From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755269AbaCKSs3 (ORCPT ); Tue, 11 Mar 2014 14:48:29 -0400 Received: from smtp.citrix.com ([66.165.176.89]:46701 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752058AbaCKSs2 (ORCPT ); Tue, 11 Mar 2014 14:48:28 -0400 X-IronPort-AV: E=Sophos;i="4.97,632,1389744000"; d="scan'208";a="110337525" From: David Vrabel To: CC: , Andrew Morton , , Dietmar Hahn , David Vrabel Subject: [PATCHv2] mm/vmalloc: avoid soft lockup warnings when vunmap()'ing large ranges Date: Tue, 11 Mar 2014 18:40:23 +0000 Message-ID: <1394563223-5045-1-git-send-email-david.vrabel@citrix.com> X-Mailer: git-send-email 1.7.2.5 MIME-Version: 1.0 Content-Type: text/plain X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If vunmap() is used to unmap a large (e.g., 50 GB) region, it may take sufficiently long that it triggers soft lockup warnings. Add a cond_resched() into vunmap_pmd_range() so the calling task may be resheduled after unmapping each PMD entry. This is how zap_pmd_range() fixes the same problem for userspace mappings. All callers may sleep except for the APEI GHES driver (apei/ghes.c) which calls unmap_kernel_range_no_flush() from NMI and IRQ contexts. This driver only unmaps a single pages so don't call cond_resched() if the unmap doesn't cross a PMD boundary. Reported-by: Dietmar Hahn Signed-off-by: David Vrabel --- v2: don't call cond_resched() at the end of a PMD range. --- mm/vmalloc.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 0fdf968..1a8b162 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -75,6 +75,8 @@ static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end) if (pmd_none_or_clear_bad(pmd)) continue; vunmap_pte_range(pmd, addr, next); + if (next != end) + cond_resched(); } while (pmd++, addr = next, addr != end); } -- 1.7.2.5