Witness finds "malloc(M_WAITOK) with non-sleepable lock held" in FreeBSD 7.0-CURRENT (amd64)

[John-Mark Gurney]

David Christensen wrote this message on Wed, Mar 22, 2006 at 21:55 -0800:
> I'm developing an Ethernet driver with FreeBSD 7.0-CURRENT (amd64) and
> I'm 
> receiving many of the following witness errors:
> 
> malloc(M_WAITOK) of "128", forcing M_NOWAIT with the following
> non-sleepable locks held:
> exclusive sleep mutex bce0 (network driver) r = 0 (0xffffffff8111e068)
> locked @ if_bce.c:4607
> KDB: stack backtrace:
> kdb_backtrace() at kdb_backtrace+0x37
> witness_warn() at witness_warn+0x2c1
> uma_zalloc_arg() at uma_zalloc_arg+0x69
> malloc() at malloc+0xf5
> sysctl_add_oid() at sysctl_add_oid+0xa9
> alloc_bounce_zone() at alloc_bounce_zone+0x16b
> bus_dma_tag_create() at bus_dma_tag_create+0x1ea
> bce_init_rx_chain() at bce_init_rx_chain+0x8e
> bce_init_locked() at bce_init_locked+0x1e2
> bce_init() at bce_init+0x39
> ether_ioctl() at ether_ioctl+0x87
> bce_ioctl() at bce_ioctl+0x48e
> in6_ifinit() at in6_ifinit+0xbd
> in6_update_ifa() at in6_update_ifa+0x563
> in6_ifattach_linklocal() at in6_ifattach_linklocal+0x126
> in6_ifattach() at in6_ifattach+0xdf
> in6_if_up() at in6_if_up+0x59
> if_route() at if_route+0x8a
> if_up() at if_up+0x13
> ifhwioctl() at ifhwioctl+0x2f4
> ifioctl() at ifioctl+0x10b
> soo_ioctl() at soo_ioctl+0x38c
> ioctl() at ioctl+0x436
> syscall() at syscall+0x350
> Xfast_syscall() at Xfast_syscall+0xa8
> --- syscall (54, FreeBSD ELF64, ioctl), rip = 0x8008219ac, rsp =
> 0x7fffffffe6b8, rbp = 0x1 ---
> 
> The bus_dma_tag_create looks like this:
> 
> bus_dma_tag_create(
> 	sc->parent_tag,		/* parent      */
>     	4096,				/* alignment   */
>     	0,				/* boundary    */
> 	BUS_SPACE_MAXADDR,	/* lowaddr     */
> 	BUS_SPACE_MAX_ADDR,	/* lowaddr     */
> 	NULL,				/* filter      */
> 	NULL, 			/* filterarg   */
> 	4096,				/* maxsize     */
> 	1, 				/* nsegments   */
> 	4096,				/* maxsegsize  */
> 	BUS_DMA_ALLOCNOW, 	/* flags       */
> 	NULL,				/* lockfunc    */
> 	NULL,				/* lockarg     */
> 	&sc->rx_bd_chain_tag));
> 
> Am I doing something wrong?  The function bce_init_rx_chain is called
> from with
> a lock but isn't that normal?

Yeh, you have to unlock your driver lock before calling
bus_dma_tag_create..  If you look at the other ethernet drivers, some
call _tag_create as part of attach, not in _init...  at this point,
it's safe to release your lock and allocate memory...

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."