sleep until they have called + * page_ext_put(). + */ +struct page_ext *page_ext_from_phys(phys_addr_t phys) +{ + struct page *page =3D pfn_to_online_page(__phys_to_pfn(phys)); + + if (!page) + return NULL; + + return page_ext_get(page); +} + /** * page_ext_put() - Working with page extended information is done. * @page_ext: Page extended information received from page_ext_get(). --=20 2.52.0.457.g6b5491de43-goog