From 27a353c026a879a1001e5eac4bda75b16262c44a Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Wed, 24 Feb 2016 17:38:28 -0800 Subject: [PATCH] RAID5: check_reshape() shouldn't call mddev_suspend check_reshape() is called from raid5d thread. raid5d thread shouldn't call mddev_suspend(), because mddev_suspend() waits for all IO finish but IO is handled in raid5d thread, we could easily deadlock here. This issue is introduced by 738a273 ("md/raid5: fix allocation of 'scribble' array.") Cc: stable@vger.kernel.org (v4.1+) Reported-and-tested-by: Artur Paszkiewicz Reviewed-by: NeilBrown Signed-off-by: Shaohua Li --- drivers/md/raid5.c | 18 ++++++++++++++++++ drivers/md/raid5.h | 2 ++ 2 files changed, 20 insertions(+) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 7f770b0c0348..b628cd525b32 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2089,6 +2089,14 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors) unsigned long cpu; int err = 0; + /* + * Never shrink. And mddev_suspend() could deadlock if this is called + * from raid5d. In that case, scribble_disks and scribble_sectors + * should equal to new_disks and new_sectors + */ + if (conf->scribble_disks >= new_disks && + conf->scribble_sectors >= new_sectors) + return 0; mddev_suspend(conf->mddev); get_online_cpus(); for_each_present_cpu(cpu) { @@ -2110,6 +2118,10 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors) } put_online_cpus(); mddev_resume(conf->mddev); + if (!err) { + conf->scribble_disks = new_disks; + conf->scribble_sectors = new_sectors; + } return err; } @@ -6413,6 +6425,12 @@ static int raid5_alloc_percpu(struct r5conf *conf) } put_online_cpus(); + if (!err) { + conf->scribble_disks = max(conf->raid_disks, + conf->previous_raid_disks); + conf->scribble_sectors = max(conf->chunk_sectors, + conf->prev_chunk_sectors); + } return err; } diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h index a415e1cd39b8..ae6068deefdf 100644 --- a/drivers/md/raid5.h +++ b/drivers/md/raid5.h @@ -510,6 +510,8 @@ struct r5conf { * conversions */ } __percpu *percpu; + int scribble_disks; + int scribble_sectors; #ifdef CONFIG_HOTPLUG_CPU struct notifier_block cpu_notify; #endif