From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.21]) (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 4B1842EFD9C for ; Thu, 20 Nov 2025 23:08:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.21 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763680113; cv=none; b=BeSE06gMiuwia4Ci3iNZrMFFol1Kki/6eH2wGeQdJNG2ZLGzY6Yl9mkReRdNSnIS/Ik/c46r2lqE87sP59tR8BPndz9XAX/kI9N33Aky4N/bjjHHyTol7sRJxmyStssNIMpeFsgXgcHZ5dwc3XXki7LY/e4s9GhfaPMwCjX3B/U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763680113; c=relaxed/simple; bh=x2VAm+R3jcI1JiM4uWkT0rwamPlQO26XoY+4izZN9Gs=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=UJw94xXrIuLm+ZCrpCYc/OS/neTf2v6A2xWPdjaqD5GHQefM5V4fACtiPWgHJ+C8uUQgCAK/A1AWvTlJWS60PTg3olCDo9AfgBda57JpZA8u02mdv0LV52I83IS6BFj/XsKD2ffnJP4JertXnEN5E4TXSh1M3RS+fMpf8qlZ3TI= 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=nOaJGdes; arc=none smtp.client-ip=198.175.65.21 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="nOaJGdes" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1763680111; x=1795216111; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=x2VAm+R3jcI1JiM4uWkT0rwamPlQO26XoY+4izZN9Gs=; b=nOaJGdesE0YiFb4f/HkBojr2qo7wYo6Nm9+k6leHydYHnUrmeC15K4Vg tqiFHQ1rmEOMPC7QRIHxAEARCWr9wsGnOqnrcXpxwUsXFxfAKfzAgeZNg lkrWTxCu7ujD4AYeeCLD6sT2OEfAySxQ4fa4LJILOUbMZKd4RTL5wTJsl S2x27Qtgh8SE84IZLyef/2R/K7ex0YLD8SNFbCbrB9hzg4iRY/+1041bn QQwM6v+kIf1eDRym1vHIdMucdB3jpJBf05Nh3JUHXymXyB2BAb5qHnrPR +/S48MqjjFAWwEh1SreZ1KjuSNyI4kzr3UgxZemkyNwx6N5G2mujng/Bd w==; X-CSE-ConnectionGUID: BeJufgI4TUGgSNi9S6P57w== X-CSE-MsgGUID: XnsWskhJQWaMyK0YO8iBlw== X-IronPort-AV: E=McAfee;i="6800,10657,11619"; a="65699766" X-IronPort-AV: E=Sophos;i="6.20,214,1758610800"; d="scan'208";a="65699766" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by orvoesa113.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Nov 2025 15:08:31 -0800 X-CSE-ConnectionGUID: v6v9bqX9QrmQXgFYt1OkiA== X-CSE-MsgGUID: MjETsGsXRL2vrmvo3mUyBQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.20,214,1758610800"; d="scan'208";a="191364901" Received: from lstrano-desk.jf.intel.com ([10.54.39.91]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Nov 2025 15:08:29 -0800 From: Matthew Brost To: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org Cc: Andrew Morton , David Hildenbrand , Zi Yan , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Oscar Salvador , Lorenzo Stoakes , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , Ralph Campbell , =?UTF-8?q?Mika=20Penttil=C3=A4?= , Francois Dugast , Balbir Singh Subject: [PATCH v2 1/2] fixup: mm/migrate_device: handle partially mapped folios during Date: Thu, 20 Nov 2025 15:08:24 -0800 Message-Id: <20251120230825.181072-1-matthew.brost@intel.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Splitting a partially mapped folio caused a regression in the Intel Xe SVM test suite in the mremap section, resulting in the following stack trace: NFO: task kworker/u65:2:1642 blocked for more than 30 seconds. [ 212.624286] Tainted: G S W 6.18.0-rc6-xe+ #1719 [ 212.638288] Workqueue: xe_page_fault_work_queue xe_pagefault_queue_work [xe] [ 212.638323] Call Trace: [ 212.638324] [ 212.638325] __schedule+0x4b0/0x990 [ 212.638330] schedule+0x22/0xd0 [ 212.638331] io_schedule+0x41/0x60 [ 212.638333] migration_entry_wait_on_locked+0x1d8/0x2d0 [ 212.638336] ? __pfx_wake_page_function+0x10/0x10 [ 212.638339] migration_entry_wait+0xd2/0xe0 [ 212.638341] hmm_vma_walk_pmd+0x7c9/0x8d0 [ 212.638343] walk_pgd_range+0x51d/0xa40 [ 212.638345] __walk_page_range+0x75/0x1e0 [ 212.638347] walk_page_range_mm+0x138/0x1f0 [ 212.638349] hmm_range_fault+0x59/0xa0 [ 212.638351] drm_gpusvm_get_pages+0x194/0x7b0 [drm_gpusvm_helper] [ 212.638354] drm_gpusvm_range_get_pages+0x2d/0x40 [drm_gpusvm_helper] [ 212.638355] __xe_svm_handle_pagefault+0x259/0x900 [xe] [ 212.638375] ? update_load_avg+0x7f/0x6c0 [ 212.638377] ? update_curr+0x13d/0x170 [ 212.638379] xe_svm_handle_pagefault+0x37/0x90 [xe] [ 212.638396] xe_pagefault_queue_work+0x2da/0x3c0 [xe] [ 212.638420] process_one_work+0x16e/0x2e0 [ 212.638422] worker_thread+0x284/0x410 [ 212.638423] ? __pfx_worker_thread+0x10/0x10 [ 212.638425] kthread+0xec/0x210 [ 212.638427] ? __pfx_kthread+0x10/0x10 [ 212.638428] ? __pfx_kthread+0x10/0x10 [ 212.638430] ret_from_fork+0xbd/0x100 [ 212.638433] ? __pfx_kthread+0x10/0x10 [ 212.638434] ret_from_fork_asm+0x1a/0x30 [ 212.638436] The issue appears to be that migration PTEs are not properly removed after a split due to incorrect retry handling after a split failure or success. Upon failure, collect a skip, and upon success, continue the collection from the current position in the sequence. Also, while here, fix migrate_vma_split_folio to only lock the new fault folio if it is different from the original fault folio (i.e., it’s possible the original fault folio is not the same as the one being split). Cc: Andrew Morton Cc: David Hildenbrand Cc: Zi Yan Cc: Joshua Hahn Cc: Rakie Kim Cc: Byungchul Park Cc: Gregory Price Cc: Ying Huang Cc: Alistair Popple Cc: Oscar Salvador Cc: Lorenzo Stoakes Cc: Baolin Wang Cc: Liam R. Howlett Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lyude Paul Cc: Danilo Krummrich Cc: David Airlie Cc: Simona Vetter Cc: Ralph Campbell Cc: Mika Penttilä Cc: Francois Dugast Cc: Balbir Singh Signed-off-by: Matthew Brost --- This fixup should be squashed into the patch "mm/migrate_device: handle partially mapped folios during" in mm/mm-unstable --- mm/migrate_device.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/mm/migrate_device.c b/mm/migrate_device.c index fa42d2ebd024..4506e96dcd20 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -110,8 +110,10 @@ static int migrate_vma_split_folio(struct folio *folio, folio_unlock(folio); folio_put(folio); } else if (folio != new_fault_folio) { - folio_get(new_fault_folio); - folio_lock(new_fault_folio); + if (new_fault_folio != fault_folio) { + folio_get(new_fault_folio); + folio_lock(new_fault_folio); + } folio_unlock(folio); folio_put(folio); } @@ -266,10 +268,11 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, return 0; } - ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); + ptep = pte_offset_map_lock(mm, pmdp, start, &ptl); if (!ptep) goto again; arch_enter_lazy_mmu_mode(); + ptep += (addr - start) / PAGE_SIZE; for (; addr < end; addr += PAGE_SIZE, ptep++) { struct dev_pagemap *pgmap; @@ -351,16 +354,18 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, if (folio && folio_test_large(folio)) { int ret; + arch_leave_lazy_mmu_mode(); pte_unmap_unlock(ptep, ptl); ret = migrate_vma_split_folio(folio, migrate->fault_page); if (ret) { - ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); - goto next; + if (unmapped) + flush_tlb_range(walk->vma, start, end); + + return migrate_vma_collect_skip(addr, end, walk); } - addr = start; goto again; } mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE; -- 2.34.1