Thanks! I will take a look at the modifications soon. I applied the patches to Andrew's mmotm-2021-04-21-23-03, ran some tests and got the following warning. We may need to special case that call to __prep_new_huge_page/free_huge_page_vmemmap from alloc_and_dissolve_huge_page as it is holding hugetlb lock with IRQs disabled. Sorry I missed that previously. -- Mike Kravetz [ 1521.579890] ------------[ cut here ]------------ [ 1521.581309] WARNING: CPU: 1 PID: 1046 at kernel/smp.c:884 smp_call_function_many_cond+0x1bb/0x390 [ 1521.583895] Modules linked in: ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_conntrack ebtable_nat ip6table_nat ip6table_mangle ip6table_raw ip6table_security iptable_nat nf_nat iptable_mangle iptable_raw iptable_security nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 rfkill ebtable_filter ebtables 9p 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 joydev crct10dif_pclmul snd_seq_device crc32_pclmul snd_pcm ghash_clmulni_intel snd_timer 9pnet_virtio snd 9pnet virtio_balloon soundcore i2c_piix4 virtio_net virtio_console net_failover virtio_blk failover 8139too qxl drm_ttm_helper ttm drm_kms_helper drm crc32c_intel serio_raw virtio_pci virtio_pci_modern_dev 8139cp virtio_ring mii ata_generic virtio pata_acpi [ 1521.598644] CPU: 1 PID: 1046 Comm: bash Not tainted 5.12.0-rc8-mm1+ #2 [ 1521.599787] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 [ 1521.601259] RIP: 0010:smp_call_function_many_cond+0x1bb/0x390 [ 1521.602232] Code: 87 75 71 01 85 d2 0f 84 c8 fe ff ff 65 8b 05 94 3d e9 7e 85 c0 0f 85 b9 fe ff ff 65 8b 05 f9 3a e8 7e 85 c0 0f 85 aa fe ff ff <0f> 0b e9 a3 fe ff ff 65 8b 05 47 33 e8 7e a9 ff ff ff 7f 0f 85 75 [ 1521.605167] RSP: 0018:ffffc90001fcb928 EFLAGS: 00010046 [ 1521.606049] RAX: 0000000000000000 RBX: ffffffff828a85d0 RCX: 0000000000000001 [ 1521.607103] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000001 [ 1521.608127] RBP: 0000000000000000 R08: 0000000000000000 R09: ffffea0008fa6f88 [ 1521.609144] R10: 0000000000000001 R11: 0000000000000001 R12: ffff888237d3bfc0 [ 1521.610112] R13: dead000000000122 R14: dead000000000100 R15: ffffea0007bb8000 [ 1521.611106] FS: 00007f8a11223740(0000) GS:ffff888237d00000(0000) knlGS:0000000000000000 [ 1521.612231] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1521.612952] CR2: 0000555e1d00a430 CR3: 000000019ef5a005 CR4: 0000000000370ee0 [ 1521.614295] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 1521.615539] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 1521.616814] Call Trace: [ 1521.617241] ? flush_tlb_one_kernel+0x20/0x20 [ 1521.618041] on_each_cpu_cond_mask+0x25/0x30 [ 1521.618797] flush_tlb_kernel_range+0xa5/0xc0 [ 1521.619577] vmemmap_remap_free+0x7d/0x150 [ 1521.620319] ? sparse_remove_section+0x80/0x80 [ 1521.621120] free_huge_page_vmemmap+0x2f/0x40 [ 1521.621898] __prep_new_huge_page+0xe/0xd0 [ 1521.622633] isolate_or_dissolve_huge_page+0x300/0x360 [ 1521.623559] isolate_migratepages_block+0x4c4/0xe20 [ 1521.624430] ? verify_cpu+0x100/0x100 [ 1521.625096] isolate_migratepages_range+0x6b/0xc0 [ 1521.625936] alloc_contig_range+0x220/0x3d0 [ 1521.626729] cma_alloc+0x1ae/0x5f0 [ 1521.627333] alloc_fresh_huge_page+0x67/0x190 [ 1521.628054] alloc_pool_huge_page+0x72/0xf0 [ 1521.628769] set_max_huge_pages+0x128/0x2c0 [ 1521.629540] __nr_hugepages_store_common+0x3d/0xb0 [ 1521.630457] ? _kstrtoull+0x35/0xd0 [ 1521.631182] nr_hugepages_store+0x73/0x80 [ 1521.631903] kernfs_fop_write_iter+0x127/0x1c0 [ 1521.632698] new_sync_write+0x11f/0x1b0 [ 1521.633408] vfs_write+0x26f/0x380 [ 1521.633946] ksys_write+0x68/0xe0 [ 1521.634444] do_syscall_64+0x40/0x80 [ 1521.634914] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 1521.635669] RIP: 0033:0x7f8a11313ff8 [ 1521.636251] Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8d 05 25 77 0d 00 8b 00 85 c0 75 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49 89 d4 55 [ 1521.639758] RSP: 002b:00007ffd26f79b18 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 1521.641118] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f8a11313ff8 [ 1521.642425] RDX: 0000000000000002 RSI: 0000555e1cf94960 RDI: 0000000000000001 [ 1521.643644] RBP: 0000555e1cf94960 R08: 000000000000000a R09: 00007f8a113a5e80 [ 1521.644904] R10: 000000000000000a R11: 0000000000000246 R12: 00007f8a113e7780 [ 1521.646177] R13: 0000000000000002 R14: 00007f8a113e2740 R15: 0000000000000002 [ 1521.647450] irq event stamp: 10006640 [ 1521.648103] hardirqs last enabled at (10006639): [<ffffffff812ad02b>] bad_range+0x15b/0x180 [ 1521.649577] hardirqs last disabled at (10006640): [<ffffffff81abcea1>] _raw_spin_lock_irq+0x51/0x60 [ 1521.651194] softirqs last enabled at (10006630): [<ffffffff810da5e2>] __irq_exit_rcu+0xd2/0x100 [ 1521.652763] softirqs last disabled at (10006625): [<ffffffff810da5e2>] __irq_exit_rcu+0xd2/0x100 [ 1521.654251] ---[ end trace 561fa19f90280f2f ]---