From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.19]) (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 3FA903D75; Thu, 14 Mar 2024 00:37:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710376642; cv=none; b=jiljoG8y+13QjqxHeIa6DEhBPCP9BiSl5fGcTO1FC2d+CT2gNTBqSejYRL7VCz576e09sZWwI3TyXMP+TsKBUkjea59ggW9xyzjpmsG2+rW75PbH5otxi+JQU2xIlOCtNQgR30/ZxgTMzuQXr1JfjZQg63OQf1EYXeMG9QhEUIc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710376642; c=relaxed/simple; bh=/QlMMY4Hg9yaPdoSTOcaEY42ynVEhlurCMB1qau/fbs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=YdWsOFoRm9fP9z+rTqBXauvh3HuxnkpWyeWBWQBlHun6PjXtreGul6iDyz+kq4ssZ6xw+sxKLHFZ+QQiVoVRhGWlnn2t223yoAlM52W8UHVacI6vjLHYl0sD8h/BGk7PnLCbUKiYxRX3AVYX3u8hAsC2hd3DNL/N6IOTGbRXSAw= 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=NtVM7fZ7; arc=none smtp.client-ip=198.175.65.19 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="NtVM7fZ7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1710376641; x=1741912641; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=/QlMMY4Hg9yaPdoSTOcaEY42ynVEhlurCMB1qau/fbs=; b=NtVM7fZ73wU0gqAB5xSSQl3aIW2J8WvLGH/kVJr8pVSf1URZQ8eXAsqH QWkYJphA6diEPaBsdcwmmyG0pGTxOFI0pRO/UYgE2nugZQwDOncjhzx8o h+uiCelNV0iIFIWndGOVE3HjIlv4SZ8tRt4yi0acFzoEh2JxXV36b95P+ 4DwGoYw+wtUDZ1ifEqr999hR3dRuRZhkFlhHwglZf8J2lUC1KF2znYvme OKI+tR/axhlWoVZSnUskxbBK65HmIYTRWbFN1eKo9m4WlIfG5nCUqS2rd +UkBYfhdwusl9RWfe6qHbWUTM0iR1yfXMTUDusBdFX3zVUERym63Mfhc+ Q==; X-IronPort-AV: E=McAfee;i="6600,9927,11012"; a="5041966" X-IronPort-AV: E=Sophos;i="6.07,124,1708416000"; d="scan'208";a="5041966" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Mar 2024 17:37:20 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,124,1708416000"; d="scan'208";a="12189279" Received: from djiang5-mobl3.amr.corp.intel.com (HELO [10.212.112.230]) ([10.212.112.230]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Mar 2024 17:37:19 -0700 Message-ID: Date: Wed, 13 Mar 2024 17:37:18 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] dmaengine: idxd: Fix oops during rmmod on single-CPU platforms Content-Language: en-US To: Fenghua Yu , Vinod Koul Cc: dmaengine@vger.kernel.org, linux-kernel , Terrence Xu , "Zanussi, Tom" References: <20240313214031.1658045-1-fenghua.yu@intel.com> From: Dave Jiang In-Reply-To: <20240313214031.1658045-1-fenghua.yu@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/13/24 2:40 PM, Fenghua Yu wrote: > During the removal of the idxd driver, registered offline callback is > invoked as part of the clean up process. However, on systems with only > one CPU online, no valid target is available to migrate the > perf context, resulting in a kernel oops: > > BUG: unable to handle page fault for address: 000000000002a2b8 > #PF: supervisor write access in kernel mode > #PF: error_code(0x0002) - not-present page > PGD 1470e1067 P4D 0 > Oops: 0002 [#1] PREEMPT SMP NOPTI > CPU: 0 PID: 20 Comm: cpuhp/0 Not tainted 6.8.0-rc6-dsa+ #57 > Hardware name: Intel Corporation AvenueCity/AvenueCity, BIOS BHSDCRB1.86B.2492.D03.2307181620 07/18/2023 > RIP: 0010:mutex_lock+0x2e/0x50 > ... > Call Trace: > > __die+0x24/0x70 > page_fault_oops+0x82/0x160 > do_user_addr_fault+0x65/0x6b0 > __pfx___rdmsr_safe_on_cpu+0x10/0x10 > exc_page_fault+0x7d/0x170 > asm_exc_page_fault+0x26/0x30 > mutex_lock+0x2e/0x50 > mutex_lock+0x1e/0x50 > perf_pmu_migrate_context+0x87/0x1f0 > perf_event_cpu_offline+0x76/0x90 [idxd] > cpuhp_invoke_callback+0xa2/0x4f0 > __pfx_perf_event_cpu_offline+0x10/0x10 [idxd] > cpuhp_thread_fun+0x98/0x150 > smpboot_thread_fn+0x27/0x260 > smpboot_thread_fn+0x1af/0x260 > __pfx_smpboot_thread_fn+0x10/0x10 > kthread+0x103/0x140 > __pfx_kthread+0x10/0x10 > ret_from_fork+0x31/0x50 > __pfx_kthread+0x10/0x10 > ret_from_fork_asm+0x1b/0x30 > > > Fix the issue by preventing the migration of the perf context to an > invalid target. > > Fixes: 81dd4d4d6178 ("dmaengine: idxd: Add IDXD performance monitor support") > Reported-by: Terrence Xu > Tested-by: Terrence Xu > Signed-off-by: Fenghua Yu Cc: Tom Zanussi > --- > drivers/dma/idxd/perfmon.c | 9 +++------ > 1 file changed, 3 insertions(+), 6 deletions(-) > > diff --git a/drivers/dma/idxd/perfmon.c b/drivers/dma/idxd/perfmon.c > index fdda6d604262..5e94247e1ea7 100644 > --- a/drivers/dma/idxd/perfmon.c > +++ b/drivers/dma/idxd/perfmon.c > @@ -528,14 +528,11 @@ static int perf_event_cpu_offline(unsigned int cpu, struct hlist_node *node) > return 0; > > target = cpumask_any_but(cpu_online_mask, cpu); > - > /* migrate events if there is a valid target */ > - if (target < nr_cpu_ids) > + if (target < nr_cpu_ids) { > cpumask_set_cpu(target, &perfmon_dsa_cpu_mask); > - else > - target = -1; > - > - perf_pmu_migrate_context(&idxd_pmu->pmu, cpu, target); > + perf_pmu_migrate_context(&idxd_pmu->pmu, cpu, target); > + } > > return 0; > }