Using mutex_acquire_nest() as used in __ww_mutex_lock() fixes the
splat below. Remove superfluous line break in __ww_mutex_lock()
as well.
[ 56.999063] =============================================
[ 56.999063] [ INFO: possible recursive locking detected ]
[ 56.999065] 3.14.4-rt5 #26 Not tainted
[ 56.999065] ---------------------------------------------
[ 56.999067] Xorg/4298 is trying to acquire lock:
[ 56.999107] (reservation_ww_class_mutex){+.+.+.}, at: [<ffffffffa02b4270>] nouveau_gem_ioctl_pushbuf+0x870/0x19f0 [nouveau]
[ 56.999107]
but task is already holding lock:
[ 56.999130] (reservation_ww_class_mutex){+.+.+.}, at: [<ffffffffa02b4270>] nouveau_gem_ioctl_pushbuf+0x870/0x19f0 [nouveau]
[ 56.999131]
other info that might help us debug this:
[ 56.999131] Possible unsafe locking scenario:
[ 56.999132] CPU0
[ 56.999132] ----
[ 56.999133] lock(reservation_ww_class_mutex);
[ 56.999134] lock(reservation_ww_class_mutex);
[ 56.999134]
*** DEADLOCK ***
[ 56.999135] May be due to missing lock nesting notation
[ 56.999136] 3 locks held by Xorg/4298:
[ 56.999160] #0: (&cli->mutex){+.+.+.}, at: [<ffffffffa02b597b>] nouveau_abi16_get+0x2b/0x100 [nouveau]
[ 56.999174] #1: (reservation_ww_class_acquire){+.+...}, at: [<ffffffffa0160cd2>] drm_ioctl+0x4d2/0x610 [drm]
[ 56.999197] #2: (reservation_ww_class_mutex){+.+.+.}, at: [<ffffffffa02b4270>] nouveau_gem_ioctl_pushbuf+0x870/0x19f0 [nouveau]
[ 56.999198]
stack backtrace:
[ 56.999200] CPU: 1 PID: 4298 Comm: Xorg Not tainted 3.14.4-rt5 #26
[ 56.999200] Hardware name: MEDIONPC MS-7502/MS-7502, BIOS 6.00 PG 12/26/2007
[ 56.999203] ffffffff820309b0 ffff8802217a9ac8 ffffffff8157e53e ffffffff820309b0
[ 56.999205] ffff8802217a9b90 ffffffff810964ce ffff8802217a9b40 0000000000000246
[ 56.999207] 0000000000000003 ffffffff8204f130 0001e09300000000 0001e093347523a9
[ 56.999207] Call Trace:
[ 56.999212] [<ffffffff8157e53e>] dump_stack+0x4f/0x9d
[ 56.999215] [<ffffffff810964ce>] __lock_acquire+0x169e/0x1a50
[ 56.999218] [<ffffffff81588da9>] ? preempt_count_sub+0x49/0x50
[ 56.999219] [<ffffffff81584541>] ? _raw_spin_unlock+0x31/0x60
[ 56.999221] [<ffffffff8109701d>] lock_acquire+0x8d/0x140
[ 56.999243] [<ffffffffa02b4270>] ? nouveau_gem_ioctl_pushbuf+0x870/0x19f0 [nouveau]
[ 56.999246] [<ffffffff8158313d>] __ww_mutex_lock_interruptible+0x3d/0xf0
[ 56.999268] [<ffffffffa02b4270>] ? nouveau_gem_ioctl_pushbuf+0x870/0x19f0 [nouveau]
[ 56.999290] [<ffffffffa02b4270>] nouveau_gem_ioctl_pushbuf+0x870/0x19f0 [nouveau]
[ 56.999298] [<ffffffffa0160cd2>] ? drm_ioctl+0x4d2/0x610 [drm]
[ 56.999308] [<ffffffffa0160cd2>] drm_ioctl+0x4d2/0x610 [drm]
[ 56.999311] [<ffffffff81588da9>] ? preempt_count_sub+0x49/0x50
[ 56.999313] [<ffffffff8107cd60>] ? migrate_enable+0xe0/0x1e0
[ 56.999335] [<ffffffffa02aaece>] nouveau_drm_ioctl+0x4e/0x90 [nouveau]
[ 56.999338] [<ffffffff81185ff0>] do_vfs_ioctl+0x300/0x530
[ 56.999340] [<ffffffff8158d33b>] ? sysret_check+0x1b/0x56
[ 56.999342] [<ffffffff81094a8d>] ? trace_hardirqs_on_caller+0x10d/0x1d0
[ 56.999344] [<ffffffff81186261>] SyS_ioctl+0x41/0x80
[ 56.999345] [<ffffffff8158d316>] system_call_fastpath+0x1a/0x1f
Signed-off-by: Mike Galbraith <umgwanakikbuti@xxxxxxxxx>
---
kernel/locking/rtmutex.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1780,7 +1780,7 @@ __ww_mutex_lock_interruptible(struct ww_
might_sleep();
- mutex_acquire(&lock->base.dep_map, 0, 0, _RET_IP_);
+ mutex_acquire_nest(&lock->base.dep_map, 0, 0, &ww_ctx->dep_map, _RET_IP_);
ret = rt_mutex_slowlock(&lock->base.lock, TASK_INTERRUPTIBLE, NULL, 0, ww_ctx);
if (ret)
mutex_release(&lock->base.dep_map, 1, _RET_IP_);
@@ -1798,8 +1798,7 @@ __ww_mutex_lock(struct ww_mutex *lock, s
might_sleep();
- mutex_acquire_nest(&lock->base.dep_map, 0, 0, &ww_ctx->dep_map,
- _RET_IP_);
+ mutex_acquire_nest(&lock->base.dep_map, 0, 0, &ww_ctx->dep_map, _RET_IP_);
ret = rt_mutex_slowlock(&lock->base.lock, TASK_UNINTERRUPTIBLE, NULL, 0, ww_ctx);
if (ret)
mutex_release(&lock->base.dep_map, 1, _RET_IP_);
--
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