On 3/4/25 08:58, Hannes Reinecke wrote: > On 3/3/25 23:02, Vlastimil Babka wrote: >> On 3/3/25 17:15, Vlastimil Babka wrote: >>> On 3/3/25 16:48, Matthew Wilcox wrote: >>>> You need to turn on the debugging options Vlastimil mentioned and try to >>>> figure out what nvme is doing wrong. >>> >>> Agree, looks like some error path going wrong? >>> Since there seems to be actual non-large kmalloc usage involved, another >>> debug parameter that could help: CONFIG_SLUB_DEBUG=y, and boot with >>> "slab_debug=FZPU,kmalloc-*" >> >> Also make sure you have CONFIG_DEBUG_VM please. >> > Here you go: > > [ 134.506802] page: refcount:0 mapcount:0 mapping:0000000000000000 > index:0x0 pfn:0x101ef8 > [ 134.509253] head: order:3 mapcount:0 entire_mapcount:0 > nr_pages_mapped:0 pincount:0 > [ 134.511594] flags: > 0x17ffffc0000040(head|node=0|zone=2|lastcpupid=0x1fffff) > [ 134.513556] page_type: f5(slab) > [ 134.513563] raw: 0017ffffc0000040 ffff888100041b00 ffffea0004a90810 > ffff8881000402f0 > [ 134.513568] raw: 0000000000000000 00000000000a000a 00000000f5000000 > 0000000000000000 > [ 134.513572] head: 0017ffffc0000040 ffff888100041b00 ffffea0004a90810 > ffff8881000402f0 > [ 134.513575] head: 0000000000000000 00000000000a000a 00000000f5000000 > 0000000000000000 > [ 134.513579] head: 0017ffffc0000003 ffffea000407be01 ffffffffffffffff > 0000000000000000 > [ 134.513583] head: 0000000000000008 0000000000000000 00000000ffffffff > 0000000000000000 > [ 134.513585] page dumped because: VM_BUG_ON_FOLIO(((unsigned int) > folio_ref_count(folio) + 127u <= 127u)) > [ 134.513615] ------------[ cut here ]------------ > [ 134.529822] kernel BUG at ./include/linux/mm.h:1455! Yeah, just as I suspected, folio_get() says the refcount is 0. > [ 134.529835] Oops: invalid opcode: 0000 [#1] PREEMPT SMP > DEBUG_PAGEALLOC NOPTI > [ 134.529843] CPU: 0 UID: 0 PID: 274 Comm: kworker/0:1H Kdump: loaded > Tainted: G E 6.14.0-rc4-default+ #309 > 03b131f1ef70944969b40df9d90a283ed638556f > [ 134.536577] Tainted: [E]=UNSIGNED_MODULE > [ 134.536580] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS > 0.0.0 02/06/2015 > [ 134.536583] Workqueue: nvme_tcp_wq nvme_tcp_io_work [nvme_tcp] > [ 134.536595] RIP: 0010:__iov_iter_get_pages_alloc+0x676/0x710 > [ 134.542810] Code: e8 4c 39 e0 49 0f 47 c4 48 01 45 08 48 29 45 18 e9 > 90 fa ff ff 48 83 ef 01 e9 7f fe ff ff 48 c7 c6 40 57 4f 82 e8 6a e2 ce > ff <0f> 0b e8 43 b8 b1 ff eb c5 f7 c1 ff 0f 00 00 48 89 cf 0f 85 4f ff > [ 134.542816] RSP: 0018:ffffc900004579d8 EFLAGS: 00010282 > [ 134.542821] RAX: 000000000000005c RBX: ffffc90000457a90 RCX: > 0000000000000027 > [ 134.542825] RDX: 0000000000000000 RSI: 0000000000000002 RDI: > ffff88817f423748 > [ 134.542828] RBP: ffffc90000457d60 R08: 0000000000000000 R09: > 0000000000000001 > [ 134.554485] R10: ffffc900004579c0 R11: ffffc90000457720 R12: > 0000000000000000 > [ 134.554488] R13: ffffea000407be40 R14: ffffc90000457a70 R15: > ffffc90000457d60 > [ 134.554495] FS: 0000000000000000(0000) GS:ffff88817f400000(0000) > knlGS:0000000000000000 > [ 134.554499] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 134.554502] CR2: 0000556b0675b600 CR3: 0000000106bd8000 CR4: > 0000000000350ef0 > [ 134.554509] Call Trace: > [ 134.554512] <TASK> > [ 134.554516] ? __die_body+0x1a/0x60 > [ 134.554525] ? die+0x38/0x60 > [ 134.554531] ? do_trap+0x10f/0x120 > [ 134.554538] ? __iov_iter_get_pages_alloc+0x676/0x710 > [ 134.568839] ? do_error_trap+0x64/0xa0 > [ 134.568847] ? __iov_iter_get_pages_alloc+0x676/0x710 > [ 134.568855] ? exc_invalid_op+0x53/0x60 > [ 134.572489] ? __iov_iter_get_pages_alloc+0x676/0x710 > [ 134.572496] ? asm_exc_invalid_op+0x16/0x20 > [ 134.572512] ? __iov_iter_get_pages_alloc+0x676/0x710 > [ 134.576726] ? __iov_iter_get_pages_alloc+0x676/0x710 > [ 134.576733] ? srso_return_thunk+0x5/0x5f > [ 134.576740] ? ___slab_alloc+0x924/0xb60 > [ 134.580253] ? mempool_alloc_noprof+0x41/0x190 > [ 134.580262] ? tls_get_rec+0x3d/0x1b0 [tls > 47f199c97f69357468c91efdbba24395e9dbfa77] > [ 134.580282] iov_iter_get_pages2+0x19/0x30 Presumably that's __iov_iter_get_pages_alloc() doing get_page() either in the " if (iov_iter_is_bvec(i)) " branch or via iter_folioq_get_pages()? Which doesn't work for a sub-size kmalloc() from a slab folio, which after the frozen refcount conversion no longer supports get_page(). The question is if this is a mistake specific for this path that's easy to fix or there are more paths that do this. At the very least the pinning of page through a kmalloc() allocation from it is useless - the object itself has to be kfree()'d and that would never happen through a put_page() reaching zero. > [ 134.580289] sk_msg_zerocopy_from_iter+0x85/0x1d0 > [ 134.580301] ? srso_return_thunk+0x5/0x5f > [ 134.586842] ? srso_return_thunk+0x5/0x5f > [ 134.586847] ? __kmalloc_noprof+0x187/0x500 > [ 134.586854] ? srso_return_thunk+0x5/0x5f > [ 134.586859] ? __sk_mem_raise_allocated+0x2ba/0x4a0 > [ 134.591697] ? srso_return_thunk+0x5/0x5f > [ 134.591703] ? sk_page_frag_refill+0x19/0xb0 > [ 134.591708] ? srso_return_thunk+0x5/0x5f > [ 134.591712] ? sk_msg_alloc+0x5a/0x2b0 > [ 134.591722] tls_sw_sendmsg+0x6bf/0x9b0 [tls > 47f199c97f69357468c91efdbba24395e9dbfa77] > [ 134.598284] __sock_sendmsg+0x98/0xc0 > [ 134.598293] sock_sendmsg+0x5c/0xa0 > [ 134.600490] ? srso_return_thunk+0x5/0x5f > [ 134.600495] ? __sock_sendmsg+0x98/0xc0 > [ 134.600500] ? srso_return_thunk+0x5/0x5f > [ 134.600504] ? sock_sendmsg+0x5c/0xa0 > [ 134.600515] nvme_tcp_try_send_data+0x13f/0x410 [nvme_tcp > 71d3ffab2b48b41b11556946fd79065f8f8b0f42] > [ 134.607125] ? __dequeue_entity+0x401/0x470 > [ 134.607142] nvme_tcp_try_send+0x299/0x330 [nvme_tcp > 71d3ffab2b48b41b11556946fd79065f8f8b0f42] > [ 134.607153] nvme_tcp_io_work+0x37/0xb0 [nvme_tcp > 71d3ffab2b48b41b11556946fd79065f8f8b0f42] > [ 134.607162] process_scheduled_works+0x97/0x400 > [ 134.613657] ? __pfx_worker_thread+0x10/0x10 > [ 134.613663] worker_thread+0x105/0x240 > [ 134.613669] ? __pfx_worker_thread+0x10/0x10 > [ 134.613675] kthread+0xec/0x200 > [ 134.618136] ? __pfx_kthread+0x10/0x10 > [ 134.618144] ret_from_fork+0x30/0x50 > [ 134.618151] ? __pfx_kthread+0x10/0x10 > [ 134.618157] ret_from_fork_asm+0x1a/0x30 > [ 134.622519] </TASK> > [ 134.622522] Modules linked in: tls(E) nvme_tcp(E) af_packet(E) > iscsi_ibft(E) iscsi_boot_sysfs(E) xfs(E) nls_iso8859_1(E) nls_cp437(E) > vfat(E) fat(E) iTCO_wdt(E) intel_rapl_msr(E) intel_pmc_bxt(E) > intel_rapl_common(E) iTCO_vendor_support(E) bnxt_en(E) i2c_i801(E) > i2c_mux(E) lpc_ich(E) i2c_smbus(E) joydev(E) mfd_core(E) > virtio_balloon(E) button(E) nvme_fabrics(E) nvme_keyring(E) nvme_core(E) > fuse(E) nvme_auth(E) efi_pstore(E) configfs(E) dmi_sysfs(E) ip_tables(E) > x_tables(E) hid_generic(E) usbhid(E) qxl(E) ahci(E) drm_client_lib(E) > libahci(E) drm_exec(E) xhci_pci(E) drm_ttm_helper(E) virtio_scsi(E) > libata(E) ttm(E) xhci_hcd(E) sd_mod(E) scsi_dh_emc(E) drm_kms_helper(E) > scsi_dh_rdac(E) ghash_clmulni_intel(E) scsi_dh_alua(E) sg(E) > sha512_ssse3(E) sha256_ssse3(E) drm(E) usbcore(E) scsi_mod(E) > sha1_ssse3(E) scsi_common(E) serio_raw(E) btrfs(E) blake2b_generic(E) > xor(E) raid6_pq(E) efivarfs(E) qemu_fw_cfg(E) virtio_rng(E) > aesni_intel(E) crypto_simd(E) cryptd(E) > > Cheers, > > Hannes
