> On 23.11.23 14:53, Stefan Förster wrote: > > > > starting with kernel 6.1.39, we see the following error message > > with > > heavy I/O loads. We needed to revert > > Thx for the report. I assume that problem still occurs with the > latest > 6.1.y kernel? > > > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=68118c339c6e1e16ae017bef160dbe28a27ae9c8 > > FWIW, that is mainline commit 028ddcac477b69 ("bcache: Remove > unnecessary NULL point check in node allocations") [v6.5-rc1]. > > Did a quick check and noticed a fix for that change was recently > mainlined as f72f4312d43883 ("bcache: replace a mistaken IS_ERR() by > IS_ERR_OR_NULL() in btree_gc_coalesce()") [v6.7-rc2-post]: > https://lore.kernel.org/all/20231118163852.9692-1-colyli@xxxxxxx/ > > It is expected to soon be interegrated into a 6.1.y kernel. > > But maybe it's something else. I CCed the involved people, they might > know. We applied f72f4312d43883 to the current Debian kernel (based on 6.1.55) but it didn't help, same stack trace. Looking at the description, __bch_btree_node_alloc() should never be able to return NULL anyway after https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v6.1.39&id=7ecea5ce3dc17339c280c75b58ac93d8c8620d9f But I didn't verify all callers, so this might still be correct, if it's not always initialized with the return value of __bch_btree_node_alloc(). Anyway, I think we fixed it by applying this: diff -Naurp a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c --- a/drivers/md/bcache/btree.c 2023-09-23 11:11:13.000000000 +0200 +++ b/drivers/md/bcache/btree.c 2023-11-24 13:13:09.840013759 +0100 @@ -1489,7 +1489,7 @@ out_nocoalesce: bch_keylist_free(&keylist); for (i = 0; i < nodes; i++) - if (!IS_ERR(new_nodes[i])) { + if (!IS_ERR_OR_NULL(new_nodes[i])) { btree_node_free(new_nodes[i]); rw_unlock(true, new_nodes[i]); } -- That seems to run stable now. I suppose the culprit is here: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/md/bcache/btree.c?h=v6.1.55#n1448 new_nodes[0] = NULL; for (i = 0; i < nodes; i++) { if (__bch_keylist_realloc(&keylist, bkey_u64s(&r[i].b- >key))) goto out_nocoalesce; So if __bch_keylist_realloc() succeeds, then btree_node_free() will be called with new_nodes[0] which is NULL. This is still the same in mainline: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/md/bcache/btree.c?id=31f5b956a197d4ec25c8a07cb3a2ab69d0c0b82f#n1481 > > Ciao, Thorsten > > > to make sure the systems don't suddenly get stuck. > > > > 1. Kernel 6.6.2-arch1-1 on Dell Latitude: > > > > [16816.214942] BUG: kernel NULL pointer dereference, address: > > 0000000000000080 > > [16816.214948] #PF: supervisor read access in kernel mode > > [16816.214951] #PF: error_code(0x0000) - not-present page > > [16816.214953] PGD 0 P4D 0 [16816.214956] Oops: 0000 [#1] PREEMPT > > SMP NOPTI > > [16816.214960] CPU: 7 PID: 83416 Comm: bcache_gc Tainted: > > P > > OE 6.6.2-arch1-1 #1 11215f9ba7ddfb51644674a5b2ced71612c62fe9 > > [16816.214964] Hardware name: Dell Inc. Latitude 5431/06F77M, BIOS > > 1.17.0 09/21/2023 > > [16816.214965] RIP: 0010:btree_node_free+0xf/0x160 [bcache] > > [16816.214999] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 > > 90 90 > > 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f > > 44 00 > > 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3 00 00 > > 75 > > [16816.215001] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207 > > [16816.215004] RAX: 0000000000000001 RBX: 0000000000000000 RCX: > > ffff888515ce0670 > > [16816.215006] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI: > > 0000000000000000 > > [16816.215007] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09: > > 00000000013ffde8 > > [16816.215009] R10: 0000000000000000 R11: ffffc9000061b000 R12: > > ffffc90021777e40 > > [16816.215010] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15: > > ffff88819476c000 > > [16816.215011] FS: 0000000000000000(0000) > > GS:ffff88886fdc0000(0000) > > knlGS:0000000000000000 > > [16816.215013] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [16816.215015] CR2: 0000000000000080 CR3: 0000000294a20000 CR4: > > 0000000000f50ee0 > > [16816.215017] PKRU: 55555554 > > [16816.215018] Call Trace: > > [16816.215021] <TASK> > > [16816.215024] ? __die+0x23/0x70 > > [16816.215030] ? page_fault_oops+0x171/0x4e0 > > [16816.215035] ? __pfx_bch_ptr_bad+0x10/0x10 [bcache > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6] > > [16816.215059] ? exc_page_fault+0x7f/0x180 > > [16816.215065] ? asm_exc_page_fault+0x26/0x30 > > [16816.215070] ? btree_node_free+0xf/0x160 [bcache > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6] > > [16816.215095] ? btree_node_free+0xa3/0x160 [bcache > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6] > > [16816.215118] btree_gc_coalesce+0x2a7/0x890 [bcache > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6] > > [16816.215144] ? bch_extent_bad+0x81/0x190 [bcache > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6] > > [16816.215172] btree_gc_recurse+0x130/0x390 [bcache > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6] > > [16816.215197] ? btree_gc_mark_node+0x72/0x240 [bcache > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6] > > [16816.215221] bch_btree_gc+0x4b6/0x620 [bcache > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6] > > [16816.215246] ? __pfx_autoremove_wake_function+0x10/0x10 > > [16816.215250] ? __pfx_bch_gc_thread+0x10/0x10 [bcache > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6] > > [16816.215272] bch_gc_thread+0x139/0x190 [bcache > > 33eebe64448bb81d5f2a10179a48eb0a5bdb25a6] > > [16816.215295] ? __pfx_autoremove_wake_function+0x10/0x10 > > [16816.215298] kthread+0xe5/0x120 > > [16816.215302] ? __pfx_kthread+0x10/0x10 > > [16816.215306] ret_from_fork+0x31/0x50 > > [16816.215309] ? __pfx_kthread+0x10/0x10 > > [16816.215312] ret_from_fork_asm+0x1b/0x30 > > [16816.215318] </TASK> > > [16816.215319] Modules linked in: bcache tun ccm rfcomm > > snd_seq_dummy > > snd_hrtimer snd_seq nvidia(POE) typec_displayport cmac algif_hash > > algif_skcipher af_alg bnep hid_sensor_custom hid_sensor_hub > > intel_ishtp_hid snd_hda_codec_hdmi snd_sof_pci_intel_tgl > > snd_sof_intel_hda_common soundwire_intel snd_sof_intel_hda_mlink > > soundwire_cadence snd_sof_intel_hda snd_sof_pci snd_sof_xtensa_dsp > > snd_sof snd_sof_utils intel_uncore_frequency > > intel_uncore_frequency_common snd_ctl_led snd_soc_hdac_hda > > r8153_ecm > > snd_hda_ext_core iwlmvm cdc_ether snd_soc_acpi_intel_match usbnet > > snd_soc_acpi soundwire_generic_allocation soundwire_bus > > snd_soc_core > > x86_pkg_temp_thermal snd_compress snd_hda_codec_realtek > > intel_powerclamp > > ac97_bus snd_hda_codec_generic dell_rbtn coretemp btusb > > snd_pcm_dmaengine snd_usb_audio mac80211 btrtl snd_hda_intel > > kvm_intel > > btintel snd_intel_dspcfg snd_intel_sdw_acpi snd_usbmidi_lib btbcm > > dell_laptop snd_ump btmtk libarc4 snd_hda_codec uvcvideo kvm > > snd_rawmidi > > bluetooth snd_hda_core videobuf2_vmalloc hid_multitouch iwlwifi > > [16816.215367] dell_wmi snd_hwdep iTCO_wdt snd_seq_device uvc > > nls_iso8859_1 videobuf2_memops dell_smbios intel_pmc_bxt mei_hdcp > > mei_pxp spi_nor snd_pcm processor_thermal_device_pci r8152 > > videobuf2_v4l2 dell_wmi_sysman irqbypass intel_rapl_msr dcdbas vfat > > iTCO_vendor_support fat rapl intel_cstate intel_uncore psmouse > > pcspkr > > dell_wmi_ddv firmware_attributes_class ledtrig_audio > > videobuf2_common > > ucsi_acpi dell_wmi_descriptor processor_thermal_device mousedev > > ecdh_generic snd_timer mii joydev mtd wmi_bmof e1000e cfg80211 > > processor_thermal_rfim mei_me intel_lpss_pci i2c_i801 snd > > processor_thermal_mbox typec_ucsi intel_ish_ipc intel_lpss mei > > soundcore > > i2c_smbus processor_thermal_rapl rfkill thunderbolt typec idma64 > > intel_ishtp roles intel_rapl_common igen6_edac i2c_hid_acpi > > int3403_thermal i2c_hid int340x_thermal_zone intel_hid > > int3400_thermal > > acpi_thermal_rel sparse_keymap acpi_tad acpi_pad mac_hid > > vboxnetflt(OE) > > vboxnetadp(OE) vboxdrv(OE) v4l2loopback(OE) videodev mc i2c_dev > > crypto_user fuse loop ip_tables x_tables ext4 > > [16816.215420] crc32c_generic crc16 mbcache jbd2 dm_crypt cbc > > encrypted_keys trusted asn1_encoder tee usbhid i915 dm_mod > > crct10dif_pclmul crc32_pclmul crc32c_intel polyval_clmulni > > i2c_algo_bit > > polyval_generic serio_raw rtsx_pci_sdmmc drm_buddy gf128mul atkbd > > ghash_clmulni_intel ttm mmc_core sha512_ssse3 libps2 vivaldi_fmap > > intel_gtt aesni_intel nvme crypto_simd drm_display_helper video > > nvme_core cryptd spi_intel_pci rtsx_pci spi_intel i8042 xhci_pci > > cec > > nvme_common xhci_pci_renesas serio wmi > > [16816.215451] CR2: 0000000000000080 > > [16816.215453] ---[ end trace 0000000000000000 ]--- > > [16816.215455] RIP: 0010:btree_node_free+0xf/0x160 [bcache] > > [16816.215478] Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 > > 90 90 > > 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f > > 44 00 > > 00 <48> 8b 83 80 00 00 00 48 8d ab 90 00 00 00 48 39 98 60 c3 00 00 > > 75 > > [16816.215480] RSP: 0018:ffffc90021777af8 EFLAGS: 00010207 > > [16816.215481] RAX: 0000000000000001 RBX: 0000000000000000 RCX: > > ffff888515ce0670 > > [16816.215483] RDX: 0000000000000000 RSI: ffff888515ce0680 RDI: > > 0000000000000000 > > [16816.215484] RBP: ffffc90021777bf0 R08: ffff88819476d9e0 R09: > > 00000000013ffde8 > > [16816.215486] R10: 0000000000000000 R11: ffffc9000061b000 R12: > > ffffc90021777e40 > > [16816.215487] R13: ffffc90021777bf0 R14: ffffc90021777bd8 R15: > > ffff88819476c000 > > [16816.215488] FS: 0000000000000000(0000) > > GS:ffff88886fdc0000(0000) > > knlGS:0000000000000000 > > [16816.215490] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [16816.215492] CR2: 0000000000000080 CR3: 0000000294a20000 CR4: > > 0000000000f50ee0 > > [16816.215493] PKRU: 55555554 > > [16816.215494] note: bcache_gc[83416] exited with irqs disabled > > > > 2. Kernel 6.1.55 (Debian 6.1.0-13) on HPE Gen11: > > > > [60654.670443] BUG: kernel NULL pointer dereference, address: > > 0000000000000080 > > [60654.677474] #PF: supervisor read access in kernel mode > > [60654.682651] #PF: error_code(0x0000) - not-present page > > [60654.687825] PGD 0 [60654.689852] Oops: 0000 [#1] PREEMPT SMP > > NOPTI > > [60654.694240] CPU: 16 PID: 146330 Comm: bcache_gc Tainted: > > G > > W 6.1.0-13-amd64 #1 Debian 6.1.55-1 > > [60654.704399] Hardware name: HPE ProLiant DL380 Gen11/ProLiant > > DL380 > > Gen11, BIOS 1.48 10/19/2023 > > [60654.713071] RIP: 0010:btree_node_free+0xf/0x160 [bcache] > > [60654.718437] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc cc > > 66 66 > > 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f > > 44 00 > > 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00 00 48 > > 8d > > [60654.737342] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207 > > [60654.742604] RAX: 0000000080000000 RBX: 0000000000000000 RCX: > > 0000000000000000 > > [60654.749790] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI: > > 0000000000000000 > > [60654.756975] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09: > > ff2971b8de800000 > > [60654.764536] R10: 0000000000000000 R11: ff77daed34a4d000 R12: > > ff77daed34cc3e60 > > [60654.771987] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15: > > ff2971d851096400 > > [60654.779410] FS: 0000000000000000(0000) > > GS:ff2971f7bf400000(0000) > > knlGS:0000000000000000 > > [60654.787784] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [60654.793794] CR2: 0000000000000080 CR3: 0000000150610002 CR4: > > 0000000000771ee0 > > [60654.801203] DR0: 0000000000000000 DR1: 0000000000000000 DR2: > > 0000000000000000 > > [60654.808609] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: > > 0000000000000400 > > [60654.816009] PKRU: 55555554 > > [60654.818949] Call Trace: > > [60654.821623] <TASK> > > [60654.823950] ? __die_body.cold+0x1a/0x1f > > [60654.828110] ? page_fault_oops+0xd2/0x2b0 > > [60654.832352] ? exc_page_fault+0x70/0x170 > > [60654.836505] ? asm_exc_page_fault+0x22/0x30 > > [60654.840922] ? btree_node_free+0xf/0x160 [bcache] > > [60654.845863] ? up_write+0x32/0x60 > > [60654.849396] btree_gc_coalesce+0x2aa/0x890 [bcache] > > [60654.854512] ? bch_extent_bad+0x70/0x170 [bcache] > > [60654.859452] btree_gc_recurse+0x130/0x390 [bcache] > > [60654.864475] ? btree_gc_mark_node+0x72/0x230 [bcache] > > [60654.869758] bch_btree_gc+0x5da/0x600 [bcache] > > [60654.874428] ? cpuusage_read+0x10/0x10 > > [60654.878390] ? bch_btree_gc+0x600/0x600 [bcache] > > [60654.883232] bch_gc_thread+0x135/0x180 [bcache] > > [60654.887986] ? cpuusage_read+0x10/0x10 > > [60654.891944] kthread+0xe6/0x110 > > [60654.895290] ? kthread_complete_and_exit+0x20/0x20 > > [60654.900296] ret_from_fork+0x1f/0x30 > > [60654.904079] </TASK> > > [60654.906455] Modules linked in: bonding tls cfg80211 rfkill > > intel_rapl_msr intel_rapl_common intel_uncore_frequency > > intel_uncore_frequency_common i10nm_edac nfit binfmt_misc libnvdimm > > x86_pkg_temp_thermal intel_powerclamp ipt_REJECT nf_reject_ipv4 > > coretemp > > xt_comment nft_compat nf_tables nfnetlink nls_ascii nls_cp437 > > kvm_intel > > vfat ipmi_ssif fat kvm irqbypass ghash_clmulni_intel sha512_ssse3 > > sha512_generic aesni_intel crypto_simd cryptd mgag200 > > drm_shmem_helper > > pmt_telemetry pmt_crashlog rapl intel_cstate acpi_ipmi evdev > > intel_sdsi > > pmt_class idxd hpwdt mei_me isst_if_mbox_pci isst_if_mmio > > drm_kms_helper > > intel_uncore pcspkr isst_if_common mei watchdog hpilo i2c_algo_bit > > ipmi_si idxd_bus acpi_tad intel_vsec sg acpi_power_meter button > > ipmi_devintf ipmi_msghandler loop fuse efi_pstore drm configfs > > efivarfs > > ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 btrfs > > blake2b_generic > > xor raid6_pq zstd_compress libcrc32c crc32c_generic ses enclosure > > bcache > > sd_mod scsi_transport_sas dm_mod nvme > > [60654.906508] nvme_core xhci_pci t10_pi megaraid_sas ehci_pci > > xhci_hcd > > ehci_hcd crc64_rocksoft crc64 tg3 crc_t10dif scsi_mod usbcore > > crct10dif_generic crc32_pclmul crc32c_intel crct10dif_pclmul libphy > > scsi_common usb_common crct10dif_common wmi > > [60655.017712] CR2: 0000000000000080 > > [60655.021262] ---[ end trace 0000000000000000 ]--- > > [60655.173744] RIP: 0010:btree_node_free+0xf/0x160 [bcache] > > [60655.179337] Code: ff 48 89 d8 5b 5d 41 5c 41 5d c3 cc cc cc cc > > 66 66 > > 2e 0f 1f 84 00 00 00 00 00 90 0f 1f 44 00 00 55 53 48 89 fb 0f 1f > > 44 00 > > 00 <48> 8b 83 80 00 00 00 48 39 98 70 c3 00 00 0f 84 34 01 00 00 48 > > 8d > > [60655.198649] RSP: 0018:ff77daed34cc3b18 EFLAGS: 00010207 > > [60655.204121] RAX: 0000000080000000 RBX: 0000000000000000 RCX: > > 0000000000000000 > > [60655.211515] RDX: 0000000000000001 RSI: ff2971b8de800690 RDI: > > 0000000000000000 > > [60655.218908] RBP: ff77daed34cc3c10 R08: ff2971d852dc65e0 R09: > > ff2971b8de800000 > > [60655.226302] R10: 0000000000000000 R11: ff77daed34a4d000 R12: > > ff77daed34cc3e60 > > [60655.233696] R13: ff77daed34cc3c10 R14: ff77daed34cc3c00 R15: > > ff2971d851096400 > > [60655.241086] FS: 0000000000000000(0000) > > GS:ff2971f7bf400000(0000) > > knlGS:0000000000000000 > > [60655.249438] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [60655.255432] CR2: 0000000000000080 CR3: 0000000150610002 CR4: > > 0000000000771ee0 > > [60655.262825] DR0: 0000000000000000 DR1: 0000000000000000 DR2: > > 0000000000000000 > > [60655.270218] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: > > 0000000000000400 > > [60655.277607] PKRU: 55555554 > > [60655.280543] note: bcache_gc[146330] exited with irqs disabled > > > > Reproducer for us: > > > > dd if=/dev/zero of=loop0 bs=1M count=1024 > > dd if=/dev/zero of=loop1 bs=1M count=10240 > > losetup loop0 loop0 > > losetup loop1 loop1 > > make-bcache -C /dev/loop0 -B /dev/loop1 --writeback > > mkfs.ext4 /dev/bcache0 > > mount /dev/bcache0 /mnt > > > > Then run fio with: > > > > [global] > > bs=4k > > ioengine=libaio > > iodepth=4 > > size=8g > > direct=1 > > runtime=60 > > directory=/mnt > > filename=ssd.test.file > > > > [seq-write] > > rw=write > > stonewall > > > > [rand-write] > > rw=randwrite > > stonewall > > > > [seq-read] > > rw=read > > stonewall > > > > [rand-read] > > rw=randread > > stonewall > > > > > > Cheers, > > Stefan
