[syzbot] [mm?] [squashfs?] WARNING in vma_merge_existing_range (2)

[syzbot] [mm?] [squashfs?] WARNING in vma_merge_existing_range (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    d7fa1af5b33e Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=107b19d4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=89c13de706fbf07a
dashboard link: https://syzkaller.appspot.com/bug?extid=b9b432686bcbcac1ca01
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1424b60c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=147b19d4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/da97ad659b2c/disk-d7fa1af5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/659e123552a8/vmlinux-d7fa1af5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6ec5dbf4643e/Image-d7fa1af5.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/3df2a90115c7/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b9b432686bcbcac1ca01@syzkaller.appspotmail.com

    ffff93069000-ffffd1a12fff: 0000000000000000
    ffffd1a13000-ffffd1a33fff: ffff0000ca00b640
    ffffd1a34000-ffffffffffffffff: 0000000000000000
------------[ cut here ]------------
WARNING: CPU: 0 PID: 6489 at mm/vma.c:768 vma_merge_existing_range+0x14a8/0x1964 mm/vma.c:768
Modules linked in:
CPU: 0 UID: 0 PID: 6489 Comm: syz-executor371 Not tainted 6.15.0-rc7-syzkaller-gd7fa1af5b33e #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : vma_merge_existing_range+0x14a8/0x1964 mm/vma.c:768
lr : vma_merge_existing_range+0x14a8/0x1964 mm/vma.c:768
sp : ffff8000a0d67910
x29: ffff8000a0d67990 x28: dfff800000000000 x27: 0000000000000001
x26: 0000000020000000 x25: ffff8000a0d67a80 x24: 0000000020000000
x23: 1ffff000141acf50 x22: ffff0000c712ca00 x21: 0000000020800000
x20: ffff0000c712ca00 x19: ffff8000a0d67a60 x18: 00000000ffffffff
x17: 0000000000000000 x16: ffff80008adbe9e4 x15: 0000000000000001
x14: 1fffe0003386aae2 x13: 0000000000000000 x12: 0000000000000000
x11: ffff60003386aae3 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : ffff0000ca6a9e80 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000a0d66ef8 x4 : ffff80008f415ba0 x3 : ffff8000807b4b68
x2 : 0000000000000001 x1 : ffffffffffffffff x0 : ffffffffffffffff
Call trace:
 vma_merge_existing_range+0x14a8/0x1964 mm/vma.c:768 (P)
 vma_modify+0x7c/0x424 mm/vma.c:1564
 vma_modify_flags+0x18c/0x1dc mm/vma.c:1605
 mlock_fixup+0x18c/0x2c4 mm/mlock.c:483
 apply_mlockall_flags+0x290/0x344 mm/mlock.c:736
 __arm64_sys_munlockall+0x11c/0x238 mm/mlock.c:782
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767
 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
irq event stamp: 15466
hardirqs last  enabled at (15465): [<ffff80008055041c>] __up_console_sem kernel/printk/printk.c:344 [inline]
hardirqs last  enabled at (15465): [<ffff80008055041c>] __console_unlock+0x70/0xc4 kernel/printk/printk.c:2885
hardirqs last disabled at (15466): [<ffff80008adb9eb8>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:511
softirqs last  enabled at (14694): [<ffff8000803cf71c>] softirq_handle_end kernel/softirq.c:425 [inline]
softirqs last  enabled at (14694): [<ffff8000803cf71c>] handle_softirqs+0xaf8/0xc88 kernel/softirq.c:607
softirqs last disabled at (14683): [<ffff800080020efc>] __do_softirq+0x14/0x20 kernel/softirq.c:613
---[ end trace 0000000000000000 ]---


---
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:
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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] [mm?] [squashfs?] WARNING in vma_merge_existing_range (2)

[Lorenzo Stoakes]

#syz dup: [syzbot] [mm?] WARNING in vma_modify

Hi this is a duplicate of
https://lore.kernel.org/linux-mm/6842cc67.a00a0220.29ac89.003b.GAE@google.com/

See the analysis for this at
https://lore.kernel.org/linux-mm/e6e71e0b-347b-4edb-b558-b502f55a637d@lucifer.local/

This is addressed in commit 0cf4b1687a18 ("mm/vma: reset VMA iterator on
commit_merge() OOM failure") which was merged to mainline yesterday.

The repro reliably reproduces without this patch, and with it does not trigger.

The issue is not one that is likely (if _ever_) going to happen in practice as
it relies upon a 'too small to fail' allocation failure and can only be achieved
through fault injection.

Thanks, Lorenzo

On Sat, Jun 14, 2025 at 10:13:28PM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    d7fa1af5b33e Merge branch 'for-next/core' into for-kernelci
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=107b19d4580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=89c13de706fbf07a
> dashboard link: https://syzkaller.appspot.com/bug?extid=b9b432686bcbcac1ca01
> compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
> userspace arch: arm64
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1424b60c580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=147b19d4580000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/da97ad659b2c/disk-d7fa1af5.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/659e123552a8/vmlinux-d7fa1af5.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/6ec5dbf4643e/Image-d7fa1af5.gz.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/3df2a90115c7/mount_0.gz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b9b432686bcbcac1ca01@syzkaller.appspotmail.com
>
>     ffff93069000-ffffd1a12fff: 0000000000000000
>     ffffd1a13000-ffffd1a33fff: ffff0000ca00b640
>     ffffd1a34000-ffffffffffffffff: 0000000000000000
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 6489 at mm/vma.c:768 vma_merge_existing_range+0x14a8/0x1964 mm/vma.c:768
> Modules linked in:
> CPU: 0 UID: 0 PID: 6489 Comm: syz-executor371 Not tainted 6.15.0-rc7-syzkaller-gd7fa1af5b33e #0 PREEMPT
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
> pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : vma_merge_existing_range+0x14a8/0x1964 mm/vma.c:768
> lr : vma_merge_existing_range+0x14a8/0x1964 mm/vma.c:768
> sp : ffff8000a0d67910
> x29: ffff8000a0d67990 x28: dfff800000000000 x27: 0000000000000001
> x26: 0000000020000000 x25: ffff8000a0d67a80 x24: 0000000020000000
> x23: 1ffff000141acf50 x22: ffff0000c712ca00 x21: 0000000020800000
> x20: ffff0000c712ca00 x19: ffff8000a0d67a60 x18: 00000000ffffffff
> x17: 0000000000000000 x16: ffff80008adbe9e4 x15: 0000000000000001
> x14: 1fffe0003386aae2 x13: 0000000000000000 x12: 0000000000000000
> x11: ffff60003386aae3 x10: 0000000000ff0100 x9 : 0000000000000000
> x8 : ffff0000ca6a9e80 x7 : 0000000000000001 x6 : 0000000000000001
> x5 : ffff8000a0d66ef8 x4 : ffff80008f415ba0 x3 : ffff8000807b4b68
> x2 : 0000000000000001 x1 : ffffffffffffffff x0 : ffffffffffffffff
> Call trace:
>  vma_merge_existing_range+0x14a8/0x1964 mm/vma.c:768 (P)
>  vma_modify+0x7c/0x424 mm/vma.c:1564
>  vma_modify_flags+0x18c/0x1dc mm/vma.c:1605
>  mlock_fixup+0x18c/0x2c4 mm/mlock.c:483
>  apply_mlockall_flags+0x290/0x344 mm/mlock.c:736
>  __arm64_sys_munlockall+0x11c/0x238 mm/mlock.c:782
>  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>  invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
>  el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
>  do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
>  el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767
>  el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
>  el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
> irq event stamp: 15466
> hardirqs last  enabled at (15465): [<ffff80008055041c>] __up_console_sem kernel/printk/printk.c:344 [inline]
> hardirqs last  enabled at (15465): [<ffff80008055041c>] __console_unlock+0x70/0xc4 kernel/printk/printk.c:2885
> hardirqs last disabled at (15466): [<ffff80008adb9eb8>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:511
> softirqs last  enabled at (14694): [<ffff8000803cf71c>] softirq_handle_end kernel/softirq.c:425 [inline]
> softirqs last  enabled at (14694): [<ffff8000803cf71c>] handle_softirqs+0xaf8/0xc88 kernel/softirq.c:607
> softirqs last disabled at (14683): [<ffff800080020efc>] __do_softirq+0x14/0x20 kernel/softirq.c:613
> ---[ end trace 0000000000000000 ]---
>
>
> ---
> 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