Hi, When a sector mode namespace is initially created, the arena's err_lock is not initialized. If, on the other hand, the namespace already exists, the mutex is initialized. To fix the issue, I moved the mutex initialization into the arena_alloc, which is called by both discover_arenas and create_arenas.
This was discovered on an older kernel where mutex_trylock checks the count to determine whether the lock is held. Because the data structure is kzalloc-d, that count was 0 (held), and I/O to the device would hang forever waiting for the lock to be released (see btt_write_pg, for example). Current kernels have a different mutex implementation that checks for a non-null owner, and so this doesn't show up as a problem. If that lock were ever contended, it might cause issues, but you'd have to be really unlucky, I think. Signed-off-by: Jeff Moyer <[email protected]> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c index e949e33..5860f99 100644 --- a/drivers/nvdimm/btt.c +++ b/drivers/nvdimm/btt.c @@ -630,6 +630,7 @@ static struct arena_info *alloc_arena(struct btt *btt, size_t size, return NULL; arena->nd_btt = btt->nd_btt; arena->sector_size = btt->sector_size; + mutex_init(&arena->err_lock); if (!size) return arena; @@ -758,7 +759,6 @@ static int discover_arenas(struct btt *btt) arena->external_lba_start = cur_nlba; parse_arena_meta(arena, super, cur_off); - mutex_init(&arena->err_lock); ret = btt_freelist_init(arena); if (ret) goto out; _______________________________________________ Linux-nvdimm mailing list [email protected] https://lists.01.org/mailman/listinfo/linux-nvdimm
