6.4-stable review patch. If anyone has any objections, please let me know.
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From: Gerald Schaefer gerald.schaefer@linux.ibm.com
commit c8f40a0bccefd613748d080147469a4652d6e74c upstream.
Commit fb08a1908cb1 ("dax: simplify the dax_device <-> gendisk association") introduced new logic for gendisk association, requiring drivers to explicitly call dax_add_host() and dax_remove_host().
For dcssblk driver, some dax_remove_host() calls were missing, e.g. in device remove path. The commit also broke error handling for out_dax case in device add path, resulting in an extra put_device() w/o the previous get_device() in that case.
This lead to stale xarray entries after device add / remove cycles. In the case when a previously used struct gendisk pointer (xarray index) would be used again, because blk_alloc_disk() happened to return such a pointer, the xa_insert() in dax_add_host() would fail and go to out_dax, doing the extra put_device() in the error path. In combination with an already flawed error handling in dcssblk (device_register() cleanup), which needs to be addressed in a separate patch, this resulted in a missing device_del() / klist_del(), and eventually in the kernel crash with list_add corruption on a subsequent device_add() / klist_add().
Fix this by adding the missing dax_remove_host() calls, and also move the put_device() in the error path to restore the previous logic.
Fixes: fb08a1908cb1 ("dax: simplify the dax_device <-> gendisk association") Cc: stable@vger.kernel.org # 5.17+ Acked-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Gerald Schaefer gerald.schaefer@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/s390/block/dcssblk.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/s390/block/dcssblk.c +++ b/drivers/s390/block/dcssblk.c @@ -411,6 +411,7 @@ removeseg: } list_del(&dev_info->lh);
+ dax_remove_host(dev_info->gd); kill_dax(dev_info->dax_dev); put_dax(dev_info->dax_dev); del_gendisk(dev_info->gd); @@ -706,9 +707,9 @@ dcssblk_add_store(struct device *dev, st goto out;
out_dax_host: + put_device(&dev_info->dev); dax_remove_host(dev_info->gd); out_dax: - put_device(&dev_info->dev); kill_dax(dev_info->dax_dev); put_dax(dev_info->dax_dev); put_dev: @@ -788,6 +789,7 @@ dcssblk_remove_store(struct device *dev, }
list_del(&dev_info->lh); + dax_remove_host(dev_info->gd); kill_dax(dev_info->dax_dev); put_dax(dev_info->dax_dev); del_gendisk(dev_info->gd);