Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753514AbbGUIE4 (ORCPT ); Tue, 21 Jul 2015 04:04:56 -0400 Received: from mga02.intel.com ([134.134.136.20]:63297 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750771AbbGUIEw (ORCPT ); Tue, 21 Jul 2015 04:04:52 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,514,1432623600"; d="scan'208";a="768174455" Message-ID: <55ADFC78.9070707@intel.com> Date: Tue, 21 Jul 2015 16:02:00 +0800 From: Pan Xinhui User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: "linux-kernel@vger.kernel.org" CC: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, bp@suse.de, toshi.kani@hp.com, jgross@suse.com, mcgrof@suse.com, "mnipxh@163.com" , "yanmin_zhang@linux.intel.com" Subject: [PATCH V2] x86/mm/pat: Do a small optimization and fix in reserve_memtype Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1993 Lines: 59 From: Pan Xinhui It's safe and more reasonable to unlock memtype_lock right after rbt_memtype_check_insert. It's not cool to call kfree, pr_info, etc with this lock held. So move spin_unlock a little ahead. memory_lock protects data stored in rb-tree, if *new* succeed to be stored into the rb-tree, we might hit panic. Because we access *new* in dprintk "cattr_name(new->type)". data stored in the rb-tree might be freed at any possbile time. It's abviously wrong to access such data without lock. So save new->type to actual_type, and use actual_type in dprintk. Signed-off-by: Pan Xinhui --- change from V1: fix an access of *new* without memtype_lock held. --- arch/x86/mm/pat.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 188e3e0..f3c49fa 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -538,22 +538,20 @@ int reserve_memtype(u64 start, u64 end, enum page_cache_mode req_type, new->type = actual_type; spin_lock(&memtype_lock); - err = rbt_memtype_check_insert(new, new_type); + actual_type = new->type; + spin_unlock(&memtype_lock); + if (err) { pr_info("x86/PAT: reserve_memtype failed [mem %#010Lx-%#010Lx], track %s, req %s\n", start, end - 1, cattr_name(new->type), cattr_name(req_type)); kfree(new); - spin_unlock(&memtype_lock); - return err; } - spin_unlock(&memtype_lock); - dprintk("reserve_memtype added [mem %#010Lx-%#010Lx], track %s, req %s, ret %s\n", - start, end - 1, cattr_name(new->type), cattr_name(req_type), + start, end - 1, cattr_name(actual_type), cattr_name(req_type), new_type ? cattr_name(*new_type) : "-"); return err; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/