Date: Thu, 23 Mar 2006 07:59:50 -0700 From: Scott Long <scottl@samsco.org> To: David Christensen <dave@randomparity.com> Cc: John-Mark Gurney <gurney_j@resnet.uoregon.edu>, freebsd-current@freebsd.org Subject: Re: Witness finds "malloc(M_WAITOK) with non-sleepable lock held" in FreeBSD 7.0-CURRENT (amd64) Message-ID: <4422B7E6.8090704@samsco.org> In-Reply-To: <22C21BFBEB52B340A1F422CB0D88F5872E0B@snoopy.randomparity.com> References: <22C21BFBEB52B340A1F422CB0D88F5872E0B@snoopy.randomparity.com>
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Wow, I didn't realize how screwed up that was. Yes, if_em is definitely wrong. It's not clear to me if the number of rx and tx descriptors that the driver wants will change with each call to em_init, but at the very least the busdma tag allocation should move to the attach routine. Scott David Christensen wrote: > 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] > 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: > >>>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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