From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B76F4C021A0 for ; Mon, 17 Feb 2025 09:19:17 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 668D910E2D8; Mon, 17 Feb 2025 09:19:17 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="Wih1k7/y"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) by gabe.freedesktop.org (Postfix) with ESMTPS id 96F1B10E2D8 for ; Mon, 17 Feb 2025 09:19:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1739783956; x=1771319956; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=r/Gwa//y0lYyDEogMeLWJ5YpBC9J0mVmavf3W+j2hgU=; b=Wih1k7/ybcIW+SZDicd32yVtzP25I329BkUxc6QpZAs3VM2BakxWelJK Rs9ajBC1jsft0L6CbEpFrP1njyy65ehdlC6O0Ybt1VIDXdWcpT+9q4AJR tvV9wLd03bOpROQ+ZI4ftAE2fB8SC2NMLvIS6UgaeZZKotRHe0w/ALN1l rZZT19gT24PMgI/6VLNT8ElgkEInVS4FWRnmU02WjV+Cx5+cydnHEAZ2D yOyH4u07bt8bfymj3c95VLwYvJKvZY2bH34RfQhdHp7ocV40FOnCi4TY3 Q1w/C1MJNBMdeVXPit+L5hDOsbx7ipt126Ve4XwChMTi74BfZuoX4aZq5 g==; X-CSE-ConnectionGUID: z8UA8dtiSpqfNTga93+XvA== X-CSE-MsgGUID: SfbnZiC9QPCv5VyrC3BjWQ== X-IronPort-AV: E=McAfee;i="6700,10204,11347"; a="62928927" X-IronPort-AV: E=Sophos;i="6.13,292,1732608000"; d="scan'208";a="62928927" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Feb 2025 01:19:15 -0800 X-CSE-ConnectionGUID: X7ejjno2RTaQtvlQD1L2aA== X-CSE-MsgGUID: CnPUX6qNQFWlbEzKVIvWvg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,224,1728975600"; d="scan'208";a="118703860" Received: from pgcooper-mobl3.ger.corp.intel.com (HELO [10.245.244.174]) ([10.245.244.174]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Feb 2025 01:19:13 -0800 Message-ID: <43e7703d-b53d-4b68-b4d3-edcfea95e44e@intel.com> Date: Mon, 17 Feb 2025 09:19:11 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/3] drm/xe/userptr: fix EFAULT handling To: Matthew Brost Cc: intel-xe@lists.freedesktop.org, =?UTF-8?Q?Thomas_Hellstr=C3=B6m?= , stable@vger.kernel.org References: <20250214170527.272182-4-matthew.auld@intel.com> <20250214170527.272182-5-matthew.auld@intel.com> Content-Language: en-GB From: Matthew Auld In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On 15/02/2025 01:23, Matthew Brost wrote: > On Fri, Feb 14, 2025 at 05:05:29PM +0000, Matthew Auld wrote: >> Currently we treat EFAULT from hmm_range_fault() as a non-fatal error >> when called from xe_vm_userptr_pin() with the idea that we want to avoid >> killing the entire vm and chucking an error, under the assumption that >> the user just did an unmap or something, and has no intention of >> actually touching that memory from the GPU. At this point we have >> already zapped the PTEs so any access should generate a page fault, and >> if the pin fails there also it will then become fatal. >> >> However it looks like it's possible for the userptr vma to still be on >> the rebind list in preempt_rebind_work_func(), if we had to retry the >> pin again due to something happening in the caller before we did the >> rebind step, but in the meantime needing to re-validate the userptr and >> this time hitting the EFAULT. >> >> This might explain an internal user report of hitting: >> >> [ 191.738349] WARNING: CPU: 1 PID: 157 at drivers/gpu/drm/xe/xe_res_cursor.h:158 xe_pt_stage_bind.constprop.0+0x60a/0x6b0 [xe] >> [ 191.738551] Workqueue: xe-ordered-wq preempt_rebind_work_func [xe] >> [ 191.738616] RIP: 0010:xe_pt_stage_bind.constprop.0+0x60a/0x6b0 [xe] >> [ 191.738690] Call Trace: >> [ 191.738692] >> [ 191.738694] ? show_regs+0x69/0x80 >> [ 191.738698] ? __warn+0x93/0x1a0 >> [ 191.738703] ? xe_pt_stage_bind.constprop.0+0x60a/0x6b0 [xe] >> [ 191.738759] ? report_bug+0x18f/0x1a0 >> [ 191.738764] ? handle_bug+0x63/0xa0 >> [ 191.738767] ? exc_invalid_op+0x19/0x70 >> [ 191.738770] ? asm_exc_invalid_op+0x1b/0x20 >> [ 191.738777] ? xe_pt_stage_bind.constprop.0+0x60a/0x6b0 [xe] >> [ 191.738834] ? ret_from_fork_asm+0x1a/0x30 >> [ 191.738849] bind_op_prepare+0x105/0x7b0 [xe] >> [ 191.738906] ? dma_resv_reserve_fences+0x301/0x380 >> [ 191.738912] xe_pt_update_ops_prepare+0x28c/0x4b0 [xe] >> [ 191.738966] ? kmemleak_alloc+0x4b/0x80 >> [ 191.738973] ops_execute+0x188/0x9d0 [xe] >> [ 191.739036] xe_vm_rebind+0x4ce/0x5a0 [xe] >> [ 191.739098] ? trace_hardirqs_on+0x4d/0x60 >> [ 191.739112] preempt_rebind_work_func+0x76f/0xd00 [xe] >> >> Followed by NPD, when running some workload, since the sg was never >> actually populated but the vma is still marked for rebind when it should >> be skipped for this special EFAULT case. And from the logs it does seem >> like we hit this special EFAULT case before the explosions. >> > > It would be nice to verify if this fixes the bug report. Yes, reporter said it fixes it. Or at least the previous version did. See GSD-10562 if you are curious. Will re-phrase the commit message to make that clear. > >> v2 (MattB): >> - Move earlier >> >> Fixes: 521db22a1d70 ("drm/xe: Invalidate userptr VMA on page pin fault") >> Signed-off-by: Matthew Auld >> Cc: Matthew Brost > > Anyways, LGTM: > Reviewed-by: Matthew Brost Thanks. > >> Cc: Thomas Hellström >> Cc: # v6.10+ >> --- >> drivers/gpu/drm/xe/xe_vm.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c >> index 668b0bde7822..f36e2cc1d155 100644 >> --- a/drivers/gpu/drm/xe/xe_vm.c >> +++ b/drivers/gpu/drm/xe/xe_vm.c >> @@ -681,6 +681,18 @@ int xe_vm_userptr_pin(struct xe_vm *vm) >> err = xe_vma_userptr_pin_pages(uvma); >> if (err == -EFAULT) { >> list_del_init(&uvma->userptr.repin_link); >> + /* >> + * We might have already done the pin once already, but >> + * then had to retry before the re-bind happened, due >> + * some other condition in the caller, but in the >> + * meantime the userptr got dinged by the notifier such >> + * that we need to revalidate here, but this time we hit >> + * the EFAULT. In such a case make sure we remove >> + * ourselves from the rebind list to avoid going down in >> + * flames. >> + */ >> + if (!list_empty(&uvma->vma.combined_links.rebind)) >> + list_del_init(&uvma->vma.combined_links.rebind); >> >> /* Wait for pending binds */ >> xe_vm_lock(vm, false); >> -- >> 2.48.1 >>