Re: [PATCH V2 0/6] mm: page_alloc: freelist migratetype hygiene

[Mike Kravetz]

In next-20230913, I started hitting the following BUG.  Seems related
to this series.  And, if series is reverted I do not see the BUG.

I can easily reproduce on a small 16G VM.  kernel command line contains
"hugetlb_free_vmemmap=on hugetlb_cma=4G".  Then run the script,
while true; do
 echo 4 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages
 echo 4 > /sys/kernel/mm/hugepages/hugepages-1048576kB/demote
 echo 0 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
done

For the BUG below I believe it was the first (or second) 1G page creation from
CMA that triggered:  cma_alloc of 1G.

Sorry, have not looked deeper into the issue.

[   28.643019] page:ffffea0004fb4280 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x13ed0a
[   28.645455] flags: 0x200000000000000(node=0|zone=2)
[   28.646835] page_type: 0xffffffff()
[   28.647886] raw: 0200000000000000 dead000000000100 dead000000000122 0000000000000000
[   28.651170] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
[   28.653124] page dumped because: VM_BUG_ON_PAGE(is_migrate_isolate(mt))
[   28.654769] ------------[ cut here ]------------
[   28.655972] kernel BUG at mm/page_alloc.c:1231!
[   28.657139] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[   28.658354] CPU: 2 PID: 885 Comm: bash Not tainted 6.6.0-rc1-next-20230913+ #3
[   28.660090] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc37 04/01/2014
[   28.662054] RIP: 0010:free_pcppages_bulk+0x192/0x240
[   28.663284] Code: 22 48 89 45 08 8b 44 24 0c 41 29 44 24 04 41 29 c6 41 83 f8 05 0f 85 4c ff ff ff 48 c7 c6 20 a5 22 82 48 89 df e8 4e cf fc ff <0f> 0b 65 8b 05 41 8b d3 7e 89 c0 48 0f a3 05 fb 35 39 01 0f 83 40
[   28.667422] RSP: 0018:ffffc90003b9faf0 EFLAGS: 00010046
[   28.668643] RAX: 000000000000003b RBX: ffffea0004fb4280 RCX: 0000000000000000
[   28.670245] RDX: 0000000000000000 RSI: ffffffff8224dace RDI: 00000000ffffffff
[   28.671920] RBP: ffffea0004fb4288 R08: 0000000000009ffb R09: 00000000ffffdfff
[   28.673614] R10: 00000000ffffdfff R11: ffffffff824660c0 R12: ffff888477c30540
[   28.675213] R13: ffff888477c30550 R14: 00000000000012f5 R15: 000000000013ed0a
[   28.676832] FS:  00007f60039b9740(0000) GS:ffff888477c00000(0000) knlGS:0000000000000000
[   28.678709] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   28.680046] CR2: 00005615f9bf3048 CR3: 00000003128b6005 CR4: 0000000000370ee0
[   28.682897] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   28.684501] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   28.686098] Call Trace:
[   28.686792]  <TASK>
[   28.687414]  ? die+0x32/0x80
[   28.688197]  ? do_trap+0xd6/0x100
[   28.689069]  ? free_pcppages_bulk+0x192/0x240
[   28.690135]  ? do_error_trap+0x6a/0x90
[   28.691082]  ? free_pcppages_bulk+0x192/0x240
[   28.692187]  ? exc_invalid_op+0x49/0x60
[   28.693154]  ? free_pcppages_bulk+0x192/0x240
[   28.694225]  ? asm_exc_invalid_op+0x16/0x20
[   28.695291]  ? free_pcppages_bulk+0x192/0x240
[   28.696405]  drain_pages_zone+0x3f/0x50
[   28.697404]  __drain_all_pages+0xe2/0x1e0
[   28.698472]  alloc_contig_range+0x143/0x280
[   28.699581]  ? bitmap_find_next_zero_area_off+0x3d/0x90
[   28.700902]  cma_alloc+0x156/0x470
[   28.701852]  ? kernfs_fop_write_iter+0x160/0x1f0
[   28.703053]  alloc_fresh_hugetlb_folio+0x7e/0x270
[   28.704272]  alloc_pool_huge_page+0x7d/0x100
[   28.705448]  set_max_huge_pages+0x162/0x390
[   28.706530]  nr_hugepages_store_common+0x91/0xf0
[   28.707689]  kernfs_fop_write_iter+0x108/0x1f0
[   28.708819]  vfs_write+0x207/0x400
[   28.709743]  ksys_write+0x63/0xe0
[   28.710640]  do_syscall_64+0x37/0x90
[   28.712649]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[   28.713919] RIP: 0033:0x7f6003aade87
[   28.714879] Code: 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
[   28.719096] RSP: 002b:00007ffdfd9d2e98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[   28.720945] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f6003aade87
[   28.722626] RDX: 0000000000000002 RSI: 00005615f9bac620 RDI: 0000000000000001
[   28.724288] RBP: 00005615f9bac620 R08: 000000000000000a R09: 00007f6003b450c0
[   28.725939] R10: 00007f6003b44fc0 R11: 0000000000000246 R12: 0000000000000002
[   28.727611] R13: 00007f6003b81520 R14: 0000000000000002 R15: 00007f6003b81720
[   28.729285]  </TASK>
[   28.729944] Modules linked in: rfkill ip6table_filter ip6_tables sunrpc snd_hda_codec_generic snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hwdep snd_hda_core snd_seq 9p snd_seq_device netfs joydev snd_pcm snd_timer 9pnet_virtio snd soundcore virtio_balloon 9pnet virtio_console virtio_net virtio_blk net_failover failover crct10dif_pclmul crc32_pclmul crc32c_intel virtio_pci ghash_clmulni_intel serio_raw virtio virtio_pci_legacy_dev virtio_pci_modern_dev virtio_ring fuse
[   28.739325] ---[ end trace 0000000000000000 ]---

-- 
Mike Kravetz