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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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