Chris Wilson 637ee29eff 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: 1d2ac403ae ("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		2016-08-22 15:08:05 +01:00
..
drm	drm/i915: Fix nesting of filelist_mutex vs struct_mutex in i915_ppgtt_info	2016-08-22 15:08:05 +01:00
host1x	gpu: host1x: Remove useless local variable	2016-06-23 11:59:33 +02:00
ipu-v3	gpu: ipu-v3: rename CSI client device	2016-08-08 11:44:20 +02:00
vga	vga_switcheroo: Sphinxify docs	2016-07-12 16:14:36 +02:00
Makefile