* [moderation/CI] Re: mm/hugetlb: fix possible deadlock in __hugetlb_zap_begin
@ 2025-11-10 9:03 syzbot ci
2025-11-10 9:14 ` Aleksandr Nogikh
0 siblings, 1 reply; 2+ messages in thread
From: syzbot ci @ 2025-11-10 9:03 UTC (permalink / raw)
To: syzkaller-upstream-moderation; +Cc: syzbot
syzbot ci has tested the following series
[v1] mm/hugetlb: fix possible deadlock in __hugetlb_zap_begin
https://lore.kernel.org/all/20251110051421.29436-1-lance.yang@linux.dev
* [PATCH 1/1] mm/hugetlb: fix possible deadlock in __hugetlb_zap_begin
and found the following issues:
* possible deadlock in move_hugetlb_page_tables
* possible deadlock in remove_inode_hugepages
* possible deadlock in unmap_vmas
Full report is available here:
https://ci.syzbot.org/series/4162a577-196d-48cb-908e-f31fe5f186e2
***
possible deadlock in move_hugetlb_page_tables
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/b444c811-3577-4885-8522-093253539e5d/config
C repro: https://ci.syzbot.org/findings/118b63ad-708b-4ada-abd9-4d6e18a8384f/c_repro
syz repro: https://ci.syzbot.org/findings/118b63ad-708b-4ada-abd9-4d6e18a8384f/syz_repro
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.17/5959 is trying to acquire lock:
ffff888167d5c918 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: i_mmap_lock_write include/linux/fs.h:548 [inline]
ffff888167d5c918 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: move_hugetlb_page_tables+0x5a5/0x1560 mm/hugetlb.c:5114
but task is already holding lock:
ffff8881b5f35e78 (&vma_lock->rw_sema){+.+.}-{4:4}, at: hugetlb_vma_lock_write mm/hugetlb.c:-1 [inline]
ffff8881b5f35e78 (&vma_lock->rw_sema){+.+.}-{4:4}, at: move_hugetlb_page_tables+0x589/0x1560 mm/hugetlb.c:5113
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&vma_lock->rw_sema){+.+.}-{4:4}:
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
vms_clear_ptes+0x353/0x530 mm/vma.c:1231
vms_complete_munmap_vmas+0x206/0x8a0 mm/vma.c:1280
do_vmi_align_munmap+0x364/0x440 mm/vma.c:1539
do_vmi_munmap+0x253/0x2e0 mm/vma.c:1587
shrink_vma mm/mremap.c:1340 [inline]
mremap_to+0x21e/0x790 mm/mremap.c:1394
do_mremap mm/mremap.c:1940 [inline]
__do_sys_mremap mm/mremap.c:1996 [inline]
__se_sys_mremap+0xd45/0xfb0 mm/mremap.c:1964
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 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{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
i_mmap_lock_write include/linux/fs.h:548 [inline]
move_hugetlb_page_tables+0x5a5/0x1560 mm/hugetlb.c:5114
move_page_tables+0x35c/0x1c80 mm/mremap.c:806
copy_vma_and_data mm/mremap.c:1211 [inline]
move_vma+0x942/0x1820 mm/mremap.c:1291
mremap_to+0x6ce/0x790 mm/mremap.c:1415
do_mremap mm/mremap.c:1940 [inline]
__do_sys_mremap mm/mremap.c:1996 [inline]
__se_sys_mremap+0xd45/0xfb0 mm/mremap.c:1964
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(&vma_lock->rw_sema);
lock(&hugetlbfs_i_mmap_rwsem_key);
lock(&vma_lock->rw_sema);
lock(&hugetlbfs_i_mmap_rwsem_key);
*** DEADLOCK ***
2 locks held by syz.0.17/5959:
#0: ffff888172d8d7e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:327 [inline]
#0: ffff888172d8d7e0 (&mm->mmap_lock){++++}-{4:4}, at: do_mremap mm/mremap.c:1927 [inline]
#0: ffff888172d8d7e0 (&mm->mmap_lock){++++}-{4:4}, at: __do_sys_mremap mm/mremap.c:1996 [inline]
#0: ffff888172d8d7e0 (&mm->mmap_lock){++++}-{4:4}, at: __se_sys_mremap+0x42e/0xfb0 mm/mremap.c:1964
#1: ffff8881b5f35e78 (&vma_lock->rw_sema){+.+.}-{4:4}, at: hugetlb_vma_lock_write mm/hugetlb.c:-1 [inline]
#1: ffff8881b5f35e78 (&vma_lock->rw_sema){+.+.}-{4:4}, at: move_hugetlb_page_tables+0x589/0x1560 mm/hugetlb.c:5113
stack backtrace:
CPU: 1 UID: 0 PID: 5959 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:
<TASK>
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
i_mmap_lock_write include/linux/fs.h:548 [inline]
move_hugetlb_page_tables+0x5a5/0x1560 mm/hugetlb.c:5114
move_page_tables+0x35c/0x1c80 mm/mremap.c:806
copy_vma_and_data mm/mremap.c:1211 [inline]
move_vma+0x942/0x1820 mm/mremap.c:1291
mremap_to+0x6ce/0x790 mm/mremap.c:1415
do_mremap mm/mremap.c:1940 [inline]
__do_sys_mremap mm/mremap.c:1996 [inline]
__se_sys_mremap+0xd45/0xfb0 mm/mremap.c:1964
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: 0033:0x7f043598efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe808cfc08 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
RAX: ffffffffffffffda RBX: 00007f0435be5fa0 RCX: 00007f043598efc9
RDX: 0000000000400000 RSI: 0000000000c00000 RDI: 0000200000000000
RBP: 00007f0435a11f91 R08: 0000200000c00000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0435be5fa0 R14: 00007f0435be5fa0 R15: 0000000000000005
</TASK>
***
possible deadlock in remove_inode_hugepages
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/b444c811-3577-4885-8522-093253539e5d/config
syz repro: https://ci.syzbot.org/findings/e3555fcc-3852-4e88-aea4-f3445e8a6ffb/syz_repro
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.22/5989 is trying to acquire lock:
ffff8881bc18d318 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: i_mmap_lock_write include/linux/fs.h:548 [inline]
ffff8881bc18d318 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: hugetlb_unmap_file_folio fs/hugetlbfs/inode.c:451 [inline]
ffff8881bc18d318 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: remove_inode_single_folio fs/hugetlbfs/inode.c:535 [inline]
ffff8881bc18d318 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: remove_inode_hugepages+0x972/0x1110 fs/hugetlbfs/inode.c:602
but task is already holding lock:
ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: hugetlb_unmap_file_folio fs/hugetlbfs/inode.c:450 [inline]
ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: remove_inode_single_folio fs/hugetlbfs/inode.c:535 [inline]
ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: remove_inode_hugepages+0x96a/0x1110 fs/hugetlbfs/inode.c:602
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&vma_lock->rw_sema){++++}-{4:4}:
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
get_signal+0x1285/0x1340 kernel/signal.c:3034
arch_do_signal_or_restart+0xa0/0x790 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop+0x72/0x130 kernel/entry/common.c:40
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{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
i_mmap_lock_write include/linux/fs.h:548 [inline]
hugetlb_unmap_file_folio fs/hugetlbfs/inode.c:451 [inline]
remove_inode_single_folio fs/hugetlbfs/inode.c:535 [inline]
remove_inode_hugepages+0x972/0x1110 fs/hugetlbfs/inode.c:602
hugetlbfs_punch_hole fs/hugetlbfs/inode.c:725 [inline]
hugetlbfs_fallocate+0xbc2/0x1100 fs/hugetlbfs/inode.c:751
vfs_fallocate+0x669/0x7e0 fs/open.c:342
madvise_remove mm/madvise.c:1046 [inline]
madvise_vma_behavior+0x341a/0x3d70 mm/madvise.c:1350
madvise_walk_vmas+0x51c/0xa30 mm/madvise.c:1673
madvise_do_behavior+0x38e/0x550 mm/madvise.c:1889
do_madvise+0x1bc/0x270 mm/madvise.c:1982
__do_sys_madvise mm/madvise.c:1991 [inline]
__se_sys_madvise mm/madvise.c:1989 [inline]
__x64_sys_madvise+0xa7/0xc0 mm/madvise.c:1989
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(&vma_lock->rw_sema);
lock(&hugetlbfs_i_mmap_rwsem_key);
lock(&vma_lock->rw_sema);
lock(&hugetlbfs_i_mmap_rwsem_key);
*** DEADLOCK ***
4 locks held by syz.2.22/5989:
#0: ffff8881056ac420 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3111 [inline]
#0: ffff8881056ac420 (sb_writers#12){.+.+}-{0:0}, at: vfs_fallocate+0x5f0/0x7e0 fs/open.c:341
#1: ffff8881bc18d048 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:980 [inline]
#1: ffff8881bc18d048 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: hugetlbfs_punch_hole fs/hugetlbfs/inode.c:693 [inline]
#1: ffff8881bc18d048 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: hugetlbfs_fallocate+0x3cc/0x1100 fs/hugetlbfs/inode.c:751
#2: ffff888103e8e4e8 (&hugetlb_fault_mutex_table[i]){+.+.}-{4:4}, at: remove_inode_hugepages+0x332/0x1110 fs/hugetlbfs/inode.c:597
#3: ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: hugetlb_unmap_file_folio fs/hugetlbfs/inode.c:450 [inline]
#3: ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: remove_inode_single_folio fs/hugetlbfs/inode.c:535 [inline]
#3: ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: remove_inode_hugepages+0x96a/0x1110 fs/hugetlbfs/inode.c:602
stack backtrace:
CPU: 1 UID: 0 PID: 5989 Comm: syz.2.22 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:
<TASK>
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
i_mmap_lock_write include/linux/fs.h:548 [inline]
hugetlb_unmap_file_folio fs/hugetlbfs/inode.c:451 [inline]
remove_inode_single_folio fs/hugetlbfs/inode.c:535 [inline]
remove_inode_hugepages+0x972/0x1110 fs/hugetlbfs/inode.c:602
hugetlbfs_punch_hole fs/hugetlbfs/inode.c:725 [inline]
hugetlbfs_fallocate+0xbc2/0x1100 fs/hugetlbfs/inode.c:751
vfs_fallocate+0x669/0x7e0 fs/open.c:342
madvise_remove mm/madvise.c:1046 [inline]
madvise_vma_behavior+0x341a/0x3d70 mm/madvise.c:1350
madvise_walk_vmas+0x51c/0xa30 mm/madvise.c:1673
madvise_do_behavior+0x38e/0x550 mm/madvise.c:1889
do_madvise+0x1bc/0x270 mm/madvise.c:1982
__do_sys_madvise mm/madvise.c:1991 [inline]
__se_sys_madvise mm/madvise.c:1989 [inline]
__x64_sys_madvise+0xa7/0xc0 mm/madvise.c:1989
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: 0033:0x7fca36b8efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fca37a80038 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007fca36de6090 RCX: 00007fca36b8efc9
RDX: 0000000000000009 RSI: 0000000000600000 RDI: 0000200000bc0000
RBP: 00007fca36c11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fca36de6128 R14: 00007fca36de6090 R15: 00007ffeef05aaf8
</TASK>
***
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/b444c811-3577-4885-8522-093253539e5d/config
C repro: https://ci.syzbot.org/findings/0f0a7c70-e594-4359-9971-50a723bbbd7a/c_repro
syz repro: https://ci.syzbot.org/findings/0f0a7c70-e594-4359-9971-50a723bbbd7a/syz_repro
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.17/5961 is trying to acquire lock:
ffff88810be5c178 (&vma_lock->rw_sema){+.+.}-{4:4}, at: hugetlb_zap_begin include/linux/hugetlb.h:257 [inline]
ffff88810be5c178 (&vma_lock->rw_sema){+.+.}-{4:4}, at: unmap_vmas+0x23d/0x580 mm/memory.c:2098
but task is already holding lock:
ffff88816a110418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: i_mmap_lock_write include/linux/fs.h:548 [inline]
ffff88816a110418 (&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 (&vma_lock->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(&vma_lock->rw_sema);
lock(&hugetlbfs_i_mmap_rwsem_key);
lock(&vma_lock->rw_sema);
*** DEADLOCK ***
2 locks held by syz.0.17/5961:
#0: ffff8881151362a0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:365 [inline]
#0: ffff8881151362a0 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x126/0xb30 mm/mmap.c:1262
#1: ffff88816a110418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: i_mmap_lock_write include/linux/fs.h:548 [inline]
#1: ffff88816a110418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: __hugetlb_zap_begin+0x2aa/0x3a0 mm/hugetlb.c:5331
stack backtrace:
CPU: 1 UID: 0 PID: 5961 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:
<TASK>
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: 0033:0x7f470758efc9
Code: Unable to access opcode bytes at 0x7f470758ef9f.
RSP: 002b:00007ffed0f73318 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f470758efc9
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 00000002d0f7340f R09: 00007f47077b1280
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f47077b1280 R14: 0000000000000003 R15: 00007ffed0f733d0
</TASK>
***
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.
The email will later be sent 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@syzkaller.appspotmail.com syzkaller-bugs@googlegroups.com]
If the report looks fine to you, reply with:
#syz upstream
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [moderation/CI] Re: mm/hugetlb: fix possible deadlock in __hugetlb_zap_begin
2025-11-10 9:03 [moderation/CI] Re: mm/hugetlb: fix possible deadlock in __hugetlb_zap_begin syzbot ci
@ 2025-11-10 9:14 ` Aleksandr Nogikh
0 siblings, 0 replies; 2+ messages in thread
From: Aleksandr Nogikh @ 2025-11-10 9:14 UTC (permalink / raw)
To: syzbot ci; +Cc: syzkaller-upstream-moderation, syzbot
#syz upstream
On Mon, Nov 10, 2025 at 10:03 AM syzbot ci
<syzbot+cia2636f62ae091d67@syzkaller.appspotmail.com> wrote:
>
> syzbot ci has tested the following series
>
> [v1] mm/hugetlb: fix possible deadlock in __hugetlb_zap_begin
> https://lore.kernel.org/all/20251110051421.29436-1-lance.yang@linux.dev
> * [PATCH 1/1] mm/hugetlb: fix possible deadlock in __hugetlb_zap_begin
>
> and found the following issues:
> * possible deadlock in move_hugetlb_page_tables
> * possible deadlock in remove_inode_hugepages
> * possible deadlock in unmap_vmas
>
> Full report is available here:
> https://ci.syzbot.org/series/4162a577-196d-48cb-908e-f31fe5f186e2
>
> ***
>
> possible deadlock in move_hugetlb_page_tables
>
> 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/b444c811-3577-4885-8522-093253539e5d/config
> C repro: https://ci.syzbot.org/findings/118b63ad-708b-4ada-abd9-4d6e18a8384f/c_repro
> syz repro: https://ci.syzbot.org/findings/118b63ad-708b-4ada-abd9-4d6e18a8384f/syz_repro
>
> ======================================================
> WARNING: possible circular locking dependency detected
> syzkaller #0 Not tainted
> ------------------------------------------------------
> syz.0.17/5959 is trying to acquire lock:
> ffff888167d5c918 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: i_mmap_lock_write include/linux/fs.h:548 [inline]
> ffff888167d5c918 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: move_hugetlb_page_tables+0x5a5/0x1560 mm/hugetlb.c:5114
>
> but task is already holding lock:
> ffff8881b5f35e78 (&vma_lock->rw_sema){+.+.}-{4:4}, at: hugetlb_vma_lock_write mm/hugetlb.c:-1 [inline]
> ffff8881b5f35e78 (&vma_lock->rw_sema){+.+.}-{4:4}, at: move_hugetlb_page_tables+0x589/0x1560 mm/hugetlb.c:5113
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #1 (&vma_lock->rw_sema){+.+.}-{4:4}:
> 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
> vms_clear_ptes+0x353/0x530 mm/vma.c:1231
> vms_complete_munmap_vmas+0x206/0x8a0 mm/vma.c:1280
> do_vmi_align_munmap+0x364/0x440 mm/vma.c:1539
> do_vmi_munmap+0x253/0x2e0 mm/vma.c:1587
> shrink_vma mm/mremap.c:1340 [inline]
> mremap_to+0x21e/0x790 mm/mremap.c:1394
> do_mremap mm/mremap.c:1940 [inline]
> __do_sys_mremap mm/mremap.c:1996 [inline]
> __se_sys_mremap+0xd45/0xfb0 mm/mremap.c:1964
> 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 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{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
> i_mmap_lock_write include/linux/fs.h:548 [inline]
> move_hugetlb_page_tables+0x5a5/0x1560 mm/hugetlb.c:5114
> move_page_tables+0x35c/0x1c80 mm/mremap.c:806
> copy_vma_and_data mm/mremap.c:1211 [inline]
> move_vma+0x942/0x1820 mm/mremap.c:1291
> mremap_to+0x6ce/0x790 mm/mremap.c:1415
> do_mremap mm/mremap.c:1940 [inline]
> __do_sys_mremap mm/mremap.c:1996 [inline]
> __se_sys_mremap+0xd45/0xfb0 mm/mremap.c:1964
> 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(&vma_lock->rw_sema);
> lock(&hugetlbfs_i_mmap_rwsem_key);
> lock(&vma_lock->rw_sema);
> lock(&hugetlbfs_i_mmap_rwsem_key);
>
> *** DEADLOCK ***
>
> 2 locks held by syz.0.17/5959:
> #0: ffff888172d8d7e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:327 [inline]
> #0: ffff888172d8d7e0 (&mm->mmap_lock){++++}-{4:4}, at: do_mremap mm/mremap.c:1927 [inline]
> #0: ffff888172d8d7e0 (&mm->mmap_lock){++++}-{4:4}, at: __do_sys_mremap mm/mremap.c:1996 [inline]
> #0: ffff888172d8d7e0 (&mm->mmap_lock){++++}-{4:4}, at: __se_sys_mremap+0x42e/0xfb0 mm/mremap.c:1964
> #1: ffff8881b5f35e78 (&vma_lock->rw_sema){+.+.}-{4:4}, at: hugetlb_vma_lock_write mm/hugetlb.c:-1 [inline]
> #1: ffff8881b5f35e78 (&vma_lock->rw_sema){+.+.}-{4:4}, at: move_hugetlb_page_tables+0x589/0x1560 mm/hugetlb.c:5113
>
> stack backtrace:
> CPU: 1 UID: 0 PID: 5959 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:
> <TASK>
> 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
> i_mmap_lock_write include/linux/fs.h:548 [inline]
> move_hugetlb_page_tables+0x5a5/0x1560 mm/hugetlb.c:5114
> move_page_tables+0x35c/0x1c80 mm/mremap.c:806
> copy_vma_and_data mm/mremap.c:1211 [inline]
> move_vma+0x942/0x1820 mm/mremap.c:1291
> mremap_to+0x6ce/0x790 mm/mremap.c:1415
> do_mremap mm/mremap.c:1940 [inline]
> __do_sys_mremap mm/mremap.c:1996 [inline]
> __se_sys_mremap+0xd45/0xfb0 mm/mremap.c:1964
> 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: 0033:0x7f043598efc9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffe808cfc08 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
> RAX: ffffffffffffffda RBX: 00007f0435be5fa0 RCX: 00007f043598efc9
> RDX: 0000000000400000 RSI: 0000000000c00000 RDI: 0000200000000000
> RBP: 00007f0435a11f91 R08: 0000200000c00000 R09: 0000000000000000
> R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f0435be5fa0 R14: 00007f0435be5fa0 R15: 0000000000000005
> </TASK>
>
>
> ***
>
> possible deadlock in remove_inode_hugepages
>
> 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/b444c811-3577-4885-8522-093253539e5d/config
> syz repro: https://ci.syzbot.org/findings/e3555fcc-3852-4e88-aea4-f3445e8a6ffb/syz_repro
>
> ======================================================
> WARNING: possible circular locking dependency detected
> syzkaller #0 Not tainted
> ------------------------------------------------------
> syz.2.22/5989 is trying to acquire lock:
> ffff8881bc18d318 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: i_mmap_lock_write include/linux/fs.h:548 [inline]
> ffff8881bc18d318 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: hugetlb_unmap_file_folio fs/hugetlbfs/inode.c:451 [inline]
> ffff8881bc18d318 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: remove_inode_single_folio fs/hugetlbfs/inode.c:535 [inline]
> ffff8881bc18d318 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: remove_inode_hugepages+0x972/0x1110 fs/hugetlbfs/inode.c:602
>
> but task is already holding lock:
> ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: hugetlb_unmap_file_folio fs/hugetlbfs/inode.c:450 [inline]
> ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: remove_inode_single_folio fs/hugetlbfs/inode.c:535 [inline]
> ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: remove_inode_hugepages+0x96a/0x1110 fs/hugetlbfs/inode.c:602
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #1 (&vma_lock->rw_sema){++++}-{4:4}:
> 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
> get_signal+0x1285/0x1340 kernel/signal.c:3034
> arch_do_signal_or_restart+0xa0/0x790 arch/x86/kernel/signal.c:337
> exit_to_user_mode_loop+0x72/0x130 kernel/entry/common.c:40
> exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
> syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
> syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
> do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> -> #0 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{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
> i_mmap_lock_write include/linux/fs.h:548 [inline]
> hugetlb_unmap_file_folio fs/hugetlbfs/inode.c:451 [inline]
> remove_inode_single_folio fs/hugetlbfs/inode.c:535 [inline]
> remove_inode_hugepages+0x972/0x1110 fs/hugetlbfs/inode.c:602
> hugetlbfs_punch_hole fs/hugetlbfs/inode.c:725 [inline]
> hugetlbfs_fallocate+0xbc2/0x1100 fs/hugetlbfs/inode.c:751
> vfs_fallocate+0x669/0x7e0 fs/open.c:342
> madvise_remove mm/madvise.c:1046 [inline]
> madvise_vma_behavior+0x341a/0x3d70 mm/madvise.c:1350
> madvise_walk_vmas+0x51c/0xa30 mm/madvise.c:1673
> madvise_do_behavior+0x38e/0x550 mm/madvise.c:1889
> do_madvise+0x1bc/0x270 mm/madvise.c:1982
> __do_sys_madvise mm/madvise.c:1991 [inline]
> __se_sys_madvise mm/madvise.c:1989 [inline]
> __x64_sys_madvise+0xa7/0xc0 mm/madvise.c:1989
> 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(&vma_lock->rw_sema);
> lock(&hugetlbfs_i_mmap_rwsem_key);
> lock(&vma_lock->rw_sema);
> lock(&hugetlbfs_i_mmap_rwsem_key);
>
> *** DEADLOCK ***
>
> 4 locks held by syz.2.22/5989:
> #0: ffff8881056ac420 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3111 [inline]
> #0: ffff8881056ac420 (sb_writers#12){.+.+}-{0:0}, at: vfs_fallocate+0x5f0/0x7e0 fs/open.c:341
> #1: ffff8881bc18d048 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:980 [inline]
> #1: ffff8881bc18d048 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: hugetlbfs_punch_hole fs/hugetlbfs/inode.c:693 [inline]
> #1: ffff8881bc18d048 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: hugetlbfs_fallocate+0x3cc/0x1100 fs/hugetlbfs/inode.c:751
> #2: ffff888103e8e4e8 (&hugetlb_fault_mutex_table[i]){+.+.}-{4:4}, at: remove_inode_hugepages+0x332/0x1110 fs/hugetlbfs/inode.c:597
> #3: ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: hugetlb_unmap_file_folio fs/hugetlbfs/inode.c:450 [inline]
> #3: ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: remove_inode_single_folio fs/hugetlbfs/inode.c:535 [inline]
> #3: ffff8881ae823178 (&vma_lock->rw_sema){++++}-{4:4}, at: remove_inode_hugepages+0x96a/0x1110 fs/hugetlbfs/inode.c:602
>
> stack backtrace:
> CPU: 1 UID: 0 PID: 5989 Comm: syz.2.22 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:
> <TASK>
> 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
> i_mmap_lock_write include/linux/fs.h:548 [inline]
> hugetlb_unmap_file_folio fs/hugetlbfs/inode.c:451 [inline]
> remove_inode_single_folio fs/hugetlbfs/inode.c:535 [inline]
> remove_inode_hugepages+0x972/0x1110 fs/hugetlbfs/inode.c:602
> hugetlbfs_punch_hole fs/hugetlbfs/inode.c:725 [inline]
> hugetlbfs_fallocate+0xbc2/0x1100 fs/hugetlbfs/inode.c:751
> vfs_fallocate+0x669/0x7e0 fs/open.c:342
> madvise_remove mm/madvise.c:1046 [inline]
> madvise_vma_behavior+0x341a/0x3d70 mm/madvise.c:1350
> madvise_walk_vmas+0x51c/0xa30 mm/madvise.c:1673
> madvise_do_behavior+0x38e/0x550 mm/madvise.c:1889
> do_madvise+0x1bc/0x270 mm/madvise.c:1982
> __do_sys_madvise mm/madvise.c:1991 [inline]
> __se_sys_madvise mm/madvise.c:1989 [inline]
> __x64_sys_madvise+0xa7/0xc0 mm/madvise.c:1989
> 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: 0033:0x7fca36b8efc9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fca37a80038 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
> RAX: ffffffffffffffda RBX: 00007fca36de6090 RCX: 00007fca36b8efc9
> RDX: 0000000000000009 RSI: 0000000000600000 RDI: 0000200000bc0000
> RBP: 00007fca36c11f91 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007fca36de6128 R14: 00007fca36de6090 R15: 00007ffeef05aaf8
> </TASK>
>
>
> ***
>
> 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/b444c811-3577-4885-8522-093253539e5d/config
> C repro: https://ci.syzbot.org/findings/0f0a7c70-e594-4359-9971-50a723bbbd7a/c_repro
> syz repro: https://ci.syzbot.org/findings/0f0a7c70-e594-4359-9971-50a723bbbd7a/syz_repro
>
> ======================================================
> WARNING: possible circular locking dependency detected
> syzkaller #0 Not tainted
> ------------------------------------------------------
> syz.0.17/5961 is trying to acquire lock:
> ffff88810be5c178 (&vma_lock->rw_sema){+.+.}-{4:4}, at: hugetlb_zap_begin include/linux/hugetlb.h:257 [inline]
> ffff88810be5c178 (&vma_lock->rw_sema){+.+.}-{4:4}, at: unmap_vmas+0x23d/0x580 mm/memory.c:2098
>
> but task is already holding lock:
> ffff88816a110418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: i_mmap_lock_write include/linux/fs.h:548 [inline]
> ffff88816a110418 (&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 (&vma_lock->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(&vma_lock->rw_sema);
> lock(&hugetlbfs_i_mmap_rwsem_key);
> lock(&vma_lock->rw_sema);
>
> *** DEADLOCK ***
>
> 2 locks held by syz.0.17/5961:
> #0: ffff8881151362a0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:365 [inline]
> #0: ffff8881151362a0 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x126/0xb30 mm/mmap.c:1262
> #1: ffff88816a110418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: i_mmap_lock_write include/linux/fs.h:548 [inline]
> #1: ffff88816a110418 (&hugetlbfs_i_mmap_rwsem_key){+.+.}-{4:4}, at: __hugetlb_zap_begin+0x2aa/0x3a0 mm/hugetlb.c:5331
>
> stack backtrace:
> CPU: 1 UID: 0 PID: 5961 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:
> <TASK>
> 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: 0033:0x7f470758efc9
> Code: Unable to access opcode bytes at 0x7f470758ef9f.
> RSP: 002b:00007ffed0f73318 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f470758efc9
> RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000003 R08: 00000002d0f7340f R09: 00007f47077b1280
> R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f47077b1280 R14: 0000000000000003 R15: 00007ffed0f733d0
> </TASK>
>
>
> ***
>
> 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.
>
> The email will later be sent 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@syzkaller.appspotmail.com syzkaller-bugs@googlegroups.com]
>
> If the report looks fine to you, reply with:
> #syz upstream
>
> --
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2025-11-10 9:03 [moderation/CI] Re: mm/hugetlb: fix possible deadlock in __hugetlb_zap_begin syzbot ci
2025-11-10 9:14 ` Aleksandr Nogikh
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