This is a note to let you know that I've just added the patch titled
s390/dcssblk: fix deadlock when adding a DCSS
to the 6.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-dcssblk-fix-deadlock-when-adding-a-dcss.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a41a11b4009580edb6e2b4c76e5e2ee303f87157 Mon Sep 17 00:00:00 2001
From: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Date: Thu, 27 Oct 2022 16:19:38 +0200
Subject: s390/dcssblk: fix deadlock when adding a DCSS
From: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
commit a41a11b4009580edb6e2b4c76e5e2ee303f87157 upstream.
After the rework from commit 1ebe2e5f9d68 ("block: remove
GENHD_FL_EXT_DEVT"), when calling device_add_disk(), dcssblk will end up
in disk_scan_partitions(), and not break out early w/o GENHD_FL_NO_PART.
This will trigger implicit open/release via blkdev_get/put_whole()
later. dcssblk_release() will then deadlock on dcssblk_devices_sem
semaphore, which is already held from dcssblk_add_store() when calling
device_add_disk().
dcssblk does not support partitions (DCSSBLK_MINORS_PER_DISK == 1), and
never scanned partitions before. Therefore restore the previous
behavior, and explicitly disallow partition scanning by setting the
GENHD_FL_NO_PART flag. This will also prevent this deadlock scenario.
Fixes: 1ebe2e5f9d68 ("block: remove GENHD_FL_EXT_DEVT")
Cc: <stable@xxxxxxxxxxxxxxx> # 5.17+
Signed-off-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Acked-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/s390/block/dcssblk.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 93b80da60277..b392b9f5482e 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -636,6 +636,7 @@ dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char
dev_info->gd->minors = DCSSBLK_MINORS_PER_DISK;
dev_info->gd->fops = &dcssblk_devops;
dev_info->gd->private_data = dev_info;
+ dev_info->gd->flags |= GENHD_FL_NO_PART;
blk_queue_logical_block_size(dev_info->gd->queue, 4096);
blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->gd->queue);
--
2.38.1
Patches currently in stable-queue which might be from gerald.schaefer@xxxxxxxxxxxxx are
queue-6.0/s390-dcssblk-fix-deadlock-when-adding-a-dcss.patch
