linux-kernel - Re: [syzbot] [iommu?] kernel BUG in iommu_pages_start

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Message-ID: <aTp0jpmWZ49Ql-Kp@google.com>
Date: Thu, 11 Dec 2025 16:36:46 +0900
From: Will Deacon <will@...nel.org>
To: syzbot <syzbot+e06bb7478e687f235ad7@...kaller.appspotmail.com>
Cc: iommu@...ts.linux.dev, joro@...tes.org, linux-kernel@...r.kernel.org,
	robin.murphy@....com, syzkaller-bugs@...glegroups.com, jgg@...pe.ca
Subject: Re: [syzbot] [iommu?] kernel BUG in iommu_pages_start_incoherent

[+Jason]

On Wed, Dec 10, 2025 at 07:26:22PM -0800, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    c06c303832ec ocfs2: fix xattr array entry __counted_by error
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=175a2992580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=d3ce1cfe3996fc8b
> dashboard link: https://syzkaller.appspot.com/bug?extid=e06bb7478e687f235ad7
> compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-c06c3038.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/aa14148a2ef4/vmlinux-c06c3038.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/d2d5f3a106bf/bzImage-c06c3038.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+e06bb7478e687f235ad7@...kaller.appspotmail.com
> 
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
>  fail_dump lib/fault-inject.c:73 [inline]
>  should_fail_ex+0x414/0x560 lib/fault-inject.c:174
>  prepare_alloc_pages+0x22b/0x650 mm/page_alloc.c:4985
>  __alloc_frozen_pages_noprof+0x123/0x370 mm/page_alloc.c:5199
>  __alloc_pages_noprof mm/page_alloc.c:5244 [inline]
>  __folio_alloc_noprof+0x18/0x120 mm/page_alloc.c:5254
>  __folio_alloc_node_noprof include/linux/gfp.h:296 [inline]
>  iommu_alloc_pages_node_sz+0x152/0x320 drivers/iommu/iommu-pages.c:66
>  _table_alloc drivers/iommu/generic_pt/iommu_pt.h:373 [inline]
>  table_alloc drivers/iommu/generic_pt/iommu_pt.h:408 [inline]
>  pt_iommu_new_table drivers/iommu/generic_pt/iommu_pt.h:424 [inline]
>  __map_range+0x1f2/0xa80 drivers/iommu/generic_pt/iommu_pt.h:584
>  pt_descend drivers/iommu/generic_pt/pt_iter.h:391 [inline]
>  __map_range+0x511/0xa80 drivers/iommu/generic_pt/iommu_pt.h:619
>  pt_descend drivers/iommu/generic_pt/pt_iter.h:391 [inline]
>  __map_range+0x511/0xa80 drivers/iommu/generic_pt/iommu_pt.h:619
>  pt_iommu_vtdss_map_pages+0x6a3/0x960 drivers/iommu/generic_pt/iommu_pt.h:905
>  iommu_map_nosync+0x30a/0x840 drivers/iommu/iommu.c:2549
>  iommu_map_sg+0x579/0xae0 drivers/iommu/iommu.c:2721
>  iommu_dma_map_sg+0x908/0x1000 drivers/iommu/dma-iommu.c:1493
>  __dma_map_sg_attrs+0xd0/0x520 kernel/dma/mapping.c:245
>  dma_map_sg_attrs+0x32/0x50 kernel/dma/mapping.c:284
>  ata_sg_setup drivers/ata/libata-core.c:4773 [inline]
>  ata_qc_issue+0x515/0xf30 drivers/ata/libata-core.c:5085
>  ata_scsi_translate drivers/ata/libata-scsi.c:1755 [inline]
>  __ata_scsi_queuecmd+0x957/0xf60 drivers/ata/libata-scsi.c:4355
>  ata_scsi_queuecmd+0x3d4/0x5c0 drivers/ata/libata-scsi.c:4400
>  scsi_dispatch_cmd drivers/scsi/scsi_lib.c:1638 [inline]
>  scsi_queue_rq+0x18bc/0x30d0 drivers/scsi/scsi_lib.c:1895
>  blk_mq_dispatch_rq_list+0x4c0/0x1900 block/blk-mq.c:2137
>  __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
>  blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
>  __blk_mq_sched_dispatch_requests+0xdac/0x1570 block/blk-mq-sched.c:307
>  blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
>  blk_mq_run_hw_queue+0x404/0x4f0 block/blk-mq.c:2375
>  blk_mq_dispatch_list+0xd0b/0xe00 include/linux/spinlock.h:-1
>  blk_mq_flush_plug_list+0x469/0x550 block/blk-mq.c:2986
>  blk_add_rq_to_plug+0x175/0x450 block/blk-mq.c:1407
>  blk_mq_submit_bio+0xd5b/0x26b0 block/blk-mq.c:3232
>  __submit_bio+0x207/0x5a0 block/blk-core.c:637
>  __submit_bio_noacct_mq block/blk-core.c:724 [inline]
>  submit_bio_noacct_nocheck+0x377/0xa30 block/blk-core.c:755
>  __blkdev_direct_IO+0x915/0xf90 block/fops.c:264
>  blkdev_direct_IO+0x1261/0x17e0 block/fops.c:441
>  blkdev_direct_write+0x7c/0x140 block/fops.c:727
>  blkdev_write_iter+0x547/0x710 block/fops.c:795
>  do_iter_readv_writev+0x623/0x8c0 fs/read_write.c:-1
>  vfs_writev+0x31a/0x960 fs/read_write.c:1057
>  do_writev+0x14d/0x2d0 fs/read_write.c:1103
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fae01b8f7c9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fae02b02038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
> RAX: ffffffffffffffda RBX: 00007fae01de5fa0 RCX: 00007fae01b8f7c9
> RDX: 0000000000000021 RSI: 0000200000000a40 RDI: 0000000000000004
> RBP: 00007fae02b02090 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
> R13: 00007fae01de6038 R14: 00007fae01de5fa0 R15: 00007ffd45480c38
>  </TASK>
> ------------[ cut here ]------------
> kernel BUG at arch/x86/mm/physaddr.c:28!
> Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
> CPU: 0 UID: 0 PID: 5336 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> RIP: 0010:__phys_addr+0x16b/0x180 arch/x86/mm/physaddr.c:28
> Code: 8b b3 00 e9 45 ff ff ff e8 b2 af 4b 00 48 c7 c7 f0 33 fb 8d 48 89 de 4c 89 f2 e8 50 c0 52 03 e9 4d ff ff ff e8 96 af 4b 00 90 <0f> 0b e8 8e af 4b 00 90 0f 0b e8 86 af 4b 00 90 0f 0b 0f 1f 00 90
> RSP: 0018:ffffc9000aae5f80 EFLAGS: 00010093
> RAX: ffffffff817610fa RBX: 0000778000000000 RCX: ffff8880007ca4c0
> RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000778000000000
> RBP: ffffc9000aae6130 R08: ffffffff8e26c433 R09: 1ffffffff1c4d886
> R10: dffffc0000000000 R11: fffffbfff1c4d887 R12: 0000000000000011
> R13: dffffc0000000000 R14: 0000000080000000 R15: dffffc0000000000
> FS:  00007fae02b026c0(0000) GS:ffff88808d23e000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fae01d2dea0 CR3: 000000000b669000 CR4: 0000000000352ef0
> Call Trace:
>  <TASK>
>  virt_to_folio include/linux/mm.h:1432 [inline]
>  virt_to_ioptdesc drivers/iommu/iommu-pages.h:49 [inline]
>  iommu_pages_start_incoherent+0x52/0x310 drivers/iommu/iommu-pages.c:148
>  _table_alloc drivers/iommu/generic_pt/iommu_pt.h:377 [inline]
>  table_alloc drivers/iommu/generic_pt/iommu_pt.h:408 [inline]
>  pt_iommu_new_table drivers/iommu/generic_pt/iommu_pt.h:424 [inline]
>  __map_range+0x270/0xa80 drivers/iommu/generic_pt/iommu_pt.h:584
>  pt_descend drivers/iommu/generic_pt/pt_iter.h:391 [inline]
>  __map_range+0x511/0xa80 drivers/iommu/generic_pt/iommu_pt.h:619
>  pt_descend drivers/iommu/generic_pt/pt_iter.h:391 [inline]
>  __map_range+0x511/0xa80 drivers/iommu/generic_pt/iommu_pt.h:619
>  pt_iommu_vtdss_map_pages+0x6a3/0x960 drivers/iommu/generic_pt/iommu_pt.h:905
>  iommu_map_nosync+0x30a/0x840 drivers/iommu/iommu.c:2549
>  iommu_map_sg+0x579/0xae0 drivers/iommu/iommu.c:2721
>  iommu_dma_map_sg+0x908/0x1000 drivers/iommu/dma-iommu.c:1493
>  __dma_map_sg_attrs+0xd0/0x520 kernel/dma/mapping.c:245
>  dma_map_sg_attrs+0x32/0x50 kernel/dma/mapping.c:284
>  ata_sg_setup drivers/ata/libata-core.c:4773 [inline]
>  ata_qc_issue+0x515/0xf30 drivers/ata/libata-core.c:5085
>  ata_scsi_translate drivers/ata/libata-scsi.c:1755 [inline]
>  __ata_scsi_queuecmd+0x957/0xf60 drivers/ata/libata-scsi.c:4355
>  ata_scsi_queuecmd+0x3d4/0x5c0 drivers/ata/libata-scsi.c:4400
>  scsi_dispatch_cmd drivers/scsi/scsi_lib.c:1638 [inline]
>  scsi_queue_rq+0x18bc/0x30d0 drivers/scsi/scsi_lib.c:1895
>  blk_mq_dispatch_rq_list+0x4c0/0x1900 block/blk-mq.c:2137
>  __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
>  blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
>  __blk_mq_sched_dispatch_requests+0xdac/0x1570 block/blk-mq-sched.c:307
>  blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
>  blk_mq_run_hw_queue+0x404/0x4f0 block/blk-mq.c:2375
>  blk_mq_dispatch_list+0xd0b/0xe00 include/linux/spinlock.h:-1
>  blk_mq_flush_plug_list+0x469/0x550 block/blk-mq.c:2986
>  blk_add_rq_to_plug+0x175/0x450 block/blk-mq.c:1407
>  blk_mq_submit_bio+0xd5b/0x26b0 block/blk-mq.c:3232
>  __submit_bio+0x207/0x5a0 block/blk-core.c:637
>  __submit_bio_noacct_mq block/blk-core.c:724 [inline]
>  submit_bio_noacct_nocheck+0x377/0xa30 block/blk-core.c:755
>  __blkdev_direct_IO+0x915/0xf90 block/fops.c:264
>  blkdev_direct_IO+0x1261/0x17e0 block/fops.c:441
>  blkdev_direct_write+0x7c/0x140 block/fops.c:727
>  blkdev_write_iter+0x547/0x710 block/fops.c:795
>  do_iter_readv_writev+0x623/0x8c0 fs/read_write.c:-1
>  vfs_writev+0x31a/0x960 fs/read_write.c:1057
>  do_writev+0x14d/0x2d0 fs/read_write.c:1103
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fae01b8f7c9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fae02b02038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
> RAX: ffffffffffffffda RBX: 00007fae01de5fa0 RCX: 00007fae01b8f7c9
> RDX: 0000000000000021 RSI: 0000200000000a40 RDI: 0000000000000004
> RBP: 00007fae02b02090 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
> R13: 00007fae01de6038 R14: 00007fae01de5fa0 R15: 00007ffd45480c38
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:__phys_addr+0x16b/0x180 arch/x86/mm/physaddr.c:28
> Code: 8b b3 00 e9 45 ff ff ff e8 b2 af 4b 00 48 c7 c7 f0 33 fb 8d 48 89 de 4c 89 f2 e8 50 c0 52 03 e9 4d ff ff ff e8 96 af 4b 00 90 <0f> 0b e8 8e af 4b 00 90 0f 0b e8 86 af 4b 00 90 0f 0b 0f 1f 00 90
> RSP: 0018:ffffc9000aae5f80 EFLAGS: 00010093
> RAX: ffffffff817610fa RBX: 0000778000000000 RCX: ffff8880007ca4c0
> RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000778000000000
> RBP: ffffc9000aae6130 R08: ffffffff8e26c433 R09: 1ffffffff1c4d886
> R10: dffffc0000000000 R11: fffffbfff1c4d887 R12: 0000000000000011
> R13: dffffc0000000000 R14: 0000000080000000 R15: dffffc0000000000
> FS:  00007fae02b026c0(0000) GS:ffff88808d23e000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fae01d2dea0 CR3: 000000000b669000 CR4: 0000000000352ef0
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> If the report is already addressed, let syzbot know by replying with:
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> 
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> 
> If the report is a duplicate of another one, reply with:
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> 
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