The btrfs zstd workspace manager uses a background timer to reclaim not recently used workspaces. I dumbly call spin_lock() from this context which I should have caught with lockdep but.. This deadlock was reported in [1]. The fix is to switch the zstd wsm lock to use spin_lock_bh().
[1] https://bugzilla.kernel.org/show_bug.cgi?id=203517 Signed-off-by: Dennis Zhou <den...@kernel.org> --- fs/btrfs/zstd.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c index a6ff07cf11d5..3837ca180d52 100644 --- a/fs/btrfs/zstd.c +++ b/fs/btrfs/zstd.c @@ -105,10 +105,10 @@ static void zstd_reclaim_timer_fn(struct timer_list *timer) unsigned long reclaim_threshold = jiffies - ZSTD_BTRFS_RECLAIM_JIFFIES; struct list_head *pos, *next; - spin_lock(&wsm.lock); + spin_lock_bh(&wsm.lock); if (list_empty(&wsm.lru_list)) { - spin_unlock(&wsm.lock); + spin_unlock_bh(&wsm.lock); return; } @@ -137,7 +137,7 @@ static void zstd_reclaim_timer_fn(struct timer_list *timer) if (!list_empty(&wsm.lru_list)) mod_timer(&wsm.timer, jiffies + ZSTD_BTRFS_RECLAIM_JIFFIES); - spin_unlock(&wsm.lock); + spin_unlock_bh(&wsm.lock); } /* @@ -198,7 +198,7 @@ static void zstd_cleanup_workspace_manager(void) struct workspace *workspace; int i; - spin_lock(&wsm.lock); + spin_lock_bh(&wsm.lock); for (i = 0; i < ZSTD_BTRFS_MAX_LEVEL; i++) { while (!list_empty(&wsm.idle_ws[i])) { workspace = container_of(wsm.idle_ws[i].next, @@ -208,7 +208,7 @@ static void zstd_cleanup_workspace_manager(void) zstd_free_workspace(&workspace->list); } } - spin_unlock(&wsm.lock); + spin_unlock_bh(&wsm.lock); del_timer_sync(&wsm.timer); } @@ -230,7 +230,7 @@ static struct list_head *zstd_find_workspace(unsigned int level) struct workspace *workspace; int i = level - 1; - spin_lock(&wsm.lock); + spin_lock_bh(&wsm.lock); for_each_set_bit_from(i, &wsm.active_map, ZSTD_BTRFS_MAX_LEVEL) { if (!list_empty(&wsm.idle_ws[i])) { ws = wsm.idle_ws[i].next; @@ -242,11 +242,11 @@ static struct list_head *zstd_find_workspace(unsigned int level) list_del(&workspace->lru_list); if (list_empty(&wsm.idle_ws[i])) clear_bit(i, &wsm.active_map); - spin_unlock(&wsm.lock); + spin_unlock_bh(&wsm.lock); return ws; } } - spin_unlock(&wsm.lock); + spin_unlock_bh(&wsm.lock); return NULL; } @@ -305,7 +305,7 @@ static void zstd_put_workspace(struct list_head *ws) { struct workspace *workspace = list_to_workspace(ws); - spin_lock(&wsm.lock); + spin_lock_bh(&wsm.lock); /* A node is only taken off the lru if we are the corresponding level */ if (workspace->req_level == workspace->level) { @@ -325,7 +325,7 @@ static void zstd_put_workspace(struct list_head *ws) list_add(&workspace->list, &wsm.idle_ws[workspace->level - 1]); workspace->req_level = 0; - spin_unlock(&wsm.lock); + spin_unlock_bh(&wsm.lock); if (workspace->level == ZSTD_BTRFS_MAX_LEVEL) cond_wake_up(&wsm.wait); -- 2.17.1
