diff options
| author | Chris Wilson <chris@chris-wilson.co.uk> | 2016-08-22 14:28:20 +0100 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2016-08-22 15:08:05 +0100 |
| commit | 637ee29eff53fd718a454aacd3b7190cb4e15df8 (patch) | |
| tree | 6ea0c4197b9af2fb8bf71a0534953b135d43c74c /drivers/gpu/drm/i915/intel_i2c.c | |
| parent | 34730fed9fd54e893ec0177c97a509de3ee0a5a4 (diff) | |
drm/i915: Fix nesting of filelist_mutex vs struct_mutex in i915_ppgtt_info
An unlikely ABBA deadlock in debugfs that no one has reported.
[ 284.922349] ======================================================
[ 284.922355] [ INFO: possible circular locking dependency detected ]
[ 284.922361] 4.8.0-rc2+ #430 Tainted: G W
[ 284.922366] -------------------------------------------------------
[ 284.922371] cat/1197 is trying to acquire lock:
[ 284.922376] (&dev->filelist_mutex){+.+...}, at: [<ffffffffa0055ba2>] i915_ppgtt_info+0x82/0x390 [i915]
[ 284.922423]
[ 284.922423] but task is already holding lock:
[ 284.922429] (&dev->struct_mutex){+.+.+.}, at: [<ffffffffa0055b55>] i915_ppgtt_info+0x35/0x390 [i915]
[ 284.922465]
[ 284.922465] which lock already depends on the new lock.
[ 284.922465]
[ 284.922471]
[ 284.922471] the existing dependency chain (in reverse order) is:
[ 284.922477]
-> #1 (&dev->struct_mutex){+.+.+.}:
[ 284.922493] [<ffffffff81087710>] lock_acquire+0x60/0x80
[ 284.922505] [<ffffffff8143e96f>] mutex_lock_nested+0x5f/0x360
[ 284.922520] [<ffffffffa004f877>] print_context_stats+0x37/0xf0 [i915]
[ 284.922549] [<ffffffffa00535f5>] i915_gem_object_info+0x265/0x490 [i915]
[ 284.922581] [<ffffffff81144491>] seq_read+0xe1/0x3b0
[ 284.922592] [<ffffffff811f77b3>] full_proxy_read+0x83/0xb0
[ 284.922604] [<ffffffff8111ba03>] __vfs_read+0x23/0x110
[ 284.922616] [<ffffffff8111c9b9>] vfs_read+0x89/0x110
[ 284.922626] [<ffffffff8111dbf4>] SyS_read+0x44/0xa0
[ 284.922636] [<ffffffff81442be9>] entry_SYSCALL_64_fastpath+0x1c/0xac
[ 284.922648]
-> #0 (&dev->filelist_mutex){+.+...}:
[ 284.922667] [<ffffffff810871fc>] __lock_acquire+0x10fc/0x1270
[ 284.922678] [<ffffffff81087710>] lock_acquire+0x60/0x80
[ 284.922689] [<ffffffff8143e96f>] mutex_lock_nested+0x5f/0x360
[ 284.922701] [<ffffffffa0055ba2>] i915_ppgtt_info+0x82/0x390 [i915]
[ 284.922729] [<ffffffff81144491>] seq_read+0xe1/0x3b0
[ 284.922739] [<ffffffff811f77b3>] full_proxy_read+0x83/0xb0
[ 284.922750] [<ffffffff8111ba03>] __vfs_read+0x23/0x110
[ 284.922761] [<ffffffff8111c9b9>] vfs_read+0x89/0x110
[ 284.922771] [<ffffffff8111dbf4>] SyS_read+0x44/0xa0
[ 284.922781] [<ffffffff81442be9>] entry_SYSCALL_64_fastpath+0x1c/0xac
[ 284.922793]
[ 284.922793] other info that might help us debug this:
[ 284.922793]
[ 284.922809] Possible unsafe locking scenario:
[ 284.922809]
[ 284.922818] CPU0 CPU1
[ 284.922825] ---- ----
[ 284.922831] lock(&dev->struct_mutex);
[ 284.922842] lock(&dev->filelist_mutex);
[ 284.922854] lock(&dev->struct_mutex);
[ 284.922865] lock(&dev->filelist_mutex);
[ 284.922875]
[ 284.922875] *** DEADLOCK ***
[ 284.922875]
[ 284.922888] 3 locks held by cat/1197:
[ 284.922895] #0: (debugfs_srcu){......}, at: [<ffffffff811f7730>] full_proxy_read+0x0/0xb0
[ 284.922919] #1: (&p->lock){+.+.+.}, at: [<ffffffff811443e8>] seq_read+0x38/0x3b0
[ 284.922942] #2: (&dev->struct_mutex){+.+.+.}, at: [<ffffffffa0055b55>] i915_ppgtt_info+0x35/0x390 [i915]
[ 284.922983]
Fixes: 1d2ac403ae3b ("drm: Protect dev->filelist with its own mutex")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160822132820.21725-1-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/intel_i2c.c')
0 files changed, 0 insertions, 0 deletions