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Wed, 14 Jan 2026 00:03:09 -0800 (PST) Date: Wed, 14 Jan 2026 00:03:09 -0800 In-Reply-To: <202601141124178748cM66DJW2fzNea7Uym1mG@zte.com.cn> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69674dbd.050a0220.ac870.0007.GAE@google.com> Subject: [syzbot ci] Re: mm/madvise: prefer VMA lock for MADV_REMOVE From: syzbot ci To: akpm@linux-foundation.org, david@kernel.org, fan.yu9@zte.com.cn, he.peilin@zte.com.cn, jannh@google.com, jiang.kun2@zte.com.cn, liam.howlett@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, lu.zhongjun@zte.com.cn, qiu.yutan@zte.com.cn, tu.qiang35@zte.com.cn, vbabka@suse.cz, wang.yaxin@zte.com.cn, xu.xin16@zte.com.cn, yang.yang29@zte.com.cn Cc: syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot ci has tested the following series [v1] mm/madvise: prefer VMA lock for MADV_REMOVE https://lore.kernel.org/all/202601141124178748cM66DJW2fzNea7Uym1mG@zte.com.cn * [PATCH linux-next] mm/madvise: prefer VMA lock for MADV_REMOVE and found the following issue: possible deadlock in blkdev_fallocate Full report is available here: https://ci.syzbot.org/series/30acb9df-ca55-4cbf-81ed-89b84da8edc1 *** possible deadlock in blkdev_fallocate tree: linux-next URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next base: 4c81c9dc03a068745eeb56984ea9836d86fa3eb2 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/eaa5a44b-5d87-4428-b098-72b46efdb983/config C repro: https://ci.syzbot.org/findings/e3240f02-6d2c-4c6d-bc6e-e7f4be22e433/c_repro syz repro: https://ci.syzbot.org/findings/e3240f02-6d2c-4c6d-bc6e-e7f4be22e433/syz_repro ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.17/5976 is trying to acquire lock: ffff888167a287a8 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline] ffff888167a287a8 (&sb->s_type->i_mutex_key#10){++++}-{4:4}, at: blkdev_fallocate+0x260/0x530 block/fops.c:908 but task is already holding lock: ffff8881043c3b88 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1d1/0x500 mm/mmap_lock.c:259 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (vm_lock){++++}-{0:0}: __vma_enter_locked+0x243/0x710 mm/mmap_lock.c:72 __vma_start_write+0x23/0x140 mm/mmap_lock.c:104 vma_start_write include/linux/mmap_lock.h:213 [inline] mprotect_fixup+0x5e1/0xa50 mm/mprotect.c:768 setup_arg_pages+0x565/0xae0 fs/exec.c:670 load_elf_binary+0xc5e/0x2980 fs/binfmt_elf.c:1028 search_binary_handler fs/exec.c:1669 [inline] exec_binprm fs/exec.c:1701 [inline] bprm_execve+0x93d/0x1410 fs/exec.c:1753 kernel_execve+0x8ef/0x9e0 fs/exec.c:1919 try_to_run_init_process+0x13/0x60 init/main.c:1506 kernel_init+0xad/0x1d0 init/main.c:1634 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 -> #1 (&mm->mmap_lock){++++}-{4:4}: __might_fault+0xcb/0x130 mm/memory.c:7174 _copy_to_iter+0xf9/0x17d0 lib/iov_iter.c:196 copy_page_to_iter+0x10c/0x1c0 lib/iov_iter.c:374 copy_folio_to_iter include/linux/uio.h:204 [inline] filemap_read+0x811/0x1230 mm/filemap.c:2851 blkdev_read_iter+0x30a/0x440 block/fops.c:856 new_sync_read fs/read_write.c:491 [inline] vfs_read+0x582/0xa70 fs/read_write.c:572 ksys_read+0x150/0x270 fs/read_write.c:715 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&sb->s_type->i_mutex_key#10){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868 down_write+0x96/0x200 kernel/locking/rwsem.c:1590 inode_lock include/linux/fs.h:1027 [inline] blkdev_fallocate+0x260/0x530 block/fops.c:908 vfs_fallocate+0x669/0x7e0 fs/open.c:339 madvise_remove mm/madvise.c:1055 [inline] madvise_vma_behavior+0x120d/0x4460 mm/madvise.c:1379 madvise_walk_vmas+0x90e/0xaf0 mm/madvise.c:1706 madvise_do_behavior+0x386/0x540 mm/madvise.c:1956 do_madvise+0x1fa/0x2e0 mm/madvise.c:2049 __do_sys_madvise mm/madvise.c:2058 [inline] __se_sys_madvise mm/madvise.c:2056 [inline] __x64_sys_madvise+0xa6/0xc0 mm/madvise.c:2056 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &sb->s_type->i_mutex_key#10 --> &mm->mmap_lock --> vm_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(vm_lock); lock(&mm->mmap_lock); lock(vm_lock); lock(&sb->s_type->i_mutex_key#10); *** DEADLOCK *** 1 lock held by syz.0.17/5976: #0: ffff8881043c3b88 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1d1/0x500 mm/mmap_lock.c:259 stack backtrace: CPU: 1 UID: 0 PID: 5976 Comm: syz.0.17 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 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868 down_write+0x96/0x200 kernel/locking/rwsem.c:1590 inode_lock include/linux/fs.h:1027 [inline] blkdev_fallocate+0x260/0x530 block/fops.c:908 vfs_fallocate+0x669/0x7e0 fs/open.c:339 madvise_remove mm/madvise.c:1055 [inline] madvise_vma_behavior+0x120d/0x4460 mm/madvise.c:1379 madvise_walk_vmas+0x90e/0xaf0 mm/madvise.c:1706 madvise_do_behavior+0x386/0x540 mm/madvise.c:1956 do_madvise+0x1fa/0x2e0 mm/madvise.c:2049 __do_sys_madvise mm/madvise.c:2058 [inline] __se_sys_madvise mm/madvise.c:2056 [inline] __x64_sys_madvise+0xa6/0xc0 mm/madvise.c:2056 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5ceb59acb9 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:00007ffd12a05518 EFLAGS: 00000246 ORIG_RAX: 000000000000001c RAX: ffffffffffffffda RBX: 00007f5ceb815fa0 RCX: 00007f5ceb59acb9 RDX: 0000000000000009 RSI: 0000000000004000 RDI: 0000200000119000 RBP: 00007f5ceb608bf7 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5ceb815fac R14: 00007f5ceb815fa0 R15: 00007f5ceb815fa0 *** 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: syzbot@syzkaller.appspotmail.com --- This report is generated by a bot. It may contain errors. syzbot ci engineers can be reached at syzkaller@googlegroups.com.