mirror of https://gitee.com/openkylin/linux.git
io_uring: don't hold uring_lock when calling io_run_task_work*
Abaci reported the below issue:
[ 141.400455] hrtimer: interrupt took 205853 ns
[ 189.869316] process 'usr/local/ilogtail/ilogtail_0.16.26' started with executable stack
[ 250.188042]
[ 250.188327] ============================================
[ 250.189015] WARNING: possible recursive locking detected
[ 250.189732] 5.11.0-rc4 #1 Not tainted
[ 250.190267] --------------------------------------------
[ 250.190917] a.out/7363 is trying to acquire lock:
[ 250.191506] ffff888114dbcbe8 (&ctx->uring_lock){+.+.}-{3:3}, at: __io_req_task_submit+0x29/0xa0
[ 250.192599]
[ 250.192599] but task is already holding lock:
[ 250.193309] ffff888114dbfbe8 (&ctx->uring_lock){+.+.}-{3:3}, at: __x64_sys_io_uring_register+0xad/0x210
[ 250.194426]
[ 250.194426] other info that might help us debug this:
[ 250.195238] Possible unsafe locking scenario:
[ 250.195238]
[ 250.196019] CPU0
[ 250.196411] ----
[ 250.196803] lock(&ctx->uring_lock);
[ 250.197420] lock(&ctx->uring_lock);
[ 250.197966]
[ 250.197966] *** DEADLOCK ***
[ 250.197966]
[ 250.198837] May be due to missing lock nesting notation
[ 250.198837]
[ 250.199780] 1 lock held by a.out/7363:
[ 250.200373] #0: ffff888114dbfbe8 (&ctx->uring_lock){+.+.}-{3:3}, at: __x64_sys_io_uring_register+0xad/0x210
[ 250.201645]
[ 250.201645] stack backtrace:
[ 250.202298] CPU: 0 PID: 7363 Comm: a.out Not tainted 5.11.0-rc4 #1
[ 250.203144] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
[ 250.203887] Call Trace:
[ 250.204302] dump_stack+0xac/0xe3
[ 250.204804] __lock_acquire+0xab6/0x13a0
[ 250.205392] lock_acquire+0x2c3/0x390
[ 250.205928] ? __io_req_task_submit+0x29/0xa0
[ 250.206541] __mutex_lock+0xae/0x9f0
[ 250.207071] ? __io_req_task_submit+0x29/0xa0
[ 250.207745] ? 0xffffffffa0006083
[ 250.208248] ? __io_req_task_submit+0x29/0xa0
[ 250.208845] ? __io_req_task_submit+0x29/0xa0
[ 250.209452] ? __io_req_task_submit+0x5/0xa0
[ 250.210083] __io_req_task_submit+0x29/0xa0
[ 250.210687] io_async_task_func+0x23d/0x4c0
[ 250.211278] task_work_run+0x89/0xd0
[ 250.211884] io_run_task_work_sig+0x50/0xc0
[ 250.212464] io_sqe_files_unregister+0xb2/0x1f0
[ 250.213109] __io_uring_register+0x115a/0x1750
[ 250.213718] ? __x64_sys_io_uring_register+0xad/0x210
[ 250.214395] ? __fget_files+0x15a/0x260
[ 250.214956] __x64_sys_io_uring_register+0xbe/0x210
[ 250.215620] ? trace_hardirqs_on+0x46/0x110
[ 250.216205] do_syscall_64+0x2d/0x40
[ 250.216731] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 250.217455] RIP: 0033:0x7f0fa17e5239
[ 250.218034] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 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 3d 01 f0 ff ff 73 01 c3 48 8b 0d 27 ec 2c 00 f7 d8 64 89 01 48
[ 250.220343] RSP: 002b:00007f0fa1eeac48 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab
[ 250.221360] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0fa17e5239
[ 250.222272] RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000008
[ 250.223185] RBP: 00007f0fa1eeae20 R08: 0000000000000000 R09: 0000000000000000
[ 250.224091] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[ 250.224999] R13: 0000000000021000 R14: 0000000000000000 R15: 00007f0fa1eeb700
This is caused by calling io_run_task_work_sig() to do work under
uring_lock while the caller io_sqe_files_unregister() already held
uring_lock.
To fix this issue, briefly drop uring_lock when calling
io_run_task_work_sig(), and there are two things to concern:
- hold uring_lock in io_ring_ctx_free() around io_sqe_files_unregister()
this is for consistency of lock/unlock.
- add new fixed rsrc ref node before dropping uring_lock
it's not safe to do io_uring_enter-->percpu_ref_get() with a dying one.
- check if rsrc_data->refs is dying to avoid parallel io_sqe_files_unregister
Reported-by: Abaci <abaci@linux.alibaba.com>
Fixes: 1ffc54220c ("io_uring: fix io_sqe_files_unregister() hangs")
Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
[axboe: fixes from Pavel folded in]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Hao Xu
Jens Axboe
parent
a3df769899
commit
8bad28d8a3
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@ -236,6 +236,7 @@ struct fixed_rsrc_data {
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struct fixed_rsrc_ref_node *node;
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struct percpu_ref refs;
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struct completion done;
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bool quiesce;
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};
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struct io_buffer {
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@ -7316,38 +7317,57 @@ static void io_sqe_rsrc_set_node(struct io_ring_ctx *ctx,
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percpu_ref_get(&rsrc_data->refs);
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}
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static int io_rsrc_ref_quiesce(struct fixed_rsrc_data *data,
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struct io_ring_ctx *ctx,
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struct fixed_rsrc_ref_node *backup_node)
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static void io_sqe_rsrc_kill_node(struct io_ring_ctx *ctx, struct fixed_rsrc_data *data)
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{
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struct fixed_rsrc_ref_node *ref_node;
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int ret;
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struct fixed_rsrc_ref_node *ref_node = NULL;
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io_rsrc_ref_lock(ctx);
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ref_node = data->node;
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io_rsrc_ref_unlock(ctx);
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if (ref_node)
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percpu_ref_kill(&ref_node->refs);
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}
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percpu_ref_kill(&data->refs);
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static int io_rsrc_ref_quiesce(struct fixed_rsrc_data *data,
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struct io_ring_ctx *ctx,
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struct fixed_rsrc_ref_node *backup_node)
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{
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int ret;
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/* wait for all refs nodes to complete */
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flush_delayed_work(&ctx->rsrc_put_work);
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if (data->quiesce)
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return -ENXIO;
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data->quiesce = true;
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do {
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io_sqe_rsrc_kill_node(ctx, data);
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percpu_ref_kill(&data->refs);
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flush_delayed_work(&ctx->rsrc_put_work);
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ret = wait_for_completion_interruptible(&data->done);
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if (!ret)
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break;
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ret = io_run_task_work_sig();
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if (ret < 0) {
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percpu_ref_resurrect(&data->refs);
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reinit_completion(&data->done);
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io_sqe_rsrc_set_node(ctx, data, backup_node);
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return ret;
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}
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} while (1);
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destroy_fixed_rsrc_ref_node(backup_node);
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return 0;
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percpu_ref_resurrect(&data->refs);
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io_sqe_rsrc_set_node(ctx, data, backup_node);
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backup_node = NULL;
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reinit_completion(&data->done);
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mutex_unlock(&ctx->uring_lock);
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ret = io_run_task_work_sig();
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mutex_lock(&ctx->uring_lock);
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if (ret < 0)
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break;
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backup_node = alloc_fixed_rsrc_ref_node(ctx);
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ret = -ENOMEM;
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if (!backup_node)
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break;
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init_fixed_file_ref_node(ctx, backup_node);
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} while (1);
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data->quiesce = false;
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if (backup_node)
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destroy_fixed_rsrc_ref_node(backup_node);
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return ret;
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}
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static struct fixed_rsrc_data *alloc_fixed_rsrc_data(struct io_ring_ctx *ctx)
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@ -7382,7 +7402,12 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
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unsigned nr_tables, i;
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int ret;
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if (!data)
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/*
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* percpu_ref_is_dying() is to stop parallel files unregister
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* Since we possibly drop uring lock later in this function to
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* run task work.
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*/
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if (!data || percpu_ref_is_dying(&data->refs))
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return -ENXIO;
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backup_node = alloc_fixed_rsrc_ref_node(ctx);
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if (!backup_node)
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@ -8731,7 +8756,9 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
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css_put(ctx->sqo_blkcg_css);
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#endif
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mutex_lock(&ctx->uring_lock);
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io_sqe_files_unregister(ctx);
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mutex_unlock(&ctx->uring_lock);
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io_eventfd_unregister(ctx);
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io_destroy_buffers(ctx);
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idr_destroy(&ctx->personality_idr);
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