From: Vlastimil Babka <vbabka@suse.cz>
Date: Wed, 2 Jun 2021 03:53:25 +0000 (+1000)
Subject: mm/slub: use stackdepot to save stack trace in objects-fix
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d255021c42fc1e04e2b47065427c4b8861aebb3d;p=users%2Fjedix%2Flinux-maple.git

mm/slub: use stackdepot to save stack trace in objects-fix

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/

Link: https://lkml.kernel.org/r/20210516195150.26740-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---

diff --git a/mm/slub.c b/mm/slub.c
index e37f58882fb3..2bfaa9c42e5b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -638,7 +638,7 @@ 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();