[syzbot] [fs?] [mm?] WARNING in sched_mm_cid_fork

[syzbot] [fs?] [mm?] WARNING in sched_mm_cid_fork

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    7d31f578f323 Add linux-next specific files for 20251128
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=165b14b4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6336d8e94a7c517d
dashboard link: https://syzkaller.appspot.com/bug?extid=9ca2c6e6b098bf5ae60a
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=104a30c2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6b49d8ad90de/disk-7d31f578.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dbe2d4988ca7/vmlinux-7d31f578.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fc0448ab2411/bzImage-7d31f578.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9ca2c6e6b098bf5ae60a@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: kernel/sched/core.c:10573 at sched_mm_cid_fork+0x66/0xc30 kernel/sched/core.c:10573, CPU#0: kworker/u8:4/6077
Modules linked in:
CPU: 0 UID: 0 PID: 6077 Comm: kworker/u8:4 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:sched_mm_cid_fork+0x66/0xc30 kernel/sched/core.c:10573
Code: 4c 8b 3b 4d 85 ff 74 21 49 8d 9d d4 15 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 13 0a 00 00 31 c0 3b 03 70 04 90 <0f> 0b 90 49 8d 9f 00 01 00 00 49 8d bf c0 01 00 00 48 89 7c 24 20
RSP: 0018:ffffc90003167bd8 EFLAGS: 00010246
RAX: 1ffff1100584e853 RBX: ffff88802c274298 RCX: ffff88802c273d00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88802c273d00
RBP: ffffc90003167d68 R08: ffffffff8e093e83 R09: 1ffffffff1c127d0
R10: dffffc0000000000 R11: fffffbfff1c127d1 R12: ffff88802c273d00
R13: ffff88802c273d00 R14: dffffc0000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125e4f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcc18973e9c CR3: 000000003470a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 bprm_execve+0xd88/0x1400 fs/exec.c:1776
 kernel_execve+0x8f0/0x9f0 fs/exec.c:1919
 call_usermodehelper_exec_async+0x210/0x360 kernel/umh.c:109
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>


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

Re: [syzbot] [fs?] [mm?] WARNING in sched_mm_cid_fork

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    d358e5254674 Merge tag 'for-6.19/dm-changes' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11c0d1c2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=de48dccdf203ea90
dashboard link: https://syzkaller.appspot.com/bug?extid=9ca2c6e6b098bf5ae60a
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=144621b4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=124621b4580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-d358e525.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3fa1d04c1a85/vmlinux-d358e525.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a9b253146e36/bzImage-d358e525.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/4a5df3575982/mount_1.gz
  fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=11119592580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9ca2c6e6b098bf5ae60a@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: kernel/sched/core.c:10569 at sched_mm_cid_fork+0x66/0xc30 kernel/sched/core.c:10569, CPU#0: kworker/u4:4/5674
Modules linked in:
CPU: 0 UID: 0 PID: 5674 Comm: kworker/u4:4 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:sched_mm_cid_fork+0x66/0xc30 kernel/sched/core.c:10569
Code: 4c 8b 3b 4d 85 ff 74 21 49 8d 9d d4 15 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 13 0a 00 00 31 c0 3b 03 70 04 90 <0f> 0b 90 49 8d 9f 00 01 00 00 49 8d bf c0 01 00 00 48 89 7c 24 20
RSP: 0000:ffffc900036cfbd8 EFLAGS: 00010246
RAX: 1ffff110067b79e3 RBX: ffff888033dbcf18 RCX: ffff888033dbc980
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888033dbc980
RBP: ffffc900036cfd68 R08: ffffffff8e295e83 R09: 1ffffffff1c52bd0
R10: dffffc0000000000 R11: fffffbfff1c52bd1 R12: ffff888033dbc980
R13: ffff888033dbc980 R14: dffffc0000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88808d22f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6ad913e000 CR3: 0000000041a50000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 bprm_execve+0xd88/0x1400 fs/exec.c:1776
 kernel_execve+0x8f0/0x9f0 fs/exec.c:1919
 call_usermodehelper_exec_async+0x210/0x360 kernel/umh.c:109
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>


---
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.

Forwarded: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail

[syzbot]

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

***

Subject: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail
Author: wangjinchao600@gmail.com

sched_mm_cid_after_execve() is called from the failure path
of bprm_execve(). At that point exec has not completed successfully,
so updating the mm CID state is incorrect and can trigger a panic,
as reported by syzbot.

Remove the call from the exec failure path.

#syz test
Reported-by: syzbot+9ca2c6e6b098bf5ae60a@syzkaller.appspotmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
---
 fs/exec.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/exec.c b/fs/exec.c
index 9d5ebc9d15b0..9044a75d26ab 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1773,7 +1773,6 @@ static int bprm_execve(struct linux_binprm *bprm)
 	if (bprm->point_of_no_return && !fatal_signal_pending(current))
 		force_fatal_sig(SIGSEGV);
 
-	sched_mm_cid_after_execve(current);
 	rseq_force_update();
 	current->in_execve = 0;
 
-- 
2.43.0

Forwarded: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail

[syzbot]

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

***

Subject: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail
Author: wangjinchao600@gmail.com

sched_mm_cid_after_execve() is called from the failure path
of bprm_execve(). At that point exec has not completed successfully,
so updating the mm CID state is incorrect and can trigger a panic,
as reported by syzbot.

Remove the call from the exec failure path.

#syz test

Cc: stable@vger.kernel.org
Reported-by: syzbot+9ca2c6e6b098bf5ae60a@syzkaller.appspotmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
---
 fs/exec.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/exec.c b/fs/exec.c
index 9d5ebc9d15b0..9044a75d26ab 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1773,7 +1773,6 @@ static int bprm_execve(struct linux_binprm *bprm)
 	if (bprm->point_of_no_return && !fatal_signal_pending(current))
 		force_fatal_sig(SIGSEGV);
 
-	sched_mm_cid_after_execve(current);
 	rseq_force_update();
 	current->in_execve = 0;
 
-- 
2.43.0

Forwarded: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail

[syzbot]

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

***

Subject: [PATCH] exec: do not call sched_mm_cid_after_execve() on exec fail
Author: wangjinchao600@gmail.com

sched_mm_cid_after_execve() is called from the failure path
of bprm_execve(). At that point exec has not completed successfully,
so updating the mm CID state is incorrect and can trigger a panic,
as reported by syzbot.

Remove the call from the exec failure path.

#syz test

Reported-by: syzbot+9ca2c6e6b098bf5ae60a@syzkaller.appspotmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
---
 fs/exec.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/exec.c b/fs/exec.c
index 9d5ebc9d15b0..9044a75d26ab 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1773,7 +1773,6 @@ static int bprm_execve(struct linux_binprm *bprm)
 	if (bprm->point_of_no_return && !fatal_signal_pending(current))
 		force_fatal_sig(SIGSEGV);
 
-	sched_mm_cid_after_execve(current);
 	rseq_force_update();
 	current->in_execve = 0;
 
-- 
2.43.0

Forwarded: call for test on upstream

[syzbot]

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

***

Subject: call for test on upstream
Author: wangjinchao600@gmail.com

#syz test

only used to check the process of this issue.