Paul reports [1] lockdep splat HARDIRQ-safe -> HARDIRQ-unsafe lock order detected. Kernel test robot reports [2] BUG:sleeping_function_called_from_invalid_context_at_mm/page_alloc.c The stack trace might be saved from contexts where we can't block so GFP_KERNEL is unsafe. So Use GFP_NOWAIT. Under memory pressure we might thus fail to save some new unique stack, but that should be extremely rare. [1] https://lore.kernel.org/linux-mm/20210515204622.GA2672367@paulmck-ThinkPad-P17-Gen-1/ [2] https://lore.kernel.org/linux-mm/20210516144152.GA25903@xsang-OptiPlex-9020/ Reported-and-tested-by: Paul E. McKenney <paulmck@xxxxxxxxxx> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> --- mm/slub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 6b896b8c36f0..04824dae2e32 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -623,7 +623,7 @@ static void set_track(struct kmem_cache *s, void *object, if (addr) { #ifdef CONFIG_STACKDEPOT - p->handle = save_stack_depot_trace(GFP_KERNEL); + p->handle = save_stack_depot_trace(GFP_NOWAIT); #endif p->addr = addr; p->cpu = smp_processor_id(); -- 2.31.1
