Re: [PATCH 1.2/2] mm: introduce memalloc_nofs_{save,restore} API

Michal Hocko
2016-04-27T21:14:14Z

OK, so the lockdep splats I was seeing [1] were much easier to fix than
I originally thought. So the following should be folded into the
original patch. I will send the full patch later on.

[1] http://lkml.kernel.org/r/20160427200927.GC22544@dhcp22.suse.cz
---
>From 1968c0a8ace4090a9deca8f4c1a206ee546e595a Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Wed, 27 Apr 2016 22:32:57 +0200
Subject: [PATCH] fold me "mm: introduce memalloc_nofs_{save,restore} API"

Lockdep infrastructure is hooked into early hot paths of the allocator
so __lockdep_trace_alloc has to check for PF_MEMALLOC_NOFS directly and
do not rely on current_gfp_context

Signed-off-by: Michal Hocko <mhocko@suse.com>

---
kernel/locking/lockdep.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 716547fdb873..f60124d0871c 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2750,7 +2750,7 @@ static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
return;

/* We're only interested __GFP_FS allocations for now */
- if (!(gfp_mask & __GFP_FS))
+ if (!(gfp_mask & __GFP_FS) || (curr->flags & PF_MEMALLOC_NOFS))
return;

/*
--
2.8.0.rc3

--
Michal Hocko
SUSE Labs