Hi, my system triggers this bug, and the vmcore shows the anon_vma seems be freed.
The kernel is RHEL 7.2, and the bug is hard to reproduce, so I don't know if it
exists in mainline, any reply is welcome!
[35030.332666] general protection fault: 0000 [#1] SMP
[35030.333016] Modules linked in: veth ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 xt_addrtype iptable_filter xt_conntrack nf_nat nf_conntrack bridge stp llc dm_thin_pool dm_persistent_data dm_bio_prison dm_bufio libcrc32c rtos_kbox_panic(OE) ipmi_devintf ipmi_si ipmi_msghandler signo_catch(O) cirrus syscopyarea sysfillrect sysimgblt ttm crc32_pclmul ghash_clmulni_intel drm_kms_helper aesni_intel ppdev drm lrw gf128mul parport_pc glue_helper ablk_helper serio_raw cryptd i2c_piix4 parport pcspkr sg floppy i2c_core dm_mod sha512_generic ip_tables sd_mod crc_t10dif crct10dif_generic sr_mod cdrom virtio_console virtio_scsi virtio_net ata_generic pata_acpi crct10dif_pclmul crct10dif_common crc32c_intel virtio_pci virtio_ring virtio ata_piix libata ext4 mbcache
[35030.333016] jbd2
[35030.333016] CPU: 3 PID: 48 Comm: kswapd0 Tainted: G OE ---- ------- 3.10.0-327.36.58.4.x86_64 #1
[35030.333016] Hardware name: OpenStack Foundation OpenStack Nova, BIOS rel-1.8.1-0-g4adadbd-20160826_044443-hghoulaslx112 04/01/2014
[35030.333016] task: ffff8801b2d20000 ti: ffff8801b4c38000 task.ti: ffff8801b4c38000
[35030.333016] RIP: 0010:[<ffffffff810acac5>] [<ffffffff810acac5>] down_read_trylock+0x5/0x50
[35030.333016] RSP: 0000:ffff8801b4c3ba90 EFLAGS: 00010282
[35030.333016] RAX: 0000000000000000 RBX: ffff8801b3e2a100 RCX: 0000000000000000
[35030.333016] RDX: 0000000000000000 RSI: 0000000000000000 RDI: deb604d497705c5d
[35030.333016] RBP: ffff8801b4c3bab8 R08: ffffea0002c34460 R09: ffff8801b3d7e8a0
[35030.333016] R10: 0000000000000004 R11: fff00000fe000000 R12: ffff8801b3e2a101
[35030.333016] R13: ffffea0002c34440 R14: deb604d497705c5d R15: ffffea0002c34440
[35030.333016] FS: 0000000000000000(0000) GS:ffff8801bed80000(0000) knlGS:0000000000000000
[35030.333016] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[35030.333016] CR2: 000000c422011080 CR3: 0000000001976000 CR4: 00000000001407e0
[35030.333016] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[35030.333016] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[35030.333016] Stack:
[35030.333016] ffffffff811b2795 ffffea0002c34440 0000000000000000 000000000000000f
[35030.333016] 0000000000000001 ffff8801b4c3bb30 ffffffff811b2a17 ffff8800a712d640
[35030.333016] 000000000c4229e2 ffff8801b4c3bb80 0000000100000000 000000000c41fe38
[35030.333016] Call Trace:
[35030.333016] [<ffffffff811b2795>] ? page_lock_anon_vma_read+0x55/0x110
[35030.333016] [<ffffffff811b2a17>] page_referenced+0x1c7/0x350
[35030.333016] [<ffffffff8118d9b4>] shrink_active_list+0x1e4/0x400
[35030.333016] [<ffffffff8118e08d>] shrink_lruvec+0x4bd/0x770
[35030.333016] [<ffffffff8118e3b6>] shrink_zone+0x76/0x1a0
[35030.333016] [<ffffffff8118f6cc>] balance_pgdat+0x49c/0x610
[35030.333016] [<ffffffff8118f9b3>] kswapd+0x173/0x450
[35030.333016] [<ffffffff810a8a00>] ? wake_up_atomic_t+0x30/0x30
[35030.333016] [<ffffffff8118f840>] ? balance_pgdat+0x610/0x610
[35030.333016] [<ffffffff810a79bf>] kthread+0xcf/0xe0
[35030.333016] [<ffffffff810a78f0>] ? kthread_create_on_node+0x120/0x120
[35030.333016] [<ffffffff81665bd8>] ret_from_fork+0x58/0x90
[35030.333016] [<ffffffff810a78f0>] ? kthread_create_on_node+0x120/0x120
[35030.333016] Code: 00 ba ff ff ff ff 48 89 d8 f0 48 0f c1 10 79 05 e8 31 06 27 00 5b 5d c3 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 <48> 8b 07 48 89 c2 48 83 c2 01 7e 07 f0 48 0f b1 17 75 f0 48 f7
[35030.333016] RIP [<ffffffff810acac5>] down_read_trylock+0x5/0x50
[35030.333016] RSP <ffff8801b4c3ba90>
[35030.333016] ------------[ cut here ]------------
struct page {
flags = 9007194960298056,
mapping = 0xffff8801b3e2a101,
{
{
index = 34324593617,
freelist = 0x7fde7bbd1,
pfmemalloc = 209,
thp_mmu_gather = {
counter = -35144751
},
pmd_huge_pte = 0x7fde7bbd1
},
{
counters = 8589934592,
{
{
_mapcount = {
counter = 0
},
{
inuse = 0,
objects = 0,
frozen = 0
},
units = 0
},
_count = {
counter = 2
}
}
}
},
{
lru = {
next = 0xdead000000100100,
prev = 0xdead000000200200
},
{
next = 0xdead000000100100,
pages = 2097664,
pobjects = -559087616
},
list = {
next = 0xdead000000100100,
prev = 0xdead000000200200
},
slab_page = 0xdead000000100100
},
{
private = 0,
ptl = {
{
rlock = {
raw_lock = {
{
head_tail = 0,
tickets = {
head = 0,
tail = 0
}
}
}
}
}
},
slab_cache = 0x0,
first_page = 0x0
}
}
crash> struct anon_vma 0xffff8801b3e2a100
struct anon_vma {
root = 0xdeb604d497705c55,
rwsem = {
count = -8192007903225070328,
wait_lock = {
raw_lock = {
{
head_tail = 2955503940,
tickets = {
head = 26948,
tail = 45097
}
}
}
},
wait_list = {
next = 0x559f9107c1b47439,
prev = 0x3de13f709bfa043b
}
},
refcount = {
counter = -13243516
},
rb_root = {
rb_node = 0x11dd18f9ce0bb2e9
}
}
This address 0xffff8801b3e2a100 can not find in "kmem -S anon_vma"
The page flags is
crash> kmem -g 0x1FFFFF00080048
FLAGS: 1fffff00080048
PAGE-FLAG BIT VALUE
PG_uptodate 3 0000008
PG_active 6 0000040
PG_swapbacked 19 0080000
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