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WARNING in unlink_anon_vmas (2)

Status: upstream: reported C repro on 2026/01/18 07:30
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+c27fa543e10a45d4e149@syzkaller.appspotmail.com
First crash: 56d, last: 2h35m
Cause bisection: failed (error log, bisect log)
  
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH] mm/rmap: fix unlink_anon_vmas() handling of error case from anon_vma_fork 5 (5) 2026/01/18 12:31
[syzbot] [mm?] WARNING in unlink_anon_vmas (2) 1 (4) 2026/01/18 12:16
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in unlink_anon_vmas mm -1 1 2757d 2757d 0/29 closed as invalid on 2018/09/05 12:51
▶ ▼ Last patch testing requests (5)
Created Duration User Patch Repo Result
2026/02/09 20:02 26m retest repro linux-next OK log
2026/02/09 20:02 27m retest repro linux-next OK log
2026/02/09 20:02 34m retest repro linux-next OK log
2026/01/18 09:23 58m kartikey406@gmail.com patch linux-next OK log
2026/01/18 09:01 18m kartikey406@gmail.com patch linux-next error

Sample crash report:
RBP: 00007ffcf6019d10 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007efcdca15fac R14: 00007efcdca15fa0 R15: 00007efcdca15fa0
 </TASK>
------------[ cut here ]------------
anon_vma->num_active_vmas
WARNING: mm/rmap.c:528 at unlink_anon_vmas+0x6c5/0x730 mm/rmap.c:528, CPU#0: syz.0.17/6024
Modules linked in:
CPU: 0 UID: 0 PID: 6024 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:unlink_anon_vmas+0x6c5/0x730 mm/rmap.c:528
Code: 08 00 48 3b 6c 24 18 74 29 e8 07 44 aa ff 49 89 ee e9 cf fd ff ff e8 fa 43 aa ff 90 0f 0b 90 e9 4d fe ff ff e8 ec 43 aa ff 90 <0f> 0b 90 e9 81 fe ff ff e8 de 43 aa ff eb 05 e8 d7 43 aa ff 48 83
RSP: 0018:ffffc90003527888 EFLAGS: 00010293
RAX: ffffffff821b5e74 RBX: ffff88807c272110 RCX: ffff88802b2f0000
RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000000
RBP: ffff888030e51170 R08: ffff88807c27211f R09: 1ffff1100f84e423
R10: dffffc0000000000 R11: ffffed100f84e424 R12: ffffffffffffffff
R13: 1ffff11006b31f98 R14: ffff88803598fcc0 R15: ffff88807c272110
FS:  0000000000000000(0000) GS:ffff888125460000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa1d3728e9c CR3: 000000000e54c000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 free_pgtables+0x836/0xb70 mm/memory.c:427
 exit_mmap+0x490/0xa10 mm/mmap.c:1314
 __mmput+0x118/0x430 kernel/fork.c:1174
 exit_mm+0x168/0x220 kernel/exit.c:581
 do_exit+0x62e/0x2320 kernel/exit.c:959
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
 __do_sys_exit_group kernel/exit.c:1123 [inline]
 __se_sys_exit_group kernel/exit.c:1121 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1121
 x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efcdc79bf79
Code: Unable to access opcode bytes at 0x7efcdc79bf4f.
RSP: 002b:00007ffcf6019f48 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007efcdc79bf79
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 0000000000000000 R09: 00007efcdc9e4280
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efcdc9e4280 R14: 0000000000000003 R15: 00007ffcf601a000
 </TASK>

Crashes (21):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/14 07:32 linux-next 635c467cc14e 1e62d198 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in unlink_anon_vmas
2026/03/11 11:55 upstream b4f0dd314b39 86914af9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in unlink_anon_vmas
2026/03/11 11:45 upstream b4f0dd314b39 86914af9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in unlink_anon_vmas
2026/03/09 11:39 upstream 014441d1e4b2 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in unlink_anon_vmas
2026/03/09 11:38 upstream 014441d1e4b2 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in unlink_anon_vmas
2026/03/09 06:42 upstream 014441d1e4b2 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in unlink_anon_vmas
2026/03/02 00:17 upstream eb71ab2bf722 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in unlink_anon_vmas
2026/02/28 02:04 upstream a75cb869a8cc 2cf092b8 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in unlink_anon_vmas
2026/02/25 21:55 upstream 7dff99b35460 df2e85d4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in unlink_anon_vmas
2026/02/23 08:05 upstream aaf96df9593b 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in unlink_anon_vmas
2026/03/10 12:48 upstream 1f318b96cc84 6972f302 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in unlink_anon_vmas
2026/03/03 01:48 upstream af4e9ef3d784 28b83e23 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in unlink_anon_vmas
2026/03/02 17:26 upstream 11439c4635ed b9dd6534 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in unlink_anon_vmas
2026/03/04 13:58 linux-next c025f6cf4209 e6b6b96b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in unlink_anon_vmas
2026/02/14 07:07 linux-next 635c467cc14e 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in unlink_anon_vmas
2026/01/26 19:57 linux-next ca3a02fda4da a4c52dd6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in unlink_anon_vmas
2026/01/17 11:05 linux-next 46fe65a2c28e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in unlink_anon_vmas
2026/01/14 09:09 linux-next b775e489bec7 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in unlink_anon_vmas
2026/01/14 08:38 linux-next b775e489bec7 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in unlink_anon_vmas
2026/01/14 08:05 linux-next b775e489bec7 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in unlink_anon_vmas
2026/01/14 07:26 linux-next b775e489bec7 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in unlink_anon_vmas
* Struck through repros no longer work on HEAD.