Date: Thu, 23 Mar 2006 06:53:12 -0800 From: "David Christensen" <dave@randomparity.com> To: "Scott Long" <scottl@samsco.org>, "John-Mark Gurney" <gurney_j@resnet.uoregon.edu> Cc: freebsd-current@freebsd.org Subject: RE: Witness finds "malloc(M_WAITOK) with non-sleepable lock held" in FreeBSD 7.0-CURRENT (amd64) Message-ID: <22C21BFBEB52B340A1F422CB0D88F5872E0B@snoopy.randomparity.com>
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Actually I was following the example in sys/dev/if_em.c. The call chain is: bus_dma_tag_create() is called from em_allocate_receive_structures() is called from em_setup_receive_structures() is called from em_init_locked() The em driver doesn't release its lock before calling bus_dma_tag_create() and it definitely does it outside of the attach routine. Is the em driver also FUBAR or is there something else going on? David Christensen -----Original Message----- From: Scott Long [mailto:scottl@samsco.org]=20 Sent: Wednesday, March 22, 2006 11:23 PM To: John-Mark Gurney Cc: David Christensen; freebsd-current@freebsd.org Subject: Re: Witness finds "malloc(M_WAITOK) with non-sleepable lock held" in FreeBSD 7.0-CURRENT (amd64) John-Mark Gurney wrote: > David Christensen wrote this message on Wed, Mar 22, 2006 at 21:55 -0800: >=20 >>I'm developing an Ethernet driver with FreeBSD 7.0-CURRENT (amd64) and >>I'm=20 >>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 =3D 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 =3D 0x8008219ac, rsp =3D >>0x7fffffffe6b8, rbp =3D 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? >=20 >=20 > 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... >=20 In fact, it's really bad to be initializing the rx data structures like=20 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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