Messages in this thread | | | Date | Mon, 02 Apr 2012 14:04:47 -0600 | From | David Ahern <> | Subject | Re: [3.4-rc1 crash]: NULL pointer deref in fs/sysfs/group.c:create_files -- sysctl related? |
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On 4/2/12 1:34 PM, Bruno Prémont wrote: > [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.
Perhaps: 641cc93 perf: Adding sysfs group format attribute for pmu device
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