Re: [syzbot] [io-uring?] WARNING in __vmap_pages_range_noflush (2)

[Jens Axboe <axboe@kernel.dk>]

On 9/9/25 3:10 PM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    be5d4872e528 Add linux-next specific files for 20250905
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1458a962580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=114fb6eb337a294b
> dashboard link: https://syzkaller.appspot.com/bug?extid=42d478f812698fed9f41
> compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1510d312580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1258a962580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/fb814704342a/disk-be5d4872.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/4f4366b3c12b/vmlinux-be5d4872.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/7b2472ced6f9/bzImage-be5d4872.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+42d478f812698fed9f41@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> WARNING: mm/vmalloc.c:538 at vmap_pages_pte_range mm/vmalloc.c:538 [inline], CPU#0: syz.0.17/6034
> WARNING: mm/vmalloc.c:538 at vmap_pages_pmd_range mm/vmalloc.c:569 [inline], CPU#0: syz.0.17/6034
> WARNING: mm/vmalloc.c:538 at vmap_pages_pud_range mm/vmalloc.c:587 [inline], CPU#0: syz.0.17/6034
> WARNING: mm/vmalloc.c:538 at vmap_pages_p4d_range mm/vmalloc.c:605 [inline], CPU#0: syz.0.17/6034
> WARNING: mm/vmalloc.c:538 at vmap_small_pages_range_noflush mm/vmalloc.c:627 [inline], CPU#0: syz.0.17/6034
> WARNING: mm/vmalloc.c:538 at __vmap_pages_range_noflush+0xdf1/0xf30 mm/vmalloc.c:656, CPU#0: syz.0.17/6034
> Modules linked in:
> CPU: 0 UID: 0 PID: 6034 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
> RIP: 0010:vmap_pages_pte_range mm/vmalloc.c:538 [inline]
> RIP: 0010:vmap_pages_pmd_range mm/vmalloc.c:569 [inline]
> RIP: 0010:vmap_pages_pud_range mm/vmalloc.c:587 [inline]
> RIP: 0010:vmap_pages_p4d_range mm/vmalloc.c:605 [inline]
> RIP: 0010:vmap_small_pages_range_noflush mm/vmalloc.c:627 [inline]
> RIP: 0010:__vmap_pages_range_noflush+0xdf1/0xf30 mm/vmalloc.c:656
> Code: eb 7b e8 92 1e ad ff eb 2f e8 8b 1e ad ff eb 6d e8 84 1e ad ff 31 ed eb 64 e8 7b 1e ad ff 90 0f 0b 90 eb 14 e8 70 1e ad ff 90 <0f> 0b 90 eb 09 e8 65 1e ad ff 90 0f 0b 90 bd f4 ff ff ff 44 8b 74
> RSP: 0018:ffffc90003dff950 EFLAGS: 00010293
> RAX: ffffffff8213e750 RBX: dffffc0000000000 RCX: ffff888030da3c80
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8213e9c5
> R10: fffff520014d3800 R11: ffffed10170c7fa9 R12: ffff888028890828
> R13: ffff88802e700d08 R14: 0000000000000000 R15: 1ffff11005ce01a1
> FS:  0000555592944500(0000) GS:ffff8881257ba000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000001b32163fff CR3: 0000000077ab6000 CR4: 00000000003526f0
> Call Trace:
>  <TASK>
>  vmap_pages_range_noflush mm/vmalloc.c:681 [inline]
>  vmap_pages_range mm/vmalloc.c:701 [inline]
>  vmap+0x1ca/0x310 mm/vmalloc.c:3515
>  io_region_init_ptr+0x24d/0x350 io_uring/memmap.c:125
>  io_create_region+0x3a4/0x480 io_uring/memmap.c:228
>  io_allocate_scq_urings+0x2b0/0x870 io_uring/io_uring.c:3626
>  io_uring_create+0x591/0xba0 io_uring/io_uring.c:3867
>  io_uring_setup io_uring/io_uring.c:3963 [inline]
>  __do_sys_io_uring_setup io_uring/io_uring.c:3997 [inline]
>  __se_sys_io_uring_setup+0x264/0x270 io_uring/io_uring.c:3988
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f3093f8ebe9
> 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:00007fffcd7235a8 EFLAGS: 00000206 ORIG_RAX: 00000000000001a9
> RAX: ffffffffffffffda RBX: 00007f30941c5fa0 RCX: 00007f3093f8ebe9
> RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000000000007688
> RBP: 0000200000000040 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000007688 R15: 0000000000000000
>  </TASK>

This seems specific to the 0905 release, which had some sketchy mm
bits in it. Doesn't reproduce on my -next branch, mainline, or on
newer linux-next either. Hence most likely a specific mm issue
in that broken release.

#syz invalid

-- 
Jens Axboe