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Subjectpossible deadlock in uprobe_clear_state (2)
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Hello,

syzbot found the following issue on:

HEAD commit: a581387e Merge tag 'io_uring-5.8-2020-07-10' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=111a004f100000
kernel config: https://syzkaller.appspot.com/x/.config?x=66ad203c2bb6d8b
dashboard link: https://syzkaller.appspot.com/bug?extid=e5344baa319c9a96edec
compiler: gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e5344baa319c9a96edec@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.8.0-rc4-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.1/4807 is trying to acquire lock:
ffffffff89c3a988 (delayed_uprobe_lock){+.+.}-{3:3}, at: uprobe_clear_state+0x47/0x3b0 kernel/events/uprobes.c:1550

but task is already holding lock:
ffffffff89c6c360 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_release mm/page_alloc.c:4202 [inline]
ffffffff89c6c360 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_release mm/page_alloc.c:4198 [inline]
ffffffff89c6c360 (fs_reclaim){+.+.}-{0:0}, at: __perform_reclaim mm/page_alloc.c:4227 [inline]
ffffffff89c6c360 (fs_reclaim){+.+.}-{0:0}, at: __alloc_pages_direct_reclaim mm/page_alloc.c:4244 [inline]
ffffffff89c6c360 (fs_reclaim){+.+.}-{0:0}, at: __alloc_pages_slowpath.constprop.0+0x1554/0x2780 mm/page_alloc.c:4650

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (fs_reclaim){+.+.}-{0:0}:
__fs_reclaim_acquire mm/page_alloc.c:4183 [inline]
fs_reclaim_acquire+0x2f/0x40 mm/page_alloc.c:4194
slab_pre_alloc_hook mm/slab.h:564 [inline]
slab_alloc mm/slab.c:3306 [inline]
kmem_cache_alloc_trace+0x29/0x2d0 mm/slab.c:3549
kmalloc include/linux/slab.h:555 [inline]
kzalloc include/linux/slab.h:669 [inline]
delayed_uprobe_add kernel/events/uprobes.c:304 [inline]
update_ref_ctr+0x4b6/0x700 kernel/events/uprobes.c:438
uprobe_write_opcode+0xe07/0x1650 kernel/events/uprobes.c:497
install_breakpoint kernel/events/uprobes.c:915 [inline]
install_breakpoint.isra.0+0x5a5/0x7c0 kernel/events/uprobes.c:897
uprobe_mmap+0x5d7/0x1050 kernel/events/uprobes.c:1394
mmap_region+0x5cf/0x1590 mm/mmap.c:1818
do_mmap+0xca8/0x1170 mm/mmap.c:1545
do_mmap_pgoff include/linux/mm.h:2596 [inline]
vm_mmap_pgoff+0x197/0x200 mm/util.c:506
ksys_mmap_pgoff+0x455/0x5a0 mm/mmap.c:1595
do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #0 (delayed_uprobe_lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:2496 [inline]
check_prevs_add kernel/locking/lockdep.c:2601 [inline]
validate_chain kernel/locking/lockdep.c:3218 [inline]
__lock_acquire+0x2acb/0x56e0 kernel/locking/lockdep.c:4380
lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:4959
__mutex_lock_common kernel/locking/mutex.c:956 [inline]
__mutex_lock+0x134/0x10d0 kernel/locking/mutex.c:1103
uprobe_clear_state+0x47/0x3b0 kernel/events/uprobes.c:1550
__mmput+0x73/0x470 kernel/fork.c:1089
mmput+0x53/0x60 kernel/fork.c:1114
binder_alloc_free_page+0x441/0xf90 drivers/android/binder_alloc.c:950
__list_lru_walk_one+0x178/0x5c0 mm/list_lru.c:222
list_lru_walk_one mm/list_lru.c:266 [inline]
list_lru_walk_node+0x67/0x2a0 mm/list_lru.c:295
list_lru_walk include/linux/list_lru.h:215 [inline]
binder_shrink_scan+0x123/0x190 drivers/android/binder_alloc.c:984
do_shrink_slab+0x3c6/0xab0 mm/vmscan.c:518
shrink_slab+0x16f/0x5c0 mm/vmscan.c:679
shrink_node_memcgs mm/vmscan.c:2658 [inline]
shrink_node+0x519/0x1b60 mm/vmscan.c:2770
shrink_zones mm/vmscan.c:2973 [inline]
do_try_to_free_pages+0x38b/0x1340 mm/vmscan.c:3026
try_to_free_pages+0x29a/0x8b0 mm/vmscan.c:3265
__perform_reclaim mm/page_alloc.c:4223 [inline]
__alloc_pages_direct_reclaim mm/page_alloc.c:4244 [inline]
__alloc_pages_slowpath.constprop.0+0x949/0x2780 mm/page_alloc.c:4650
__alloc_pages_nodemask+0x68f/0x930 mm/page_alloc.c:4863
alloc_pages_current+0x187/0x280 mm/mempolicy.c:2292
alloc_pages include/linux/gfp.h:545 [inline]
alloc_mmu_pages+0x7f/0x170 arch/x86/kvm/mmu/mmu.c:5671
kvm_mmu_create+0x3cb/0x560 arch/x86/kvm/mmu/mmu.c:5704
kvm_arch_vcpu_create+0x16d/0xb70 arch/x86/kvm/x86.c:9433
kvm_vm_ioctl_create_vcpu arch/x86/kvm/../../../virt/kvm/kvm_main.c:3060 [inline]
kvm_vm_ioctl+0x1547/0x23c0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3621
vfs_ioctl fs/ioctl.c:48 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
__do_sys_ioctl fs/ioctl.c:762 [inline]
__se_sys_ioctl fs/ioctl.c:760 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
entry_SYSCALL_64_after_hwframe+0x44/0xa9

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(delayed_uprobe_lock);
lock(fs_reclaim);
lock(delayed_uprobe_lock);

*** DEADLOCK ***

3 locks held by syz-executor.1/4807:
#0: ffffffff89c6c360 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_release mm/page_alloc.c:4202 [inline]
#0: ffffffff89c6c360 (fs_reclaim){+.+.}-{0:0}, at: fs_reclaim_release mm/page_alloc.c:4198 [inline]
#0: ffffffff89c6c360 (fs_reclaim){+.+.}-{0:0}, at: __perform_reclaim mm/page_alloc.c:4227 [inline]
#0: ffffffff89c6c360 (fs_reclaim){+.+.}-{0:0}, at: __alloc_pages_direct_reclaim mm/page_alloc.c:4244 [inline]
#0: ffffffff89c6c360 (fs_reclaim){+.+.}-{0:0}, at: __alloc_pages_slowpath.constprop.0+0x1554/0x2780 mm/page_alloc.c:4650
#1: ffffffff89c46b90 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0xc7/0x5c0 mm/vmscan.c:669
#2: ffff88808ea481e0 (&alloc->mutex){+.+.}-{3:3}, at: binder_alloc_free_page+0x4f/0xf90 drivers/android/binder_alloc.c:923

stack backtrace:
CPU: 0 PID: 4807 Comm: syz-executor.1 Not tainted 5.8.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x18f/0x20d lib/dump_stack.c:118
check_noncircular+0x324/0x3e0 kernel/locking/lockdep.c:1827
check_prev_add kernel/locking/lockdep.c:2496 [inline]
check_prevs_add kernel/locking/lockdep.c:2601 [inline]
validate_chain kernel/locking/lockdep.c:3218 [inline]
__lock_acquire+0x2acb/0x56e0 kernel/locking/lockdep.c:4380
lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:4959
__mutex_lock_common kernel/locking/mutex.c:956 [inline]
__mutex_lock+0x134/0x10d0 kernel/locking/mutex.c:1103
uprobe_clear_state+0x47/0x3b0 kernel/events/uprobes.c:1550
__mmput+0x73/0x470 kernel/fork.c:1089
mmput+0x53/0x60 kernel/fork.c:1114
binder_alloc_free_page+0x441/0xf90 drivers/android/binder_alloc.c:950
__list_lru_walk_one+0x178/0x5c0 mm/list_lru.c:222
list_lru_walk_one mm/list_lru.c:266 [inline]
list_lru_walk_node+0x67/0x2a0 mm/list_lru.c:295
list_lru_walk include/linux/list_lru.h:215 [inline]
binder_shrink_scan+0x123/0x190 drivers/android/binder_alloc.c:984
do_shrink_slab+0x3c6/0xab0 mm/vmscan.c:518
shrink_slab+0x16f/0x5c0 mm/vmscan.c:679
shrink_node_memcgs mm/vmscan.c:2658 [inline]
shrink_node+0x519/0x1b60 mm/vmscan.c:2770
shrink_zones mm/vmscan.c:2973 [inline]
do_try_to_free_pages+0x38b/0x1340 mm/vmscan.c:3026
try_to_free_pages+0x29a/0x8b0 mm/vmscan.c:3265
__perform_reclaim mm/page_alloc.c:4223 [inline]
__alloc_pages_direct_reclaim mm/page_alloc.c:4244 [inline]
__alloc_pages_slowpath.constprop.0+0x949/0x2780 mm/page_alloc.c:4650
__alloc_pages_nodemask+0x68f/0x930 mm/page_alloc.c:4863
alloc_pages_current+0x187/0x280 mm/mempolicy.c:2292
alloc_pages include/linux/gfp.h:545 [inline]
alloc_mmu_pages+0x7f/0x170 arch/x86/kvm/mmu/mmu.c:5671
kvm_mmu_create+0x3cb/0x560 arch/x86/kvm/mmu/mmu.c:5704
kvm_arch_vcpu_create+0x16d/0xb70 arch/x86/kvm/x86.c:9433
kvm_vm_ioctl_create_vcpu arch/x86/kvm/../../../virt/kvm/kvm_main.c:3060 [inline]
kvm_vm_ioctl+0x1547/0x23c0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3621
vfs_ioctl fs/ioctl.c:48 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
__do_sys_ioctl fs/ioctl.c:762 [inline]
__se_sys_ioctl fs/ioctl.c:760 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cba9
Code: Bad RIP value.
RSP: 002b:00007f45444f8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e85c0 RCX: 000000000045cba9
RDX: 0000000000000000 RSI: 000000000000ae41 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000003a3 R14: 00000000004c652f R15: 00007f45444f96d4


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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