Date: Tue, 18 Jan 2011 21:22:24 +0300 From: Sergey Kandaurov <pluknet@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-current@freebsd.org, Robert Watson <rwatson@freebsd.org> Subject: Re: uma_zalloc_arg: zone "256" with non-sleepable exclusive rw ifnet_rw @ /usr/src/sys/net/if.c:414 Message-ID: <AANLkTi=DtUa5%2BfhOrOW_N11rn6WVp8fHZvL%2BOE6n-S6c@mail.gmail.com> In-Reply-To: <201101180954.46903.jhb@freebsd.org> References: <AANLkTi=dZ4vOSx82Wp%2BqAwmT97mucqwtf6dDu4pnOCR2@mail.gmail.com> <201101180954.46903.jhb@freebsd.org>
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On 18 January 2011 17:54, John Baldwin <jhb@freebsd.org> wrote:
> On Monday, January 17, 2011 12:55:26 pm Sergey Kandaurov wrote:
>> Hi,
>>
>> I see this "malloc with non-sleepable" on current during boot.
>> It's strange that I don't see it if I boot via pxe/nfs.
>>
>> if_alloc() calls ifindex_alloc_locked() under IFNET_WLOCK() which
>> might call if_grow().
>> Looks like a regression from r196553.
>
> I'm guessing that ifindex_alloc() should drop the lock and retry the
> allocation after calling if_grow()? This compiles, but I haven't booted it
> yet:
>
> Index: if.c
> ===================================================================
> --- if.c (revision 217400)
> +++ if.c (working copy)
> @@ -266,6 +266,7 @@ ifindex_alloc_locked(u_short *idxp)
>
> IFNET_WLOCK_ASSERT();
>
> +retry:
> /*
> * Try to find an empty slot below V_if_index. If we fail, take the
> * next slot.
> @@ -278,10 +279,11 @@ ifindex_alloc_locked(u_short *idxp)
> /* Catch if_index overflow. */
> if (idx < 1)
> return (ENOSPC);
> - if (idx > V_if_index)
> - V_if_index = idx;
> - if (V_if_index >= V_if_indexlim)
> + if (idx > V_if_index) {
> if_grow();
> + goto retry;
> + }
> + V_if_index = idx;
> *idxp = idx;
> return (0);
> }
> @@ -385,16 +387,25 @@ VNET_SYSUNINIT(vnet_if_uninit, SI_SUB_INIT_IF, SI_
> static void
> if_grow(void)
> {
> + int oldlim;
> u_int n;
> struct ifindex_entry *e;
>
> - V_if_indexlim <<= 1;
> - n = V_if_indexlim * sizeof(*e);
> + IFNET_WLOCK_ASSERT();
> + oldlim = V_if_indexlim;
> + IFNET_WUNLOCK();
> + n = (oldlim << 1) * sizeof(*e);
> e = malloc(n, M_IFNET, M_WAITOK | M_ZERO);
> + IFNET_WLOCK();
> + if (V_if_indexlim != oldlim) {
> + free(e, M_IFNET);
> + return;
> + }
> if (V_ifindex_table != NULL) {
> memcpy((caddr_t)e, (caddr_t)V_ifindex_table, n/2);
> free((caddr_t)V_ifindex_table, M_IFNET);
> }
> + V_if_indexlim <<= 1;
> V_ifindex_table = e;
> }
vnet_if_init() calls if_grow() without lock.
panic: Lock (null) not exclusively locked @ /usr/src/sys/net/if.c:394
db> bt
Tracing pid 0 tid 100000 td 0xffffffff80ccff40
kdb_enter() at kdb_enter+0x3d
panic() at panic+0x180
assert_sx() at assert_sx
if_grow() at if_grow+0x2a
vnet_if_init() at vnet_if_init+0x35
mi_startup() at mi_startup+0x77
btext() at btext+0x2c
--
wbr,
pluknet
help
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