Witness finds "malloc(M_WAITOK) with non-sleepable lock held"
in FreeBSD 7.0-CURRENT (amd64)
Scott Long
scottl at samsco.org
Thu Mar 23 07:22:55 UTC 2006
John-Mark Gurney wrote:
> 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...
>
In fact, it's really bad to be initializing the rx data structures like
this in if_init. It should be done in dev_attach. The reason is that
if_init can be called at any time and will almost certainly be called
multiple times. Also, do not use the BUS_DMA_ALLOCNOW flag here, as I
assume that you are trying to use the busdma tag to allocate a static
piece of memory for the rx chain/ring. The flag should only be used
for flags that deal with dynamic buffers like mbufs and bio_data
objects, or memory that has been allocated in the kernel with normal
malloc.
Scott
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