linux-kernel - [syzbot] WARNING: suspicious RCU usage in do_page

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Date:   Mon, 05 Sep 2022 07:25:31 -0700
From:   syzbot <syzbot+3bca50295c8d986d2d16@...kaller.appspotmail.com>
To:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: [syzbot] WARNING: suspicious RCU usage in do_page_fault

Hello,

syzbot found the following issue on:

HEAD commit:    85413d1e802e Merge branch 'for-next/fixes' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=110d078b080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=57b9bfeca947ab90
dashboard link: https://syzkaller.appspot.com/bug?extid=3bca50295c8d986d2d16
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1796b3ad080000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13081a8b080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3bca50295c8d986d2d16@...kaller.appspotmail.com

=============================
WARNING: suspicious RCU usage
6.0.0-rc3-syzkaller-16800-g85413d1e802e #0 Not tainted
-----------------------------
kernel/sched/core.c:9854 Illegal context switch in RCU-bh read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
3 locks held by syz-executor478/3038:
 #0: ffff0000c90e7188 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0x5c/0x5e0 fs/seq_file.c:182
 #1: ffff80000d82d328 (binder_procs_lock){+.+.}-{3:3}, at: stats_show+0x60/0x3e0 drivers/android/binder.c:6350
 #2: ffff0000c937aa48 (&alloc->mutex){+.+.}-{3:3}, at: binder_alloc_print_pages+0x38/0x218 drivers/android/binder_alloc.c:930

stack backtrace:
CPU: 0 PID: 3038 Comm: syz-executor478 Not tainted 6.0.0-rc3-syzkaller-16800-g85413d1e802e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call trace:
 dump_backtrace+0x1b0/0x1dc arch/arm64/kernel/stacktrace.c:182
 show_stack+0x2c/0x64 arch/arm64/kernel/stacktrace.c:189
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 lockdep_rcu_suspicious+0x138/0x154 kernel/locking/lockdep.c:6595
 __might_resched+0x6c/0x218 kernel/sched/core.c:9854
 __might_sleep+0x48/0x78 kernel/sched/core.c:9821
 do_page_fault+0x214/0x79c arch/arm64/mm/fault.c:593
 do_translation_fault+0x78/0x194 arch/arm64/mm/fault.c:685
 do_mem_abort+0x54/0x130 arch/arm64/mm/fault.c:818
 el1_abort+0x3c/0x5c arch/arm64/kernel/entry-common.c:366
 el1h_64_sync_handler+0x5c/0x98 arch/arm64/kernel/entry-common.c:417
 el1h_64_sync+0x64/0x68
 __lock_acquire+0x60/0x30a4 kernel/locking/lockdep.c:4923
 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
 down_read+0x5c/0x78 kernel/locking/rwsem.c:1499
 mmap_read_lock include/linux/mmap_lock.h:117 [inline]
 binder_alloc_print_pages+0x48/0x218 drivers/android/binder_alloc.c:936
 print_binder_proc_stats drivers/android/binder.c:6289 [inline]
 stats_show+0x2d8/0x3e0 drivers/android/binder.c:6352
 seq_read_iter+0x220/0x5e0 fs/seq_file.c:230
 seq_read+0x98/0xd0 fs/seq_file.c:162
 full_proxy_read+0x94/0x140 fs/debugfs/file.c:231
 vfs_read+0x19c/0x448 fs/read_write.c:468
 ksys_read+0xb4/0x160 fs/read_write.c:607
 __do_sys_read fs/read_write.c:617 [inline]
 __se_sys_read fs/read_write.c:615 [inline]
 __arm64_sys_read+0x24/0x34 fs/read_write.c:615
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x154 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:624
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:642
 el0t_64_sync+0x18c/0x190

=============================
WARNING: suspicious RCU usage
6.0.0-rc3-syzkaller-16800-g85413d1e802e #0 Not tainted
-----------------------------
kernel/sched/core.c:9854 Illegal context switch in RCU-sched read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
3 locks held by syz-executor478/3038:
 #0: ffff0000c90e7188 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0x5c/0x5e0 fs/seq_file.c:182
 #1: ffff80000d82d328 (binder_procs_lock){+.+.}-{3:3}, at: stats_show+0x60/0x3e0 drivers/android/binder.c:6350
 #2: ffff0000c937aa48 (&alloc->mutex){+.+.}-{3:3}, at: binder_alloc_print_pages+0x38/0x218 drivers/android/binder_alloc.c:930

stack backtrace:
CPU: 0 PID: 3038 Comm: syz-executor478 Not tainted 6.0.0-rc3-syzkaller-16800-g85413d1e802e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call trace:
 dump_backtrace+0x1b0/0x1dc arch/arm64/kernel/stacktrace.c:182
 show_stack+0x2c/0x64 arch/arm64/kernel/stacktrace.c:189
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 lockdep_rcu_suspicious+0x138/0x154 kernel/locking/lockdep.c:6595
 __might_resched+0xb4/0x218 kernel/sched/core.c:9854
 __might_sleep+0x48/0x78 kernel/sched/core.c:9821
 do_page_fault+0x214/0x79c arch/arm64/mm/fault.c:593
 do_translation_fault+0x78/0x194 arch/arm64/mm/fault.c:685
 do_mem_abort+0x54/0x130 arch/arm64/mm/fault.c:818
 el1_abort+0x3c/0x5c arch/arm64/kernel/entry-common.c:366
 el1h_64_sync_handler+0x5c/0x98 arch/arm64/kernel/entry-common.c:417
 el1h_64_sync+0x64/0x68
 __lock_acquire+0x60/0x30a4 kernel/locking/lockdep.c:4923
 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
 down_read+0x5c/0x78 kernel/locking/rwsem.c:1499
 mmap_read_lock include/linux/mmap_lock.h:117 [inline]
 binder_alloc_print_pages+0x48/0x218 drivers/android/binder_alloc.c:936
 print_binder_proc_stats drivers/android/binder.c:6289 [inline]
 stats_show+0x2d8/0x3e0 drivers/android/binder.c:6352
 seq_read_iter+0x220/0x5e0 fs/seq_file.c:230
 seq_read+0x98/0xd0 fs/seq_file.c:162
 full_proxy_read+0x94/0x140 fs/debugfs/file.c:231
 vfs_read+0x19c/0x448 fs/read_write.c:468
 ksys_read+0xb4/0x160 fs/read_write.c:607
 __do_sys_read fs/read_write.c:617 [inline]
 __se_sys_read fs/read_write.c:615 [inline]
 __arm64_sys_read+0x24/0x34 fs/read_write.c:615
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x154 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:624
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:642
 el0t_64_sync+0x18c/0x190
BUG: sleeping function called from invalid context at arch/arm64/mm/fault.c:593
in_atomic(): 0, irqs_disabled(): 128, non_block: 0, pid: 3038, name: syz-executor478
preempt_count: 0, expected: 0
RCU nest depth: 0, expected: 0
3 locks held by syz-executor478/3038:
 #0: ffff0000c90e7188 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0x5c/0x5e0 fs/seq_file.c:182
 #1: ffff80000d82d328 (binder_procs_lock){+.+.}-{3:3}, at: stats_show+0x60/0x3e0 drivers/android/binder.c:6350
 #2: ffff0000c937aa48 (&alloc->mutex){+.+.}-{3:3}, at: binder_alloc_print_pages+0x38/0x218 drivers/android/binder_alloc.c:930
irq event stamp: 519
hardirqs last  enabled at (519): [<ffff800008038c9c>] local_daif_restore arch/arm64/include/asm/daifflags.h:75 [inline]
hardirqs last  enabled at (519): [<ffff800008038c9c>] el0_svc_common+0x40/0x220 arch/arm64/kernel/syscall.c:107
hardirqs last disabled at (518): [<ffff80000c001358>] el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:642
softirqs last  enabled at (504): [<ffff8000080102e4>] _stext+0x2e4/0x37c
softirqs last disabled at (495): [<ffff800008104658>] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
softirqs last disabled at (495): [<ffff800008104658>] invoke_softirq+0x70/0xbc kernel/softirq.c:452
CPU: 0 PID: 3038 Comm: syz-executor478 Not tainted 6.0.0-rc3-syzkaller-16800-g85413d1e802e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call trace:
 dump_backtrace+0x1b0/0x1dc arch/arm64/kernel/stacktrace.c:182
 show_stack+0x2c/0x64 arch/arm64/kernel/stacktrace.c:189
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x104/0x16c lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 __might_resched+0x208/0x218 kernel/sched/core.c:9892
 __might_sleep+0x48/0x78 kernel/sched/core.c:9821
 do_page_fault+0x214/0x79c arch/arm64/mm/fault.c:593
 do_translation_fault+0x78/0x194 arch/arm64/mm/fault.c:685
 do_mem_abort+0x54/0x130 arch/arm64/mm/fault.c:818
 el1_abort+0x3c/0x5c arch/arm64/kernel/entry-common.c:366
 el1h_64_sync_handler+0x5c/0x98 arch/arm64/kernel/entry-common.c:417
 el1h_64_sync+0x64/0x68
 __lock_acquire+0x60/0x30a4 kernel/locking/lockdep.c:4923
 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
 down_read+0x5c/0x78 kernel/locking/rwsem.c:1499
 mmap_read_lock include/linux/mmap_lock.h:117 [inline]
 binder_alloc_print_pages+0x48/0x218 drivers/android/binder_alloc.c:936
 print_binder_proc_stats drivers/android/binder.c:6289 [inline]
 stats_show+0x2d8/0x3e0 drivers/android/binder.c:6352
 seq_read_iter+0x220/0x5e0 fs/seq_file.c:230
 seq_read+0x98/0xd0 fs/seq_file.c:162
 full_proxy_read+0x94/0x140 fs/debugfs/file.c:231
 vfs_read+0x19c/0x448 fs/read_write.c:468
 ksys_read+0xb4/0x160 fs/read_write.c:607
 __do_sys_read fs/read_write.c:617 [inline]
 __se_sys_read fs/read_write.c:615 [inline]
 __arm64_sys_read+0x24/0x34 fs/read_write.c:615
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x154 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:624
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:642
 el0t_64_sync+0x18c/0x190
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000118
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=000000010c4fd000
[0000000000000118] pgd=080000010c4cd003, p4d=080000010c4cd003, pud=080000010c4cc003, pmd=0000000000000000
Internal error: Oops: 96000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 3038 Comm: syz-executor478 Tainted: G        W          6.0.0-rc3-syzkaller-16800-g85413d1e802e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
pstate: 804000c5 (Nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __lock_acquire+0x60/0x30a4 kernel/locking/lockdep.c:4923
lr : lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
sp : ffff8000126e38c0
x29: ffff8000126e39a0 x28: 0000000000000000 x27: 0000000000000000
x26: 0000000000000118 x25: ffff80000aff1fcc x24: 0000000000000000
x23: 0000000000000000 x22: 0000000000000118 x21: 0000000000000000
x20: 0000000000000001 x19: 0000000000000000 x18: 00000000000000c0
x17: ffff80000dd7a698 x16: ffff80000dbb8658 x15: ffff0000c4a2b500
x14: 00000000000000b8 x13: 00000000ffffffff x12: ffff0000c4a2b500
x11: ff808000095ecde4 x10: 0000000000000000 x9 : 0000000000000001
x8 : 0000000000000001 x7 : ffff80000aff1fcc x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000001
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000118
Call trace:
 __lock_acquire+0x60/0x30a4 kernel/locking/lockdep.c:4923
 lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
 down_read+0x5c/0x78 kernel/locking/rwsem.c:1499
 mmap_read_lock include/linux/mmap_lock.h:117 [inline]
 binder_alloc_print_pages+0x48/0x218 drivers/android/binder_alloc.c:936
 print_binder_proc_stats drivers/android/binder.c:6289 [inline]
 stats_show+0x2d8/0x3e0 drivers/android/binder.c:6352
 seq_read_iter+0x220/0x5e0 fs/seq_file.c:230
 seq_read+0x98/0xd0 fs/seq_file.c:162
 full_proxy_read+0x94/0x140 fs/debugfs/file.c:231
 vfs_read+0x19c/0x448 fs/read_write.c:468
 ksys_read+0xb4/0x160 fs/read_write.c:607
 __do_sys_read fs/read_write.c:617 [inline]
 __se_sys_read fs/read_write.c:615 [inline]
 __arm64_sys_read+0x24/0x34 fs/read_write.c:615
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x154 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:624
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:642
 el0t_64_sync+0x18c/0x190
Code: 2a0303f4 2a0203f7 aa0003fa 34000148 (f9400348) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	2a0303f4 	mov	w20, w3
   4:	2a0203f7 	mov	w23, w2
   8:	aa0003fa 	mov	x26, x0
   c:	34000148 	cbz	w8, 0x34
* 10:	f9400348 	ldr	x8, [x26] <-- trapping instruction


---
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