Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946272AbXBCCjq (ORCPT ); Fri, 2 Feb 2007 21:39:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946276AbXBCCjq (ORCPT ); Fri, 2 Feb 2007 21:39:46 -0500 Received: from 216-99-217-87.dsl.aracnet.com ([216.99.217.87]:53266 "EHLO sous-sol.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946272AbXBCCja (ORCPT ); Fri, 2 Feb 2007 21:39:30 -0500 Message-Id: <20070203024415.110184000@sous-sol.org> References: <20070203023504.435051000@sous-sol.org> User-Agent: quilt/0.45-1 Date: Fri, 02 Feb 2007 18:35:45 -0800 From: Chris Wright To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, NeilBrown Subject: [patch 41/59] md: fix potential memalloc deadlock in md Content-Disposition: inline; filename=md-fix-potential-memalloc-deadlock-in-md.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3595 Lines: 117 -stable review patch. If anyone has any objections, please let us know. ------------------ From: NeilBrown If a GFP_KERNEL allocation is attempted in md while the mddev_lock is held, it is possible for a deadlock to eventuate. This happens if the array was marked 'clean', and the memalloc triggers a write-out to the md device. For the writeout to succeed, the array must be marked 'dirty', and that requires getting the mddev_lock. So, before attempting a GFP_KERNEL alloction while holding the lock, make sure the array is marked 'dirty' (unless it is currently read-only). Signed-off-by: Neil Brown Signed-off-by: Chris Wright --- drivers/md/md.c | 29 +++++++++++++++++++++++++++++ drivers/md/raid1.c | 2 ++ drivers/md/raid5.c | 3 +++ include/linux/raid/md.h | 2 +- 4 files changed, 35 insertions(+), 1 deletion(-) --- linux-2.6.19.2.orig/drivers/md/md.c +++ linux-2.6.19.2/drivers/md/md.c @@ -3561,6 +3561,8 @@ static int get_bitmap_file(mddev_t * mdd char *ptr, *buf = NULL; int err = -ENOMEM; + md_allow_write(mddev); + file = kmalloc(sizeof(*file), GFP_KERNEL); if (!file) goto out; @@ -5029,6 +5031,33 @@ void md_write_end(mddev_t *mddev) } } +/* md_allow_write(mddev) + * Calling this ensures that the array is marked 'active' so that writes + * may proceed without blocking. It is important to call this before + * attempting a GFP_KERNEL allocation while holding the mddev lock. + * Must be called with mddev_lock held. + */ +void md_allow_write(mddev_t *mddev) +{ + if (!mddev->pers) + return; + if (mddev->ro) + return; + + spin_lock_irq(&mddev->write_lock); + if (mddev->in_sync) { + mddev->in_sync = 0; + set_bit(MD_CHANGE_CLEAN, &mddev->flags); + if (mddev->safemode_delay && + mddev->safemode == 0) + mddev->safemode = 1; + spin_unlock_irq(&mddev->write_lock); + md_update_sb(mddev, 0); + } else + spin_unlock_irq(&mddev->write_lock); +} +EXPORT_SYMBOL_GPL(md_allow_write); + static DECLARE_WAIT_QUEUE_HEAD(resync_wait); #define SYNC_MARKS 10 --- linux-2.6.19.2.orig/drivers/md/raid1.c +++ linux-2.6.19.2/drivers/md/raid1.c @@ -2104,6 +2104,8 @@ static int raid1_reshape(mddev_t *mddev) return -EINVAL; } + md_allow_write(mddev); + raid_disks = mddev->raid_disks + mddev->delta_disks; if (raid_disks < conf->raid_disks) { --- linux-2.6.19.2.orig/drivers/md/raid5.c +++ linux-2.6.19.2/drivers/md/raid5.c @@ -403,6 +403,8 @@ static int resize_stripes(raid5_conf_t * if (newsize <= conf->pool_size) return 0; /* never bother to shrink */ + md_allow_write(conf->mddev); + /* Step 1 */ sc = kmem_cache_create(conf->cache_name[1-conf->active_name], sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev), @@ -3045,6 +3047,7 @@ raid5_store_stripe_cache_size(mddev_t *m else break; } + md_allow_write(mddev); while (new > conf->max_nr_stripes) { if (grow_one_stripe(conf)) conf->max_nr_stripes++; --- linux-2.6.19.2.orig/include/linux/raid/md.h +++ linux-2.6.19.2/include/linux/raid/md.h @@ -94,7 +94,7 @@ extern int sync_page_io(struct block_dev struct page *page, int rw); extern void md_do_sync(mddev_t *mddev); extern void md_new_event(mddev_t *mddev); - +extern void md_allow_write(mddev_t *mddev); #endif /* CONFIG_MD */ #endif -- - 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/