[syzbot] possible deadlock in exfat_get_block

From: syzbot
Date: Tue Oct 11 2022 - 11:20:00 EST

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Hello,

syzbot found the following issue on:

HEAD commit: bbed346d5a96 Merge branch 'for-next/core' 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=16c2cd84880000
kernel config: https://syzkaller.appspot.com/x/.config?x=3a4a45d2d827c1e
dashboard link: https://syzkaller.appspot.com/bug?extid=247e66a2c3ea756332c7
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

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e8e91bc79312/disk-bbed346d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c1cb3fb3b77e/vmlinux-bbed346d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+247e66a2c3ea756332c7@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0 Not tainted
------------------------------------------------------
syz-executor.4/3569 is trying to acquire lock:
ffff0000edcdd0e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_get_block+0x6c/0x9ec fs/exfat/inode.c:282

but task is already holding lock:
ffff0001036340a0 (mapping.invalidate_lock#3){.+.+}-{3:3}, at: filemap_invalidate_lock_shared include/linux/fs.h:811 [inline]
ffff0001036340a0 (mapping.invalidate_lock#3){.+.+}-{3:3}, at: page_cache_ra_unbounded+0x5c/0x338 mm/readahead.c:220

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (mapping.invalidate_lock#3){.+.+}-{3:3}:
down_read+0x5c/0x78 kernel/locking/rwsem.c:1499
filemap_invalidate_lock_shared include/linux/fs.h:811 [inline]
filemap_fault+0x104/0x804 mm/filemap.c:3112
__do_fault+0x60/0x358 mm/memory.c:4173
do_read_fault mm/memory.c:4518 [inline]
do_fault+0x338/0x550 mm/memory.c:4647
handle_pte_fault mm/memory.c:4911 [inline]
__handle_mm_fault mm/memory.c:5053 [inline]
handle_mm_fault+0x784/0xa40 mm/memory.c:5151
__do_page_fault arch/arm64/mm/fault.c:502 [inline]
do_page_fault+0x428/0x79c arch/arm64/mm/fault.c:602
do_translation_fault+0x78/0x194 arch/arm64/mm/fault.c:685
do_mem_abort+0x54/0x130 arch/arm64/mm/fault.c:821
el1_abort+0x3c/0x5c arch/arm64/kernel/entry-common.c:366
el1h_64_sync_handler+0x60/0xac arch/arm64/kernel/entry-common.c:426
el1h_64_sync+0x64/0x68 arch/arm64/kernel/entry.S:576
__arch_copy_from_user+0xb8/0x230 arch/arm64/lib/copy_template.S:110
copy_from_iter include/linux/uio.h:184 [inline]
copy_from_iter_full include/linux/uio.h:191 [inline]
memcpy_from_msg include/linux/skbuff.h:3959 [inline]
netlink_sendmsg+0x394/0x584 net/netlink/af_netlink.c:1906
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg net/socket.c:734 [inline]
sock_write_iter+0x140/0x1bc net/socket.c:1108
call_write_iter include/linux/fs.h:2187 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x2dc/0x46c fs/read_write.c:578
ksys_write+0xb4/0x160 fs/read_write.c:631
__do_sys_write fs/read_write.c:643 [inline]
__se_sys_write fs/read_write.c:640 [inline]
__arm64_sys_write+0x24/0x34 fs/read_write.c:640
__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+0x48/0x164 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:636
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

-> #1 (&mm->mmap_lock){++++}-{3:3}:
__might_fault+0x7c/0xb4 mm/memory.c:5577
filldir64+0x1e4/0x56c fs/readdir.c:335
dir_emit_dot include/linux/fs.h:3547 [inline]
dir_emit_dots include/linux/fs.h:3558 [inline]
exfat_iterate+0xd8/0xcd8 fs/exfat/dir.c:231
iterate_dir+0x114/0x28c
__do_sys_getdents64 fs/readdir.c:369 [inline]
__se_sys_getdents64 fs/readdir.c:354 [inline]
__arm64_sys_getdents64+0x80/0x204 fs/readdir.c:354
__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+0x48/0x164 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:636
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

-> #0 (&sbi->s_lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3829 [inline]
__lock_acquire+0x1530/0x30a4 kernel/locking/lockdep.c:5053
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
exfat_get_block+0x6c/0x9ec fs/exfat/inode.c:282
do_mpage_readpage+0x474/0xd38 fs/mpage.c:208
mpage_readahead+0xf0/0x1b8 fs/mpage.c:361
exfat_readahead+0x28/0x38 fs/exfat/inode.c:345
read_pages+0x74/0x4a0 mm/readahead.c:158
page_cache_ra_unbounded+0x2cc/0x338 mm/readahead.c:263
do_page_cache_ra mm/readahead.c:293 [inline]
page_cache_ra_order+0x348/0x380 mm/readahead.c:550
ondemand_readahead+0x3cc/0x724 mm/readahead.c:672
page_cache_sync_ra+0xc4/0xdc mm/readahead.c:699
page_cache_sync_readahead include/linux/pagemap.h:1215 [inline]
filemap_get_pages+0x108/0x574 mm/filemap.c:2566
filemap_read+0x14c/0x6fc mm/filemap.c:2660
generic_file_read_iter+0x6c/0x25c mm/filemap.c:2806
__kernel_read+0x128/0x2cc fs/read_write.c:428
kernel_read+0xb8/0x150 fs/read_write.c:446
prepare_binprm fs/exec.c:1657 [inline]
search_binary_handler fs/exec.c:1711 [inline]
exec_binprm+0x1c8/0x670 fs/exec.c:1768
bprm_execve+0x334/0x404 fs/exec.c:1837
do_execveat_common+0x57c/0x5e4 fs/exec.c:1942
do_execve fs/exec.c:2016 [inline]
__do_sys_execve fs/exec.c:2092 [inline]
__se_sys_execve fs/exec.c:2087 [inline]
__arm64_sys_execve+0x44/0x58 fs/exec.c:2087
__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+0x48/0x164 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:636
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

other info that might help us debug this:

Chain exists of:
&sbi->s_lock --> &mm->mmap_lock --> mapping.invalidate_lock#3

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(mapping.invalidate_lock#3);
lock(&mm->mmap_lock);
lock(mapping.invalidate_lock#3);
lock(&sbi->s_lock);

*** DEADLOCK ***

2 locks held by syz-executor.4/3569:
#0: ffff0000c659c3d0 (&sig->cred_guard_mutex){+.+.}-{3:3}, at: prepare_bprm_creds fs/exec.c:1470 [inline]
#0: ffff0000c659c3d0 (&sig->cred_guard_mutex){+.+.}-{3:3}, at: bprm_execve+0x48/0x404 fs/exec.c:1805
#1: ffff0001036340a0 (mapping.invalidate_lock#3){.+.+}-{3:3}, at: filemap_invalidate_lock_shared include/linux/fs.h:811 [inline]
#1: ffff0001036340a0 (mapping.invalidate_lock#3){.+.+}-{3:3}, at: page_cache_ra_unbounded+0x5c/0x338 mm/readahead.c:220

stack backtrace:
CPU: 0 PID: 3569 Comm: syz-executor.4 Not tainted 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
Call trace:
dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:156
show_stack+0x2c/0x54 arch/arm64/kernel/stacktrace.c:163
__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
print_circular_bug+0x2c4/0x2c8 kernel/locking/lockdep.c:2053
check_noncircular+0x14c/0x154 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3829 [inline]
__lock_acquire+0x1530/0x30a4 kernel/locking/lockdep.c:5053
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
__mutex_lock_common+0xd4/0xca8 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
exfat_get_block+0x6c/0x9ec fs/exfat/inode.c:282
do_mpage_readpage+0x474/0xd38 fs/mpage.c:208
mpage_readahead+0xf0/0x1b8 fs/mpage.c:361
exfat_readahead+0x28/0x38 fs/exfat/inode.c:345
read_pages+0x74/0x4a0 mm/readahead.c:158
page_cache_ra_unbounded+0x2cc/0x338 mm/readahead.c:263
do_page_cache_ra mm/readahead.c:293 [inline]
page_cache_ra_order+0x348/0x380 mm/readahead.c:550
ondemand_readahead+0x3cc/0x724 mm/readahead.c:672
page_cache_sync_ra+0xc4/0xdc mm/readahead.c:699
page_cache_sync_readahead include/linux/pagemap.h:1215 [inline]
filemap_get_pages+0x108/0x574 mm/filemap.c:2566
filemap_read+0x14c/0x6fc mm/filemap.c:2660
generic_file_read_iter+0x6c/0x25c mm/filemap.c:2806
__kernel_read+0x128/0x2cc fs/read_write.c:428
kernel_read+0xb8/0x150 fs/read_write.c:446
prepare_binprm fs/exec.c:1657 [inline]
search_binary_handler fs/exec.c:1711 [inline]
exec_binprm+0x1c8/0x670 fs/exec.c:1768
bprm_execve+0x334/0x404 fs/exec.c:1837
do_execveat_common+0x57c/0x5e4 fs/exec.c:1942
do_execve fs/exec.c:2016 [inline]
__do_sys_execve fs/exec.c:2092 [inline]
__se_sys_execve fs/exec.c:2087 [inline]
__arm64_sys_execve+0x44/0x58 fs/exec.c:2087
__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+0x48/0x164 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:636
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

---
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Next message: chengwei: "[PATCH v3 1/2] mfd: Add support for UP board CPLD/FPGA"
Previous message: Dawei Li: "[PATCH 0/2] block: queue flag helpers and atomic refcnt impl"
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