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SubjectRe: [PATCH] debugobjects: Use GFP_ATOMIC to allocate when initializing
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On Mon, 2012-04-02 at 11:12 +0200, Thomas Gleixner wrote:
> On Sun, 1 Apr 2012, Sasha Levin wrote:
> > On Sun, Apr 1, 2012 at 7:36 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
> > > On Sat, 31 Mar 2012, Sasha Levin wrote:
>
> Peter ????
>
> > >> During the init stage, we have only 1 cpu and run with IRQs disabled,
> > >> we can't allocate with GFP_KERNEL.
> > >>
> > >> This also fixes the related warning on boot.
> > >
> > > Hrmm. This should not be the case. In early boot GFP_KERNEL
> > > allocations should not trigger a warning when interrupts are
> > > disabled. Which kind of warning are you observing ?
> >
> > There were two, both pointing at the same WARN(). I don't have the
> > first one which was fixed in this patch handy, but the second one is:
> >
> > [ 0.000000] WARNING: at kernel/lockdep.c:2739
> > lockdep_trace_alloc+0x11f/0x130()
> > [ 0.000000] Pid: 0, comm: swapper/0 Not tainted
> > 3.3.0-next-20120330-sasha-dirty #40
> > [ 0.000000] Call Trace:
> > [ 0.000000] [<ffffffff810b4175>] warn_slowpath_common+0x75/0xb0
> > [ 0.000000] [<ffffffff810b41c5>] warn_slowpath_null+0x15/0x20
> > [ 0.000000] [<ffffffff8111999f>] lockdep_trace_alloc+0x11f/0x130
> > [ 0.000000] [<ffffffff81182e0c>] __alloc_pages_nodemask+0x9c/0x260
> > [ 0.000000] [<ffffffff826bcea7>] ? retint_restore_args+0x6/0x13
> > [ 0.000000] [<ffffffff811cc2cd>] kmemcheck_alloc_shadow+0x4d/0xf0
> > [ 0.000000] [<ffffffff811c5597>] allocate_slab+0x197/0x270
> > [ 0.000000] [<ffffffff811c569b>] new_slab+0x2b/0x190
> > [ 0.000000] [<ffffffff811c7e7a>] ? __slab_alloc+0x5a/0x6b0
> > [ 0.000000] [<ffffffff811c82b3>] __slab_alloc+0x493/0x6b0
> > [ 0.000000] [<ffffffff81114f61>] ? trace_hardirqs_off_caller+0xe1/0x150
> > [ 0.000000] [<ffffffff81886f1d>] ? trace_hardirqs_off_thunk+0x3a/0x3c
> > [ 0.000000] [<ffffffff8395eb55>] ?
> > debug_objects_replace_static_objects+0x2a/0x1f5
> > [ 0.000000] [<ffffffff8395eb55>] ?
> > debug_objects_replace_static_objects+0x2a/0x1f5
> > [ 0.000000] [<ffffffff811c900e>] kmem_cache_alloc+0x17e/0x1a0
> > [ 0.000000] [<ffffffff8395eb55>]
> > debug_objects_replace_static_objects+0x2a/0x1f5
> > [ 0.000000] [<ffffffff8395ed59>] debug_objects_mem_init+0x39/0x68
> > [ 0.000000] [<ffffffff8392af65>] start_kernel+0x33a/0x3f8
> > [ 0.000000] [<ffffffff8392aa13>] ? kernel_init+0x280/0x280
> > [ 0.000000] [<ffffffff8392a2b6>] x86_64_start_reservations+0xa1/0xa6
> > [ 0.000000] [<ffffffff8392a410>] x86_64_start_kernel+0x155/0x164
> > [ 0.000000] ---[ end trace a7919e7f17c0a725 ]---
>
>

Something like so?

---
kernel/lockdep.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index ea9ee45..a028ba9 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2718,6 +2718,13 @@ static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
{
struct task_struct *curr = current;

+ /*
+ * We do GFP_KERNEL allocations with IRQs disabled during system
+ * bringup..
+ */
+ if (unlikely(system_state != SYSTEM_RUNNING))
+ return;
+
if (unlikely(!debug_locks))
return;




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