Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754004Ab3IFO7e (ORCPT ); Fri, 6 Sep 2013 10:59:34 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:21284 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752866Ab3IFO7c (ORCPT ); Fri, 6 Sep 2013 10:59:32 -0400 From: Boris Ostrovsky To: stefano.stabellini@eu.citrix.com, david.vrabel@citrix.com, konrad.wilk@oracle.com Cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, Boris Ostrovsky Subject: [PATCH] xen/p2m: Don't call get_balloon_scratch_page() twice, keep interrupts disabled for multicalls Date: Fri, 6 Sep 2013 11:00:46 -0400 Message-Id: <1378479646-12592-1-git-send-email-boris.ostrovsky@oracle.com> X-Mailer: git-send-email 1.8.3.1 X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1965 Lines: 57 m2p_remove_override() calls get_balloon_scratch_page() in MULTI_update_va_mapping() even though it already has pointer to this page from the earlier call (in scratch_page). This second call doesn't have a matching put_balloon_scratch_page() thus not restoring preempt count back. (Also, there is no put_balloon_scratch_page() in the error path.) In addition, the second multicall uses __xen_mc_entry() which does not disable interrupts. Rearrange xen_mc_* calls to keep interrupts off while performing multicalls. Signed-off-by: Boris Ostrovsky --- arch/x86/xen/p2m.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 0d4ec35..8b901e8 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -990,10 +990,13 @@ int m2p_remove_override(struct page *page, printk(KERN_WARNING "m2p_remove_override: " "pfn %lx mfn %lx, failed to modify kernel mappings", pfn, mfn); + put_balloon_scratch_page(); return -1; } - mcs = xen_mc_entry( + xen_mc_batch(); + + mcs = __xen_mc_entry( sizeof(struct gnttab_unmap_and_replace)); unmap_op = mcs.args; unmap_op->host_addr = kmap_op->host_addr; @@ -1003,12 +1006,11 @@ int m2p_remove_override(struct page *page, MULTI_grant_table_op(mcs.mc, GNTTABOP_unmap_and_replace, unmap_op, 1); - xen_mc_issue(PARAVIRT_LAZY_MMU); - mcs = __xen_mc_entry(0); MULTI_update_va_mapping(mcs.mc, scratch_page_address, - pfn_pte(page_to_pfn(get_balloon_scratch_page()), + pfn_pte(page_to_pfn(scratch_page), PAGE_KERNEL_RO), 0); + xen_mc_issue(PARAVIRT_LAZY_MMU); kmap_op->host_addr = 0; -- 1.8.3.1 -- 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/