forked from Minki/linux
mainlining shenanigans
70deeaddc6
This patch fixes lockdep issue due to circular locking dependency of
struct_mutex, i_mutex_key, mmap_sem, relay_channels_mutex.
For GuC log relay channel we create debugfs file that requires i_mutex_key
lock and we are doing that under struct_mutex. So we introduced newer
dependency as:
&dev->struct_mutex --> &sb->s_type->i_mutex_key#3 --> &mm->mmap_sem
However, there is dependency from mmap_sem to struct_mutex. Hence we
separate the relay create/destroy operation from under struct_mutex.
Also added runtime check of relay buffer status.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
======================================================
WARNING: possible circular locking dependency detected
4.15.0-rc6-CI-Patchwork_7614+ #1 Not tainted
------------------------------------------------------
debugfs_test/1388 is trying to acquire lock:
(&dev->struct_mutex){+.+.}, at: [<00000000d5e1d915>] i915_mutex_lock_interruptible+0x47/0x130 [i915]
but task is already holding lock:
(&mm->mmap_sem){++++}, at: [<0000000029a9c131>] __do_page_fault+0x106/0x560
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&mm->mmap_sem){++++}:
_copy_to_user+0x1e/0x70
filldir+0x8c/0xf0
dcache_readdir+0xeb/0x160
iterate_dir+0xdc/0x140
SyS_getdents+0xa0/0x130
entry_SYSCALL_64_fastpath+0x1c/0x89
-> #2 (&sb->s_type->i_mutex_key#3){++++}:
start_creating+0x59/0x110
__debugfs_create_file+0x2e/0xe0
relay_create_buf_file+0x62/0x80
relay_late_setup_files+0x84/0x250
guc_log_late_setup+0x4f/0x110 [i915]
i915_guc_log_register+0x32/0x40 [i915]
i915_driver_load+0x7b6/0x1720 [i915]
i915_pci_probe+0x2e/0x90 [i915]
pci_device_probe+0x9c/0x120
driver_probe_device+0x2a3/0x480
__driver_attach+0xd9/0xe0
bus_for_each_dev+0x57/0x90
bus_add_driver+0x168/0x260
driver_register+0x52/0xc0
do_one_initcall+0x39/0x150
do_init_module+0x56/0x1ef
load_module+0x231c/0x2d70
SyS_finit_module+0xa5/0xe0
entry_SYSCALL_64_fastpath+0x1c/0x89
-> #1 (relay_channels_mutex){+.+.}:
relay_open+0x12c/0x2b0
intel_guc_log_runtime_create+0xab/0x230 [i915]
intel_guc_init+0x81/0x120 [i915]
intel_uc_init+0x29/0xa0 [i915]
i915_gem_init+0x182/0x530 [i915]
i915_driver_load+0xaa9/0x1720 [i915]
i915_pci_probe+0x2e/0x90 [i915]
pci_device_probe+0x9c/0x120
driver_probe_device+0x2a3/0x480
__driver_attach+0xd9/0xe0
bus_for_each_dev+0x57/0x90
bus_add_driver+0x168/0x260
driver_register+0x52/0xc0
do_one_initcall+0x39/0x150
do_init_module+0x56/0x1ef
load_module+0x231c/0x2d70
SyS_finit_module+0xa5/0xe0
entry_SYSCALL_64_fastpath+0x1c/0x89
-> #0 (&dev->struct_mutex){+.+.}:
__mutex_lock+0x81/0x9b0
i915_mutex_lock_interruptible+0x47/0x130 [i915]
i915_gem_fault+0x201/0x790 [i915]
__do_fault+0x15/0x70
__handle_mm_fault+0x677/0xdc0
handle_mm_fault+0x14f/0x2f0
__do_page_fault+0x2d1/0x560
page_fault+0x4c/0x60
other info that might help us debug this:
Chain exists of:
&dev->struct_mutex --> &sb->s_type->i_mutex_key#3 --> &mm->mmap_sem
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&mm->mmap_sem);
lock(&sb->s_type->i_mutex_key#3);
lock(&mm->mmap_sem);
lock(&dev->struct_mutex);
*** DEADLOCK ***
1 lock held by debugfs_test/1388:
#0: (&mm->mmap_sem){++++}, at: [<0000000029a9c131>] __do_page_fault+0x106/0x560
stack backtrace:
CPU: 2 PID: 1388 Comm: debugfs_test Not tainted 4.15.0-rc6-CI-Patchwork_7614+ #1
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./J4205-ITX, BIOS P1.10 09/29/2016
Call Trace:
dump_stack+0x5f/0x86
print_circular_bug.isra.18+0x1d0/0x2c0
__lock_acquire+0x14ae/0x1b60
? lock_acquire+0xaf/0x200
lock_acquire+0xaf/0x200
? i915_mutex_lock_interruptible+0x47/0x130 [i915]
__mutex_lock+0x81/0x9b0
? i915_mutex_lock_interruptible+0x47/0x130 [i915]
? i915_mutex_lock_interruptible+0x47/0x130 [i915]
? i915_mutex_lock_interruptible+0x47/0x130 [i915]
i915_mutex_lock_interruptible+0x47/0x130 [i915]
? __pm_runtime_resume+0x4f/0x80
i915_gem_fault+0x201/0x790 [i915]
__do_fault+0x15/0x70
? _raw_spin_unlock+0x29/0x40
__handle_mm_fault+0x677/0xdc0
handle_mm_fault+0x14f/0x2f0
__do_page_fault+0x2d1/0x560
? page_fault+0x36/0x60
page_fault+0x4c/0x60
v2: Added lock protection to guc->log.runtime.relay_chan (Chris)
Fixed locking inside guc_flush_logs uncovered by new lockdep.
v3: Locking guc_read_update_log_buffer entirely with relay_lock. (Chris)
Prepared intel_guc_init_early. Moved relay_lock inside relay_create
relay_destroy, relay_file_create, guc_read_update_log_buffer. (Michal)
Removed struct_mutex lock around guc_log_flush and removed usage
of guc_log_has_relay() from runtime_create path as it needs
struct_mutex lock.
v4: Handle NULL relay sub buffer pointer earlier in read_update_log_buffer
(Chris). Fixed comment suffix **/. (Michal)
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104693
Testcase: igt/debugfs_test/read_all_entries # with enable_guc=1 and guc_log_level=1
Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Marta Lofstedt <marta.lofstedt@intel.com>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/1516808821-3638-3-git-send-email-sagar.a.kamble@intel.com
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