On Tuesday 02 March 2010, Michal Hocko wrote: > On Tue, Mar 02, 2010 at 09:25:43AM +0100, Michal Hocko wrote: > > On Tue, Mar 02, 2010 at 01:06:06AM +0100, Rafael J. Wysocki wrote: > > > On Monday 01 March 2010, Michal Hocko wrote: > > > > [Let's CC mm guys] > > > > > > I guess it's rather architecture-related than a genering mm issue. s/genering/generic/ (why did I write that?) ... > > > > Yes, it really looks strange. dup_mm+0x1c7 matches to: > > > > c102fc0e: 81 60 14 ff df ff ff andl $0xffffdfff,0x14(%eax) > > > > c102fc15: 8b 45 ec mov -0x14(%ebp),%eax > > > > c102fc18: c7 43 0c 00 00 00 00 movl $0x0,0xc(%ebx) > > > > c102fc1f: 89 03 mov %eax,(%ebx) > > > > c102fc21: 89 d8 mov %ebx,%eax > > > > c102fc23: e8 38 e6 06 00 call c109e260 <anon_vma_link> > > > > c102fc28: 8b 43 48 mov 0x48(%ebx),%eax <<< BANG > > > > > > > > which corresponds to: > > > > kernel/fork.c:336 > > > > tmp->vm_flags &= ~VM_LOCKED; > > > > tmp->vm_mm = mm; > > > > tmp->vm_next = NULL; > > > > anon_vma_link(tmp); > > > > file = tmp->vm_file; <<< BANG > > > > > > > > ebx is tmp which somehow got deallocated. I cannot see how this could happened. > > > > > > Through a page tables corruption or a TLB issue, for example. > > > > I thought so. Is there any other possibility? Like a race with vma > > unlinking? I don't think that particular instruction would trigger the NULL poiter dereference in that case. In theory, it may be a result of a stack corruption if EBX was saved on the stack by anon_vma_link(). I'm not sure if that happens, though. > It really looks like some memory corruption. Now I got the following: > > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: [<c026db57>] strcmp+0xe/0x22 > *pde = 00000000 > Oops: 0000 [#1] PREEMPT SMP > last sysfs file: /sys/devices/pci0000:00/0000:00:1e.0/0000:08:03.4/fw-host0/00000e1003d248c6/uevent > Modules linked in: fbcon font bitblit softcursor i915 drm_kms_helper drm fb i2c_algo_bit cfbcopyarea i2c > on snd_hda_codec_realtek arc4 ecb snd_hda_intel snd_hda_codec snd_pcm_oss snd_mixer_oss snd_pcm iwl3945 > d_timer snd_seq_device mac80211 snd fujitsu_laptop rtc_cmos cfg80211 rtc_core rtc_lib led_class snd_page > i_wait_scan] > > Pid: 16719, comm: udev-acl.ck Not tainted 2.6.33-00001-gbaac35c #11 FJNB1B5/LIFEBOOK S7110 > EIP: 0060:[<c026db57>] EFLAGS: 00010286 CPU: 0 > EIP is at strcmp+0xe/0x22 > EAX: 00000000 EBX: f71c0600 ECX: f70d0f00 EDX: f5a1d49c > ESI: 00000000 EDI: f5a1d49c EBP: f70d0dec ESP: f70d0de4 > DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 > Process udev-acl.ck (pid: 16719, ti=f70d0000 task=f6a65710 task.ti=f70d0000) > Stack: > f5a1d49c fffffffe f70d0dfc c01ea0c0 f5a1d440 f71c05a0 f70d0e14 c01ea267 > <0> f5a1d330 c044cfac f70d0f00 f6f44968 f70d0e3c c01b3a14 f70fcc80 f70d0e7c > <0> f6f449e0 f5a1d330 f5a1d440 f70d0f00 f6f44968 087bed70 f70d0e90 c01b508a > Call Trace: > [<c01ea0c0>] ? sysfs_find_dirent+0x1b/0x2c > [<c01ea267>] ? sysfs_lookup+0x2f/0xa6 > [<c01b3a14>] ? do_lookup+0xca/0x174 > [<c01b508a>] ? link_path_walk+0x691/0xa22 > [<c01bf3e8>] ? mntput_no_expire+0x1e/0xb2 > [<c01b552c>] ? path_walk+0x3f/0x89 > [<c01b3dd1>] ? path_init+0x73/0x114 > [<c01b5601>] ? do_path_lookup+0x26/0x47 > [<c01b6072>] ? do_filp_open+0xdc/0x79e > [<c01899d0>] ? free_hot_page+0x55/0x59 > [<c01eaad0>] ? sysfs_put_link+0x0/0x1f > [<c0189a6b>] ? free_pages+0x22/0x24 > [<c01b3d54>] ? generic_readlink+0x69/0x73 > [<c04371c9>] ? add_preempt_count+0x8/0x75 > [<c0437155>] ? sub_preempt_count+0x8/0x74 > [<c0434547>] ? _raw_spin_unlock+0x14/0x28 > [<c01aae0a>] ? do_sys_open+0x4d/0xe9 > [<c01aad0e>] ? filp_close+0x56/0x60 > [<c01aaef2>] ? sys_open+0x23/0x2b > [<c0102850>] ? sysenter_do_call+0x12/0x26 > Code: 31 c0 83 c9 ff f2 ae 4f 89 d1 49 78 06 ac aa 84 c0 75 f7 31 c0 aa 89 d8 5b 5e 5f 5d c3 55 89 e5 57 56 0f 1f 44 00 00 89 c6 89 d7 <ac> ae 75 08 84 c0 75 f8 31 c0 eb 04 19 c0 0c 01 5e 5f 5d c3 55 > EIP: [<c026db57>] strcmp+0xe/0x22 SS:ESP 0068:f70d0de4 > CR2: 0000000000000000 > ---[ end trace 877af85bb64785ae ]--- The question is whether hibernation is the reason of this or it's only a messenger. > > > > > What's the HEAD commit in this kernel tree? > > > > > > > > $ git describe > > > > v2.6.33-1-gbaac35c > > > > > > I can't find gbaac35c anywhere post 2.6.33. > > > > you should look at baac35c. Git describe displays gHASH Ah. > > > Can you just send the output > > > of "git show | head -1", please? > > > > The whole commit ID is baac35c4155a8aa826c70acee6553368ca5243a2 So this is just plain 2.6.33 plus one commit. Hmm. There are only a few changes directly related to hibernation in that kernel and none of them can possibly introduce a problem like that. Do you use s2disk or the in-kernel thing? Rafael -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>