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Hao Xu 81dfee4731 io_uring: fix possible deadlock in io_uring_poll [ Upstream commit `ed670c3f90` ] Abaci reported follow issue: [ 30.615891] ====================================================== [ 30.616648] WARNING: possible circular locking dependency detected [ 30.617423] 5.11.0-rc3-next-20210115 #1 Not tainted [ 30.618035] ------------------------------------------------------ [ 30.618914] a.out/1128 is trying to acquire lock: [ 30.619520] ffff88810b063868 (&ep->mtx){+.+.}-{3:3}, at: __ep_eventpoll_poll+0x9f/0x220 [ 30.620505] [ 30.620505] but task is already holding lock: [ 30.621218] ffff88810e952be8 (&ctx->uring_lock){+.+.}-{3:3}, at: __x64_sys_io_uring_enter+0x3f0/0x5b0 [ 30.622349] [ 30.622349] which lock already depends on the new lock. [ 30.622349] [ 30.623289] [ 30.623289] the existing dependency chain (in reverse order) is: [ 30.624243] [ 30.624243] -> #1 (&ctx->uring_lock){+.+.}-{3:3}: [ 30.625263] lock_acquire+0x2c7/0x390 [ 30.625868] __mutex_lock+0xae/0x9f0 [ 30.626451] io_cqring_overflow_flush.part.95+0x6d/0x70 [ 30.627278] io_uring_poll+0xcb/0xd0 [ 30.627890] ep_item_poll.isra.14+0x4e/0x90 [ 30.628531] do_epoll_ctl+0xb7e/0x1120 [ 30.629122] __x64_sys_epoll_ctl+0x70/0xb0 [ 30.629770] do_syscall_64+0x2d/0x40 [ 30.630332] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 30.631187] [ 30.631187] -> #0 (&ep->mtx){+.+.}-{3:3}: [ 30.631985] check_prevs_add+0x226/0xb00 [ 30.632584] __lock_acquire+0x1237/0x13a0 [ 30.633207] lock_acquire+0x2c7/0x390 [ 30.633740] __mutex_lock+0xae/0x9f0 [ 30.634258] __ep_eventpoll_poll+0x9f/0x220 [ 30.634879] __io_arm_poll_handler+0xbf/0x220 [ 30.635462] io_issue_sqe+0xa6b/0x13e0 [ 30.635982] __io_queue_sqe+0x10b/0x550 [ 30.636648] io_queue_sqe+0x235/0x470 [ 30.637281] io_submit_sqes+0xcce/0xf10 [ 30.637839] __x64_sys_io_uring_enter+0x3fb/0x5b0 [ 30.638465] do_syscall_64+0x2d/0x40 [ 30.638999] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 30.639643] [ 30.639643] other info that might help us debug this: [ 30.639643] [ 30.640618] Possible unsafe locking scenario: [ 30.640618] [ 30.641402] CPU0 CPU1 [ 30.641938] ---- ---- [ 30.642664] lock(&ctx->uring_lock); [ 30.643425] lock(&ep->mtx); [ 30.644498] lock(&ctx->uring_lock); [ 30.645668] lock(&ep->mtx); [ 30.646321] [ 30.646321] * DEADLOCK * [ 30.646321] [ 30.647642] 1 lock held by a.out/1128: [ 30.648424] #0: ffff88810e952be8 (&ctx->uring_lock){+.+.}-{3:3}, at: __x64_sys_io_uring_enter+0x3f0/0x5b0 [ 30.649954] [ 30.649954] stack backtrace: [ 30.650592] CPU: 1 PID: 1128 Comm: a.out Not tainted 5.11.0-rc3-next-20210115 #1 [ 30.651554] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [ 30.652290] Call Trace: [ 30.652688] dump_stack+0xac/0xe3 [ 30.653164] check_noncircular+0x11e/0x130 [ 30.653747] ? check_prevs_add+0x226/0xb00 [ 30.654303] check_prevs_add+0x226/0xb00 [ 30.654845] ? add_lock_to_list.constprop.49+0xac/0x1d0 [ 30.655564] __lock_acquire+0x1237/0x13a0 [ 30.656262] lock_acquire+0x2c7/0x390 [ 30.656788] ? __ep_eventpoll_poll+0x9f/0x220 [ 30.657379] ? __io_queue_proc.isra.88+0x180/0x180 [ 30.658014] __mutex_lock+0xae/0x9f0 [ 30.658524] ? __ep_eventpoll_poll+0x9f/0x220 [ 30.659112] ? mark_held_locks+0x5a/0x80 [ 30.659648] ? __ep_eventpoll_poll+0x9f/0x220 [ 30.660229] ? _raw_spin_unlock_irqrestore+0x2d/0x40 [ 30.660885] ? trace_hardirqs_on+0x46/0x110 [ 30.661471] ? __io_queue_proc.isra.88+0x180/0x180 [ 30.662102] ? __ep_eventpoll_poll+0x9f/0x220 [ 30.662696] __ep_eventpoll_poll+0x9f/0x220 [ 30.663273] ? __ep_eventpoll_poll+0x220/0x220 [ 30.663875] __io_arm_poll_handler+0xbf/0x220 [ 30.664463] io_issue_sqe+0xa6b/0x13e0 [ 30.664984] ? __lock_acquire+0x782/0x13a0 [ 30.665544] ? __io_queue_proc.isra.88+0x180/0x180 [ 30.666170] ? __io_queue_sqe+0x10b/0x550 [ 30.666725] __io_queue_sqe+0x10b/0x550 [ 30.667252] ? __fget_files+0x131/0x260 [ 30.667791] ? io_req_prep+0xd8/0x1090 [ 30.668316] ? io_queue_sqe+0x235/0x470 [ 30.668868] io_queue_sqe+0x235/0x470 [ 30.669398] io_submit_sqes+0xcce/0xf10 [ 30.669931] ? xa_load+0xe4/0x1c0 [ 30.670425] __x64_sys_io_uring_enter+0x3fb/0x5b0 [ 30.671051] ? lockdep_hardirqs_on_prepare+0xde/0x180 [ 30.671719] ? syscall_enter_from_user_mode+0x2b/0x80 [ 30.672380] do_syscall_64+0x2d/0x40 [ 30.672901] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 30.673503] RIP: 0033:0x7fd89c813239 [ 30.673962] 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 [ 30.675920] RSP: 002b:00007ffc65a7c628 EFLAGS: 00000217 ORIG_RAX: 00000000000001aa [ 30.676791] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd89c813239 [ 30.677594] RDX: 0000000000000000 RSI: 0000000000000014 RDI: 0000000000000003 [ 30.678678] RBP: 00007ffc65a7c720 R08: 0000000000000000 R09: 0000000003000000 [ 30.679492] R10: 0000000000000000 R11: 0000000000000217 R12: 0000000000400ff0 [ 30.680282] R13: 00007ffc65a7c840 R14: 0000000000000000 R15: 0000000000000000 This might happen if we do epoll_wait on a uring fd while reading/writing the former epoll fd in a sqe in the former uring instance. So let's don't flush cqring overflow list, just do a simple check. Reported-by: Abaci <abaci@linux.alibaba.com> Fixes: `6c503150ae` ("io_uring: patch up IOPOLL overflow_flush sync") Signed-off-by: Hao Xu <haoxu@linux.alibaba.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>		2021-03-04 11:37:49 +01:00
arch	KVM: x86: Restore all 64 bits of DR6 and DR7 during RSM on x86-64	2021-03-04 11:37:48 +01:00
block	bsg: free the request before return error code	2021-03-04 11:37:42 +01:00
certs	.gitignore: add SPDX License Identifier	2020-03-25 11:50:48 +01:00
crypto	crypto: ecdh_helper - Ensure 'len >= secret.len' in decode_key()	2021-03-04 11:37:49 +01:00
Documentation	perf/arm-cmn: Fix PMU instance naming	2021-03-04 11:37:44 +01:00
drivers	hwrng: timeriomem - Fix cooldown period calculation	2021-03-04 11:37:49 +01:00
fs	io_uring: fix possible deadlock in io_uring_poll	2021-03-04 11:37:49 +01:00
include	drm/fourcc: fix Amlogic format modifier masks	2021-03-04 11:37:38 +01:00
init	fgraph: Initialize tracing_graph_pause at task creation	2021-02-10 09:29:16 +01:00
ipc	ipc: adjust proc_ipc_sem_dointvec definition to match prototype	2020-09-05 12:14:29 -07:00
kernel	locking/lockdep: Avoid unmatched unlock	2021-03-04 11:37:47 +01:00
lib	udp: fix skb_copy_and_csum_datagram with odd segment sizes	2021-02-17 11:02:28 +01:00
LICENSES	LICENSES/deprecated: add Zlib license text	2020-09-16 14:33:49 +02:00
mm	mm: provide a saner PTE walking API for modules	2021-02-26 10:13:01 +01:00
net	tty: convert tty_ldisc_ops 'read()' function to take a kernel pointer	2021-03-04 11:37:36 +01:00
samples	samples/bpf: Fix possible hang in xdpsock with multiple threads	2020-12-30 11:53:49 +01:00
scripts	scripts/recordmcount.pl: support big endian for ARCH sh	2021-02-26 10:13:02 +01:00
security	evm: Fix memleak in init_desc	2021-03-04 11:37:40 +01:00
sound	ASoC: SOF: debug: Fix a potential issue on string buffer termination	2021-03-04 11:37:47 +01:00
tools	selftests: mptcp: fix ACKRX debug message	2021-03-04 11:37:33 +01:00
usr	Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2020-08-07 13:29:39 -07:00
virt	KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped()	2021-02-26 10:13:01 +01:00
.clang-format	RDMA 5.10 pull request	2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore	Opt out of scripts/get_maintainer.pl	2019-05-16 10:53:40 -07:00
.gitattributes	.gitattributes: use 'dts' diff driver for dts files	2019-12-04 19:44:11 -08:00
.gitignore	.gitignore: docs: ignore sphinx_*/ directories	2020-09-10 10:44:31 -06:00
.mailmap	mailmap: add two more addresses of Uwe Kleine-König	2020-12-06 10:19:07 -08:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: Move Jason Cooper to CREDITS	2020-11-30 10:20:34 +01:00
Kbuild	kbuild: rename hostprogs-y/always to hostprogs/always-y	2020-02-04 01:53:07 +09:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net	2020-12-10 15:30:13 -08:00
Makefile	Linux 5.10.19	2021-02-26 10:14:35 +01:00
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README

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