[syzbot] [bcachefs?] WARNING in rhashtable_init_noprof

[syzbot] [bcachefs?] WARNING in rhashtable_init_noprof

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    176e917e010c Add linux-next specific files for 20250523
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13d555f4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e7902c752bef748
dashboard link: https://syzkaller.appspot.com/bug?extid=bcc38a9556d0324c2ec2
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=145948e8580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13d6a170580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5f7692c642fa/disk-176e917e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/057a442d42d0/vmlinux-176e917e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f8ebdb4dd96/bzImage-176e917e.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/d3d310848021/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bcc38a9556d0324c2ec2@syzkaller.appspotmail.com

ODEBUG: object ffffc9000469fb90 is on stack ffffc90004698000, but NOT annotated.
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5924 at lib/debugobjects.c:655 debug_object_is_on_stack lib/debugobjects.c:655 [inline]
WARNING: CPU: 1 PID: 5924 at lib/debugobjects.c:655 lookup_object_or_alloc lib/debugobjects.c:688 [inline]
WARNING: CPU: 1 PID: 5924 at lib/debugobjects.c:655 __debug_object_init+0x2c9/0x3c0 lib/debugobjects.c:743
Modules linked in:
CPU: 1 UID: 0 PID: 5924 Comm: bch-copygc/loop Not tainted 6.15.0-rc7-next-20250523-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:debug_object_is_on_stack lib/debugobjects.c:655 [inline]
RIP: 0010:lookup_object_or_alloc lib/debugobjects.c:688 [inline]
RIP: 0010:__debug_object_init+0x2c9/0x3c0 lib/debugobjects.c:743
Code: cc cc cc 41 ff c7 44 89 3d a4 18 14 15 48 c7 c1 80 9b e2 8b 48 c7 c7 e0 9b e2 8b 84 c0 48 0f 45 f9 48 89 de e8 48 2b 61 fc 90 <0f> 0b 90 e9 c0 fe ff ff e8 3a 1c 00 00 8b 05 1c 9c c6 09 3b 05 1a
RSP: 0018:ffffc9000469f6e0 EFLAGS: 00010046
RAX: 0000000000000050 RBX: ffffc9000469fb90 RCX: 0aa01120dfd08500
RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000
RBP: ffff88802f5c9e20 R08: ffffc9000469f3c7 R09: 1ffff920008d3e78
R10: dffffc0000000000 R11: fffff520008d3e79 R12: 0000000000000040
R13: ffff8880771e5d20 R14: dffffc0000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff888125d56000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1c5ee80000 CR3: 0000000077540000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 rhashtable_init_noprof+0x7c0/0xbb0 lib/rhashtable.c:1085
 bch2_copygc_thread+0x116/0xdc0 fs/bcachefs/movinggc.c:355
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot will keep track of this issue. See:
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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Re: [syzbot] [bcachefs?] WARNING in rhashtable_init_noprof

[Alan Huang]

On May 26, 2025, at 16:50, syzbot <syzbot+bcc38a9556d0324c2ec2@syzkaller.appspotmail.com> wrote:
> 
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    176e917e010c Add linux-next specific files for 20250523
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=13d555f4580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=e7902c752bef748
> dashboard link: https://syzkaller.appspot.com/bug?extid=bcc38a9556d0324c2ec2
> compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=145948e8580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13d6a170580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/5f7692c642fa/disk-176e917e.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/057a442d42d0/vmlinux-176e917e.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/8f8ebdb4dd96/bzImage-176e917e.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/d3d310848021/mount_0.gz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+bcc38a9556d0324c2ec2@syzkaller.appspotmail.com
> 
> ODEBUG: object ffffc9000469fb90 is on stack ffffc90004698000, but NOT annotated.
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 5924 at lib/debugobjects.c:655 debug_object_is_on_stack lib/debugobjects.c:655 [inline]
> WARNING: CPU: 1 PID: 5924 at lib/debugobjects.c:655 lookup_object_or_alloc lib/debugobjects.c:688 [inline]
> WARNING: CPU: 1 PID: 5924 at lib/debugobjects.c:655 __debug_object_init+0x2c9/0x3c0 lib/debugobjects.c:743
> Modules linked in:
> CPU: 1 UID: 0 PID: 5924 Comm: bch-copygc/loop Not tainted 6.15.0-rc7-next-20250523-syzkaller #0 PREEMPT(full) 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
> RIP: 0010:debug_object_is_on_stack lib/debugobjects.c:655 [inline]
> RIP: 0010:lookup_object_or_alloc lib/debugobjects.c:688 [inline]
> RIP: 0010:__debug_object_init+0x2c9/0x3c0 lib/debugobjects.c:743
> Code: cc cc cc 41 ff c7 44 89 3d a4 18 14 15 48 c7 c1 80 9b e2 8b 48 c7 c7 e0 9b e2 8b 84 c0 48 0f 45 f9 48 89 de e8 48 2b 61 fc 90 <0f> 0b 90 e9 c0 fe ff ff e8 3a 1c 00 00 8b 05 1c 9c c6 09 3b 05 1a
> RSP: 0018:ffffc9000469f6e0 EFLAGS: 00010046
> RAX: 0000000000000050 RBX: ffffc9000469fb90 RCX: 0aa01120dfd08500
> RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000
> RBP: ffff88802f5c9e20 R08: ffffc9000469f3c7 R09: 1ffff920008d3e78
> R10: dffffc0000000000 R11: fffff520008d3e79 R12: 0000000000000040
> R13: ffff8880771e5d20 R14: dffffc0000000000 R15: 0000000000000001
> FS:  0000000000000000(0000) GS:ffff888125d56000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f1c5ee80000 CR3: 0000000077540000 CR4: 00000000003526f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> rhashtable_init_noprof+0x7c0/0xbb0 lib/rhashtable.c:1085
> bch2_copygc_thread+0x116/0xdc0 fs/bcachefs/movinggc.c:355
> kthread+0x711/0x8a0 kernel/kthread.c:464
> ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
> </TASK>
> 
> 
> ---
> 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@googlegroups.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:
> #syz fix: exact-commit-title
> 
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
> 
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup
> 


#syz test: https://github.com/alanskind/bcachefs 9b38df1f0d770aef29fd6aea023b28b053e14ecf

Re: [syzbot] [bcachefs?] WARNING in rhashtable_init_noprof

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in rhashtable_free_and_destroy

==================================================================
BUG: KASAN: slab-use-after-free in rhashtable_free_and_destroy+0x7d7/0x940 lib/rhashtable.c:1172
Read of size 8 at addr ffff8880294ab830 by task bch-copygc/loop/7051

CPU: 0 UID: 0 PID: 7051 Comm: bch-copygc/loop Not tainted 6.15.0-rc4-syzkaller-00272-g9b38df1f0d77 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 rhashtable_free_and_destroy+0x7d7/0x940 lib/rhashtable.c:1172
 bch2_copygc_thread+0xc69/0xd40 fs/bcachefs/movinggc.c:427
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 7051:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4341 [inline]
 __kvmalloc_node_noprof+0x314/0x600 mm/slub.c:5026
 bucket_table_alloc lib/rhashtable.c:186 [inline]
 rhashtable_init_noprof+0x4ee/0xbb0 lib/rhashtable.c:1075
 bch2_copygc_thread+0xb7/0xd40 fs/bcachefs/movinggc.c:356
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 7048:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2398 [inline]
 slab_free mm/slub.c:4656 [inline]
 kfree+0x18e/0x440 mm/slub.c:4855
 rhashtable_free_and_destroy+0x7e8/0x940 lib/rhashtable.c:1173
 bch2_copygc_thread+0xc69/0xd40 fs/bcachefs/movinggc.c:427
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff8880294ab800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 48 bytes inside of
 freed 1024-byte region [ffff8880294ab800, ffff8880294abc00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x294a8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801a041dc0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a041dc0 dead000000000122 0000000000000000
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0000a52a01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6998, tgid 6996 (syz.4.25), ts 143611566388, free_ts 143543501461
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1718
 prep_new_page mm/page_alloc.c:1726 [inline]
 get_page_from_freelist+0x21ce/0x22b0 mm/page_alloc.c:3688
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4970
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2301
 alloc_slab_page mm/slub.c:2468 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2632
 new_slab mm/slub.c:2686 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3872
 __slab_alloc mm/slub.c:3962 [inline]
 __slab_alloc_node mm/slub.c:4037 [inline]
 slab_alloc_node mm/slub.c:4198 [inline]
 __do_kmalloc_node mm/slub.c:4340 [inline]
 __kmalloc_noprof+0x305/0x4f0 mm/slub.c:4353
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 __alloc_workqueue+0x103/0x1b70 kernel/workqueue.c:5683
 alloc_workqueue+0xd4/0x210 kernel/workqueue.c:5786
 bch2_fs_journal_init+0x2dc/0x4d0 fs/bcachefs/journal.c:1648
 bch2_fs_init_rw fs/bcachefs/super.c:830 [inline]
 __bch2_fs_read_write+0x837/0x880 fs/bcachefs/super.c:500
 bch2_fs_read_write_early+0x26/0x40 fs/bcachefs/super.c:588
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:415 [inline]
 __bch2_run_recovery_passes+0x391/0x1110 fs/bcachefs/recovery_passes.c:470
 bch2_run_recovery_passes+0x184/0x210 fs/bcachefs/recovery_passes.c:541
 bch2_fs_recovery+0x2617/0x3970 fs/bcachefs/recovery.c:974
 bch2_fs_start+0xa43/0xd30 fs/bcachefs/super.c:1206
page last free pid 7040 tgid 7040 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 __free_frozen_pages+0xc68/0xe50 mm/page_alloc.c:2725
 discard_slab mm/slub.c:2730 [inline]
 __put_partials+0x161/0x1c0 mm/slub.c:3199
 put_cpu_partial+0x17c/0x250 mm/slub.c:3274
 __slab_free+0x2f7/0x400 mm/slub.c:4526
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4161 [inline]
 slab_alloc_node mm/slub.c:4210 [inline]
 kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4217
 vm_area_alloc+0x24/0x140 kernel/fork.c:441
 __mmap_new_vma mm/vma.c:2402 [inline]
 __mmap_region mm/vma.c:2519 [inline]
 mmap_region+0xcf4/0x1e50 mm/vma.c:2597
 do_mmap+0xc68/0x1100 mm/mmap.c:561
 vm_mmap_pgoff+0x31b/0x4c0 mm/util.c:579
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x220 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8880294ab700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880294ab780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880294ab800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff8880294ab880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880294ab900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit:         9b38df1f bcachefs: Don't allocate buckets_in_flight on..
git tree:       https://github.com/alanskind/bcachefs
console output: https://syzkaller.appspot.com/x/log.txt?x=17cdbad4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=96ae50edd782e9ea
dashboard link: https://syzkaller.appspot.com/bug?extid=bcc38a9556d0324c2ec2
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

Note: no patches were applied.

Re: [syzbot] [bcachefs?] WARNING in rhashtable_init_noprof

[syzbot]

syzbot has bisected this issue to:

commit 82067c916994dd1bfec65496144dc16e17899e36
Author: Kent Overstreet <kent.overstreet@linux.dev>
Date:   Fri May 9 03:21:28 2025 +0000

    bcachefs: buckets_in_flight on stack

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1528f882580000
start commit:   176e917e010c Add linux-next specific files for 20250523
git tree:       linux-next
final oops:     https://syzkaller.appspot.com/x/report.txt?x=1728f882580000
console output: https://syzkaller.appspot.com/x/log.txt?x=1328f882580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e7902c752bef748
dashboard link: https://syzkaller.appspot.com/bug?extid=bcc38a9556d0324c2ec2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=145948e8580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13d6a170580000

Reported-by: syzbot+bcc38a9556d0324c2ec2@syzkaller.appspotmail.com
Fixes: 82067c916994 ("bcachefs: buckets_in_flight on stack")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: [syzbot]

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: 
Author: kent.overstreet@linux.dev

#syz fix: bcachefs: Don't put rhashtable on stack