From nobody Tue Feb 10 01:59:32 2026 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.12]) (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 27C53264614; Sun, 11 Jan 2026 20:59:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768165158; cv=none; b=UYS/JfVoGQqjzsYgU2Rh9w3xlqOPVNt058g3kjx/ZtFtklOeYTIAKmPvNcx8q1srOBxrFVLREdnmn9dIdiTpC1qD9LISXo1AM1VurcaNC9ugreDUOJum/GkcJaa3Xg2/Wok9R4P88R3pePB1wApizh/KxBRQ/3ifkQ3FAANpOcU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768165158; c=relaxed/simple; bh=LNpnDim8q3+dLb7XU5TehbNGB6MpSqAnHM9U6qmRx90=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dgIkb/EhHRdp4UV/08AfYmrxtVb42FS+giutHK24B3f/KKjdRiM2dIVzYI34U2KSUBCG9qNi1Qb4neT0dEBvzAJ5AoZoRdPmGsp3rYrdrxpjQS8B9G0s8mY/zUyUFi1Wbbn8MA1yuNTtK2EdJADAichFEFyvW6jkbpNdbSW5iHc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=EPnGEHUE; arc=none smtp.client-ip=198.175.65.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="EPnGEHUE" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1768165156; x=1799701156; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=LNpnDim8q3+dLb7XU5TehbNGB6MpSqAnHM9U6qmRx90=; b=EPnGEHUERnjl73tawdV+urbqr7P7cNjJskTEaWjQ0GS2aFK+7hZFd7oS QF9tERSTRtH99I4Q1srzSNVvuRF+y+nMZB9oe4co3yzX8PkaifCNk22Up 19XSTGFSO4QRfTQvIMLl7Rsbr/P/mDBdlx85QUkUPlBSiMosPsNwRL8Pp saDNyIWHsez5//mcI9YmKNqzwHA1Darm+XuhfN+miFSsi7su5HW9+kufa 9XysMiJAIxhZne6v9aeWbzh9pY7uryRFwAvSSyydnDymlHYhCxNU382e6 n0EN2Oal+HtQjbJLg7Z1Ae2Is4t+Ei6C12cP52Kh6gJOTcx/pSOaaabpg Q==; X-CSE-ConnectionGUID: r2pWd2k9Q6u6Twq7+XX8kg== X-CSE-MsgGUID: wNERepExSleyNKDw2Vl6Hg== X-IronPort-AV: E=McAfee;i="6800,10657,11668"; a="80904696" X-IronPort-AV: E=Sophos;i="6.21,219,1763452800"; d="scan'208";a="80904696" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jan 2026 12:59:16 -0800 X-CSE-ConnectionGUID: Bkff/IltSoKRlj2s67sD2g== X-CSE-MsgGUID: HR5Gkm0nQJKuc017WtcF5A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,219,1763452800"; d="scan'208";a="208419967" Received: from pgcooper-mobl3.ger.corp.intel.com (HELO fdugast-desk.home) ([10.245.245.11]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jan 2026 12:59:12 -0800 From: Francois Dugast To: intel-xe@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, Matthew Brost , Zi Yan , David Hildenbrand , Oscar Salvador , Andrew Morton , Balbir Singh , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Alistair Popple , linux-mm@kvack.org, linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, Francois Dugast Subject: [PATCH v4 2/7] mm/zone_device: Add free_zone_device_folio_prepare() helper Date: Sun, 11 Jan 2026 21:55:41 +0100 Message-ID: <20260111205820.830410-3-francois.dugast@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260111205820.830410-1-francois.dugast@intel.com> References: <20260111205820.830410-1-francois.dugast@intel.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 Content-Type: text/plain; charset="utf-8" From: Matthew Brost Add free_zone_device_folio_prepare(), a helper that restores large ZONE_DEVICE folios to a sane, initial state before freeing them. Compound ZONE_DEVICE folios overwrite per-page state (e.g. pgmap and compound metadata). Before returning such pages to the device pgmap allocator, each constituent page must be reset to a standalone ZONE_DEVICE folio with a valid pgmap and no compound state. Use this helper prior to folio_free() for device-private and device-coherent folios to ensure consistent device page state for subsequent allocations. Fixes: d245f9b4ab80 ("mm/zone_device: support large zone device private fol= ios") Cc: Zi Yan Cc: David Hildenbrand Cc: Oscar Salvador Cc: Andrew Morton Cc: Balbir Singh Cc: Lorenzo Stoakes Cc: Liam R. Howlett Cc: Vlastimil Babka Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Michal Hocko Cc: Alistair Popple Cc: linux-mm@kvack.org Cc: linux-cxl@vger.kernel.org Cc: linux-kernel@vger.kernel.org Suggested-by: Alistair Popple Signed-off-by: Matthew Brost Signed-off-by: Francois Dugast --- include/linux/memremap.h | 1 + mm/memremap.c | 55 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 56 insertions(+) diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 97fcffeb1c1e..88e1d4707296 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -230,6 +230,7 @@ static inline bool is_fsdax_page(const struct page *pag= e) =20 #ifdef CONFIG_ZONE_DEVICE void zone_device_page_init(struct page *page, unsigned int order); +void free_zone_device_folio_prepare(struct folio *folio); void *memremap_pages(struct dev_pagemap *pgmap, int nid); void memunmap_pages(struct dev_pagemap *pgmap); void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); diff --git a/mm/memremap.c b/mm/memremap.c index 39dc4bd190d0..375a61e18858 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -413,6 +413,60 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn) } EXPORT_SYMBOL_GPL(get_dev_pagemap); =20 +/** + * free_zone_device_folio_prepare() - Prepare a ZONE_DEVICE folio for free= ing. + * @folio: ZONE_DEVICE folio to prepare for release. + * + * ZONE_DEVICE pages/folios (e.g., device-private memory or fsdax-backed p= ages) + * can be compound. When freeing a compound ZONE_DEVICE folio, the tail pa= ges + * must be restored to a sane ZONE_DEVICE state before they are released. + * + * This helper: + * - Clears @folio->mapping and, for compound folios, clears each page's + * compound-head state (ClearPageHead()/clear_compound_head()). + * - Resets the compound order metadata (folio_reset_order()) and then + * initializes each constituent page as a standalone ZONE_DEVICE folio: + * * clears ->mapping + * * restores ->pgmap (prep_compound_page() overwrites it) + * * clears ->share (only relevant for fsdax; unused for device-priv= ate) + * + * If @folio is order-0, only the mapping is cleared and no further work is + * required. + */ +void free_zone_device_folio_prepare(struct folio *folio) +{ + struct dev_pagemap *pgmap =3D page_pgmap(&folio->page); + int order, i; + + VM_WARN_ON_FOLIO(!folio_is_zone_device(folio), folio); + + folio->mapping =3D NULL; + order =3D folio_order(folio); + if (!order) + return; + + folio_reset_order(folio); + + for (i =3D 0; i < (1UL << order); i++) { + struct page *page =3D folio_page(folio, i); + struct folio *new_folio =3D (struct folio *)page; + + ClearPageHead(page); + clear_compound_head(page); + + new_folio->mapping =3D NULL; + /* + * Reset pgmap which was over-written by + * prep_compound_page(). + */ + new_folio->pgmap =3D pgmap; + new_folio->share =3D 0; /* fsdax only, unused for device private */ + VM_WARN_ON_FOLIO(folio_ref_count(new_folio), new_folio); + VM_WARN_ON_FOLIO(!folio_is_zone_device(new_folio), new_folio); + } +} +EXPORT_SYMBOL_GPL(free_zone_device_folio_prepare); + void free_zone_device_folio(struct folio *folio) { struct dev_pagemap *pgmap =3D folio->pgmap; @@ -454,6 +508,7 @@ void free_zone_device_folio(struct folio *folio) case MEMORY_DEVICE_COHERENT: if (WARN_ON_ONCE(!pgmap->ops || !pgmap->ops->folio_free)) break; + free_zone_device_folio_prepare(folio); pgmap->ops->folio_free(folio, order); percpu_ref_put_many(&folio->pgmap->ref, nr); break; --=20 2.43.0