[syzbot] [bcachefs?] WARNING in bch2_dev_free

[syzbot] [bcachefs?] WARNING in bch2_dev_free

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    a4cda136f021 Add linux-next specific files for 20250404
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12c3db4c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8a257c454bb1afb7
dashboard link: https://syzkaller.appspot.com/bug?extid=aec9606169fbc3a12ca6
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17ca0c04580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11c3db4c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/59048bc9c206/disk-a4cda136.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ad2ba7306f20/vmlinux-a4cda136.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b3bef7acbf10/bzImage-a4cda136.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/110624be1513/mount_0.gz

The issue was bisected to:

commit dcffc3b1ae3251d796a25c673f614e3099ca83d3
Author: Kent Overstreet <kent.overstreet@linux.dev>
Date:   Sun Mar 30 03:11:08 2025 +0000

    bcachefs: Split up bch_dev.io_ref

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13948c04580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=10548c04580000
console output: https://syzkaller.appspot.com/x/log.txt?x=17948c04580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aec9606169fbc3a12ca6@syzkaller.appspotmail.com
Fixes: dcffc3b1ae32 ("bcachefs: Split up bch_dev.io_ref")

bcachefs (loop0): shutting down
------------[ cut here ]------------
WARNING: CPU: 0 PID: 5844 at fs/bcachefs/super.c:1229 bch2_dev_free+0x228/0x290 fs/bcachefs/super.c:1229
Modules linked in:
CPU: 0 UID: 0 PID: 5844 Comm: syz-executor121 Not tainted 6.14.0-next-20250404-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:bch2_dev_free+0x228/0x290 fs/bcachefs/super.c:1229
Code: ff e8 4c cf 74 00 4c 89 ef e8 44 cf 74 00 48 89 df 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 ee 53 96 07 e8 59 e9 32 fd 90 <0f> 0b 90 e9 09 fe ff ff e8 4b e9 32 fd 90 0f 0b 90 e9 15 fe ff ff
RSP: 0018:ffffc9000406fb88 EFLAGS: 00010293
RAX: ffffffff849073d7 RBX: ffff888035282000 RCX: ffff888034af9e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880352820c0 R08: ffffffff850552f7 R09: 0000000000000000
R10: ffff888035282208 R11: ffffed1006a5044a R12: ffff888075e003f0
R13: ffff8880352820b0 R14: ffff888075e00000 R15: ffff888075e007b2
FS:  000055558bb20380(0000) GS:ffff888124f8f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045bdd0 CR3: 00000000122a0000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 bch2_fs_free+0x2b0/0x400 fs/bcachefs/super.c:688
 deactivate_locked_super+0xc4/0x130 fs/super.c:473
 cleanup_mnt+0x422/0x4c0 fs/namespace.c:1435
 task_work_run+0x251/0x310 kernel/task_work.c:227
 ptrace_notify+0x2dc/0x390 kernel/signal.c:2520
 ptrace_report_syscall include/linux/ptrace.h:415 [inline]
 ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
 syscall_exit_work+0xc7/0x1d0 kernel/entry/common.c:173
 syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
 syscall_exit_to_user_mode+0x24a/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f49b0cec447
Code: 07 00 48 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffd94723978 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f49b0cec447
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd94723a30
RBP: 00007ffd94723a30 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000206 R12: 00007ffd94724aa0
R13: 000055558bb216c0 R14: 0000000000000001 R15: 431bde82d7b634db
 </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:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

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:
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(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 bch2_dev_free

[Charalampos Mitrodimas]

syzbot <syzbot+aec9606169fbc3a12ca6@syzkaller.appspotmail.com> writes:

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    a4cda136f021 Add linux-next specific files for 20250404
> git tree:       linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12c3db4c580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=8a257c454bb1afb7
> dashboard link: https://syzkaller.appspot.com/bug?extid=aec9606169fbc3a12ca6
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17ca0c04580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11c3db4c580000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/59048bc9c206/disk-a4cda136.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/ad2ba7306f20/vmlinux-a4cda136.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/b3bef7acbf10/bzImage-a4cda136.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/110624be1513/mount_0.gz
>
> The issue was bisected to:
>
> commit dcffc3b1ae3251d796a25c673f614e3099ca83d3
> Author: Kent Overstreet <kent.overstreet@linux.dev>
> Date:   Sun Mar 30 03:11:08 2025 +0000
>
>     bcachefs: Split up bch_dev.io_ref
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13948c04580000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=10548c04580000
> console output: https://syzkaller.appspot.com/x/log.txt?x=17948c04580000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+aec9606169fbc3a12ca6@syzkaller.appspotmail.com
> Fixes: dcffc3b1ae32 ("bcachefs: Split up bch_dev.io_ref")
>
> bcachefs (loop0): shutting down
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 5844 at fs/bcachefs/super.c:1229 bch2_dev_free+0x228/0x290 fs/bcachefs/super.c:1229
> Modules linked in:
> CPU: 0 UID: 0 PID: 5844 Comm: syz-executor121 Not tainted 6.14.0-next-20250404-syzkaller #0 PREEMPT(full) 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
> RIP: 0010:bch2_dev_free+0x228/0x290 fs/bcachefs/super.c:1229
> Code: ff e8 4c cf 74 00 4c 89 ef e8 44 cf 74 00 48 89 df 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 ee 53 96 07 e8 59 e9 32 fd 90 <0f> 0b 90 e9 09 fe ff ff e8 4b e9 32 fd 90 0f 0b 90 e9 15 fe ff ff
> RSP: 0018:ffffc9000406fb88 EFLAGS: 00010293
> RAX: ffffffff849073d7 RBX: ffff888035282000 RCX: ffff888034af9e00
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: ffff8880352820c0 R08: ffffffff850552f7 R09: 0000000000000000
> R10: ffff888035282208 R11: ffffed1006a5044a R12: ffff888075e003f0
> R13: ffff8880352820b0 R14: ffff888075e00000 R15: ffff888075e007b2
> FS:  000055558bb20380(0000) GS:ffff888124f8f000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000000045bdd0 CR3: 00000000122a0000 CR4: 00000000003526f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  bch2_fs_free+0x2b0/0x400 fs/bcachefs/super.c:688
>  deactivate_locked_super+0xc4/0x130 fs/super.c:473
>  cleanup_mnt+0x422/0x4c0 fs/namespace.c:1435
>  task_work_run+0x251/0x310 kernel/task_work.c:227
>  ptrace_notify+0x2dc/0x390 kernel/signal.c:2520
>  ptrace_report_syscall include/linux/ptrace.h:415 [inline]
>  ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
>  syscall_exit_work+0xc7/0x1d0 kernel/entry/common.c:173
>  syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline]
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
>  syscall_exit_to_user_mode+0x24a/0x340 kernel/entry/common.c:218
>  do_syscall_64+0x100/0x230 arch/x86/entry/syscall_64.c:100
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f49b0cec447
> Code: 07 00 48 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8
> RSP: 002b:00007ffd94723978 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f49b0cec447
> RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd94723a30
> RBP: 00007ffd94723a30 R08: 0000000000000000 R09: 0000000000000000
> R10: 00000000ffffffff R11: 0000000000000206 R12: 00007ffd94724aa0
> R13: 000055558bb216c0 R14: 0000000000000001 R15: 431bde82d7b634db
>  </TASK>
>
>
> ---

#syz test

From: Charalampos Mitrodimas <charmitro@posteo.net>
Subject: [PATCH] bcachefs: Fix WARN_ON in bch2_dev_free

After splitting bch_dev.io_ref into separate READ and WRITE refs, we
need to ensure both refs are properly stopped before freeing a device.
Add bch2_dev_io_ref_stop(ca, WRITE) to bch2_fs_free() to prevent the
WARNING in bch2_dev_free().

Reported-by: syzbot+aec9606169fbc3a12ca6@syzkaller.appspotmail.com
Fixes: dcffc3b1ae32 ("bcachefs: Split up bch_dev.io_ref")
Signed-off-by: Charalampos Mitrodimas <charmitro@posteo.net>
---
 fs/bcachefs/super.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index a58edde43bee..089b69b685d9 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -684,6 +684,7 @@ void bch2_fs_free(struct bch_fs *c)
 		if (ca) {
 			EBUG_ON(atomic_long_read(&ca->ref) != 1);
 			bch2_dev_io_ref_stop(ca, READ);
+			bch2_dev_io_ref_stop(ca, WRITE);
 			bch2_free_super(&ca->disk_sb);
 			bch2_dev_free(ca);
 		}
-- 
2.39.5

Re: [syzbot] [bcachefs?] WARNING in bch2_dev_free

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
unregister_netdevice: waiting for DEV to become free

unregister_netdevice: waiting for batadv0 to become free. Usage count = 3


Tested on:

commit:         a2458824 Merge tag 'linux_kselftest-kunit-6.15-rc2' of..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=153ffb4c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fb8650d88e9fb80f
dashboard link: https://syzkaller.appspot.com/bug?extid=aec9606169fbc3a12ca6
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=17b7fb4c580000

Re: [syzbot] [bcachefs?] WARNING in bch2_dev_free

[Kent Overstreet]

On Wed, Apr 09, 2025 at 04:09:41PM +0000, Charalampos Mitrodimas wrote:
> syzbot <syzbot+aec9606169fbc3a12ca6@syzkaller.appspotmail.com> writes:
> 
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    a4cda136f021 Add linux-next specific files for 20250404
> > git tree:       linux-next
> > console+strace: https://syzkaller.appspot.com/x/log.txt?x=12c3db4c580000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=8a257c454bb1afb7
> > dashboard link: https://syzkaller.appspot.com/bug?extid=aec9606169fbc3a12ca6
> > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17ca0c04580000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11c3db4c580000
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/59048bc9c206/disk-a4cda136.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/ad2ba7306f20/vmlinux-a4cda136.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/b3bef7acbf10/bzImage-a4cda136.xz
> > mounted in repro: https://storage.googleapis.com/syzbot-assets/110624be1513/mount_0.gz
> >
> > The issue was bisected to:
> >
> > commit dcffc3b1ae3251d796a25c673f614e3099ca83d3
> > Author: Kent Overstreet <kent.overstreet@linux.dev>
> > Date:   Sun Mar 30 03:11:08 2025 +0000
> >
> >     bcachefs: Split up bch_dev.io_ref
> >
> > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13948c04580000
> > final oops:     https://syzkaller.appspot.com/x/report.txt?x=10548c04580000
> > console output: https://syzkaller.appspot.com/x/log.txt?x=17948c04580000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+aec9606169fbc3a12ca6@syzkaller.appspotmail.com
> > Fixes: dcffc3b1ae32 ("bcachefs: Split up bch_dev.io_ref")
> >
> > bcachefs (loop0): shutting down
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 5844 at fs/bcachefs/super.c:1229 bch2_dev_free+0x228/0x290 fs/bcachefs/super.c:1229
> > Modules linked in:
> > CPU: 0 UID: 0 PID: 5844 Comm: syz-executor121 Not tainted 6.14.0-next-20250404-syzkaller #0 PREEMPT(full) 
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
> > RIP: 0010:bch2_dev_free+0x228/0x290 fs/bcachefs/super.c:1229
> > Code: ff e8 4c cf 74 00 4c 89 ef e8 44 cf 74 00 48 89 df 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 ee 53 96 07 e8 59 e9 32 fd 90 <0f> 0b 90 e9 09 fe ff ff e8 4b e9 32 fd 90 0f 0b 90 e9 15 fe ff ff
> > RSP: 0018:ffffc9000406fb88 EFLAGS: 00010293
> > RAX: ffffffff849073d7 RBX: ffff888035282000 RCX: ffff888034af9e00
> > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> > RBP: ffff8880352820c0 R08: ffffffff850552f7 R09: 0000000000000000
> > R10: ffff888035282208 R11: ffffed1006a5044a R12: ffff888075e003f0
> > R13: ffff8880352820b0 R14: ffff888075e00000 R15: ffff888075e007b2
> > FS:  000055558bb20380(0000) GS:ffff888124f8f000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 000000000045bdd0 CR3: 00000000122a0000 CR4: 00000000003526f0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >  <TASK>
> >  bch2_fs_free+0x2b0/0x400 fs/bcachefs/super.c:688
> >  deactivate_locked_super+0xc4/0x130 fs/super.c:473
> >  cleanup_mnt+0x422/0x4c0 fs/namespace.c:1435
> >  task_work_run+0x251/0x310 kernel/task_work.c:227
> >  ptrace_notify+0x2dc/0x390 kernel/signal.c:2520
> >  ptrace_report_syscall include/linux/ptrace.h:415 [inline]
> >  ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
> >  syscall_exit_work+0xc7/0x1d0 kernel/entry/common.c:173
> >  syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline]
> >  __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
> >  syscall_exit_to_user_mode+0x24a/0x340 kernel/entry/common.c:218
> >  do_syscall_64+0x100/0x230 arch/x86/entry/syscall_64.c:100
> >  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> > RIP: 0033:0x7f49b0cec447
> > Code: 07 00 48 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8
> > RSP: 002b:00007ffd94723978 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
> > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f49b0cec447
> > RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd94723a30
> > RBP: 00007ffd94723a30 R08: 0000000000000000 R09: 0000000000000000
> > R10: 00000000ffffffff R11: 0000000000000206 R12: 00007ffd94724aa0
> > R13: 000055558bb216c0 R14: 0000000000000001 R15: 431bde82d7b634db
> >  </TASK>
> >
> >
> > ---
> 
> #syz test
> 
> From: Charalampos Mitrodimas <charmitro@posteo.net>
> Subject: [PATCH] bcachefs: Fix WARN_ON in bch2_dev_free
> 
> After splitting bch_dev.io_ref into separate READ and WRITE refs, we
> need to ensure both refs are properly stopped before freeing a device.
> Add bch2_dev_io_ref_stop(ca, WRITE) to bch2_fs_free() to prevent the
> WARNING in bch2_dev_free().
> 
> Reported-by: syzbot+aec9606169fbc3a12ca6@syzkaller.appspotmail.com
> Fixes: dcffc3b1ae32 ("bcachefs: Split up bch_dev.io_ref")
> Signed-off-by: Charalampos Mitrodimas <charmitro@posteo.net>
> ---
>  fs/bcachefs/super.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
> index a58edde43bee..089b69b685d9 100644
> --- a/fs/bcachefs/super.c
> +++ b/fs/bcachefs/super.c
> @@ -684,6 +684,7 @@ void bch2_fs_free(struct bch_fs *c)
>  		if (ca) {
>  			EBUG_ON(atomic_long_read(&ca->ref) != 1);
>  			bch2_dev_io_ref_stop(ca, READ);
> +			bch2_dev_io_ref_stop(ca, WRITE);
>  			bch2_free_super(&ca->disk_sb);
>  			bch2_dev_free(ca);
>  		}
> -- 
> 2.39.5
> 


This would seem to indicate shutting down without going read-only, there
might be a deeper bug here

Re: [syzbot] #syz test

[syzbot]

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

***

Subject: #syz test
Author: gshahrouzi@gmail.com

Try to remove device but fails
Reinitialize reference counting for write operations for device
Shut down the filesystem
Make the filesystem read only
	Read-write bit is not set so it skips trying to make the filesystem read-only, implying that the filesystem is already in read-only mode.
Encounter error because write operations are still assigned to a device
When the filesystem is starting up, it tries setting it to set the filesystem to read-only but it’s already set.
When failing to remove a device, it tries giving back write permissions to a device when the filesystem is read-only (not sure if this is nonsensical or not).
Since a device has write permissions, it tries to remove them but fails because the filesystem is in read-only mode.
So the fix here is to prevent it from giving the device write permissions if the filesystem is in read-only mode.

Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
---
 fs/bcachefs/super.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index b79e80a435e09..788e870bfef6a 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -1757,7 +1757,8 @@ int bch2_dev_remove(struct bch_fs *c, struct bch_dev *ca, int flags)
 	up_write(&c->state_lock);
 	return 0;
 err:
-	if (ca->mi.state == BCH_MEMBER_STATE_rw &&
+	if (test_bit(BCH_FS_rw, &c->flags) &&
+	    ca->mi.state == BCH_MEMBER_STATE_rw &&
 	    !percpu_ref_is_zero(&ca->io_ref[READ]))
 		__bch2_dev_read_write(c, ca);
 	up_write(&c->state_lock);
-- 
2.43.0

Re: [syzbot] #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5fc31936081919a8572a3d644f3fbb258038f337

[syzbot]

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Subject: #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5fc31936081919a8572a3d644f3fbb258038f337
Author: gshahrouzi@gmail.com

Another test with earlier branch because of unassociated error popping up:
unregister_netdevice: waiting for batadv0 to become free. Usage count = 3.

Signed-off-by: Gabriel Shahrouzi <gshahrouzi@gmail.com>
---
 fs/bcachefs/super.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index b79e80a435e09..788e870bfef6a 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -1757,7 +1757,8 @@ int bch2_dev_remove(struct bch_fs *c, struct bch_dev *ca, int flags)
 	up_write(&c->state_lock);
 	return 0;
 err:
-	if (ca->mi.state == BCH_MEMBER_STATE_rw &&
+	if (test_bit(BCH_FS_rw, &c->flags) &&
+	    ca->mi.state == BCH_MEMBER_STATE_rw &&
 	    !percpu_ref_is_zero(&ca->io_ref[READ]))
 		__bch2_dev_read_write(c, ca);
 	up_write(&c->state_lock);
-- 
2.43.0

Re: [syzbot]

[syzbot]

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Subject: 
Author: kent.overstreet@linux.dev

#syz fix: bcachefs: Prevent granting write refs when filesystem is read-only

[syzbot] [bcachefs?] KMSAN: uninit-value in __bch2_alloc_v4_to_text

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    e04c78d86a96 Linux 6.16-rc2
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16fdc90c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=db26f33438d76de9
dashboard link: https://syzkaller.appspot.com/bug?extid=8eb51728519f6659ef7b
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=11fdc90c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=132995d4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c0f064a5f302/disk-e04c78d8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b71205c143e3/vmlinux-e04c78d8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2abdee22b79e/bzImage-e04c78d8.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/3838d178b843/mount_2.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8eb51728519f6659ef7b@syzkaller.appspotmail.com

    cached_sectors       0
    stripe               0
    stripe_redundancy    0
    io_time[READ]        1
    io_time[WRITE]       1024
    fragmentation     0
    bp_start          7
  
  incorrectly set at freespace:0:37:0 (free 0, genbits 0 should be 0), fixing
=====================================================
BUG: KMSAN: uninit-value in __bch2_alloc_v4_to_text+0x7a4/0xdf0 fs/bcachefs/alloc_background.c:355
 __bch2_alloc_v4_to_text+0x7a4/0xdf0 fs/bcachefs/alloc_background.c:355
 bch2_alloc_v4_to_text+0x181/0x1f0 fs/bcachefs/alloc_background.c:380
 bch2_val_to_text fs/bcachefs/bkey_methods.c:321 [inline]
 bch2_bkey_val_to_text+0x1e8/0x280 fs/bcachefs/bkey_methods.c:331
 bch2_check_discard_freespace_key+0xe35/0x1a30 fs/bcachefs/alloc_background.c:1436
 try_alloc_bucket fs/bcachefs/alloc_foreground.c:272 [inline]
 bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:420 [inline]
 bch2_bucket_alloc_trans+0x225d/0x3a40 fs/bcachefs/alloc_foreground.c:544
 bch2_bucket_alloc_set_trans+0xebb/0x1c10 fs/bcachefs/alloc_foreground.c:728
 __open_bucket_add_buckets+0x21f8/0x37b0 fs/bcachefs/alloc_foreground.c:925
 open_bucket_add_buckets+0x347/0x580 fs/bcachefs/alloc_foreground.c:957
 bch2_alloc_sectors_start_trans+0x1de1/0x3560 fs/bcachefs/alloc_foreground.c:-1
 __bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:320 [inline]
 bch2_btree_reserve_get+0x9fd/0x2120 fs/bcachefs/btree_update_interior.c:534
 bch2_btree_update_start+0x2cf3/0x3620 fs/bcachefs/btree_update_interior.c:1289
 bch2_btree_node_rewrite+0x1cd/0x1b50 fs/bcachefs/btree_update_interior.c:2245
 bch2_btree_node_rewrite_key fs/bcachefs/btree_update_interior.c:2311 [inline]
 async_btree_node_rewrite_work+0x6e8/0x10d0 fs/bcachefs/btree_update_interior.c:2368
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3321
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3402
 kthread+0xd5c/0xf00 kernel/kthread.c:464
 ret_from_fork+0x1e0/0x310 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4154 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x95f/0x1310 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 __bkey_cached_alloc fs/bcachefs/btree_key_cache.c:139 [inline]
 bkey_cached_alloc fs/bcachefs/btree_key_cache.c:162 [inline]
 btree_key_cache_create fs/bcachefs/btree_key_cache.c:231 [inline]
 btree_key_cache_fill+0x784/0x4780 fs/bcachefs/btree_key_cache.c:344
 bch2_btree_path_traverse_cached+0x10d7/0x1870 fs/bcachefs/btree_key_cache.c:399
 bch2_btree_path_traverse_one+0x6db/0x4060 fs/bcachefs/btree_iter.c:1179
 bch2_btree_path_traverse fs/bcachefs/btree_iter.h:250 [inline]
 bch2_btree_iter_peek_slot+0xd74/0x3910 fs/bcachefs/btree_iter.c:2781
 __bch2_bkey_get_iter fs/bcachefs/btree_iter.h:632 [inline]
 bch2_bkey_get_iter fs/bcachefs/btree_iter.h:646 [inline]
 bch2_check_discard_freespace_key+0x321/0x1a30 fs/bcachefs/alloc_background.c:1414
 try_alloc_bucket fs/bcachefs/alloc_foreground.c:272 [inline]
 bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:420 [inline]
 bch2_bucket_alloc_trans+0x225d/0x3a40 fs/bcachefs/alloc_foreground.c:544
 bch2_bucket_alloc_set_trans+0xebb/0x1c10 fs/bcachefs/alloc_foreground.c:728
 __open_bucket_add_buckets+0x21f8/0x37b0 fs/bcachefs/alloc_foreground.c:925
 open_bucket_add_buckets+0x347/0x580 fs/bcachefs/alloc_foreground.c:957
 bch2_alloc_sectors_start_trans+0x1de1/0x3560 fs/bcachefs/alloc_foreground.c:-1
 __bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:320 [inline]
 bch2_btree_reserve_get+0x9fd/0x2120 fs/bcachefs/btree_update_interior.c:534
 bch2_btree_update_start+0x2cf3/0x3620 fs/bcachefs/btree_update_interior.c:1289
 bch2_btree_node_rewrite+0x1cd/0x1b50 fs/bcachefs/btree_update_interior.c:2245
 bch2_btree_node_rewrite_key fs/bcachefs/btree_update_interior.c:2311 [inline]
 async_btree_node_rewrite_work+0x6e8/0x10d0 fs/bcachefs/btree_update_interior.c:2368
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3321
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3402
 kthread+0xd5c/0xf00 kernel/kthread.c:464
 ret_from_fork+0x1e0/0x310 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

CPU: 1 UID: 0 PID: 4181 Comm: kworker/u8:21 Not tainted 6.16.0-rc2-syzkaller #0 PREEMPT(undef) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: btree_node_rewrite async_btree_node_rewrite_work
=====================================================


---
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:
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(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] #syz test

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Subject: #syz test
Author: abhinav.ogl@gmail.com

Re: [syzbot] #syz test

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Subject: #syz test
Author: abhinav.ogl@gmail.com

Re: [syzbot] #syz test

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Subject: #syz test
Author: abhinav.ogl@gmail.com

[syzbot] [bcachefs?] KASAN: slab-out-of-bounds Read in bch2_sb_members_v2_to_text

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    176e917e010c Add linux-next specific files for 20250523
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1159c5f4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e7902c752bef748
dashboard link: https://syzkaller.appspot.com/bug?extid=5138f00559ffb3cb3610
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=14a759f4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14e065f4580000

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/9032c3d09738/mount_0.gz

The issue was bisected to:

commit 1c8dfd7ba50dbbb72113caf4fa7868512cdad2f4
Author: Kent Overstreet <kent.overstreet@linux.dev>
Date:   Wed Apr 16 03:35:48 2025 +0000

    bcachefs: sb_validate() no longer requires members_v1

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11d21ad4580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=13d21ad4580000
console output: https://syzkaller.appspot.com/x/log.txt?x=15d21ad4580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5138f00559ffb3cb3610@syzkaller.appspotmail.com
Fixes: 1c8dfd7ba50d ("bcachefs: sb_validate() no longer requires members_v1")

loop0: detected capacity change from 0 to 32768
==================================================================
BUG: KASAN: slab-out-of-bounds in members_v2_get fs/bcachefs/sb-members.c:68 [inline]
BUG: KASAN: slab-out-of-bounds in bch2_sb_members_v2_to_text+0x1ae/0x310 fs/bcachefs/sb-members.c:347
Read of size 136 at addr ffff88807716dfb8 by task syz-executor118/5842

CPU: 0 UID: 0 PID: 5842 Comm: syz-executor118 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
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
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:189
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 members_v2_get fs/bcachefs/sb-members.c:68 [inline]
 bch2_sb_members_v2_to_text+0x1ae/0x310 fs/bcachefs/sb-members.c:347
 bch2_sb_field_validate+0x1c6/0x280 fs/bcachefs/super-io.c:1380
 bch2_sb_validate+0x14bd/0x1980 fs/bcachefs/super-io.c:552
 __bch2_read_super+0xba4/0x1040 fs/bcachefs/super-io.c:925
 bch2_fs_open+0x1fe/0x25c0 fs/bcachefs/super.c:2371
 bch2_fs_get_tree+0x44d/0x15f0 fs/bcachefs/fs.c:2463
 vfs_get_tree+0x92/0x2b0 fs/super.c:1802
 do_new_mount+0x24a/0xa40 fs/namespace.c:3869
 do_mount fs/namespace.c:4206 [inline]
 __do_sys_mount fs/namespace.c:4417 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4394
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f813c8a7dfa
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffeafb83b88 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffeafb83ba0 RCX: 00007f813c8a7dfa
RDX: 00002000000000c0 RSI: 0000200000000300 RDI: 00007ffeafb83ba0
RBP: 0000000000000010 R08: 00007ffeafb83be0 R09: 00ffffffffffffff
R10: 0000000000000010 R11: 0000000000000282 R12: 00002000000000c0
R13: 0000200000000300 R14: 00007ffeafb83be0 R15: 0000000000000003
 </TASK>

Allocated by task 5842:
 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:4327 [inline]
 __kmalloc_node_track_caller_noprof+0x271/0x4e0 mm/slub.c:4346
 __do_krealloc mm/slub.c:4904 [inline]
 krealloc_noprof+0x124/0x340 mm/slub.c:4957
 bch2_sb_realloc+0x348/0x630 fs/bcachefs/super-io.c:222
 read_one_super+0x3a3/0x850 fs/bcachefs/super-io.c:759
 __bch2_read_super+0x6c6/0x1040 fs/bcachefs/super-io.c:851
 bch2_fs_open+0x1fe/0x25c0 fs/bcachefs/super.c:2371
 bch2_fs_get_tree+0x44d/0x15f0 fs/bcachefs/fs.c:2463
 vfs_get_tree+0x92/0x2b0 fs/super.c:1802
 do_new_mount+0x24a/0xa40 fs/namespace.c:3869
 do_mount fs/namespace.c:4206 [inline]
 __do_sys_mount fs/namespace.c:4417 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4394
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88807716c000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 8120 bytes inside of
 allocated 8192-byte region [ffff88807716c000, ffff88807716e000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x77168
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 ffff88801a442280 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a442280 dead000000000122 0000000000000000
head: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0001dc5a01 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 0xd28c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5759, tgid 5759 (sshd-session), ts 67004973254, free_ts 66925363852
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2450 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2618
 new_slab mm/slub.c:2672 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3858
 __slab_alloc mm/slub.c:3948 [inline]
 __slab_alloc_node mm/slub.c:4023 [inline]
 slab_alloc_node mm/slub.c:4184 [inline]
 __do_kmalloc_node mm/slub.c:4326 [inline]
 __kmalloc_node_track_caller_noprof+0x2f8/0x4e0 mm/slub.c:4346
 kmalloc_reserve+0x136/0x290 net/core/skbuff.c:601
 __alloc_skb+0x142/0x2d0 net/core/skbuff.c:670
 alloc_skb include/linux/skbuff.h:1336 [inline]
 netlink_dump+0x1c7/0xe20 net/netlink/af_netlink.c:2275
 netlink_recvmsg+0x67b/0xe00 net/netlink/af_netlink.c:1965
 sock_recvmsg_nosec net/socket.c:1017 [inline]
 sock_recvmsg+0x229/0x270 net/socket.c:1039
 ____sys_recvmsg+0x1c9/0x460 net/socket.c:2786
 ___sys_recvmsg+0x1b5/0x510 net/socket.c:2828
 __sys_recvmsg net/socket.c:2861 [inline]
 __do_sys_recvmsg net/socket.c:2867 [inline]
 __se_sys_recvmsg net/socket.c:2864 [inline]
 __x64_sys_recvmsg+0x198/0x260 net/socket.c:2864
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
page last free pid 5758 tgid 5758 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
 discard_slab mm/slub.c:2716 [inline]
 __put_partials+0x161/0x1c0 mm/slub.c:3185
 put_cpu_partial+0x17c/0x250 mm/slub.c:3260
 __slab_free+0x2f7/0x400 mm/slub.c:4512
 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:4147 [inline]
 slab_alloc_node mm/slub.c:4196 [inline]
 kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4203
 getname_flags+0xb8/0x540 fs/namei.c:146
 getname include/linux/fs.h:2903 [inline]
 __do_sys_unlink fs/namei.c:4696 [inline]
 __se_sys_unlink fs/namei.c:4694 [inline]
 __x64_sys_unlink+0x3a/0x50 fs/namei.c:4694
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88807716df00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807716df80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807716e000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff88807716e080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88807716e100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


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Re: [syzbot] #syz test

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Subject: #syz test
Author: abhinav.ogl@gmail.com

[syzbot] [i2c?] KMSAN: uninit-value in __i2c_smbus_xfer

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    02ddfb981de8 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1034139b980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9dc42c34a3f5c357
dashboard link: https://syzkaller.appspot.com/bug?extid=0a36c1fec090c67a9885
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10c9df74580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1550f1b3980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5ca57f5a3f77/disk-02ddfb98.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3f23cbc11e68/vmlinux-02ddfb98.xz
kernel image: https://storage.googleapis.com/syzbot-assets/73e63afac354/bzImage-02ddfb98.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0a36c1fec090c67a9885@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in i2c_smbus_xfer_emulated drivers/i2c/i2c-core-smbus.c:481 [inline]
BUG: KMSAN: uninit-value in __i2c_smbus_xfer+0x23e7/0x2f60 drivers/i2c/i2c-core-smbus.c:607
 i2c_smbus_xfer_emulated drivers/i2c/i2c-core-smbus.c:481 [inline]
 __i2c_smbus_xfer+0x23e7/0x2f60 drivers/i2c/i2c-core-smbus.c:607
 i2c_smbus_xfer+0x31d/0x4d0 drivers/i2c/i2c-core-smbus.c:545
 i2cdev_ioctl_smbus+0x4a1/0x660 drivers/i2c/i2c-dev.c:389
 i2cdev_ioctl+0xa14/0xf40 drivers/i2c/i2c-dev.c:478
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0x239/0x400 fs/ioctl.c:892
 __x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:892
 x64_sys_call+0x1ebe/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x1b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable page created at:
 get_futex_key+0x6f/0x11d0 kernel/futex/core.c:227
 futex_wake+0xfe/0x890 kernel/futex/waitwake.c:166

CPU: 1 UID: 0 PID: 5795 Comm: syz-executor470 Not tainted 6.15.0-rc3-syzkaller-00094-g02ddfb981de8 #0 PREEMPT(undef) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
=====================================================


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[syzbot] [perf?] WARNING in __free_event

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    0a87d6bb6fd2 Merge tag 'powerpc-6.15-2' of git://git.kerne..
git tree:       bpf-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1780f7b0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6631c78ce6cb228d
dashboard link: https://syzkaller.appspot.com/bug?extid=ff3aa851d46ab82953a3
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15440be4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12295404580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e5cffcf83e28/disk-0a87d6bb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/905e70de24af/vmlinux-0a87d6bb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5c28ed628313/bzImage-0a87d6bb.xz

The issue was bisected to:

commit 00b35530811f2aa3d7ceec2dbada80861c7632a8
Author: Eric Dumazet <edumazet@google.com>
Date:   Thu Feb 6 14:04:22 2025 +0000

    batman-adv: adopt netdev_hold() / netdev_put()

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=10a7e94c580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=12a7e94c580000
console output: https://syzkaller.appspot.com/x/log.txt?x=14a7e94c580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ff3aa851d46ab82953a3@syzkaller.appspotmail.com
Fixes: 00b35530811f ("batman-adv: adopt netdev_hold() / netdev_put()")

------------[ cut here ]------------
WARNING: CPU: 1 PID: 6031 at kernel/events/core.c:5572 __free_event+0x50f/0x620 kernel/events/core.c:5572
Modules linked in:
CPU: 1 UID: 0 PID: 6031 Comm: syz-executor189 Not tainted 6.14.0-syzkaller-g0a87d6bb6fd2 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:__free_event+0x50f/0x620 kernel/events/core.c:5572
Code: ff 48 c7 c7 a0 0c df 8e e8 6e a5 a6 ff 43 0f b6 44 25 00 84 c0 0f 85 f5 00 00 00 41 80 26 ef e9 ea fc ff ff e8 d2 46 cb ff 90 <0f> 0b 90 42 80 3c 3b 00 0f 85 2d fe ff ff e9 30 fe ff ff e8 b9 46
RSP: 0018:ffffc9000461f858 EFLAGS: 00010293
RAX: ffffffff81f8104e RBX: 1ffff110089a873c RCX: ffff88802f5dda00
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000001
RBP: 0000000000000003 R08: ffffffff81f80e1b R09: 1ffff1100fc94b45
R10: dffffc0000000000 R11: ffffed100fc94b46 R12: ffff888044d439d8
R13: ffff888044d439e0 R14: 1ffff110089a873b R15: dffffc0000000000
FS:  00007f1a7f6516c0(0000) GS:ffff888125099000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1a7f743320 CR3: 000000003461c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 inherit_event+0x190/0x9d0 kernel/events/core.c:14036
 inherit_group kernel/events/core.c:14110 [inline]
 inherit_task_group+0x18d/0x4f0 kernel/events/core.c:14177
 perf_event_init_context kernel/events/core.c:14226 [inline]
 perf_event_init_task+0x244/0x650 kernel/events/core.c:14295
 copy_process+0x151e/0x3d10 kernel/fork.c:2403
 kernel_clone+0x242/0x930 kernel/fork.c:2844
 __do_sys_clone kernel/fork.c:2987 [inline]
 __se_sys_clone kernel/fork.c:2971 [inline]
 __x64_sys_clone+0x268/0x2e0 kernel/fork.c:2971
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1a7f6b98d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1a7f651218 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f1a7f743338 RCX: 00007f1a7f6b98d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000ab009400
RBP: 00007f1a7f743330 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1a7f710a94
R13: affffff7ffffffff R14: 0000200000000180 R15: 00000000ab009400
 </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:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

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:
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Re: [syzbot] #syz test

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Subject: #syz test
Author: gshahrouzi@gmail.com

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0bb21659e252..153ba622cfa0 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -14016,6 +14016,9 @@ inherit_event(struct perf_event *parent_event,
        if (IS_ERR(child_event))
                return child_event;

+       get_ctx(child_ctx);
+       child_event->ctx = child_ctx;
+
        pmu_ctx = find_get_pmu_context(child_event->pmu, child_ctx,
child_event);
        if (IS_ERR(pmu_ctx)) {
                free_event(child_event);
@@ -14037,8 +14040,6 @@ inherit_event(struct perf_event *parent_event,
                return NULL;
        }

-       get_ctx(child_ctx);
-
        /*
         * Make the child state follow the state of the parent event,
         * not its attr.disabled bit.  We hold the parent's mutex,
@@ -14059,7 +14060,6 @@ inherit_event(struct perf_event *parent_event,
                local64_set(&hwc->period_left, sample_period);
        }

-       child_event->ctx = child_ctx;
        child_event->overflow_handler = parent_event->overflow_handler;
        child_event->overflow_handler_context
                = parent_event->overflow_handler_context;
-- 
2.43.0

Re: [syzbot] #syz test

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Subject: #syz test
Author: gshahrouzi@gmail.com

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0bb21659e252..153ba622cfa0 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -14016,6 +14016,9 @@ inherit_event(struct perf_event *parent_event,
 	if (IS_ERR(child_event))
 		return child_event;
 
+	get_ctx(child_ctx);
+	child_event->ctx = child_ctx;
+
 	pmu_ctx = find_get_pmu_context(child_event->pmu, child_ctx, child_event);
 	if (IS_ERR(pmu_ctx)) {
 		free_event(child_event);
@@ -14037,8 +14040,6 @@ inherit_event(struct perf_event *parent_event,
 		return NULL;
 	}
 
-	get_ctx(child_ctx);
-
 	/*
 	 * Make the child state follow the state of the parent event,
 	 * not its attr.disabled bit.  We hold the parent's mutex,
@@ -14059,7 +14060,6 @@ inherit_event(struct perf_event *parent_event,
 		local64_set(&hwc->period_left, sample_period);
 	}
 
-	child_event->ctx = child_ctx;
 	child_event->overflow_handler = parent_event->overflow_handler;
 	child_event->overflow_handler_context
 		= parent_event->overflow_handler_context;
-- 
2.43.0