Messages in this thread Patch in this message | | | Date | Mon, 2 Apr 2012 21:34:40 +0200 | From | Bruno Prémont <> | Subject | Re: [3.4-rc1 crash]: NULL pointer deref in fs/sysfs/group.c:create_files -- sysctl related? |
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[adding a few perf people to CC as might originate from perf]
On Mon, 02 April 2012 Eric W. Biederman wrote: > Bruno Prémont writes: > > On Mon, 2 Apr 2012 16:27:16 Bruno Prémont wrote: > >> Trying to boot a freshly built 3.4-rc1 (x86_64) kernel I'm getting the following > >> trace (server is HP Proliant G4): > >> > >> [ 0.986317] BUG: unable to handle kernel NULL pointer dereference at (null) > >> [ 0.990542] IP: [<ffffffff81152673>] internal_create_group+0x83/0x1a0 > >> [ 0.993693] PGD 0 > >> [ 0.994682] Oops: 0000 [#1] SMP > >> [ 0.996198] CPU 0 > >> [ 0.996198] Modules linked in: > >> [ 0.996198] > >> [ 0.996198] Pid: 1, comm: swapper/0 Not tainted 3.4.0-rc1-x86_64 #3 HP ProLiant DL360 G4 > >> [ 0.996198] RIP: 0010:[<ffffffff81152673>] [<ffffffff81152673>] internal_create_group+0x83/0x1a0 > >> [ 0.996198] RSP: 0018:ffff88019485fd70 EFLAGS: 00010202 > >> [ 0.996198] RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000001 > >> [ 0.996198] RDX: ffff880192e99908 RSI: ffff880192e99630 RDI: ffffffff81a26c60 > >> [ 0.996198] RBP: ffff88019485fdc0 R08: 0000000000000000 R09: 0000000000000000 > >> [ 0.996198] R10: ffff880192e99908 R11: 0000000000000000 R12: ffffffff81a16a00 > >> [ 0.996198] R13: ffff880192e99908 R14: ffffffff81a16900 R15: 0000000000000000 > >> [ 0.996198] FS: 0000000000000000(0000) GS:ffff88019bc00000(0000) knlGS:0000000000000000 > >> [ 0.996198] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > >> [ 0.996198] CR2: 0000000000000000 CR3: 0000000001a0c000 CR4: 00000000000007f0 > >> [ 0.996198] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > >> [ 0.996198] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > >> [ 0.996198] Process swapper/0 (pid: 1, threadinfo ffff88019485e000, task ffff880194878000) > >> [ 0.996198] Stack: > >> [ 0.996198] ffff88019485fdd0 ffff880192da9d60 0000000000000000 ffff880192e99908 > >> [ 0.996198] ffff880192e995d8 0000000000000001 ffffffff81a16a00 ffff880192da9d60 > >> [ 0.996198] 0000000000000000 0000000000000000 ffff88019485fdd0 ffffffff811527be > >> [ 0.996198] Call Trace: > >> [ 0.996198] [<ffffffff811527be>] sysfs_create_group+0xe/0x10 > >> [ 0.996198] [<ffffffff81376ca6>] device_add_groups+0x46/0x80 > >> [ 0.996198] [<ffffffff81377d3d>] device_add+0x46d/0x6a0 > >> [ 0.996198] [<ffffffff81377891>] ? device_private_init+0x51/0x90 > >> [ 0.996198] [<ffffffff81a98975>] ? utsname_sysctl_init+0x14/0x14 > >> [ 0.996198] [<ffffffff810a7228>] pmu_dev_alloc+0x98/0xe0 > >> [ 0.996198] [<ffffffff81a98975>] ? utsname_sysctl_init+0x14/0x14 > >> [ 0.996198] [<ffffffff81a989c0>] perf_event_sysfs_init+0x4b/0x9a > >> [ 0.996198] [<ffffffff810002ad>] do_one_initcall+0x3d/0x170 > >> [ 0.996198] [<ffffffff81a85cbd>] kernel_init+0x12d/0x1be > >> [ 0.996198] [<ffffffff81a85505>] ? rdinit_setup+0x28/0x28 > >> [ 0.996198] [<ffffffff815f3714>] kernel_thread_helper+0x4/0x10 > >> [ 0.996198] [<ffffffff81a85b90>] ? start_kernel+0x373/0x373 > >> [ 0.996198] [<ffffffff815f3710>] ? gs_change+0xb/0xb > >> [ 0.996198] Code: ff 85 c0 0f 85 bc 00 00 00 4c 8b 6d c8 4d 85 ed 74 15 41 8b 45 00 85 c0 0f 84 0b 01 00 00 f0 41 ff 45 00 4c 8b 6d c8 49 8b 5e 10 <48> 8b 03 48 85 c0 74 71 45 31 e4 eb 44 49 8b 46 08 48 85 c0 74 > >> [ 0.996198] RIP [<ffffffff81152673>] internal_create_group+0x83/0x1a0 > >> [ 0.996198] RSP <ffff88019485fd70> > >> [ 0.996198] CR2: 0000000000000000 > >> [ 1.131357] ---[ end trace 319c95c486d7d9cd ]--- > >> [ 1.133676] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 > >> [ 1.133677] > > > > The patch below works around it and leaves exactly one trace for WARN_ON() matching > > above BUG. > > With it, system boots to userspace. > > > > Thanks, > > Bruno > > > > --- > > diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c > > index dd1701c..0040ff2 100644 > > --- a/fs/sysfs/group.c > > +++ b/fs/sysfs/group.c > > @@ -32,7 +32,8 @@ static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj, > > struct attribute *const* attr; > > int error = 0, i; > > > > - for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) { > > + WARN_ON(!grp->attrs); > > + for (i = 0, attr = grp->attrs; attr && *attr && !error; i++, attr++) { > > umode_t mode = 0; > > > > /* in update mode, we're changing the permissions or > > Sysfs has not changed in this area from 3.3. > > The sysctl in your backtrace looks like left over addresses on the stack. > > The backtrack indicates this is something perf related going wonky. > > I would suggest you try disabling your perf related options one by one > until the broken one shows up. Or possibly just initially disable perf.
Well, I didn't enable perf, all perf-related options that are enabled are selected by X86!
Symbol: HAVE_PERF_EVENTS [=y] Type : boolean Selected by: X86 [=y]
Symbol: PERF_EVENTS [=y] Type : boolean Prompt: Kernel performance events and counters Defined at init/Kconfig:1157 Depends on: HAVE_PERF_EVENTS [=y] Location: -> General setup -> Kernel Performance Events And Counters Selects: ANON_INODES [=y] && IRQ_WORK [=y] Selected by: X86 [=y] || KVM [=n] && VIRTUALIZATION [=n] && HAVE_KVM [=y] && PCI [=y] && NET [=y]
Symbol: HAVE_PERF_EVENTS_NMI [=y] Type : boolean Selected by: X86 [=y]
> This looks like one of those crazy things where something registers > with the perf subsystem, and then perf later registers it with sysfs, > and whatever was registered did not have set the needed group attrs.
From quick-reading kernel/events/core.c which contains perf_event_sysfs_init() and pmu_dev_alloc() and commits from v3.3..v3.4 for that file commit 0c9d42ed4cee2aa1dfc3a260b741baae8615744f (perf, x86: Provide means for disabling userspace RDPMC) by Peter looks like a possible candidate or at least startpoint:
diff --git a/kernel/events/core.c b/kernel/events/core.c index 05affc3..dcd4049 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5505,6 +5505,7 @@ static int pmu_dev_alloc(struct pmu *pmu) if (!pmu->dev) goto out; + pmu->dev->groups = pmu->attr_groups; device_initialize(pmu->dev); ret = dev_set_name(pmu->dev, "%s", pmu->name); if (ret) Will try bisecting corresponding merge tomorrow when I have full access to affected system.
Thanks, Bruno -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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