Re: linux-next: slab shrinkers: BUG at mm/list_lru.c:92

From: Michal Hocko
Date: Fri Jun 28 2013 - 04:39:58 EST

I have just triggered this one.

[37955.354041] BUG: unable to handle kernel paging request at 000000572ead7838
[37955.356032] IP: [<ffffffff81127e5b>] list_lru_walk_node+0xab/0x140
[37955.364062] PGD 2bf0a067 PUD 0
[37955.364062] Oops: 0000 [#1] SMP
[37955.364062] Modules linked in: edd nfsv3 nfs_acl nfs fscache lockd sunrpc af_packet bridge stp llc cpufreq_conservative cpufreq_userspace cpufreq_powersave fuse xfs libcrc32c loop dm_mod tg3 ptp powernow_k8 pps_core e1000 kvm_amd shpchp kvm edac_core i2c_amd756 pci_hotplug i2c_amd8111 sg edac_mce_amd amd_rng k8temp sr_mod pcspkr cdrom serio_raw button ohci_hcd ehci_hcd usbcore usb_common processor thermal_sys scsi_dh_emc scsi_dh_rdac scsi_dh_hp_sw scsi_dh ata_generic sata_sil pata_amd
[37955.364062] CPU 3
[37955.364062] Pid: 3351, comm: as Not tainted 3.9.0mmotm+ #1490 AMD A8440/WARTHOG
[37955.364062] RIP: 0010:[<ffffffff81127e5b>] [<ffffffff81127e5b>] list_lru_walk_node+0xab/0x140
[37955.364062] RSP: 0000:ffff8800374af7b8 EFLAGS: 00010286
[37955.364062] RAX: 0000000000000106 RBX: ffff88002ead7838 RCX: ffff8800374af830
[37955.364062] RDX: 0000000000000107 RSI: ffff88001d250dc0 RDI: ffff88002ead77d0
[37955.364062] RBP: ffff8800374af818 R08: 0000000000000000 R09: ffff88001ffeafc0
[37955.364062] R10: 0000000000000002 R11: 0000000000000000 R12: ffff88001d250dc0
[37955.364062] R13: 00000000000000a0 R14: 000000572ead7838 R15: ffff88001d250dc8
[37955.364062] FS: 00002aaaaaadb100(0000) GS:ffff88003fd00000(0000) knlGS:0000000000000000
[37955.364062] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[37955.364062] CR2: 000000572ead7838 CR3: 0000000036f61000 CR4: 00000000000007e0
[37955.364062] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[37955.364062] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[37955.364062] Process as (pid: 3351, threadinfo ffff8800374ae000, task ffff880036d665c0)
[37955.364062] Stack:
[37955.364062] ffff88001da3e700 ffff8800374af830 ffff8800374af838 ffffffff811846d0
[37955.364062] 0000000000000000 ffff88001ce75c48 01ff8800374af838 ffff8800374af838
[37955.364062] 0000000000000000 ffff88001ce75800 ffff8800374afa08 0000000000001014
[37955.364062] Call Trace:
[37955.364062] [<ffffffff811846d0>] ? insert_inode_locked+0x160/0x160
[37955.364062] [<ffffffff8118496c>] prune_icache_sb+0x3c/0x60
[37955.364062] [<ffffffff8116dcbe>] super_cache_scan+0x12e/0x1b0
[37955.364062] [<ffffffff8111354a>] shrink_slab_node+0x13a/0x250
[37955.364062] [<ffffffff8111671b>] shrink_slab+0xab/0x120
[37955.364062] [<ffffffff81117944>] do_try_to_free_pages+0x264/0x360
[37955.364062] [<ffffffff81117d90>] try_to_free_pages+0x130/0x180
[37955.364062] [<ffffffff81001974>] ? __switch_to+0x1b4/0x550
[37955.364062] [<ffffffff8110a2fe>] __alloc_pages_slowpath+0x39e/0x790
[37955.364062] [<ffffffff8110a8ea>] __alloc_pages_nodemask+0x1fa/0x210
[37955.364062] [<ffffffff8114d1b0>] alloc_pages_vma+0xa0/0x120
[37955.364062] [<ffffffff81129ebb>] do_anonymous_page+0x16b/0x350
[37955.364062] [<ffffffff8112f9c5>] handle_pte_fault+0x235/0x240
[37955.364062] [<ffffffff8107b8b0>] ? set_next_entity+0xb0/0xd0
[37955.364062] [<ffffffff8112fcbf>] handle_mm_fault+0x2ef/0x400
[37955.364062] [<ffffffff8157e927>] __do_page_fault+0x237/0x4f0
[37955.364062] [<ffffffff8116a8a8>] ? fsnotify_access+0x68/0x80
[37955.364062] [<ffffffff8116b0b8>] ? vfs_read+0xd8/0x130
[37955.364062] [<ffffffff8157ebe9>] do_page_fault+0x9/0x10
[37955.364062] [<ffffffff8157b348>] page_fault+0x28/0x30
[37955.364062] Code: 44 24 18 0f 84 87 00 00 00 49 83 7c 24 18 00 78 7b 49 83 c5 01 48 8b 4d a8 48 8b 11 48 8d 42 ff 48 85 d2 48 89 01 74 78 4d 39 f7 <49> 8b 06 4c 89 f3 74 6d 49 89 c6 eb a6 0f 1f 84 00 00 00 00 00
[37955.364062] RIP [<ffffffff81127e5b>] list_lru_walk_node+0xab/0x140

ffffffff81127e0e: 48 8b 55 b0 mov -0x50(%rbp),%rdx
ffffffff81127e12: 4c 89 e6 mov %r12,%rsi
ffffffff81127e15: 48 89 df mov %rbx,%rdi
ffffffff81127e18: ff 55 b8 callq *-0x48(%rbp) # isolate(item, &nlru->lock, cb_arg)
ffffffff81127e1b: 83 f8 01 cmp $0x1,%eax
ffffffff81127e1e: 74 78 je ffffffff81127e98 <list_lru_walk_node+0xe8>
ffffffff81127e20: 73 4e jae ffffffff81127e70 <list_lru_walk_node+0xc0>
[...]
ffffffff81127e45: 48 8b 4d a8 mov -0x58(%rbp),%rcx # LRU_ROTATE:
ffffffff81127e49: 48 8b 11 mov (%rcx),%rdx
ffffffff81127e4c: 48 8d 42 ff lea -0x1(%rdx),%rax
ffffffff81127e50: 48 85 d2 test %rdx,%rdx # if ((*nr_to_walk)-- == 0)
ffffffff81127e53: 48 89 01 mov %rax,(%rcx)
ffffffff81127e56: 74 78 je ffffffff81127ed0 <list_lru_walk_node+0x120>
ffffffff81127e58: 4d 39 f7 cmp %r14,%r15
ffffffff81127e5b: 49 8b 06 mov (%r14),%rax <<< BANG
ffffffff81127e5e: 4c 89 f3 mov %r14,%rbx
ffffffff81127e61: 74 6d je ffffffff81127ed0 <list_lru_walk_node+0x120>
ffffffff81127e63: 49 89 c6 mov %rax,%r14
ffffffff81127e66: eb a6 jmp ffffffff81127e0e <list_lru_walk_node+0x5e>
[...]
ffffffff81127e70: 83 f8 02 cmp $0x2,%eax
ffffffff81127e73: 74 d0 je ffffffff81127e45 <list_lru_walk_node+0x95>
ffffffff81127e75: 83 f8 03 cmp $0x3,%eax
ffffffff81127e78: 74 06 je ffffffff81127e80 <list_lru_walk_node+0xd0>
ffffffff81127e7a: 0f 0b ud2
[...]
ffffffff81127ed0: 66 41 83 04 24 01 addw $0x1,(%r12)
ffffffff81127ed6: 48 83 c4 38 add $0x38,%rsp
ffffffff81127eda: 4c 89 e8 mov %r13,%rax
ffffffff81127edd: 5b pop %rbx
ffffffff81127ede: 41 5c pop %r12
ffffffff81127ee0: 41 5d pop %r13
ffffffff81127ee2: 41 5e pop %r14
ffffffff81127ee4: 41 5f pop %r15
ffffffff81127ee6: c9 leaveq
ffffffff81127ee7: c3 retq

We are tripping over in list_for_each_safe and r14(000000572ead7838) is
obviously a garbage. So the lru is clobbered?
--
Michal Hocko
SUSE Labs
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