4.5-stable review patch. If anyone has any objections, please let me know.
------------------ From: Shaohua Li <[email protected]> commit 27a353c026a879a1001e5eac4bda75b16262c44a upstream. 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.") Reported-and-tested-by: Artur Paszkiewicz <[email protected]> Reviewed-by: NeilBrown <[email protected]> Signed-off-by: Shaohua Li <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/md/raid5.c | 18 ++++++++++++++++++ drivers/md/raid5.h | 2 ++ 2 files changed, 20 insertions(+) --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2089,6 +2089,14 @@ static int resize_chunks(struct r5conf * 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 * } 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 r5c } 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; } --- 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
