Re: [next-20260108]kernel BUG at drivers/scsi/scsi_lib.c:1173!

From: Venkat Rao Bagalkote
Date: Fri Jan 09 2026 - 07:27:59 EST


On 09/01/26 5:25 pm, Ming Lei wrote:
On Fri, Jan 09, 2026 at 05:14:36PM +0530, Venkat Rao Bagalkote wrote:
On 09/01/26 12:19 pm, Ming Lei wrote:
On Thu, Jan 08, 2026 at 09:56:39PM -0800, Christoph Hellwig wrote:
I've seen the same when running xfstests on xfs, and bisected it to:

commit ee623c892aa59003fca173de0041abc2ccc2c72d
Author: Ming Lei <ming.lei@xxxxxxxxxx>
Date: Wed Dec 31 11:00:55 2025 +0800

block: use bvec iterator helper for bio_may_need_split()

Hi Christoph and Venkat Rao Bagalkote,

Unfortunately I can't duplicate the issue in my environment, can you test
the following patch?

diff --git a/block/blk.h b/block/blk.h
index 98f4dfd4ec75..980eef1f5690 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -380,7 +380,7 @@ static inline bool bio_may_need_split(struct bio *bio,
return true;
bv = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
- if (bio->bi_iter.bi_size > bv->bv_len)
+ if (bio->bi_iter.bi_size > bv->bv_len - bio->bi_iter.bi_bvec_done)
return true;
return bv->bv_len + bv->bv_offset > lim->max_fast_segment_size;
}
Hello Ming,


This is not helping. I am hitting this issue, during kernel build itself.
Can you confirm if it can fix the blktests ext4/056 first?

If kernel building is running over new patched kernel, please provide the
dmesg log. And if it is reproduciable, can you confirm if it can be fixed
by reverting ee623c892aa59003 (block: use bvec iterator helper for bio_may_need_split())?


Unfortunately, even with revert, build fails.



commit c64b2ee9cddcb31546c8622ef018d344544a9388 (HEAD)
Author: Super User <root@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
Date:   Fri Jan 9 06:51:19 2026 -0600

    Revert "block: use bvec iterator helper for bio_may_need_split()"

    This reverts commit ee623c892aa59003fca173de0041abc2ccc2c72d.



Dmesg:



make -j 48 -s && make modules_install && make install
[ 1185.016758] hrtimer: interrupt took 7442 ns
[ 1814.191462] ------------[ cut here ]------------
[ 1814.191501] WARNING: block/blk-mq-dma.c:309 at __blk_rq_map_sg+0x220/0x280, CPU#46: kworker/46:0H/253
[ 1814.191540] Modules linked in: bonding tls rfkill nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables sg pseries_rng vmx_crypto fuse loop vsock_loopback vmw_vsock_virtio_transport_common vsock xfs nvme_tcp nvme_fabrics nvme_core sr_mod sd_mod nvme_keyring cdrom nvme_auth hkdf ibmvscsi ibmveth scsi_transport_srp dm_mirror dm_region_hash dm_log dm_mod nfnetlink
[ 1814.191886] CPU: 46 UID: 0 PID: 253 Comm: kworker/46:0H Kdump: loaded Not tainted 6.19.0-rc4-next-20260108 #1 VOLUNTARY
[ 1814.191917] Hardware name: IBM,8375-42A POWER9 (architected) 0x4e0202 0xf000005 of:IBM,FW950.80 (VL950_131) hv:phyp pSeries
[ 1814.191941] Workqueue: kblockd blk_mq_run_work_fn
[ 1814.191971] NIP:  c000000000d05840 LR: c000000000d05828 CTR: 0000000000000000
[ 1814.191992] REGS: c00000000c4e7520 TRAP: 0700   Not tainted (6.19.0-rc4-next-20260108)
[ 1814.192014] MSR:  800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 44002202  XER: 20040000
[ 1814.192109] CFAR: c0000000008f2b50 IRQMASK: 0
[ 1814.192109] GPR00: c000000000d05798 c00000000c4e77c0 c0000000024ea800 c0000000dc53d17c
[ 1814.192109] GPR04: c00000000c4e77f8 c00000000c4e77e8 c000000000d0490c 0000000000000000
[ 1814.192109] GPR08: 0000000001233cd8 0000000000000001 0000000000000000 c0080000070a18e8
[ 1814.192109] GPR12: c0000000011cf6a0 c000000011847300 c0000000002d4c08 c000000007cee280
[ 1814.192109] GPR16: c0000000d0c3e090 0000000000100001 c00000000ace1610 c0000000dc53d118
[ 1814.192109] GPR20: 0000000001233cd8 0000000000000000 c0000000dc53d12c 0000000000007000
[ 1814.192109] GPR24: c0000000dc53d328 fffffffffffffffd c0000000dc53d100 0000000000000002
[ 1814.192109] GPR28: c00000000c4e78a0 0000000000000000 c00c000000b697c0 c0000000af03ab00
[ 1814.192463] NIP [c000000000d05840] __blk_rq_map_sg+0x220/0x280
[ 1814.192488] LR [c000000000d05828] __blk_rq_map_sg+0x208/0x280
[ 1814.192513] Call Trace:
[ 1814.192526] [c00000000c4e77c0] [c000000000d05798] __blk_rq_map_sg+0x178/0x280 (unreliable)
[ 1814.192565] [c00000000c4e7880] [c0000000011cf7bc] scsi_alloc_sgtables+0x11c/0x700
[ 1814.192601] [c00000000c4e7920] [c008000007097c08] sd_setup_read_write_cmnd+0xf0/0xcd0 [sd_mod]
[ 1814.192651] [c00000000c4e7a20] [c0000000011d1ce4] scsi_prepare_cmd+0x324/0x440
[ 1814.192683] [c00000000c4e7a90] [c0000000011d2128] scsi_queue_rq+0x328/0xb00
[ 1814.192723] [c00000000c4e7b50] [c000000000cfad00] blk_mq_dispatch_rq_list+0x270/0x9b0
[ 1814.192756] [c00000000c4e7c00] [c000000000d09100] __blk_mq_do_dispatch_sched+0x580/0x5a0
[ 1814.192790] [c00000000c4e7cb0] [c000000000d09844] __blk_mq_sched_dispatch_requests+0x2b4/0x360
[ 1814.192825] [c00000000c4e7d20] [c000000000d099e4] blk_mq_sched_dispatch_requests+0x74/0x110
[ 1814.192857] [c00000000c4e7d60] [c000000000cef4e8] blk_mq_run_work_fn+0xe8/0x120
[ 1814.192892] [c00000000c4e7da0] [c0000000002c0cac] process_one_work+0x41c/0x8b0
[ 1814.192925] [c00000000c4e7eb0] [c0000000002c149c] worker_thread+0x35c/0x780
[ 1814.192956] [c00000000c4e7f80] [c0000000002d4e14] kthread+0x214/0x230
[ 1814.192986] [c00000000c4e7fe0] [c00000000000ded8] start_kernel_thread+0x14/0x18
[ 1814.193022] Code: 813a001c 39400001 71291000 40820014 387a007c 4bbed2d5 60000000 a15a007c 7c1b5000 39200001 39400000 7d29505e <0b090000> e9410068 e92d0c78 7d4a4a79
[ 1814.193151] ---[ end trace 0000000000000000 ]---
[ 1814.193232] ------------[ cut here ]------------
[ 1814.193248] kernel BUG at drivers/scsi/scsi_lib.c:1173!
[ 1814.193266] Oops: Exception in kernel mode, sig: 5 [#1]
[ 1814.193284] LE PAGE_SIZE=64K MMU=Hash  SMP NR_CPUS=8192 NUMA pSeries
[ 1814.193305] Modules linked in: bonding tls rfkill nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables sg pseries_rng vmx_crypto fuse loop vsock_loopback vmw_vsock_virtio_transport_common vsock xfs nvme_tcp nvme_fabrics nvme_core sr_mod sd_mod nvme_keyring cdrom nvme_auth hkdf ibmvscsi ibmveth scsi_transport_srp dm_mirror dm_region_hash dm_log dm_mod nfnetlink
[ 1814.193616] CPU: 46 UID: 0 PID: 253 Comm: kworker/46:0H Kdump: loaded Tainted: G        W           6.19.0-rc4-next-20260108 #1 VOLUNTARY
[ 1814.193650] Tainted: [W]=WARN
[ 1814.193664] Hardware name: IBM,8375-42A POWER9 (architected) 0x4e0202 0xf000005 of:IBM,FW950.80 (VL950_131) hv:phyp pSeries
[ 1814.193691] Workqueue: kblockd blk_mq_run_work_fn
[ 1814.193720] NIP:  c0000000011cf9a0 LR: c0000000011cf988 CTR: 0000000000000000
[ 1814.193743] REGS: c00000000c4e75e0 TRAP: 0700   Tainted: G   W            (6.19.0-rc4-next-20260108)
[ 1814.193766] MSR:  800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 84002202  XER: 20040000
[ 1814.193864] CFAR: c0000000008f2cf0 IRQMASK: 0
[ 1814.193864] GPR00: c0000000011cf7bc c00000000c4e7880 c0000000024ea800 c0000000dc53d2d0
[ 1814.193864] GPR04: c00000000c4e77f8 c00000000c4e77e8 c000000000d0490c 0000000000000000
[ 1814.193864] GPR08: 0000000000000001 0000000000000001 0000000000000000 c0080000070a18e8
[ 1814.193864] GPR12: c0000000011cf6a0 c000000011847300 c0000000002d4c08 c000000007cee280
[ 1814.193864] GPR16: c0000000d0c3e090 0000000000100001 c00000000ace1610 c0000000dc53d118
[ 1814.193864] GPR20: 0000000000010000 0000000000000000 c0000000dc53d12c 0000000000000002
[ 1814.193864] GPR24: c0000000dc53d2c8 0000000000000002 c0000000d0be4828 c0000000dc53d11c
[ 1814.193864] GPR28: c0000000dc53d100 c0000000dc53d2d0 c0000000d4315a90 c0000000dc53d200
[ 1814.194193] NIP [c0000000011cf9a0] scsi_alloc_sgtables+0x300/0x700
[ 1814.194218] LR [c0000000011cf988] scsi_alloc_sgtables+0x2e8/0x700
[ 1814.194241] Call Trace:
[ 1814.194253] [c00000000c4e7880] [c0000000011cf7bc] scsi_alloc_sgtables+0x11c/0x700 (unreliable)
[ 1814.194289] [c00000000c4e7920] [c008000007097c08] sd_setup_read_write_cmnd+0xf0/0xcd0 [sd_mod]
[ 1814.194335] [c00000000c4e7a20] [c0000000011d1ce4] scsi_prepare_cmd+0x324/0x440
[ 1814.194367] [c00000000c4e7a90] [c0000000011d2128] scsi_queue_rq+0x328/0xb00
[ 1814.194397] [c00000000c4e7b50] [c000000000cfad00] blk_mq_dispatch_rq_list+0x270/0x9b0
[ 1814.194428] [c00000000c4e7c00] [c000000000d09100] __blk_mq_do_dispatch_sched+0x580/0x5a0
[ 1814.194465] [c00000000c4e7cb0] [c000000000d09844] __blk_mq_sched_dispatch_requests+0x2b4/0x360
[ 1814.194499] [c00000000c4e7d20] [c000000000d099e4] blk_mq_sched_dispatch_requests+0x74/0x110
[ 1814.194532] [c00000000c4e7d60] [c000000000cef4e8] blk_mq_run_work_fn+0xe8/0x120
[ 1814.194564] [c00000000c4e7da0] [c0000000002c0cac] process_one_work+0x41c/0x8b0
[ 1814.194595] [c00000000c4e7eb0] [c0000000002c149c] worker_thread+0x35c/0x780
[ 1814.194626] [c00000000c4e7f80] [c0000000002d4e14] kthread+0x214/0x230
[ 1814.194659] [c00000000c4e7fe0] [c00000000000ded8] start_kernel_thread+0x14/0x18
[ 1814.194689] Code: 813f0110 7d295214 913f0110 3bbf00d0 7fa3eb78 4b723315 60000000 811f00d0 39400000 39200001 7c08b840 7d29501e <0b090000> 7f63db78 92ff00d0 4b7232ed
[ 1814.194820] ---[ end trace 0000000000000000 ]---
[ 1814.216370] pstore: backend (nvram) writing error (-1)

Logs:


make -j 48 -s && make modules_install && make install
[ 1185.016758] hrtimer: interrupt took 7442 ns
[ 1814.191462] ------------[ cut here ]------------
[ 1814.191501] WARNING: block/blk-mq-dma.c:309 at __blk_rq_map_sg+0x220/0x280, CPU#46: kworker/46:0H/253
[ 1814.191540] Modules linked in: bonding tls rfkill nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables sg pseries_rng vmx_crypto fuse loop vsock_loopback vmw_vsock_virtio_transport_common vsock xfs nvme_tcp nvme_fabrics nvme_core sr_mod sd_mod nvme_keyring cdrom nvme_auth hkdf ibmvscsi ibmveth scsi_transport_srp dm_mirror dm_region_hash dm_log dm_mod nfnetlink
[ 1814.191886] CPU: 46 UID: 0 PID: 253 Comm: kworker/46:0H Kdump: loaded Not tainted 6.19.0-rc4-next-20260108 #1 VOLUNTARY
[ 1814.191917] Hardware name: IBM,8375-42A POWER9 (architected) 0x4e0202 0xf000005 of:IBM,FW950.80 (VL950_131) hv:phyp pSeries
[ 1814.191941] Workqueue: kblockd blk_mq_run_work_fn
[ 1814.191971] NIP:  c000000000d05840 LR: c000000000d05828 CTR: 0000000000000000
[ 1814.191992] REGS: c00000000c4e7520 TRAP: 0700   Not tainted (6.19.0-rc4-next-20260108)
[ 1814.192014] MSR:  800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 44002202  XER: 20040000
[ 1814.192109] CFAR: c0000000008f2b50 IRQMASK: 0
[ 1814.192109] GPR00: c000000000d05798 c00000000c4e77c0 c0000000024ea800 c0000000dc53d17c
[ 1814.192109] GPR04: c00000000c4e77f8 c00000000c4e77e8 c000000000d0490c 0000000000000000
[ 1814.192109] GPR08: 0000000001233cd8 0000000000000001 0000000000000000 c0080000070a18e8
[ 1814.192109] GPR12: c0000000011cf6a0 c000000011847300 c0000000002d4c08 c000000007cee280
[ 1814.192109] GPR16: c0000000d0c3e090 0000000000100001 c00000000ace1610 c0000000dc53d118
[ 1814.192109] GPR20: 0000000001233cd8 0000000000000000 c0000000dc53d12c 0000000000007000
[ 1814.192109] GPR24: c0000000dc53d328 fffffffffffffffd c0000000dc53d100 0000000000000002
[ 1814.192109] GPR28: c00000000c4e78a0 0000000000000000 c00c000000b697c0 c0000000af03ab00
[ 1814.192463] NIP [c000000000d05840] __blk_rq_map_sg+0x220/0x280
[ 1814.192488] LR [c000000000d05828] __blk_rq_map_sg+0x208/0x280
[ 1814.192513] Call Trace:
[ 1814.192526] [c00000000c4e77c0] [c000000000d05798] __blk_rq_map_sg+0x178/0x280 (unreliable)
[ 1814.192565] [c00000000c4e7880] [c0000000011cf7bc] scsi_alloc_sgtables+0x11c/0x700
[ 1814.192601] [c00000000c4e7920] [c008000007097c08] sd_setup_read_write_cmnd+0xf0/0xcd0 [sd_mod]
[ 1814.192651] [c00000000c4e7a20] [c0000000011d1ce4] scsi_prepare_cmd+0x324/0x440
[ 1814.192683] [c00000000c4e7a90] [c0000000011d2128] scsi_queue_rq+0x328/0xb00
[ 1814.192723] [c00000000c4e7b50] [c000000000cfad00] blk_mq_dispatch_rq_list+0x270/0x9b0
[ 1814.192756] [c00000000c4e7c00] [c000000000d09100] __blk_mq_do_dispatch_sched+0x580/0x5a0
[ 1814.192790] [c00000000c4e7cb0] [c000000000d09844] __blk_mq_sched_dispatch_requests+0x2b4/0x360
[ 1814.192825] [c00000000c4e7d20] [c000000000d099e4] blk_mq_sched_dispatch_requests+0x74/0x110
[ 1814.192857] [c00000000c4e7d60] [c000000000cef4e8] blk_mq_run_work_fn+0xe8/0x120
[ 1814.192892] [c00000000c4e7da0] [c0000000002c0cac] process_one_work+0x41c/0x8b0
[ 1814.192925] [c00000000c4e7eb0] [c0000000002c149c] worker_thread+0x35c/0x780
[ 1814.192956] [c00000000c4e7f80] [c0000000002d4e14] kthread+0x214/0x230
[ 1814.192986] [c00000000c4e7fe0] [c00000000000ded8] start_kernel_thread+0x14/0x18
[ 1814.193022] Code: 813a001c 39400001 71291000 40820014 387a007c 4bbed2d5 60000000 a15a007c 7c1b5000 39200001 39400000 7d29505e <0b090000> e9410068 e92d0c78 7d4a4a79
[ 1814.193151] ---[ end trace 0000000000000000 ]---
[ 1814.193232] ------------[ cut here ]------------
[ 1814.193248] kernel BUG at drivers/scsi/scsi_lib.c:1173!
[ 1814.193266] Oops: Exception in kernel mode, sig: 5 [#1]
[ 1814.193284] LE PAGE_SIZE=64K MMU=Hash  SMP NR_CPUS=8192 NUMA pSeries
[ 1814.193305] Modules linked in: bonding tls rfkill nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables sg pseries_rng vmx_crypto fuse loop vsock_loopback vmw_vsock_virtio_transport_common vsock xfs nvme_tcp nvme_fabrics nvme_core sr_mod sd_mod nvme_keyring cdrom nvme_auth hkdf ibmvscsi ibmveth scsi_transport_srp dm_mirror dm_region_hash dm_log dm_mod nfnetlink
[ 1814.193616] CPU: 46 UID: 0 PID: 253 Comm: kworker/46:0H Kdump: loaded Tainted: G        W           6.19.0-rc4-next-20260108 #1 VOLUNTARY
[ 1814.193650] Tainted: [W]=WARN
[ 1814.193664] Hardware name: IBM,8375-42A POWER9 (architected) 0x4e0202 0xf000005 of:IBM,FW950.80 (VL950_131) hv:phyp pSeries
[ 1814.193691] Workqueue: kblockd blk_mq_run_work_fn
[ 1814.193720] NIP:  c0000000011cf9a0 LR: c0000000011cf988 CTR: 0000000000000000
[ 1814.193743] REGS: c00000000c4e75e0 TRAP: 0700   Tainted: G   W            (6.19.0-rc4-next-20260108)
[ 1814.193766] MSR:  800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 84002202  XER: 20040000
[ 1814.193864] CFAR: c0000000008f2cf0 IRQMASK: 0
[ 1814.193864] GPR00: c0000000011cf7bc c00000000c4e7880 c0000000024ea800 c0000000dc53d2d0
[ 1814.193864] GPR04: c00000000c4e77f8 c00000000c4e77e8 c000000000d0490c 0000000000000000
[ 1814.193864] GPR08: 0000000000000001 0000000000000001 0000000000000000 c0080000070a18e8
[ 1814.193864] GPR12: c0000000011cf6a0 c000000011847300 c0000000002d4c08 c000000007cee280
[ 1814.193864] GPR16: c0000000d0c3e090 0000000000100001 c00000000ace1610 c0000000dc53d118
[ 1814.193864] GPR20: 0000000000010000 0000000000000000 c0000000dc53d12c 0000000000000002
[ 1814.193864] GPR24: c0000000dc53d2c8 0000000000000002 c0000000d0be4828 c0000000dc53d11c
[ 1814.193864] GPR28: c0000000dc53d100 c0000000dc53d2d0 c0000000d4315a90 c0000000dc53d200
[ 1814.194193] NIP [c0000000011cf9a0] scsi_alloc_sgtables+0x300/0x700
[ 1814.194218] LR [c0000000011cf988] scsi_alloc_sgtables+0x2e8/0x700
[ 1814.194241] Call Trace:
[ 1814.194253] [c00000000c4e7880] [c0000000011cf7bc] scsi_alloc_sgtables+0x11c/0x700 (unreliable)
[ 1814.194289] [c00000000c4e7920] [c008000007097c08] sd_setup_read_write_cmnd+0xf0/0xcd0 [sd_mod]
[ 1814.194335] [c00000000c4e7a20] [c0000000011d1ce4] scsi_prepare_cmd+0x324/0x440
[ 1814.194367] [c00000000c4e7a90] [c0000000011d2128] scsi_queue_rq+0x328/0xb00
[ 1814.194397] [c00000000c4e7b50] [c000000000cfad00] blk_mq_dispatch_rq_list+0x270/0x9b0
[ 1814.194428] [c00000000c4e7c00] [c000000000d09100] __blk_mq_do_dispatch_sched+0x580/0x5a0
[ 1814.194465] [c00000000c4e7cb0] [c000000000d09844] __blk_mq_sched_dispatch_requests+0x2b4/0x360
[ 1814.194499] [c00000000c4e7d20] [c000000000d099e4] blk_mq_sched_dispatch_requests+0x74/0x110
[ 1814.194532] [c00000000c4e7d60] [c000000000cef4e8] blk_mq_run_work_fn+0xe8/0x120
[ 1814.194564] [c00000000c4e7da0] [c0000000002c0cac] process_one_work+0x41c/0x8b0
[ 1814.194595] [c00000000c4e7eb0] [c0000000002c149c] worker_thread+0x35c/0x780
[ 1814.194626] [c00000000c4e7f80] [c0000000002d4e14] kthread+0x214/0x230
[ 1814.194659] [c00000000c4e7fe0] [c00000000000ded8] start_kernel_thread+0x14/0x18
[ 1814.194689] Code: 813f0110 7d295214 913f0110 3bbf00d0 7fa3eb78 4b723315 60000000 811f00d0 39400000 39200001 7c08b840 7d29501e <0b090000> 7f63db78 92ff00d0 4b7232ed
[ 1814.194820] ---[ end trace 0000000000000000 ]---
[ 1814.216370] pstore: backend (nvram) writing error (-1)


Regards,

Venkat.



Thanks,
Ming