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aio: Fix locking in aio_poll()
wake_up_locked() may but does not have to be called with interrupts
disabled. Since the fuse filesystem calls wake_up_locked() without
disabling interrupts aio_poll_wake() may be called with interrupts
enabled. Since the kioctx.ctx_lock may be acquired from IRQ context,
all code that acquires that lock from thread context must disable
interrupts. Hence change the spin_trylock() call in aio_poll_wake()
into a spin_trylock_irqsave() call. This patch fixes the following
lockdep complaint:
=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
5.0.0-rc4-next-20190131 #23 Not tainted
-----------------------------------------------------
syz-executor2/13779 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
0000000098ac1230 (&fiq->waitq){+.+.}, at: spin_lock include/linux/spinlock.h:329 [inline]
0000000098ac1230 (&fiq->waitq){+.+.}, at: aio_poll fs/aio.c:1772 [inline]
0000000098ac1230 (&fiq->waitq){+.+.}, at: __io_submit_one fs/aio.c:1875 [inline]
0000000098ac1230 (&fiq->waitq){+.+.}, at: io_submit_one+0xedf/0x1cf0 fs/aio.c:1908
and this task is already holding:
000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq include/linux/spinlock.h:354 [inline]
000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: aio_poll fs/aio.c:1771 [inline]
000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: __io_submit_one fs/aio.c:1875 [inline]
000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: io_submit_one+0xeb6/0x1cf0 fs/aio.c:1908
which would create a new lock dependency:
(&(&ctx->ctx_lock)->rlock){..-.} -> (&fiq->waitq){+.+.}
but this new dependency connects a SOFTIRQ-irq-safe lock:
(&(&ctx->ctx_lock)->rlock){..-.}
... which became SOFTIRQ-irq-safe at:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
free_ioctx_users+0x2d/0x4a0 fs/aio.c:610
percpu_ref_put_many include/linux/percpu-refcount.h:285 [inline]
percpu_ref_put include/linux/percpu-refcount.h:301 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline]
percpu_ref_switch_to_atomic_rcu+0x3e7/0x520 lib/percpu-refcount.c:158
__rcu_reclaim kernel/rcu/rcu.h:240 [inline]
rcu_do_batch kernel/rcu/tree.c:2486 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2799 [inline]
rcu_core+0x928/0x1390 kernel/rcu/tree.c:2780
__do_softirq+0x266/0x95a kernel/softirq.c:292
run_ksoftirqd kernel/softirq.c:654 [inline]
run_ksoftirqd+0x8e/0x110 kernel/softirq.c:646
smpboot_thread_fn+0x6ab/0xa10 kernel/smpboot.c:164
kthread+0x357/0x430 kernel/kthread.c:247
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
to a SOFTIRQ-irq-unsafe lock:
(&fiq->waitq){+.+.}
... which became SOFTIRQ-irq-unsafe at:
...
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415
fuse_request_queue_background+0x2d1/0x580 fs/fuse/dev.c:676
fuse_request_send_background+0x58/0x120 fs/fuse/dev.c:687
fuse_send_init fs/fuse/inode.c:989 [inline]
fuse_fill_super+0x13bb/0x1730 fs/fuse/inode.c:1214
mount_nodev+0x68/0x110 fs/super.c:1392
fuse_mount+0x2d/0x40 fs/fuse/inode.c:1239
legacy_get_tree+0xf2/0x200 fs/fs_context.c:590
vfs_get_tree+0x123/0x450 fs/super.c:1481
do_new_mount fs/namespace.c:2610 [inline]
do_mount+0x1436/0x2c40 fs/namespace.c:2932
ksys_mount+0xdb/0x150 fs/namespace.c:3148
__do_sys_mount fs/namespace.c:3162 [inline]
__se_sys_mount fs/namespace.c:3159 [inline]
__x64_sys_mount+0xbe/0x150 fs/namespace.c:3159
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&fiq->waitq);
local_irq_disable();
lock(&(&ctx->ctx_lock)->rlock);
lock(&fiq->waitq);
<Interrupt>
lock(&(&ctx->ctx_lock)->rlock);
*** DEADLOCK ***
1 lock held by syz-executor2/13779:
#0: 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq include/linux/spinlock.h:354 [inline]
#0: 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: aio_poll fs/aio.c:1771 [inline]
#0: 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: __io_submit_one fs/aio.c:1875 [inline]
#0: 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: io_submit_one+0xeb6/0x1cf0 fs/aio.c:1908
the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (&(&ctx->ctx_lock)->rlock){..-.} {
IN-SOFTIRQ-W at:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
free_ioctx_users+0x2d/0x4a0 fs/aio.c:610
percpu_ref_put_many include/linux/percpu-refcount.h:285 [inline]
percpu_ref_put include/linux/percpu-refcount.h:301 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline]
percpu_ref_switch_to_atomic_rcu+0x3e7/0x520 lib/percpu-refcount.c:158
__rcu_reclaim kernel/rcu/rcu.h:240 [inline]
rcu_do_batch kernel/rcu/tree.c:2486 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2799 [inline]
rcu_core+0x928/0x1390 kernel/rcu/tree.c:2780
__do_softirq+0x266/0x95a kernel/softirq.c:292
run_ksoftirqd kernel/softirq.c:654 [inline]
run_ksoftirqd+0x8e/0x110 kernel/softirq.c:646
smpboot_thread_fn+0x6ab/0xa10 kernel/smpboot.c:164
kthread+0x357/0x430 kernel/kthread.c:247
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
INITIAL USE at:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
__do_sys_io_cancel fs/aio.c:2052 [inline]
__se_sys_io_cancel fs/aio.c:2035 [inline]
__x64_sys_io_cancel+0xd5/0x5a0 fs/aio.c:2035
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
}
... key at: [<ffffffff8a574140>] __key.52370+0x0/0x40
... acquired at:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
aio_poll fs/aio.c:1772 [inline]
__io_submit_one fs/aio.c:1875 [inline]
io_submit_one+0xedf/0x1cf0 fs/aio.c:1908
__do_sys_io_submit fs/aio.c:1953 [inline]
__se_sys_io_submit fs/aio.c:1923 [inline]
__x64_sys_io_submit+0x1bd/0x580 fs/aio.c:1923
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
the dependencies between the lock to be acquired
and SOFTIRQ-irq-unsafe lock:
-> (&fiq->waitq){+.+.} {
HARDIRQ-ON-W at:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415
fuse_request_queue_background+0x2d1/0x580 fs/fuse/dev.c:676
fuse_request_send_background+0x58/0x120 fs/fuse/dev.c:687
fuse_send_init fs/fuse/inode.c:989 [inline]
fuse_fill_super+0x13bb/0x1730 fs/fuse/inode.c:1214
mount_nodev+0x68/0x110 fs/super.c:1392
fuse_mount+0x2d/0x40 fs/fuse/inode.c:1239
legacy_get_tree+0xf2/0x200 fs/fs_context.c:590
vfs_get_tree+0x123/0x450 fs/super.c:1481
do_new_mount fs/namespace.c:2610 [inline]
do_mount+0x1436/0x2c40 fs/namespace.c:2932
ksys_mount+0xdb/0x150 fs/namespace.c:3148
__do_sys_mount fs/namespace.c:3162 [inline]
__se_sys_mount fs/namespace.c:3159 [inline]
__x64_sys_mount+0xbe/0x150 fs/namespace.c:3159
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
SOFTIRQ-ON-W at:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415
fuse_request_queue_background+0x2d1/0x580 fs/fuse/dev.c:676
fuse_request_send_background+0x58/0x120 fs/fuse/dev.c:687
fuse_send_init fs/fuse/inode.c:989 [inline]
fuse_fill_super+0x13bb/0x1730 fs/fuse/inode.c:1214
mount_nodev+0x68/0x110 fs/super.c:1392
fuse_mount+0x2d/0x40 fs/fuse/inode.c:1239
legacy_get_tree+0xf2/0x200 fs/fs_context.c:590
vfs_get_tree+0x123/0x450 fs/super.c:1481
do_new_mount fs/namespace.c:2610 [inline]
do_mount+0x1436/0x2c40 fs/namespace.c:2932
ksys_mount+0xdb/0x150 fs/namespace.c:3148
__do_sys_mount fs/namespace.c:3162 [inline]
__se_sys_mount fs/namespace.c:3159 [inline]
__x64_sys_mount+0xbe/0x150 fs/namespace.c:3159
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
INITIAL USE at:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415
fuse_request_queue_background+0x2d1/0x580 fs/fuse/dev.c:676
fuse_request_send_background+0x58/0x120 fs/fuse/dev.c:687
fuse_send_init fs/fuse/inode.c:989 [inline]
fuse_fill_super+0x13bb/0x1730 fs/fuse/inode.c:1214
mount_nodev+0x68/0x110 fs/super.c:1392
fuse_mount+0x2d/0x40 fs/fuse/inode.c:1239
legacy_get_tree+0xf2/0x200 fs/fs_context.c:590
vfs_get_tree+0x123/0x450 fs/super.c:1481
do_new_mount fs/namespace.c:2610 [inline]
do_mount+0x1436/0x2c40 fs/namespace.c:2932
ksys_mount+0xdb/0x150 fs/namespace.c:3148
__do_sys_mount fs/namespace.c:3162 [inline]
__se_sys_mount fs/namespace.c:3159 [inline]
__x64_sys_mount+0xbe/0x150 fs/namespace.c:3159
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
}
... key at: [<ffffffff8a60dec0>] __key.43450+0x0/0x40
... acquired at:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
aio_poll fs/aio.c:1772 [inline]
__io_submit_one fs/aio.c:1875 [inline]
io_submit_one+0xedf/0x1cf0 fs/aio.c:1908
__do_sys_io_submit fs/aio.c:1953 [inline]
__se_sys_io_submit fs/aio.c:1923 [inline]
__x64_sys_io_submit+0x1bd/0x580 fs/aio.c:1923
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
stack backtrace:
CPU: 0 PID: 13779 Comm: syz-executor2 Not tainted 5.0.0-rc4-next-20190131 #23
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+0x172/0x1f0 lib/dump_stack.c:113
print_bad_irq_dependency kernel/locking/lockdep.c:1573 [inline]
check_usage.cold+0x60f/0x940 kernel/locking/lockdep.c:1605
check_irq_usage kernel/locking/lockdep.c:1650 [inline]
check_prev_add_irq kernel/locking/lockdep_states.h:8 [inline]
check_prev_add kernel/locking/lockdep.c:1860 [inline]
check_prevs_add kernel/locking/lockdep.c:1968 [inline]
validate_chain kernel/locking/lockdep.c:2339 [inline]
__lock_acquire+0x1f12/0x4790 kernel/locking/lockdep.c:3320
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
aio_poll fs/aio.c:1772 [inline]
__io_submit_one fs/aio.c:1875 [inline]
io_submit_one+0xedf/0x1cf0 fs/aio.c:1908
__do_sys_io_submit fs/aio.c:1953 [inline]
__se_sys_io_submit fs/aio.c:1923 [inline]
__x64_sys_io_submit+0x1bd/0x580 fs/aio.c:1923
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Avi Kivity <avi@scylladb.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org>
Fixes: e8693bcfa0 ("aio: allow direct aio poll comletions for keyed wakeups") # v4.19
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
[ bvanassche: added a comment ]
Reluctantly-Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Bart Van Assche
Al Viro
parent
f612acfae8
commit
d3d6a18d7d
12
fs/aio.c
12
fs/aio.c
@ -1679,6 +1679,7 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
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struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
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struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
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__poll_t mask = key_to_poll(key);
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unsigned long flags;
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req->woken = true;
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@ -1687,10 +1688,15 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
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if (!(mask & req->events))
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return 0;
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/* try to complete the iocb inline if we can: */
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if (spin_trylock(&iocb->ki_ctx->ctx_lock)) {
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/*
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* Try to complete the iocb inline if we can. Use
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* irqsave/irqrestore because not all filesystems (e.g. fuse)
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* call this function with IRQs disabled and because IRQs
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* have to be disabled before ctx_lock is obtained.
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*/
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if (spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
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list_del(&iocb->ki_list);
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spin_unlock(&iocb->ki_ctx->ctx_lock);
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spin_unlock_irqrestore(&iocb->ki_ctx->ctx_lock, flags);
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list_del_init(&req->wait.entry);
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aio_poll_complete(iocb, mask);
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