From nobody Wed Dec 17 12:04:47 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 81B32202C27 for ; Fri, 21 Mar 2025 11:25:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742556315; cv=none; b=acBJgQKBBWl8tRdV3sF/KcCP+3R+Nh+I//UpndOxIhXaBHSnW2S0kpifBJRT7sH1uF8pBu+Hh+ntu2KneX7bGyRzJubfLIe9ZbiH9HENkTMr4IQ0mdLH1j+6Lw0M1+hDWY7TgOi8O+R3+tVIbvDa9MaHpm/XNMmDW2RAfWXDMs4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742556315; c=relaxed/simple; bh=jJntAIfVRU4t714r35ZhKF0V7tnY7tGFqkj4VRR2sUs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XnDB/LZx0Ud4UCv/eBjlydcS23LQww1J0c1xGlaJT5/QPiAeHBGAYix5azL2oQx5uyIlKlsrQb+/O9kcVj6+IISVO5E3bfsZdDwYQFoLKBw75iApAzoKyt6VqeSb4j/rT8J8lNIOwzbSC7fh2l1wRooxsBZwQObWGQG0utBBVbA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=LdOeBjF+; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LdOeBjF+" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1742556312; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3ULjzTuWq4KWWMz5FWBM7gDBkyDsf2B5DDVUjmTkqks=; b=LdOeBjF+VwE9Gl39gogjmn+MSCD3kYHdN1RQunE7nnml+qwtio7SaQlH2b+QIA9qKV+RvX Psde7GiJjNmC0IJlSEA4tl7cwY9bxJZqvHmJcKTh7cLuDCtk+WDwm8LiLoyCibLSGZEdWl W/hZsfylzLNGNSH5RpF8WChS/Hs2Vww= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-203-sWdaQcbIMZuU33p4OBIaMQ-1; Fri, 21 Mar 2025 07:25:09 -0400 X-MC-Unique: sWdaQcbIMZuU33p4OBIaMQ-1 X-Mimecast-MFC-AGG-ID: sWdaQcbIMZuU33p4OBIaMQ_1742556307 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2CD581945103; Fri, 21 Mar 2025 11:25:07 +0000 (UTC) Received: from hydra.redhat.com (unknown [10.44.34.21]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id A5F87180175B; Fri, 21 Mar 2025 11:25:01 +0000 (UTC) From: Jocelyn Falempe To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Ryosuke Yasuoka , Javier Martinez Canillas , Wei Yang , Andrew Morton , David Hildenbrand , John Ogness , Thomas Gleixner , linux-mm@kvack.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: Jocelyn Falempe , Simona Vetter Subject: [PATCH v2 1/2] mm/kmap: Add kmap_local_page_try_from_panic() Date: Fri, 21 Mar 2025 12:16:55 +0100 Message-ID: <20250321112436.1739876-2-jfalempe@redhat.com> In-Reply-To: <20250321112436.1739876-1-jfalempe@redhat.com> References: <20250321112436.1739876-1-jfalempe@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Content-Type: text/plain; charset="utf-8" kmap_local_page() can be unsafe to call from a panic handler, if CONFIG_HIGHMEM is set, and the page is in the highmem zone. So add kmap_local_page_try_from_panic() to handle this case. Suggested-by: Simona Vetter Signed-off-by: Jocelyn Falempe --- include/linux/highmem-internal.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-inter= nal.h index dd100e849f5e0..5d089b0ca56de 100644 --- a/include/linux/highmem-internal.h +++ b/include/linux/highmem-internal.h @@ -73,6 +73,13 @@ static inline void *kmap_local_page(struct page *page) return __kmap_local_page_prot(page, kmap_prot); } =20 +static inline void *kmap_local_page_try_from_panic(struct page *page) +{ + if (!PageHighMem(page)) + return page_address(page); + return NULL; +} + static inline void *kmap_local_folio(struct folio *folio, size_t offset) { struct page *page =3D folio_page(folio, offset / PAGE_SIZE); @@ -180,6 +187,11 @@ static inline void *kmap_local_page(struct page *page) return page_address(page); } =20 +static inline void *kmap_local_page_try_from_panic(struct page *page) +{ + return page_address(page); +} + static inline void *kmap_local_folio(struct folio *folio, size_t offset) { return page_address(&folio->page) + offset; --=20 2.47.1