Re: BUG: sleeping function called from invalid context at mm/slub.c:793

[Avi Kivity <avi@redhat.com>]

On 01/10/2011 09:31 PM, Kirill A. Shutemov wrote:
> On Mon, Jan 10, 2011 at 10:52:05AM -0600, Christoph Lameter wrote:
> >
> >  On Mon, 10 Jan 2011, Kirill A. Shutemov wrote:
> >
> >  >  Every time I run qemu with KVM enabled I get this in dmesg:
> >  >
> >  >  [  182.878328] BUG: sleeping function called from invalid context at mm/slub.c:793
> >  >  [  182.878339] in_atomic(): 1, irqs_disabled(): 0, pid: 4992, name: qemu
> >  >  [  182.878355] Pid: 4992, comm: qemu Not tainted 2.6.37+ #31
> >  >  [  182.878361] Call Trace:
> >  >  [  182.878381]  [<c104e317>] ? __might_sleep+0xd0/0xd7
> >  >  [  182.878394]  [<c10ec337>] ? slab_pre_alloc_hook.clone.39+0x23/0x27
> >  >  [  182.878404]  [<c10ece27>] ? kmem_cache_alloc+0x22/0xc8
> >  >  [  182.878414]  [<c1030221>] ? init_fpu+0x44/0x7b
> >
> >  fpu_alloc() does call kmem_cache_alloc with GFP_KERNEL although we are in
> >  an atomic context.
>
> Something like this?
>
> ---
>  From 7c6fbfed72e7d22cbdf7393f9711d521e0fbb4a6 Mon Sep 17 00:00:00 2001
> From: Kirill A. Shutemov<kirill@shutemov.name>
> Date: Mon, 10 Jan 2011 21:24:23 +0200
> Subject: [PATCH] x86, fpu_alloc(): call kmem_cache_alloc() with GFP_ATOMIC
>
> [  182.878328] BUG: sleeping function called from invalid context at mm/slub.c:793
> [  182.878339] in_atomic(): 1, irqs_disabled(): 0, pid: 4992, name: qemu
> [  182.878355] Pid: 4992, comm: qemu Not tainted 2.6.37+ #31
> [  182.878361] Call Trace:
> [  182.878381]  [<c104e317>] ? __might_sleep+0xd0/0xd7
> [  182.878394]  [<c10ec337>] ? slab_pre_alloc_hook.clone.39+0x23/0x27
> [  182.878404]  [<c10ece27>] ? kmem_cache_alloc+0x22/0xc8
> [  182.878414]  [<c1030221>] ? init_fpu+0x44/0x7b
> [  182.878426]  [<c130cc29>] ? do_device_not_available+0x0/0x1b
> [  182.878435]  [<c1030221>] ? init_fpu+0x44/0x7b
> [  182.878444]  [<c102a588>] ? math_state_restore+0x24/0x47
> [  182.878453]  [<c130cc39>] ? do_device_not_available+0x10/0x1b
> [  182.878462]  [<c130c4ab>] ? error_code+0x67/0x6c
> [  182.878475]  [<c1012340>] ? kvm_load_guest_fpu+0xa1/0xaa
> [  182.878484]  [<c1013364>] ? kvm_arch_vcpu_ioctl_run+0x798/0xbe8
> [  182.878496]  [<c1004523>] ? kvm_vcpu_ioctl+0x105/0x46e
> [  182.878508]  [<c107dce0>] ? get_futex_key+0x73/0x132
> [  182.878517]  [<c107e352>] ? futex_wake+0xb6/0xc0
> [  182.878527]  [<c107f8d6>] ? do_futex+0x87/0x669
> [  182.878535]  [<c100441e>] ? kvm_vcpu_ioctl+0x0/0x46e
> [  182.878545]  [<c1101ebf>] ? do_vfs_ioctl+0x4a0/0x4d1
> [  182.878554]  [<c130e348>] ? do_page_fault+0x2eb/0x316
> [  182.878564]  [<c1101f36>] ? sys_ioctl+0x46/0x68
> [  182.878572]  [<c130bdc0>] ? syscall_call+0x7/0xb
> [  182.878585]  [<c1300000>] ? aer_probe+0x1da/0x274
>
> Signed-off-by: Kirill A. Shutemov<kirill@shutemov.name>
> ---
>   arch/x86/include/asm/i387.h |    2 +-
>   1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
> index ef32890..8b896dd 100644
> --- a/arch/x86/include/asm/i387.h
> +++ b/arch/x86/include/asm/i387.h
> @@ -426,7 +426,7 @@ static inline int fpu_alloc(struct fpu *fpu)
>   {
>   	if (fpu_allocated(fpu))
>   		return 0;
> -	fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL);
> +	fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_ATOMIC);
>   	if (!fpu->state)
>   		return -ENOMEM;
>   	WARN_ON((unsigned long)fpu->state&  15);

If this fails, a task will be killed.  I'll patch kvm to ensure that the 
fpu is initialized.

-- 
error compiling committee.c: too many arguments to function