Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 15 Feb 2016 19:37:02 +0100 | From | Gerald Schaefer <> | Subject | Re: [BUG] random kernel crashes after THP rework on s390 (maybe also on PowerPC and ARM) |
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On Mon, 15 Feb 2016 13:31:59 +0200 "Kirill A. Shutemov" <kirill@shutemov.name> wrote:
> On Sat, Feb 13, 2016 at 12:58:31PM +0100, Sebastian Ott wrote: > > > > On Sat, 13 Feb 2016, Kirill A. Shutemov wrote: > > > Could you check if revert of fecffad25458 helps? > > > > I reverted fecffad25458 on top of 721675fcf277cf - it oopsed with: > > > > ¢ 1851.721062! Unable to handle kernel pointer dereference in virtual kernel address space > > ¢ 1851.721075! failing address: 0000000000000000 TEID: 0000000000000483 > > ¢ 1851.721078! Fault in home space mode while using kernel ASCE. > > ¢ 1851.721085! AS:0000000000d5c007 R3:00000000ffff0007 S:00000000ffffa800 P:000000000000003d > > ¢ 1851.721128! Oops: 0004 ilc:3 ¢#1! PREEMPT SMP DEBUG_PAGEALLOC > > ¢ 1851.721135! Modules linked in: bridge stp llc btrfs mlx4_ib mlx4_en ib_sa ib_mad vxlan xor ip6_udp_tunnel ib_core udp_tunnel ptp pps_core ib_addr ghash_s390raid6_pq prng ecb aes_s390 mlx4_core des_s390 des_generic genwqe_card sha512_s390 sha256_s390 sha1_s390 sha_common crc_itu_t dm_mod scm_block vhost_net tun vhost eadm_sch macvtap macvlan kvm autofs4 > > ¢ 1851.721183! CPU: 7 PID: 256422 Comm: bash Not tainted 4.5.0-rc3-00058-g07923d7-dirty #178 > > ¢ 1851.721186! task: 000000007fbfd290 ti: 000000008c604000 task.ti: 000000008c604000 > > ¢ 1851.721189! Krnl PSW : 0704d00180000000 000000000045d3b8 (__rb_erase_color+0x280/0x308) > > ¢ 1851.721200! R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 EA:3 > > Krnl GPRS: 0000000000000001 0000000000000020 0000000000000000 00000000bd07eff1 > > ¢ 1851.721205! 000000000027ca10 0000000000000000 0000000083e45898 0000000077b61198 > > ¢ 1851.721207! 000000007ce1a490 00000000bd07eff0 000000007ce1a548 000000000027ca10 > > ¢ 1851.721210! 00000000bd07c350 00000000bd07eff0 000000008c607aa8 000000008c607a68 > > ¢ 1851.721221! Krnl Code: 000000000045d3aa: e3c0d0080024 stg %%r12,8(%%r13) > > 000000000045d3b0: b9040039 lgr %%r3,%%r9 > > #000000000045d3b4: a53b0001 oill %%r3,1 > > >000000000045d3b8: e33010000024 stg %%r3,0(%%r1) > > 000000000045d3be: ec28000e007c cgij %%r2,0,8,45d3da > > 000000000045d3c4: e34020000004 lg %%r4,0(%%r2) > > 000000000045d3ca: b904001c lgr %%r1,%%r12 > > 000000000045d3ce: ec143f3f0056 rosbg %%r1,%%r4,63,63,0 > > ¢ 1851.721269! Call Trace: > > ¢ 1851.721273! (¢<0000000083e45898>! 0x83e45898) > > ¢ 1851.721279! ¢<000000000029342a>! unlink_anon_vmas+0x9a/0x1d8 > > ¢ 1851.721282! ¢<0000000000283f34>! free_pgtables+0xcc/0x148 > > ¢ 1851.721285! ¢<000000000028c376>! exit_mmap+0xd6/0x300 > > ¢ 1851.721289! ¢<0000000000134db8>! mmput+0x90/0x118 > > ¢ 1851.721294! ¢<00000000002d76bc>! flush_old_exec+0x5d4/0x700 > > ¢ 1851.721298! ¢<00000000003369f4>! load_elf_binary+0x2f4/0x13e8 > > ¢ 1851.721301! ¢<00000000002d6e4a>! search_binary_handler+0x9a/0x1f8 > > ¢ 1851.721304! ¢<00000000002d8970>! do_execveat_common.isra.32+0x668/0x9a0 > > ¢ 1851.721307! ¢<00000000002d8cec>! do_execve+0x44/0x58 > > ¢ 1851.721310! ¢<00000000002d8f92>! SyS_execve+0x3a/0x48 > > ¢ 1851.721315! ¢<00000000006fb096>! system_call+0xd6/0x258 > > ¢ 1851.721317! ¢<000003ff997436d6>! 0x3ff997436d6 > > ¢ 1851.721319! INFO: lockdep is turned off. > > ¢ 1851.721321! Last Breaking-Event-Address: > > ¢ 1851.721323! ¢<000000000045d31a>! __rb_erase_color+0x1e2/0x308 > > ¢ 1851.721327! > > ¢ 1851.721329! ---¢ end trace 0d80041ac00cfae2 !--- > > > > > > > > > > And could you share how crashes looks like? I haven't seen backtraces yet. > > > > > > > Sure. I didn't because they really looked random to me. Most of the time > > in rcu or list debugging but I thought these have just been the messenger > > observing a corruption first. Anyhow, here is an older one that might look > > interesting: > > > > [ 59.851421] list_del corruption. next->prev should be 000000006e1eb000, but was 0000000000000400 > > This kinda interesting: 0x400 is TAIL_MAPPING.. Hm.. > > Could you check if you see the problem on commit 1c290f642101 and its > immediate parent? >
How should the page->mapping poison end up as next->prev in the list of pre-allocated THP splitting page tables? Also, commit 1c290f642101 is before the THP rework, at least the non-bisectable part, so we should expect not to see the problem there.
0x400 is also the value of an empty pte on s390, and the thp_deposit/withdraw listheads are placed inside the pre-allocated pagetables instead of page->lru, because we have 2K pagetables on s390 and cannot use struct page == pgtable_t.
So, for example, two concurrent withdraws could produce such a list corruption, because the first withdraw will overwrite the listhead at the beginning of the pagetable with 2 empty ptes.
Has anything changed regarding the general THP deposit/withdraw logic?
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