From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Stack depot functions can be called from various contexts that do allocations, including with console locks taken. At the same time, stack depot functions might print WARNING's or refcount-related failures. This can cause a deadlock on console locks. Add printk_deferred_enter/exit guards to stack depot to avoid this. Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Closes: https://lore.kernel.org/all/000000000000f56750060b9ad216@xxxxxxxxxx/ Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> --- lib/stackdepot.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 870cce2f4cbd..a0be5d05c7f0 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -506,12 +506,14 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, bucket = &stack_table[hash & stack_hash_mask]; read_lock_irqsave(&pool_rwlock, flags); + printk_deferred_enter(); /* Fast path: look the stack trace up without full locking. */ found = find_stack(bucket, entries, nr_entries, hash); if (found) { if (depot_flags & STACK_DEPOT_FLAG_GET) refcount_inc(&found->count); + printk_deferred_exit(); read_unlock_irqrestore(&pool_rwlock, flags); goto exit; } @@ -520,6 +522,7 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, if (new_pool_required) need_alloc = true; + printk_deferred_exit(); read_unlock_irqrestore(&pool_rwlock, flags); /* @@ -541,6 +544,7 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, } write_lock_irqsave(&pool_rwlock, flags); + printk_deferred_enter(); found = find_stack(bucket, entries, nr_entries, hash); if (!found) { @@ -562,6 +566,7 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, depot_keep_new_pool(&prealloc); } + printk_deferred_exit(); write_unlock_irqrestore(&pool_rwlock, flags); exit: if (prealloc) { @@ -600,9 +605,11 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle, return 0; read_lock_irqsave(&pool_rwlock, flags); + printk_deferred_enter(); stack = depot_fetch_stack(handle); + printk_deferred_exit(); read_unlock_irqrestore(&pool_rwlock, flags); *entries = stack->entries; @@ -619,6 +626,7 @@ void stack_depot_put(depot_stack_handle_t handle) return; write_lock_irqsave(&pool_rwlock, flags); + printk_deferred_enter(); stack = depot_fetch_stack(handle); if (WARN_ON(!stack)) @@ -633,6 +641,7 @@ void stack_depot_put(depot_stack_handle_t handle) } out: + printk_deferred_exit(); write_unlock_irqrestore(&pool_rwlock, flags); } EXPORT_SYMBOL_GPL(stack_depot_put); -- 2.25.1
