From 3b97f5a05cfc55e7729ff3769f63eef64e2178bb Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Sat, 14 Sep 2024 14:01:23 +0200 Subject: [PATCH] nvme-multipath: avoid hang on inaccessible namespaces During repetitive namespace remapping operations on the target the namespace might have changed between the time the initial scan was performed, and partition scan was invoked by device_add_disk() in nvme_mpath_set_live(). We then end up with a stuck scanning process: [<0>] folio_wait_bit_common+0x12a/0x310 [<0>] filemap_read_folio+0x97/0xd0 [<0>] do_read_cache_folio+0x108/0x390 [<0>] read_part_sector+0x31/0xa0 [<0>] read_lba+0xc5/0x160 [<0>] efi_partition+0xd9/0x8f0 [<0>] bdev_disk_changed+0x23d/0x6d0 [<0>] blkdev_get_whole+0x78/0xc0 [<0>] bdev_open+0x2c6/0x3b0 [<0>] bdev_file_open_by_dev+0xcb/0x120 [<0>] disk_scan_partitions+0x5d/0x100 [<0>] device_add_disk+0x402/0x420 [<0>] nvme_mpath_set_live+0x4f/0x1f0 [nvme_core] [<0>] nvme_mpath_add_disk+0x107/0x120 [nvme_core] [<0>] nvme_alloc_ns+0xac6/0xe60 [nvme_core] [<0>] nvme_scan_ns+0x2dd/0x3e0 [nvme_core] [<0>] nvme_scan_work+0x1a3/0x490 [nvme_core] This happens when we have several paths, some of which are inaccessible, and the active paths are removed first. Then nvme_find_path() will requeue I/O in the ns_head (as paths are present), but the requeue list is never triggered as all remaining paths are inactive. This patch checks for NVME_NSHEAD_DISK_LIVE in nvme_available_path(), and requeue I/O after NVME_NSHEAD_DISK_LIVE has been cleared once the last path has been removed to properly terminate pending I/O. Signed-off-by: Hannes Reinecke Reviewed-by: Sagi Grimberg Signed-off-by: Keith Busch --- drivers/nvme/host/multipath.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index 6d97058cde7a..48e7a8906d01 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -421,6 +421,9 @@ static bool nvme_available_path(struct nvme_ns_head *head) { struct nvme_ns *ns; + if (!test_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) + return NULL; + list_for_each_entry_rcu(ns, &head->list, siblings) { if (test_bit(NVME_CTRL_FAILFAST_EXPIRED, &ns->ctrl->flags)) continue; @@ -969,11 +972,16 @@ void nvme_mpath_shutdown_disk(struct nvme_ns_head *head) { if (!head->disk) return; - kblockd_schedule_work(&head->requeue_work); - if (test_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) { + if (test_and_clear_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) { nvme_cdev_del(&head->cdev, &head->cdev_device); del_gendisk(head->disk); } + /* + * requeue I/O after NVME_NSHEAD_DISK_LIVE has been cleared + * to allow multipath to fail all I/O. + */ + synchronize_srcu(&head->srcu); + kblockd_schedule_work(&head->requeue_work); } void nvme_mpath_remove_disk(struct nvme_ns_head *head)