From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753894AbaIHNVr (ORCPT ); Mon, 8 Sep 2014 09:21:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41321 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753121AbaIHNVq (ORCPT ); Mon, 8 Sep 2014 09:21:46 -0400 From: Vitaly Kuznetsov To: xen-devel@lists.xenproject.org Cc: Konrad Rzeszutek Wilk , David Vrabel , Roger Pau Monne , Andrew Jones , linux-kernel@vger.kernel.org Subject: [PATCH] xen/blkback: unmap all persistent grants when frontend gets disconnected Date: Mon, 8 Sep 2014 15:21:33 +0200 Message-Id: <1410182493-23638-1-git-send-email-vkuznets@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org blkback does not unmap persistent grants when frontend goes to Closed state (e.g. when blkfront module is being removed). This leads to the following in guest's dmesg: [ 343.243825] xen:grant_table: WARNING: g.e. 0x445 still in use! [ 343.243825] xen:grant_table: WARNING: g.e. 0x42a still in use! ... When load module -> use device -> unload module sequence is performed multiple times it is possible to hit BUG() condition in blkfront module: [ 343.243825] kernel BUG at drivers/block/xen-blkfront.c:954! [ 343.243825] invalid opcode: 0000 [#1] SMP [ 343.243825] Modules linked in: xen_blkfront(-) ata_generic pata_acpi [last unloaded: xen_blkfront] ... [ 343.243825] Call Trace: [ 343.243825] [] ? unregister_xenbus_watch+0x16f/0x1e0 [ 343.243825] [] blkfront_remove+0x3f/0x140 [xen_blkfront] ... [ 343.243825] RIP [] blkif_free+0x34e/0x360 [xen_blkfront] [ 343.243825] RSP We don't need to keep these grants if we're disconnecting as frontend might already forgot about them. Solve the issue by moving xen_blkbk_free_caches() call from xen_blkif_free() to xen_blkif_disconnect(). Now we can see the following: [ 928.590893] xen:grant_table: WARNING: g.e. 0x587 still in use! [ 928.591861] xen:grant_table: WARNING: g.e. 0x372 still in use! ... [ 929.592146] xen:grant_table: freeing g.e. 0x587 [ 929.597174] xen:grant_table: freeing g.e. 0x372 ... Backend does not keep persistent grants any more, reconnect works fine. Signed-off-by: Vitaly Kuznetsov --- drivers/block/xen-blkback/xenbus.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c index 3a8b810..54f4089 100644 --- a/drivers/block/xen-blkback/xenbus.c +++ b/drivers/block/xen-blkback/xenbus.c @@ -270,6 +270,9 @@ static int xen_blkif_disconnect(struct xen_blkif *blkif) blkif->blk_rings.common.sring = NULL; } + /* Remove all persistent grants and the cache of ballooned pages. */ + xen_blkbk_free_caches(blkif); + return 0; } @@ -281,9 +284,6 @@ static void xen_blkif_free(struct xen_blkif *blkif) xen_blkif_disconnect(blkif); xen_vbd_free(&blkif->vbd); - /* Remove all persistent grants and the cache of ballooned pages. */ - xen_blkbk_free_caches(blkif); - /* Make sure everything is drained before shutting down */ BUG_ON(blkif->persistent_gnt_c != 0); BUG_ON(atomic_read(&blkif->persistent_gnt_in_use) != 0); -- 1.9.3