* possible deadlock in io_timeout_fn
@ 2020-08-10 15:37 syzbot
2020-08-10 16:53 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: syzbot @ 2020-08-10 15:37 UTC (permalink / raw)
To: axboe, bijan.mottahedeh, io-uring, linux-fsdevel, linux-kernel,
syzkaller-bugs, viro
Hello,
syzbot found the following issue on:
HEAD commit: 449dc8c9 Merge tag 'for-v5.9' of git://git.kernel.org/pub/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11293dc6900000
kernel config: https://syzkaller.appspot.com/x/.config?x=9d25235bf0162fbc
dashboard link: https://syzkaller.appspot.com/bug?extid=ef4b654b49ed7ff049bf
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=126b0f1a900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13e32994900000
The issue was bisected to:
commit e62753e4e2926f249d088cc0517be5ed4efec6d6
Author: Bijan Mottahedeh <[email protected]>
Date: Sat May 23 04:31:18 2020 +0000
io_uring: call statx directly
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1195de52900000
final oops: https://syzkaller.appspot.com/x/report.txt?x=1395de52900000
console output: https://syzkaller.appspot.com/x/log.txt?x=1595de52900000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]
Fixes: e62753e4e292 ("io_uring: call statx directly")
========================================================
WARNING: possible irq lock inversion dependency detected
5.8.0-syzkaller #0 Not tainted
--------------------------------------------------------
syz-executor659/6838 just changed the state of lock:
ffff8880a8bc44d8 (&ctx->completion_lock){-...}-{2:2}, at: io_timeout_fn+0x6b/0x360 fs/io_uring.c:4999
but this lock took another, HARDIRQ-unsafe lock in the past:
(&fs->lock){+.+.}-{2:2}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&fs->lock);
local_irq_disable();
lock(&ctx->completion_lock);
lock(&fs->lock);
<Interrupt>
lock(&ctx->completion_lock);
*** DEADLOCK ***
1 lock held by syz-executor659/6838:
#0: ffff8880a8bc4428 (&ctx->uring_lock){+.+.}-{3:3}, at: __do_sys_io_uring_enter fs/io_uring.c:8035 [inline]
#0: ffff8880a8bc4428 (&ctx->uring_lock){+.+.}-{3:3}, at: __se_sys_io_uring_enter+0x19d/0x1300 fs/io_uring.c:7995
the shortest dependencies between 2nd lock and 1st lock:
-> (&fs->lock){+.+.}-{2:2} {
HARDIRQ-ON-W at:
lock_acquire+0x160/0x730 kernel/locking/lockdep.c:5005
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:354 [inline]
set_fs_pwd+0x3b/0x220 fs/fs_struct.c:39
init_chdir+0xe2/0x10b fs/init.c:54
devtmpfs_setup+0xa5/0xd4 drivers/base/devtmpfs.c:415
devtmpfsd+0x11/0x40 drivers/base/devtmpfs.c:430
kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
SOFTIRQ-ON-W at:
lock_acquire+0x160/0x730 kernel/locking/lockdep.c:5005
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:354 [inline]
set_fs_pwd+0x3b/0x220 fs/fs_struct.c:39
init_chdir+0xe2/0x10b fs/init.c:54
devtmpfs_setup+0xa5/0xd4 drivers/base/devtmpfs.c:415
devtmpfsd+0x11/0x40 drivers/base/devtmpfs.c:430
kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
INITIAL USE at:
lock_acquire+0x160/0x730 kernel/locking/lockdep.c:5005
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:354 [inline]
set_fs_pwd+0x3b/0x220 fs/fs_struct.c:39
init_chdir+0xe2/0x10b fs/init.c:54
devtmpfs_setup+0xa5/0xd4 drivers/base/devtmpfs.c:415
devtmpfsd+0x11/0x40 drivers/base/devtmpfs.c:430
kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
}
... key at: [<ffffffff8b84e190>] copy_fs_struct.__key+0x0/0x10
... acquired at:
lock_acquire+0x160/0x730 kernel/locking/lockdep.c:5005
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:354 [inline]
io_req_clean_work fs/io_uring.c:1126 [inline]
io_dismantle_req+0x285/0x5d0 fs/io_uring.c:1544
__io_free_req+0x24/0x190 fs/io_uring.c:1562
__io_double_put_req fs/io_uring.c:1909 [inline]
__io_fail_links+0x1d7/0x6c0 fs/io_uring.c:1659
io_fail_links fs/io_uring.c:1675 [inline]
__io_req_find_next fs/io_uring.c:1698 [inline]
io_req_find_next+0x101a/0x1260 fs/io_uring.c:1706
io_steal_work fs/io_uring.c:1897 [inline]
io_wq_submit_work+0x446/0x590 fs/io_uring.c:5792
io_worker_handle_work+0xf8f/0x1570 fs/io-wq.c:527
io_wqe_worker+0x2ff/0x810 fs/io-wq.c:569
kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
-> (&ctx->completion_lock){-...}-{2:2} {
IN-HARDIRQ-W at:
lock_acquire+0x160/0x730 kernel/locking/lockdep.c:5005
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:159
io_timeout_fn+0x6b/0x360 fs/io_uring.c:4999
__run_hrtimer kernel/time/hrtimer.c:1520 [inline]
__hrtimer_run_queues+0x47f/0x930 kernel/time/hrtimer.c:1584
hrtimer_interrupt+0x373/0xd60 kernel/time/hrtimer.c:1646
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1079 [inline]
__sysvec_apic_timer_interrupt+0xf0/0x260 arch/x86/kernel/apic/apic.c:1096
asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
__run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
sysvec_apic_timer_interrupt+0x94/0xf0 arch/x86/kernel/apic/apic.c:1090
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:581
arch_local_irq_enable arch/x86/include/asm/paravirt.h:780 [inline]
__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline]
_raw_spin_unlock_irq+0x57/0x80 kernel/locking/spinlock.c:199
spin_unlock_irq include/linux/spinlock.h:404 [inline]
io_timeout fs/io_uring.c:5162 [inline]
io_issue_sqe+0x5b64/0xb8c0 fs/io_uring.c:5594
__io_queue_sqe+0x287/0xff0 fs/io_uring.c:5981
io_submit_sqe fs/io_uring.c:6130 [inline]
io_submit_sqes+0x14cf/0x25d0 fs/io_uring.c:6327
__do_sys_io_uring_enter fs/io_uring.c:8036 [inline]
__se_sys_io_uring_enter+0x1af/0x1300 fs/io_uring.c:7995
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
INITIAL USE at:
lock_acquire+0x160/0x730 kernel/locking/lockdep.c:5005
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:159
io_cqring_add_event fs/io_uring.c:1419 [inline]
__io_req_complete+0x15e/0x2c0 fs/io_uring.c:1458
io_issue_sqe+0x8678/0xb8c0 fs/io_uring.c:3569
io_wq_submit_work+0x35e/0x590 fs/io_uring.c:5775
io_worker_handle_work+0xf8f/0x1570 fs/io-wq.c:527
io_wqe_worker+0x2ff/0x810 fs/io-wq.c:569
kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
}
... key at: [<ffffffff8b84ef58>] io_ring_ctx_alloc.__key.111+0x0/0x10
... acquired at:
mark_lock_irq kernel/locking/lockdep.c:3568 [inline]
mark_lock+0x529/0x1b00 kernel/locking/lockdep.c:4006
mark_usage kernel/locking/lockdep.c:3902 [inline]
__lock_acquire+0xa5c/0x2ab0 kernel/locking/lockdep.c:4380
lock_acquire+0x160/0x730 kernel/locking/lockdep.c:5005
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:159
io_timeout_fn+0x6b/0x360 fs/io_uring.c:4999
__run_hrtimer kernel/time/hrtimer.c:1520 [inline]
__hrtimer_run_queues+0x47f/0x930 kernel/time/hrtimer.c:1584
hrtimer_interrupt+0x373/0xd60 kernel/time/hrtimer.c:1646
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1079 [inline]
__sysvec_apic_timer_interrupt+0xf0/0x260 arch/x86/kernel/apic/apic.c:1096
asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
__run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
sysvec_apic_timer_interrupt+0x94/0xf0 arch/x86/kernel/apic/apic.c:1090
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:581
arch_local_irq_enable arch/x86/include/asm/paravirt.h:780 [inline]
__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:168 [inline]
_raw_spin_unlock_irq+0x57/0x80 kernel/locking/spinlock.c:199
spin_unlock_irq include/linux/spinlock.h:404 [inline]
io_timeout fs/io_uring.c:5162 [inline]
io_issue_sqe+0x5b64/0xb8c0 fs/io_uring.c:5594
__io_queue_sqe+0x287/0xff0 fs/io_uring.c:5981
io_submit_sqe fs/io_uring.c:6130 [inline]
io_submit_sqes+0x14cf/0x25d0 fs/io_uring.c:6327
__do_sys_io_uring_enter fs/io_uring.c:8036 [inline]
__se_sys_io_uring_enter+0x1af/0x1300 fs/io_uring.c:7995
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
stack backtrace:
CPU: 1 PID: 6838 Comm: syz-executor659 Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1f0/0x31e lib/dump_stack.c:118
print_irq_inversion_bug+0xb67/0xe90 kernel/locking/lockdep.c:3428
check_usage_forwards+0x13f/0x240 kernel/locking/lockdep.c:3453
mark_lock_irq kernel/locking/lockdep.c:3568 [inline]
mark_lock+0x529/0x1b00 kernel/locking/lockdep.c:4006
mark_usage kernel/locking/lockdep.c:3902 [inline]
__lock_acquire+0xa5c/0x2ab0 kernel/locking/lockdep.c:4380
lock_acquire+0x160/0x730 kernel/locking/lockdep.c:5005
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:159
io_timeout_fn+0x6b/0x360 fs/io_uring.c:4999
__run_hrtimer kernel/time/hrtimer.c:1520 [inline]
__hrtimer_run_queues+0x47f/0x930 kernel/time/hrtimer.c:1584
hrtimer_interrupt+0x373/0xd60 kernel/time/hrtimer.c:1646
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1079 [inline]
__sysvec_apic_timer_interrupt+0xf0/0x260 arch/x86/kernel/apic/apic.c:1096
asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
</IRQ>
__run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
sysvec_apic_timer_interrupt+0x94/0xf0 arch/x86/kernel/apic/apic.c:1090
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:581
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x57/0x80 kernel/locking/spinlock.c:199
Code: 00 00 00 00 fc ff df 80 3c 08 00 74 0c 48 c7 c7 c8 14 4d 89 e8 6a 28 8b f9 48 83 3d 0a a9 23 01 00 74 25 fb 66 0f 1f 44 00 00 <bf> 01 00 00 00 e8 6f 62 27 f9 65 8b 05 34 92 d8 77 85 c0 74 02 5b
RSP: 0018:ffffc9000102f8f0 EFLAGS: 00000286
RAX: 1ffffffff129a299 RBX: ffff8880a8bc44c0 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff88296b8f
RBP: ffffc9000102fb80 R08: dffffc0000000000 R09: fffffbfff167c6b8
R10: fffffbfff167c6b8 R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880a2dfdc08 R15: ffff8880a2dfdc58
spin_unlock_irq include/linux/spinlock.h:404 [inline]
io_timeout fs/io_uring.c:5162 [inline]
io_issue_sqe+0x5b64/0xb8c0 fs/io_uring.c:5594
__io_queue_sqe+0x287/0xff0 fs/io_uring.c:5981
io_submit_sqe fs/io_uring.c:6130 [inline]
io_submit_sqes+0x14cf/0x25d0 fs/io_uring.c:6327
__do_sys_io_uring_enter fs/io_uring.c:8036 [inline]
__se_sys_io_uring_enter+0x1af/0x1300 fs/io_uring.c:7995
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x440b99
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffea6abdbf8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440b99
RDX: 0000000000000000 RSI: 000000000000450c RDI: 0000000000000005
RBP: 00000000006cb018 R08
---
This report is generated by a bot. It may contain errors.
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syzbot engineers can be reached at [email protected].
syzbot will keep track of this issue. See:
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
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^ permalink raw reply [flat|nested] 2+ messages in thread* Re: possible deadlock in io_timeout_fn 2020-08-10 15:37 possible deadlock in io_timeout_fn syzbot @ 2020-08-10 16:53 ` Jens Axboe 0 siblings, 0 replies; 2+ messages in thread From: Jens Axboe @ 2020-08-10 16:53 UTC (permalink / raw) To: syzbot, bijan.mottahedeh, io-uring, linux-fsdevel, linux-kernel, syzkaller-bugs, viro On 8/10/20 9:37 AM, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 449dc8c9 Merge tag 'for-v5.9' of git://git.kernel.org/pub/.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=11293dc6900000 > kernel config: https://syzkaller.appspot.com/x/.config?x=9d25235bf0162fbc > dashboard link: https://syzkaller.appspot.com/bug?extid=ef4b654b49ed7ff049bf > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=126b0f1a900000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13e32994900000 > > The issue was bisected to: > > commit e62753e4e2926f249d088cc0517be5ed4efec6d6 > Author: Bijan Mottahedeh <[email protected]> > Date: Sat May 23 04:31:18 2020 +0000 > > io_uring: call statx directly I don't think this one is to blame, it's a generic issue with needing to put the file table from the error/fail path. Something like the below should fix it - if we have the completion lock locked, then punt the file table put to a safe context through task_work instead. Looks bigger than it is, due to moving some of the generic task_work handling functions up a bit. diff --git a/fs/io_uring.c b/fs/io_uring.c index f9be665d1c5e..5df805d6251e 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1108,10 +1108,16 @@ static void __io_commit_cqring(struct io_ring_ctx *ctx) } } -static void io_req_clean_work(struct io_kiocb *req) +/* + * Returns true if we need to defer file table putting. This can only happen + * from the error path with REQ_F_COMP_LOCKED set. + */ +static bool io_req_clean_work(struct io_kiocb *req) { if (!(req->flags & REQ_F_WORK_INITIALIZED)) - return; + return false; + + req->flags &= ~REQ_F_WORK_INITIALIZED; if (req->work.mm) { mmdrop(req->work.mm); @@ -1124,6 +1130,9 @@ static void io_req_clean_work(struct io_kiocb *req) if (req->work.fs) { struct fs_struct *fs = req->work.fs; + if (req->flags & REQ_F_COMP_LOCKED) + return true; + spin_lock(&req->work.fs->lock); if (--fs->users) fs = NULL; @@ -1132,7 +1141,8 @@ static void io_req_clean_work(struct io_kiocb *req) free_fs_struct(fs); req->work.fs = NULL; } - req->flags &= ~REQ_F_WORK_INITIALIZED; + + return false; } static void io_prep_async_work(struct io_kiocb *req) @@ -1544,7 +1554,7 @@ static inline void io_put_file(struct io_kiocb *req, struct file *file, fput(file); } -static void io_dismantle_req(struct io_kiocb *req) +static bool io_dismantle_req(struct io_kiocb *req) { io_clean_op(req); @@ -1552,7 +1562,6 @@ static void io_dismantle_req(struct io_kiocb *req) kfree(req->io); if (req->file) io_put_file(req, req->file, (req->flags & REQ_F_FIXED_FILE)); - io_req_clean_work(req); if (req->flags & REQ_F_INFLIGHT) { struct io_ring_ctx *ctx = req->ctx; @@ -1564,15 +1573,108 @@ static void io_dismantle_req(struct io_kiocb *req) wake_up(&ctx->inflight_wait); spin_unlock_irqrestore(&ctx->inflight_lock, flags); } + + return io_req_clean_work(req); } -static void __io_free_req(struct io_kiocb *req) +static void __io_req_task_cancel(struct io_kiocb *req, int error) { - struct io_ring_ctx *ctx; + struct io_ring_ctx *ctx = req->ctx; + + spin_lock_irq(&ctx->completion_lock); + io_cqring_fill_event(req, error); + io_commit_cqring(ctx); + spin_unlock_irq(&ctx->completion_lock); + + io_cqring_ev_posted(ctx); + req_set_fail_links(req); + io_double_put_req(req); +} + +static void io_req_task_cancel(struct callback_head *cb) +{ + struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work); + + __io_req_task_cancel(req, -ECANCELED); +} + +static int io_req_task_work_add(struct io_kiocb *req, struct callback_head *cb) +{ + struct task_struct *tsk = req->task; + struct io_ring_ctx *ctx = req->ctx; + int ret, notify = TWA_RESUME; + + ret = __task_work_add(tsk, cb); + if (unlikely(ret)) + return ret; + + /* + * SQPOLL kernel thread doesn't need notification, just a wakeup. + * For any other work, use signaled wakeups if the task isn't + * running to avoid dependencies between tasks or threads. If + * the issuing task is currently waiting in the kernel on a thread, + * and same thread is waiting for a completion event, then we need + * to ensure that the issuing task processes task_work. TWA_SIGNAL + * is needed for that. + */ + if (ctx->flags & IORING_SETUP_SQPOLL) + notify = 0; + else if (READ_ONCE(tsk->state) != TASK_RUNNING) + notify = TWA_SIGNAL; + + __task_work_notify(tsk, notify); + wake_up_process(tsk); + return 0; +} + +static void __io_req_task_submit(struct io_kiocb *req) +{ + struct io_ring_ctx *ctx = req->ctx; + + if (!__io_sq_thread_acquire_mm(ctx)) { + mutex_lock(&ctx->uring_lock); + __io_queue_sqe(req, NULL, NULL); + mutex_unlock(&ctx->uring_lock); + } else { + __io_req_task_cancel(req, -EFAULT); + } +} + +static void io_req_task_submit(struct callback_head *cb) +{ + struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work); + + __io_req_task_submit(req); +} + + +static void __io_req_task_queue(struct io_kiocb *req, task_work_func_t func) +{ + int ret; + + init_task_work(&req->task_work, func); + + ret = io_req_task_work_add(req, &req->task_work); + if (unlikely(ret)) { + struct task_struct *tsk; + + init_task_work(&req->task_work, io_req_task_cancel); + tsk = io_wq_get_task(req->ctx->io_wq); + task_work_add(tsk, &req->task_work, 0); + wake_up_process(tsk); + } +} + +static void io_req_task_queue(struct io_kiocb *req) +{ + __io_req_task_queue(req, io_req_task_submit); +} + +static void __io_free_req_finish(struct io_kiocb *req) +{ + struct io_ring_ctx *ctx = req->ctx; - io_dismantle_req(req); __io_put_req_task(req); - ctx = req->ctx; if (likely(!io_is_fallback_req(req))) kmem_cache_free(req_cachep, req); else @@ -1580,6 +1682,29 @@ static void __io_free_req(struct io_kiocb *req) percpu_ref_put(&ctx->refs); } +static void io_req_task_file_table_put(struct callback_head *cb) +{ + struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work); + struct fs_struct *fs = req->work.fs; + + spin_lock(&req->work.fs->lock); + if (--fs->users) + fs = NULL; + spin_unlock(&req->work.fs->lock); + if (fs) + free_fs_struct(fs); + req->work.fs = NULL; + __io_free_req_finish(req); +} + +static void __io_free_req(struct io_kiocb *req) +{ + if (!io_dismantle_req(req)) + __io_free_req_finish(req); + else + __io_req_task_queue(req, io_req_task_file_table_put); +} + static bool io_link_cancel_timeout(struct io_kiocb *req) { struct io_ring_ctx *ctx = req->ctx; @@ -1667,6 +1792,7 @@ static void __io_fail_links(struct io_kiocb *req) trace_io_uring_fail_link(req, link); io_cqring_fill_event(link, -ECANCELED); + link->flags |= REQ_F_COMP_LOCKED; __io_double_put_req(link); req->flags &= ~REQ_F_LINK_TIMEOUT; } @@ -1717,93 +1843,6 @@ static struct io_kiocb *io_req_find_next(struct io_kiocb *req) return __io_req_find_next(req); } -static int io_req_task_work_add(struct io_kiocb *req, struct callback_head *cb) -{ - struct task_struct *tsk = req->task; - struct io_ring_ctx *ctx = req->ctx; - int ret, notify = TWA_RESUME; - - ret = __task_work_add(tsk, cb); - if (unlikely(ret)) - return ret; - - /* - * SQPOLL kernel thread doesn't need notification, just a wakeup. - * For any other work, use signaled wakeups if the task isn't - * running to avoid dependencies between tasks or threads. If - * the issuing task is currently waiting in the kernel on a thread, - * and same thread is waiting for a completion event, then we need - * to ensure that the issuing task processes task_work. TWA_SIGNAL - * is needed for that. - */ - if (ctx->flags & IORING_SETUP_SQPOLL) - notify = 0; - else if (READ_ONCE(tsk->state) != TASK_RUNNING) - notify = TWA_SIGNAL; - - __task_work_notify(tsk, notify); - wake_up_process(tsk); - return 0; -} - -static void __io_req_task_cancel(struct io_kiocb *req, int error) -{ - struct io_ring_ctx *ctx = req->ctx; - - spin_lock_irq(&ctx->completion_lock); - io_cqring_fill_event(req, error); - io_commit_cqring(ctx); - spin_unlock_irq(&ctx->completion_lock); - - io_cqring_ev_posted(ctx); - req_set_fail_links(req); - io_double_put_req(req); -} - -static void io_req_task_cancel(struct callback_head *cb) -{ - struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work); - - __io_req_task_cancel(req, -ECANCELED); -} - -static void __io_req_task_submit(struct io_kiocb *req) -{ - struct io_ring_ctx *ctx = req->ctx; - - if (!__io_sq_thread_acquire_mm(ctx)) { - mutex_lock(&ctx->uring_lock); - __io_queue_sqe(req, NULL, NULL); - mutex_unlock(&ctx->uring_lock); - } else { - __io_req_task_cancel(req, -EFAULT); - } -} - -static void io_req_task_submit(struct callback_head *cb) -{ - struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work); - - __io_req_task_submit(req); -} - -static void io_req_task_queue(struct io_kiocb *req) -{ - int ret; - - init_task_work(&req->task_work, io_req_task_submit); - - ret = io_req_task_work_add(req, &req->task_work); - if (unlikely(ret)) { - struct task_struct *tsk; - - init_task_work(&req->task_work, io_req_task_cancel); - tsk = io_wq_get_task(req->ctx->io_wq); - task_work_add(tsk, &req->task_work, 0); - wake_up_process(tsk); - } -} - static void io_queue_next(struct io_kiocb *req) { struct io_kiocb *nxt = io_req_find_next(req); @@ -1872,7 +1911,7 @@ static void io_req_free_batch(struct req_batch *rb, struct io_kiocb *req) req->flags &= ~REQ_F_TASK_PINNED; } - io_dismantle_req(req); + WARN_ON_ONCE(io_dismantle_req(req)); rb->reqs[rb->to_free++] = req; if (unlikely(rb->to_free == ARRAY_SIZE(rb->reqs))) __io_req_free_batch_flush(req->ctx, rb); -- Jens Axboe ^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2020-08-10 16:53 UTC | newest] Thread overview: 2+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2020-08-10 15:37 possible deadlock in io_timeout_fn syzbot 2020-08-10 16:53 ` Jens Axboe
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