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AJvYcCUd47NHJI3dHM56ucbI+hywYYly4uO5CHsVYfY5dg0sUXhB5n3ORKafGMDqVUi686Mb9l5NhA5tKAYZn1o=@vger.kernel.org X-Gm-Message-State: AOJu0Yy6nvYIvfaA9w7msx1b40bfDeu8j5zJptcTLoVcHqRZ1s4M6Dat YisOMWyiRCZltwQCS2CsmV5lNue4yxBrqd78Xb1Lo2d4NxwrvFwq8U02sSH3zRn6SF/rQaoiDLQ uZurU8twflsixUNKT5WcsRm08yRvGGBU8pz6B4QfvkS2vKae9Ef3DuuKCQ2o= X-Google-Smtp-Source: AGHT+IFT43QlM8pcln8U+Eww+O0zzAExm6XXgPQBWfT6KRG7VIkvfXjO0jztElePth8ZM3wp+BZTjgkncLB2kVRNvkTts8Hag2iy Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a92:cccd:0:b0:433:7310:f5bf with SMTP id e9e14a558f8ab-4337310f94amr69754165ab.22.1762787957532; Mon, 10 Nov 2025 07:19:17 -0800 (PST) Date: Mon, 10 Nov 2025 07:19:17 -0800 In-Reply-To: <20251110111553.88384-1-lance.yang@linux.dev> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69120275.a70a0220.22f260.00f7.GAE@google.com> Subject: [syzbot ci] Re: mm/hugetlb: fix possible deadlocks in hugetlb VMA unmap paths From: syzbot ci To: akpm@linux-foundation.org, david@redhat.com, lance.yang@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, muchun.song@linux.dev, osalvador@suse.de, syzbot@lists.linux.dev, syzbot@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com Cc: syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot ci has tested the following series [v2] mm/hugetlb: fix possible deadlocks in hugetlb VMA unmap paths https://lore.kernel.org/all/20251110111553.88384-1-lance.yang@linux.dev * [PATCH v2 1/1] mm/hugetlb: fix possible deadlocks in hugetlb VMA unmap paths and found the following issue: possible deadlock in unmap_vmas Full report is available here: https://ci.syzbot.org/series/3106300b-af9f-40dc-985b-33cb937712aa *** possible deadlock in unmap_vmas tree: mm-new URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/akpm/mm.git base: 02dafa01ec9a00c3758c1c6478d82fe601f5f1ba arch: amd64 compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 config: https://ci.syzbot.org/builds/089d8dad-bc85-4724-8a79-2ad934becf17/config C repro: https://ci.syzbot.org/findings/3dded3f6-aef2-4f4c-9dba-b23214df5e12/c_repro syz repro: https://ci.syzbot.org/findings/3dded3f6-aef2-4f4c-9dba-b23214df5e12/syz_repro ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.17/5963 is trying to acquire lock: ffff88816cbda8e8 (&resv_map->rw_sema){+.+.}-{4:4}, at: hugetlb_zap_begin include/linux/hugetlb.h:257 [inline] ffff88816cbda8e8 (&resv_map->rw_sema){+.+.}-{4:4}, at: unmap_vmas+0x23d/0x580 mm/memory.c:2098 but task is already holding lock: ffff888172c80418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: i_mmap_lock_write include/linux/fs.h:548 [inline] ffff888172c80418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: __hugetlb_zap_begin+0x2aa/0x3a0 mm/hugetlb.c:5331 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590 i_mmap_lock_write include/linux/fs.h:548 [inline] hugetlb_change_protection+0x56a/0x18c0 mm/hugetlb.c:6439 change_protection+0x386/0x38c0 mm/mprotect.c:655 mprotect_fixup+0x6fe/0x9c0 mm/mprotect.c:774 do_mprotect_pkey+0x8c5/0xcd0 mm/mprotect.c:930 __do_sys_mprotect mm/mprotect.c:951 [inline] __se_sys_mprotect mm/mprotect.c:948 [inline] __x64_sys_mprotect+0x80/0x90 mm/mprotect.c:948 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&resv_map->rw_sema){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590 hugetlb_zap_begin include/linux/hugetlb.h:257 [inline] unmap_vmas+0x23d/0x580 mm/memory.c:2098 exit_mmap+0x23e/0xb30 mm/mmap.c:1277 __mmput+0x118/0x430 kernel/fork.c:1133 exit_mm+0x1da/0x2c0 kernel/exit.c:582 do_exit+0x648/0x2300 kernel/exit.c:954 do_group_exit+0x21c/0x2d0 kernel/exit.c:1107 __do_sys_exit_group kernel/exit.c:1118 [inline] __se_sys_exit_group kernel/exit.c:1116 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1116 x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&hugetlbfs_i_mmap_rwsem_key); lock(&resv_map->rw_sema); lock(&hugetlbfs_i_mmap_rwsem_key); lock(&resv_map->rw_sema); *** DEADLOCK *** 2 locks held by syz.0.17/5963: #0: ffff88810e0f8ca0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:365 [inline] #0: ffff88810e0f8ca0 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x126/0xb30 mm/mmap.c:1262 #1: ffff888172c80418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: i_mmap_lock_write include/linux/fs.h:548 [inline] #1: ffff888172c80418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: __hugetlb_zap_begin+0x2aa/0x3a0 mm/hugetlb.c:5331 stack backtrace: CPU: 1 UID: 0 PID: 5963 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+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043 check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590 hugetlb_zap_begin include/linux/hugetlb.h:257 [inline] unmap_vmas+0x23d/0x580 mm/memory.c:2098 exit_mmap+0x23e/0xb30 mm/mmap.c:1277 __mmput+0x118/0x430 kernel/fork.c:1133 exit_mm+0x1da/0x2c0 kernel/exit.c:582 do_exit+0x648/0x2300 kernel/exit.c:954 do_group_exit+0x21c/0x2d0 kernel/exit.c:1107 __do_sys_exit_group kernel/exit.c:1118 [inline] __se_sys_exit_group kernel/exit.c:1116 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1116 x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6bb058efc9 Code: Unable to access opcode bytes at 0x7f6bb058ef9f. RSP: 002b:00007ffedbb6b2f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6bb058efc9 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000003 R08: 00000002dbb6b3ef R09: 00007f6bb07b1280 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6bb07b1280 R14: 0000000000000003 R15: 00007ffedbb6b3b0 *** 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.