Re: [moderation/CI] Re: mm: Unconditional per-VMA locks and cleanups

#syz upstream

On Thu, Jun 11, 2026 at 7:28 PM syzbot ci
<[email protected]> wrote:
>
> syzbot ci has tested the following series
>
> [v2] mm: Unconditional per-VMA locks and cleanups
> https://lore.kernel.org/all/[email protected]
> * [PATCH v2 1/5] mm: Make per-VMA locks available universally
> * [PATCH v2 2/5] binder: Make shrinker rely solely on per-VMA lock
> * [PATCH v2 3/5] mm: Add RCU-based VMA lookup helper that waits for writers
> * [PATCH v2 4/5] binder: Remove mmap_lock fallback
> * [PATCH v2 5/5] tcp: Remove mmap_lock fallback path
>
> and found the following issue:
> general protection fault in tcp_zerocopy_receive
>
> Full report is available here:
> https://ci.syzbot.org/series/3e6d125a-b2ae-49a4-b833-babfb8bc9150
>
> ***
>
> general protection fault in tcp_zerocopy_receive
>
> tree:      net-next
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net-next.git
> base:      c8459ee2fef502d6ef6c063751c33d9ac7943eab
> arch:      amd64
> compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:    https://ci.syzbot.org/builds/e7d66981-7900-4c3d-b992-664ccd13a57e/config
> syz repro: https://ci.syzbot.org/findings/59d09544-f280-48fe-8ca9-a2fd8225e9df/syz_repro
>
> Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN PTI
> KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
> CPU: 0 UID: 0 PID: 5876 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> RIP: 0010:vma_start_read_locked_nested include/linux/mmap_lock.h:240 [inline]
> RIP: 0010:vma_start_read_locked+0xa0/0x300 include/linux/mmap_lock.h:257
> Code: 28 84 c0 0f 85 2b 02 00 00 44 8b 35 ba 0d 1b 0e 31 ff 44 89 f6 e8 c0 e2 af ff 45 85 f6 74 48 4c 8d 73 10 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 b1 37 1b 00 bf 38 03 00 00 49 03
> RSP: 0018:ffffc9000399f4a0 EFLAGS: 00010202
> RAX: 0000000000000002 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: ffff88816d558000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: ffffc9000399f538 R08: ffff8881076c64df R09: 1ffff11020ed8c9b
> R10: dffffc0000000000 R11: ffffed1020ed8c9c R12: 1ffff92000733e94
> R13: dffffc0000000000 R14: 0000000000000010 R15: 0000000000011000
> FS:  00007f4866b966c0(0000) GS:ffff88818dc86000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000200000011000 CR3: 0000000117c8a000 CR4: 00000000000006f0
> Call Trace:
>  <TASK>
>  vma_start_read_unlocked+0x3f/0x70 mm/mmap_lock.c:362
>  find_tcp_vma net/ipv4/tcp.c:2173 [inline]
>  tcp_zerocopy_receive+0x762/0x2200 net/ipv4/tcp.c:2227
>  do_tcp_getsockopt+0x2079/0x2940 net/ipv4/tcp.c:4758
>  tcp_getsockopt+0x83/0x130 net/ipv4/tcp.c:4856
>  do_sock_getsockopt+0x51d/0x7e0 net/socket.c:2487
>  __sys_getsockopt net/socket.c:2518 [inline]
>  __do_sys_getsockopt net/socket.c:2525 [inline]
>  __se_sys_getsockopt net/socket.c:2522 [inline]
>  __x64_sys_getsockopt+0x1a4/0x240 net/socket.c:2522
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f4865d9ce59
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f4866b96028 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> RAX: ffffffffffffffda RBX: 00007f4866015fa0 RCX: 00007f4865d9ce59
> RDX: 0000000000000023 RSI: 0000000000000006 RDI: 0000000000000003
> RBP: 00007f4865e32d6f R08: 0000200000000380 R09: 0000000000000000
> R10: 0000200000000340 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f4866016038 R14: 00007f4866015fa0 R15: 00007ffc748de268
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:vma_start_read_locked_nested include/linux/mmap_lock.h:240 [inline]
> RIP: 0010:vma_start_read_locked+0xa0/0x300 include/linux/mmap_lock.h:257
> Code: 28 84 c0 0f 85 2b 02 00 00 44 8b 35 ba 0d 1b 0e 31 ff 44 89 f6 e8 c0 e2 af ff 45 85 f6 74 48 4c 8d 73 10 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 b1 37 1b 00 bf 38 03 00 00 49 03
> RSP: 0018:ffffc9000399f4a0 EFLAGS: 00010202
> RAX: 0000000000000002 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: ffff88816d558000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: ffffc9000399f538 R08: ffff8881076c64df R09: 1ffff11020ed8c9b
> R10: dffffc0000000000 R11: ffffed1020ed8c9c R12: 1ffff92000733e94
> R13: dffffc0000000000 R14: 0000000000000010 R15: 0000000000011000
> FS:  00007f4866b966c0(0000) GS:ffff88818dc86000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f4865dea540 CR3: 0000000117c8a000 CR4: 00000000000006f0
> ----------------
> Code disassembly (best guess):
>    0:   28 84 c0 0f 85 2b 02    sub    %al,0x22b850f(%rax,%rax,8)
>    7:   00 00                   add    %al,(%rax)
>    9:   44 8b 35 ba 0d 1b 0e    mov    0xe1b0dba(%rip),%r14d        # 0xe1b0dca
>   10:   31 ff                   xor    %edi,%edi
>   12:   44 89 f6                mov    %r14d,%esi
>   15:   e8 c0 e2 af ff          call   0xffafe2da
>   1a:   45 85 f6                test   %r14d,%r14d
>   1d:   74 48                   je     0x67
>   1f:   4c 8d 73 10             lea    0x10(%rbx),%r14
>   23:   4c 89 f0                mov    %r14,%rax
>   26:   48 c1 e8 03             shr    $0x3,%rax
> * 2a:   42 80 3c 28 00          cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
>   2f:   74 08                   je     0x39
>   31:   4c 89 f7                mov    %r14,%rdi
>   34:   e8 b1 37 1b 00          call   0x1b37ea
>   39:   bf 38 03 00 00          mov    $0x338,%edi
>   3e:   49                      rex.WB
>   3f:   03                      .byte 0x3
>
>
> ***
>
> If these findings have caused you to resend the series or submit a
> separate fix, please add the following tag to your commit message:
>   Tested-by: [email protected]
>
> ---
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