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()? =A0This compiles, but I haven't boote=
d it
> yet:
>
> Index: if.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- if.c =A0 =A0 =A0 =A0(revision 217400)
> +++ if.c =A0 =A0 =A0 =A0(working copy)
> @@ -266,6 +266,7 @@ ifindex_alloc_locked(u_short *idxp)
>
> =A0 =A0 =A0 =A0IFNET_WLOCK_ASSERT();
>
> +retry:
> =A0 =A0 =A0 =A0/*
> =A0 =A0 =A0 =A0 * Try to find an empty slot below V_if_index. =A0If we fa=
il, take the
> =A0 =A0 =A0 =A0 * next slot.
> @@ -278,10 +279,11 @@ ifindex_alloc_locked(u_short *idxp)
> =A0 =A0 =A0 =A0/* Catch if_index overflow. */
> =A0 =A0 =A0 =A0if (idx < 1)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0return (ENOSPC);
> - =A0 =A0 =A0 if (idx > V_if_index)
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 V_if_index =3D idx;
> - =A0 =A0 =A0 if (V_if_index >=3D V_if_indexlim)
> + =A0 =A0 =A0 if (idx > V_if_index) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if_grow();
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto retry;
> + =A0 =A0 =A0 }
> + =A0 =A0 =A0 V_if_index =3D idx;
> =A0 =A0 =A0 =A0*idxp =3D idx;
> =A0 =A0 =A0 =A0return (0);
> =A0}
> @@ -385,16 +387,25 @@ VNET_SYSUNINIT(vnet_if_uninit, SI_SUB_INIT_IF, SI_
> =A0static void
> =A0if_grow(void)
> =A0{
> + =A0 =A0 =A0 int oldlim;
> =A0 =A0 =A0 =A0u_int n;
> =A0 =A0 =A0 =A0struct ifindex_entry *e;
>
> - =A0 =A0 =A0 V_if_indexlim <<=3D 1;
> - =A0 =A0 =A0 n =3D V_if_indexlim * sizeof(*e);
> + =A0 =A0 =A0 IFNET_WLOCK_ASSERT();
> + =A0 =A0 =A0 oldlim =3D V_if_indexlim;
> + =A0 =A0 =A0 IFNET_WUNLOCK();
> + =A0 =A0 =A0 n =3D (oldlim << 1) * sizeof(*e);
> =A0 =A0 =A0 =A0e =3D malloc(n, M_IFNET, M_WAITOK | M_ZERO);
> + =A0 =A0 =A0 IFNET_WLOCK();
> + =A0 =A0 =A0 if (V_if_indexlim !=3D oldlim) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 free(e, M_IFNET);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return;
> + =A0 =A0 =A0 }
> =A0 =A0 =A0 =A0if (V_ifindex_table !=3D NULL) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0memcpy((caddr_t)e, (caddr_t)V_ifindex_tabl=
e, n/2);
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0free((caddr_t)V_ifindex_table, M_IFNET);
> =A0 =A0 =A0 =A0}
> + =A0 =A0 =A0 V_if_indexlim <<=3D 1;
> =A0 =A0 =A0 =A0V_ifindex_table =3D e;
> =A0}
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
--=20
wbr,
pluknet
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