From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Qian Cai <cai@lca.pw>, Thomas Gleixner <tglx@linutronix.de>,
akpm@linux-foundation.org, bigeasy@linutronix.de, cl@linux.com,
keescook@chromium.org, penberg@kernel.org, rientjes@google.com,
thgarnie@google.com, tytso@mit.edu, will@kernel.org,
Ingo Molnar <mingo@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 4.19 10/25] sched/core: Avoid spurious lock dependencies
Date: Fri, 22 Nov 2019 14:48:43 -0500 [thread overview]
Message-ID: <20191122194859.24508-10-sashal@kernel.org> (raw)
In-Reply-To: <20191122194859.24508-1-sashal@kernel.org>
From: Peter Zijlstra <peterz@infradead.org>
[ Upstream commit ff51ff84d82aea5a889b85f2b9fb3aa2b8691668 ]
While seemingly harmless, __sched_fork() does hrtimer_init(), which,
when DEBUG_OBJETS, can end up doing allocations.
This then results in the following lock order:
rq->lock
zone->lock.rlock
batched_entropy_u64.lock
Which in turn causes deadlocks when we do wakeups while holding that
batched_entropy lock -- as the random code does.
Solve this by moving __sched_fork() out from under rq->lock. This is
safe because nothing there relies on rq->lock, as also evident from the
other __sched_fork() callsite.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: bigeasy@linutronix.de
Cc: cl@linux.com
Cc: keescook@chromium.org
Cc: penberg@kernel.org
Cc: rientjes@google.com
Cc: thgarnie@google.com
Cc: tytso@mit.edu
Cc: will@kernel.org
Fixes: b7d5dc21072c ("random: add a spinlock_t to struct batched_entropy")
Link: https://lkml.kernel.org/r/20191001091837.GK4536@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/sched/core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 78ecdfae25b69..2befd2c4ce9e6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5413,10 +5413,11 @@ void init_idle(struct task_struct *idle, int cpu)
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
+ __sched_fork(0, idle);
+
raw_spin_lock_irqsave(&idle->pi_lock, flags);
raw_spin_lock(&rq->lock);
- __sched_fork(0, idle);
idle->state = TASK_RUNNING;
idle->se.exec_start = sched_clock();
idle->flags |= PF_IDLE;
--
2.20.1
next prev parent reply other threads:[~2019-11-22 19:49 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-22 19:48 [PATCH AUTOSEL 4.19 01/25] autofs: fix a leak in autofs_expire_indirect() Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 02/25] RDMA/hns: Correct the value of HNS_ROCE_HEM_CHUNK_LEN Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 03/25] xfrm: Fix memleak on xfrm state destroy Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 04/25] iwlwifi: pcie: don't consider IV len in A-MSDU Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 05/25] exportfs_decode_fh(): negative pinned may become positive without the parent locked Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 06/25] audit_get_nd(): don't unlock parent too early Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 07/25] NFC: nxp-nci: Fix NULL pointer dereference after I2C communication error Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 08/25] xfrm: release device reference for invalid state Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 09/25] Input: cyttsp4_core - fix use after free bug Sasha Levin
2019-11-22 19:48 ` Sasha Levin [this message]
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 11/25] perf/core: Consistently fail fork on allocation failures Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 12/25] ALSA: pcm: Fix stream lock usage in snd_pcm_period_elapsed() Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 13/25] drm/sun4i: tcon: Set min division of TCON0_DCLK to 1 Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 14/25] selftests: kvm: fix build with glibc >= 2.30 Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 15/25] net: usb: qmi_wwan: add support for Foxconn T77W968 LTE modules Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 16/25] slip: Fix memory leak in slip_open error path Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 17/25] net: cdc_ncm: Signedness bug in cdc_ncm_set_dgram_size() Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 18/25] slcan: Fix memory leak in error path Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 19/25] rsxx: add missed destroy_workqueue calls in remove Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 20/25] ax88172a: fix information leak on short answers Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 21/25] net: ep93xx_eth: fix mismatch of request_mem_region in remove Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 22/25] i2c: acpi: Force bus speed to 400KHz if a Silead touchscreen is present Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 23/25] i2c: core: fix use after free in of_i2c_notify Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 24/25] Input: synaptics - enable RMI mode for X1 Extreme 2nd Generation Sasha Levin
2019-11-22 19:55 ` Dmitry Torokhov
2019-12-06 12:14 ` Sasha Levin
2019-11-22 19:48 ` [PATCH AUTOSEL 4.19 25/25] net: gemini: add missed free_netdev Sasha Levin
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