Tony Lindgren bc417e30f8 net: Add back alignment for size for __alloc_skb ... Commit 87fb4b7b53 (net: more accurate skb truesize) changed the alignment of size. This can cause problems at least on some machines with NFS root: Unhandled fault: alignment exception (0x801) at 0xc183a43a Internal error: : 801 [#1] PREEMPT Modules linked in: CPU: 0 Not tainted (3.1.0-08784-g5eeee4a #733) pc : [<c02fbba0>] lr : [<c02fbb9c>] psr: 60000013 sp : c180fef8 ip : 00000000 fp : c181f580 r10: 00000000 r9 : c044b28c r8 : 00000001 r7 : c183a3a0 r6 : c1835be0 r5 : c183a412 r4 : 000001f2 r3 : 00000000 r2 : 00000000 r1 : ffffffe6 r0 : c183a43a Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel Control: 0005317f Table: 10004000 DAC: 00000017 Process swapper (pid: 1, stack limit = 0xc180e270) Stack: (0xc180fef8 to 0xc1810000) fee0: 00000024 00000000 ff00: 00000000 c183b9c0 c183b8e0 c044b28c c0507ccc c019dfc4 c180ff2c c0503cf8 ff20: c180ff4c c180ff4c 00000000 c1835420 c182c740 c18349c0 c05233c0 00000000 ff40: 00000000 c00e6bb8 c180e000 00000000 c04dd82c c0507e7c c050cc18 c183b9c0 ff60: c05233c0 00000000 00000000 c01f34f4 c0430d70 c019d364 c04dd898 c04dd898 ff80: c04dd82c c0507e7c c180e000 00000000 c04c584c c01f4918 c04dd898 c04dd82c ffa0: c04ddd28 c180e000 00000000 c0008758 c181fa60 3231d82c 00000037 00000000 ffc0: 00000000 c04dd898 c04dd82c c04ddd28 00000013 00000000 00000000 00000000 ffe0: 00000000 c04b2224 00000000 c04b21a0 c001056c c001056c 00000000 00000000 Function entered at [<c02fbba0>] from [<c019dfc4>] Function entered at [<c019dfc4>] from [<c01f34f4>] Function entered at [<c01f34f4>] from [<c01f4918>] Function entered at [<c01f4918>] from [<c0008758>] Function entered at [<c0008758>] from [<c04b2224>] Function entered at [<c04b2224>] from [<c001056c>] Code: e1a00005 e3a01028 ebfa7cb0 e35a0000 (e5858028) Here PC is at __alloc_skb and &shinfo->dataref is unaligned because skb->end can be unaligned without this patch. As explained by Eric Dumazet <eric.dumazet@gmail.com>, this happens only with SLOB, and not with SLAB or SLUB: * Eric Dumazet <eric.dumazet@gmail.com> [111102 15:56]: > > Your patch is absolutely needed, I completely forgot about SLOB :( > > since, kmalloc(386) on SLOB gives exactly ksize=386 bytes, not nearest > power of two. > > [ 60.305763] malloc(size=385)->ffff880112c11e38 ksize=386 -> nsize=2 > [ 60.305921] malloc(size=385)->ffff88007c92ce28 ksize=386 -> nsize=2 > [ 60.306898] malloc(size=656)->ffff88007c44ad28 ksize=656 -> nsize=272 > [ 60.325385] malloc(size=656)->ffff88007c575868 ksize=656 -> nsize=272 > [ 60.325531] malloc(size=656)->ffff88011c777230 ksize=656 -> nsize=272 > [ 60.325701] malloc(size=656)->ffff880114011008 ksize=656 -> nsize=272 > [ 60.346716] malloc(size=385)->ffff880114142008 ksize=386 -> nsize=2 > [ 60.346900] malloc(size=385)->ffff88011c777690 ksize=386 -> nsize=2 Signed-off-by: Tony Lindgren <tony@atomide.com> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2011-11-03 18:09:16 -04:00
..
datagram.c	net: add skb frag size accessors	2011-10-19 03:10:46 -04:00
dev_addr_lists.c	net: remove ndo_set_multicast_list callback	2011-08-17 20:22:03 -07:00
dev.c	vlan: allow nested vlan_do_receive()	2011-10-30 04:43:30 -04:00
drop_monitor.c	net,rcu: convert call_rcu(free_dm_hw_stat) to kfree_rcu()	2011-05-07 22:50:59 -07:00
dst.c	net: fix potential neighbour race in dst_ifdown()	2011-08-09 21:47:14 -07:00
ethtool.c	net: consolidate and fix ethtool_ops->get_settings calling	2011-09-15 17:32:26 -04:00
fib_rules.c	Merge branch 'master' of ra.kernel.org:/pub/scm/linux/kernel/git/davem/net	2011-10-24 18:18:09 -04:00
filter.c	filter: use unsigned int to silence static checker warning	2011-10-19 19:35:51 -04:00
flow.c	net/flow: Fix potential memory leak	2011-10-17 19:18:42 -04:00
gen_estimator.c	net,rcu: convert call_rcu(__gen_kill_estimator) to kfree_rcu()	2011-05-07 22:50:57 -07:00
gen_stats.c	net/core: EXPORT_SYMBOL cleanups	2010-07-12 12:57:55 -07:00
iovec.c	net: Limit socket I/O iovec total length to INT_MAX.	2010-10-28 11:47:52 -07:00
kmap_skb.h	net: convert core to skb paged frag APIs	2011-08-24 17:52:11 -07:00
link_watch.c	net: linkwatch: allow vlans to get carrier changes faster	2011-09-15 15:36:34 -04:00
Makefile	net: Compute protocol sequence numbers and fragment IDs using MD5.	2011-08-06 18:33:19 -07:00
neighbour.c	neigh: Kill bogus SMP protected debugging message.	2011-11-01 17:45:55 -04:00
net_namespace.c	rtnl: provide link dump consistency info	2011-07-01 15:39:53 -07:00
net-sysfs.c	net: consolidate and fix ethtool_ops->get_settings calling	2011-09-15 17:32:26 -04:00
net-sysfs.h	xps: Add CONFIG_XPS	2010-11-28 18:24:14 -08:00
net-traces.c	core: add tracepoints for queueing skb to rcvbuf	2011-06-21 16:06:10 -07:00
netevent.c	net/core: EXPORT_SYMBOL cleanups	2010-07-12 12:57:55 -07:00
netpoll.c	Merge branch 'master' of github.com:davem330/net	2011-09-22 03:23:13 -04:00
pktgen.c	pktgen: remove ndelay() call	2011-10-20 17:00:21 -04:00
request_sock.c	Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6	2010-12-08 13:47:38 -08:00
rtnetlink.c	if_link: Add additional parameter to IFLA_VF_INFO for spoof checking	2011-10-16 13:15:38 -07:00
scm.c	af_unix: dont send SCM_CREDENTIALS by default	2011-09-28 13:29:50 -04:00
secure_seq.c	tcp: add const qualifiers where possible	2011-10-21 05:22:42 -04:00
skbuff.c	net: Add back alignment for size for __alloc_skb	2011-11-03 18:09:16 -04:00
sock.c	net: Unlock sock before calling sk_free()	2011-10-25 19:17:25 -04:00
stream.c	net: Fix the condition passed to sk_wait_event()	2010-10-03 20:41:32 -07:00
sysctl_net_core.c	net: Kill ratelimit.h dependency in linux/net.h	2011-05-27 13:41:33 -04:00
timestamping.c	net: hold sock reference while processing tx timestamps	2011-10-24 02:54:50 -04:00
user_dma.c	net: add skb frag size accessors	2011-10-19 03:10:46 -04:00
utils.c	net: Kill ratelimit.h dependency in linux/net.h	2011-05-27 13:41:33 -04:00