[PATCH v3 1/3] drm/xe/xe_guc_submit: Fix exec queue stop race condition

[PATCH v3 1/3] drm/xe/xe_guc_submit: Fix exec queue stop race condition

[Jonathan Cavitt]

Reorder the xe_sched_tdr_queue_imm and set_exec_queue_banned calls in
guc_exec_queue_stop.  This prevents a possible race condition between
the two events in which it's possible for xe_sched_tdr_queue_imm to
wake the ufence waiter before the exec queue is banned, causing the
ufence waiter to miss the banned state.

Suggested-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
---

v2: Expand on cause of race condition

 drivers/gpu/drm/xe/xe_guc_submit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 9c30bd9ac8c06..1a6abb10a960e 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1430,8 +1430,8 @@ static void guc_exec_queue_stop(struct xe_guc *guc, struct xe_exec_queue *q)
 			    !xe_sched_job_completed(job)) ||
 			    xe_sched_invalidate_job(job, 2)) {
 				trace_xe_sched_job_ban(job);
-				xe_sched_tdr_queue_imm(&q->guc->sched);
 				set_exec_queue_banned(q);
+				xe_sched_tdr_queue_imm(&q->guc->sched);
 			}
 		}
 	}
-- 
2.25.1

[PATCH v3 2/3] drm/xe/xe_guc_submit: Allow lr exec queues to be banned

[Jonathan Cavitt]

LR queues currently don't get banned during a GT/GuC reset because they
lack a job.  Though they don't have a job to detect the reset status of,
it's still possible to tell when they should be banned by looking at the
LRC: if the LRC head and tail don't match, then the exec queue should be
banned and cleaned up.

This also requires swapping the usage of xe_sched_tdr_queue_imm with
xe_guc_exec_queue_trigger_cleanup, as the former is specific to non-lr
exec queues.

Suggested-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
---

v2:
- Fix Subject line
- Modify change slightly to remove need for "ban" boolean

v3: Revert change involving "ban" boolean to version 1

 drivers/gpu/drm/xe/xe_guc_submit.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 1a6abb10a960e..7e851cd486c92 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1424,15 +1424,23 @@ static void guc_exec_queue_stop(struct xe_guc *guc, struct xe_exec_queue *q)
 	 */
 	if (!(q->flags & (EXEC_QUEUE_FLAG_KERNEL | EXEC_QUEUE_FLAG_VM))) {
 		struct xe_sched_job *job = xe_sched_first_pending_job(sched);
+		bool ban = false;
 
 		if (job) {
 			if ((xe_sched_job_started(job) &&
 			    !xe_sched_job_completed(job)) ||
 			    xe_sched_invalidate_job(job, 2)) {
 				trace_xe_sched_job_ban(job);
-				set_exec_queue_banned(q);
-				xe_sched_tdr_queue_imm(&q->guc->sched);
+				ban = true;
 			}
+		} else if (xe_exec_queue_is_lr(q) &&
+			   (xe_lrc_ring_head(q->lrc) != q->lrc->ring.tail)) {
+			ban = true
+		}
+		
+		if (ban) {
+			set_exec_queue_banned(q);
+			xe_guc_exec_queue_trigger_cleanup(q);
 		}
 	}
 }
-- 
2.25.1

[PATCH v3 3/3] drm/xe/xe_guc_submit: Declare reset if banned or killed

[Jonathan Cavitt]

Add an additional condition to the reset_status guc_exec_queue_op that
returns true if the exec queue has been banned or killed.  The
reset_status op is only used for exiting any xe_wait_user_fence_ioctl
that waits on an exec queue without timing out, so doing this will exit
the ioctl early in cases where the exec queue can no longer function,
such as after a GuC stop during a reset.

Suggested-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
---
 drivers/gpu/drm/xe/xe_guc_submit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 7e851cd486c92..03060b23d0f55 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1371,7 +1371,7 @@ static void guc_exec_queue_resume(struct xe_exec_queue *q)
 
 static bool guc_exec_queue_reset_status(struct xe_exec_queue *q)
 {
-	return exec_queue_reset(q);
+	return exec_queue_reset(q) || exec_queue_killed_or_banned(q);
 }
 
 /*
-- 
2.25.1

✓ CI.Patch_applied: success for series starting with [v3,1/3] drm/xe/xe_guc_submit: Fix exec queue stop race condition

[Patchwork]

== Series Details ==

Series: series starting with [v3,1/3] drm/xe/xe_guc_submit: Fix exec queue stop race condition
URL   : https://patchwork.freedesktop.org/series/132081/
State : success

== Summary ==

=== Applying kernel patches on branch 'drm-tip' with base: ===
Base commit: 8cb1ee178ef7 drm-tip: 2024y-04m-05d-16h-52m-43s UTC integration manifest
=== git am output follows ===
.git/rebase-apply/patch:35: trailing whitespace.
		
warning: 1 line adds whitespace errors.
Applying: drm/xe/xe_guc_submit: Fix exec queue stop race condition
Applying: drm/xe/xe_guc_submit: Allow lr exec queues to be banned
Applying: drm/xe/xe_guc_submit: Declare reset if banned or killed

✗ CI.checkpatch: warning for series starting with [v3,1/3] drm/xe/xe_guc_submit: Fix exec queue stop race condition

[Patchwork]

== Series Details ==

Series: series starting with [v3,1/3] drm/xe/xe_guc_submit: Fix exec queue stop race condition
URL   : https://patchwork.freedesktop.org/series/132081/
State : warning

== Summary ==

+ KERNEL=/kernel
+ git clone https://gitlab.freedesktop.org/drm/maintainer-tools mt
Cloning into 'mt'...
warning: redirecting to https://gitlab.freedesktop.org/drm/maintainer-tools.git/
+ git -C mt rev-list -n1 origin/master
10b531c2aeb176a1a539b4a77216232f97719cec
+ cd /kernel
+ git config --global --add safe.directory /kernel
+ git log -n1
commit 1f3fe4cfad873ed7d6c5a6122acd01db404642a4
Author: Jonathan Cavitt <jonathan.cavitt@intel.com>
Date:   Fri Apr 5 06:51:00 2024 -0700

    drm/xe/xe_guc_submit: Declare reset if banned or killed
    
    Add an additional condition to the reset_status guc_exec_queue_op that
    returns true if the exec queue has been banned or killed.  The
    reset_status op is only used for exiting any xe_wait_user_fence_ioctl
    that waits on an exec queue without timing out, so doing this will exit
    the ioctl early in cases where the exec queue can no longer function,
    such as after a GuC stop during a reset.
    
    Suggested-by: Matthew Brost <matthew.brost@intel.com>
    Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
+ /mt/dim checkpatch 8cb1ee178ef7e504e233814ef50c1f18f42dac72 drm-intel
b4a6a304abd7 drm/xe/xe_guc_submit: Fix exec queue stop race condition
41e462090b81 drm/xe/xe_guc_submit: Allow lr exec queues to be banned
-:43: ERROR:TRAILING_WHITESPACE: trailing whitespace
#43: FILE: drivers/gpu/drm/xe/xe_guc_submit.c:1440:
+^I^I$

total: 1 errors, 0 warnings, 0 checks, 25 lines checked
1f3fe4cfad87 drm/xe/xe_guc_submit: Declare reset if banned or killed

✗ CI.KUnit: failure for series starting with [v3,1/3] drm/xe/xe_guc_submit: Fix exec queue stop race condition

[Patchwork]

== Series Details ==

Series: series starting with [v3,1/3] drm/xe/xe_guc_submit: Fix exec queue stop race condition
URL   : https://patchwork.freedesktop.org/series/132081/
State : failure

== Summary ==

+ trap cleanup EXIT
+ /kernel/tools/testing/kunit/kunit.py run --kunitconfig /kernel/drivers/gpu/drm/xe/.kunitconfig
ERROR:root:../arch/x86/um/user-offsets.c:17:6: warning: no previous prototype for ‘foo’ [-Wmissing-prototypes]
   17 | void foo(void)
      |      ^~~
In file included from ../arch/um/kernel/asm-offsets.c:1:
../arch/x86/um/shared/sysdep/kernel-offsets.h:9:6: warning: no previous prototype for ‘foo’ [-Wmissing-prototypes]
    9 | void foo(void)
      |      ^~~
../arch/x86/um/bugs_64.c:9:6: warning: no previous prototype for ‘arch_check_bugs’ [-Wmissing-prototypes]
    9 | void arch_check_bugs(void)
      |      ^~~~~~~~~~~~~~~
../arch/x86/um/bugs_64.c:13:6: warning: no previous prototype for ‘arch_examine_signal’ [-Wmissing-prototypes]
   13 | void arch_examine_signal(int sig, struct uml_pt_regs *regs)
      |      ^~~~~~~~~~~~~~~~~~~
../arch/x86/um/fault.c:18:5: warning: no previous prototype for ‘arch_fixup’ [-Wmissing-prototypes]
   18 | int arch_fixup(unsigned long address, struct uml_pt_regs *regs)
      |     ^~~~~~~~~~
../arch/x86/um/os-Linux/registers.c:146:15: warning: no previous prototype for ‘get_thread_reg’ [-Wmissing-prototypes]
  146 | unsigned long get_thread_reg(int reg, jmp_buf *buf)
      |               ^~~~~~~~~~~~~~
../arch/um/os-Linux/skas/process.c:107:6: warning: no previous prototype for ‘wait_stub_done’ [-Wmissing-prototypes]
  107 | void wait_stub_done(int pid)
      |      ^~~~~~~~~~~~~~
../arch/x86/um/vdso/um_vdso.c:16:5: warning: no previous prototype for ‘__vdso_clock_gettime’ [-Wmissing-prototypes]
   16 | int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
      |     ^~~~~~~~~~~~~~~~~~~~
../arch/x86/um/vdso/um_vdso.c:30:5: warning: no previous prototype for ‘__vdso_gettimeofday’ [-Wmissing-prototypes]
   30 | int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
      |     ^~~~~~~~~~~~~~~~~~~
../arch/x86/um/vdso/um_vdso.c:44:21: warning: no previous prototype for ‘__vdso_time’ [-Wmissing-prototypes]
   44 | __kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
      |                     ^~~~~~~~~~~
../arch/x86/um/vdso/um_vdso.c:57:1: warning: no previous prototype for ‘__vdso_getcpu’ [-Wmissing-prototypes]
   57 | __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
      | ^~~~~~~~~~~~~
../arch/um/os-Linux/skas/process.c:683:6: warning: no previous prototype for ‘__switch_mm’ [-Wmissing-prototypes]
  683 | void __switch_mm(struct mm_id *mm_idp)
      |      ^~~~~~~~~~~
../arch/x86/um/os-Linux/mcontext.c:7:6: warning: no previous prototype for ‘get_regs_from_mc’ [-Wmissing-prototypes]
    7 | void get_regs_from_mc(struct uml_pt_regs *regs, mcontext_t *mc)
      |      ^~~~~~~~~~~~~~~~
../arch/um/kernel/skas/mmu.c:17:5: warning: no previous prototype for ‘init_new_context’ [-Wmissing-prototypes]
   17 | int init_new_context(struct task_struct *task, struct mm_struct *mm)
      |     ^~~~~~~~~~~~~~~~
../arch/um/kernel/skas/mmu.c:60:6: warning: no previous prototype for ‘destroy_context’ [-Wmissing-prototypes]
   60 | void destroy_context(struct mm_struct *mm)
      |      ^~~~~~~~~~~~~~~
../arch/x86/um/ptrace_64.c:111:5: warning: no previous prototype for ‘poke_user’ [-Wmissing-prototypes]
  111 | int poke_user(struct task_struct *child, long addr, long data)
      |     ^~~~~~~~~
../arch/x86/um/ptrace_64.c:171:5: warning: no previous prototype for ‘peek_user’ [-Wmissing-prototypes]
  171 | int peek_user(struct task_struct *child, long addr, long data)
      |     ^~~~~~~~~
../arch/um/os-Linux/main.c:187:7: warning: no previous prototype for ‘__wrap_malloc’ [-Wmissing-prototypes]
  187 | void *__wrap_malloc(int size)
      |       ^~~~~~~~~~~~~
../arch/um/os-Linux/main.c:208:7: warning: no previous prototype for ‘__wrap_calloc’ [-Wmissing-prototypes]
  208 | void *__wrap_calloc(int n, int size)
      |       ^~~~~~~~~~~~~
../arch/um/os-Linux/main.c:222:6: warning: no previous prototype for ‘__wrap_free’ [-Wmissing-prototypes]
  222 | void __wrap_free(void *ptr)
      |      ^~~~~~~~~~~
../arch/um/kernel/skas/process.c:36:12: warning: no previous prototype for ‘start_uml’ [-Wmissing-prototypes]
   36 | int __init start_uml(void)
      |            ^~~~~~~~~
../arch/um/os-Linux/mem.c:28:6: warning: no previous prototype for ‘kasan_map_memory’ [-Wmissing-prototypes]
   28 | void kasan_map_memory(void *start, size_t len)
      |      ^~~~~~~~~~~~~~~~
../arch/um/os-Linux/mem.c:212:13: warning: no previous prototype for ‘check_tmpexec’ [-Wmissing-prototypes]
  212 | void __init check_tmpexec(void)
      |             ^~~~~~~~~~~~~
../arch/um/os-Linux/signal.c:75:6: warning: no previous prototype for ‘sig_handler’ [-Wmissing-prototypes]
   75 | void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
      |      ^~~~~~~~~~~
../arch/um/os-Linux/signal.c:111:6: warning: no previous prototype for ‘timer_alarm_handler’ [-Wmissing-prototypes]
  111 | void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
      |      ^~~~~~~~~~~~~~~~~~~
../arch/x86/um/signal.c:560:6: warning: no previous prototype for ‘sys_rt_sigreturn’ [-Wmissing-prototypes]
  560 | long sys_rt_sigreturn(void)
      |      ^~~~~~~~~~~~~~~~
../arch/um/os-Linux/start_up.c:301:12: warning: no previous prototype for ‘parse_iomem’ [-Wmissing-prototypes]
  301 | int __init parse_iomem(char *str, int *add)
      |            ^~~~~~~~~~~
../arch/um/kernel/mem.c:202:8: warning: no previous prototype for ‘pgd_alloc’ [-Wmissing-prototypes]
  202 | pgd_t *pgd_alloc(struct mm_struct *mm)
      |        ^~~~~~~~~
../arch/um/kernel/mem.c:215:7: warning: no previous prototype for ‘uml_kmalloc’ [-Wmissing-prototypes]
  215 | void *uml_kmalloc(int size, int flags)
      |       ^~~~~~~~~~~
../arch/um/kernel/process.c:51:5: warning: no previous prototype for ‘pid_to_processor_id’ [-Wmissing-prototypes]
   51 | int pid_to_processor_id(int pid)
      |     ^~~~~~~~~~~~~~~~~~~
../arch/um/kernel/process.c:87:7: warning: no previous prototype for ‘__switch_to’ [-Wmissing-prototypes]
   87 | void *__switch_to(struct task_struct *from, struct task_struct *to)
      |       ^~~~~~~~~~~
../arch/um/kernel/process.c:140:6: warning: no previous prototype for ‘fork_handler’ [-Wmissing-prototypes]
  140 | void fork_handler(void)
      |      ^~~~~~~~~~~~
../arch/um/kernel/process.c:217:6: warning: no previous prototype for ‘arch_cpu_idle’ [-Wmissing-prototypes]
  217 | void arch_cpu_idle(void)
      |      ^~~~~~~~~~~~~
../arch/um/kernel/process.c:253:5: warning: no previous prototype for ‘copy_to_user_proc’ [-Wmissing-prototypes]
  253 | int copy_to_user_proc(void __user *to, void *from, int size)
      |     ^~~~~~~~~~~~~~~~~
../arch/um/kernel/process.c:263:5: warning: no previous prototype for ‘clear_user_proc’ [-Wmissing-prototypes]
  263 | int clear_user_proc(void __user *buf, int size)
      |     ^~~~~~~~~~~~~~~
../arch/um/kernel/process.c:271:6: warning: no previous prototype for ‘set_using_sysemu’ [-Wmissing-prototypes]
  271 | void set_using_sysemu(int value)
      |      ^~~~~~~~~~~~~~~~
../arch/um/kernel/process.c:278:5: warning: no previous prototype for ‘get_using_sysemu’ [-Wmissing-prototypes]
  278 | int get_using_sysemu(void)
      |     ^~~~~~~~~~~~~~~~
../arch/um/kernel/process.c:316:12: warning: no previous prototype for ‘make_proc_sysemu’ [-Wmissing-prototypes]
  316 | int __init make_proc_sysemu(void)
      |            ^~~~~~~~~~~~~~~~
../arch/um/kernel/process.c:348:15: warning: no previous prototype for ‘arch_align_stack’ [-Wmissing-prototypes]
  348 | unsigned long arch_align_stack(unsigned long sp)
      |               ^~~~~~~~~~~~~~~~
../arch/um/kernel/reboot.c:45:6: warning: no previous prototype for ‘machine_restart’ [-Wmissing-prototypes]
   45 | void machine_restart(char * __unused)
      |      ^~~~~~~~~~~~~~~
../arch/um/kernel/reboot.c:51:6: warning: no previous prototype for ‘machine_power_off’ [-Wmissing-prototypes]
   51 | void machine_power_off(void)
      |      ^~~~~~~~~~~~~~~~~
../arch/um/kernel/reboot.c:57:6: warning: no previous prototype for ‘machine_halt’ [-Wmissing-prototypes]
   57 | void machine_halt(void)
      |      ^~~~~~~~~~~~
../arch/x86/um/syscalls_64.c:48:6: warning: no previous prototype for ‘arch_switch_to’ [-Wmissing-prototypes]
   48 | void arch_switch_to(struct task_struct *to)
      |      ^~~~~~~~~~~~~~
../arch/um/kernel/tlb.c:579:6: warning: no previous prototype for ‘flush_tlb_mm_range’ [-Wmissing-prototypes]
  579 | void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
      |      ^~~~~~~~~~~~~~~~~~
../arch/um/kernel/tlb.c:594:6: warning: no previous prototype for ‘force_flush_all’ [-Wmissing-prototypes]
  594 | void force_flush_all(void)
      |      ^~~~~~~~~~~~~~~
../arch/um/kernel/um_arch.c:408:19: warning: no previous prototype for ‘read_initrd’ [-Wmissing-prototypes]
  408 | int __init __weak read_initrd(void)
      |                   ^~~~~~~~~~~
../arch/um/kernel/um_arch.c:461:7: warning: no previous prototype for ‘text_poke’ [-Wmissing-prototypes]
  461 | void *text_poke(void *addr, const void *opcode, size_t len)
      |       ^~~~~~~~~
../arch/um/kernel/um_arch.c:473:6: warning: no previous prototype for ‘text_poke_sync’ [-Wmissing-prototypes]
  473 | void text_poke_sync(void)
      |      ^~~~~~~~~~~~~~
../arch/um/kernel/kmsg_dump.c:60:12: warning: no previous prototype for ‘kmsg_dumper_stdout_init’ [-Wmissing-prototypes]
   60 | int __init kmsg_dumper_stdout_init(void)
      |            ^~~~~~~~~~~~~~~~~~~~~~~
../drivers/gpu/drm/xe/xe_guc_submit.c: In function ‘guc_exec_queue_stop’:
../drivers/gpu/drm/xe/xe_guc_submit.c:1438:14: error: expected ‘;’ before ‘}’ token
 1438 |    ban = true
      |              ^
      |              ;
 1439 |   }
      |   ~           
make[7]: *** [../scripts/Makefile.build:244: drivers/gpu/drm/xe/xe_guc_submit.o] Error 1
make[7]: *** Waiting for unfinished jobs....
make[6]: *** [../scripts/Makefile.build:485: drivers/gpu/drm/xe] Error 2
make[6]: *** Waiting for unfinished jobs....
../lib/iomap.c:156:5: warning: no previous prototype for ‘ioread64_lo_hi’ [-Wmissing-prototypes]
  156 | u64 ioread64_lo_hi(const void __iomem *addr)
      |     ^~~~~~~~~~~~~~
../lib/iomap.c:163:5: warning: no previous prototype for ‘ioread64_hi_lo’ [-Wmissing-prototypes]
  163 | u64 ioread64_hi_lo(const void __iomem *addr)
      |     ^~~~~~~~~~~~~~
../lib/iomap.c:170:5: warning: no previous prototype for ‘ioread64be_lo_hi’ [-Wmissing-prototypes]
  170 | u64 ioread64be_lo_hi(const void __iomem *addr)
      |     ^~~~~~~~~~~~~~~~
../lib/iomap.c:178:5: warning: no previous prototype for ‘ioread64be_hi_lo’ [-Wmissing-prototypes]
  178 | u64 ioread64be_hi_lo(const void __iomem *addr)
      |     ^~~~~~~~~~~~~~~~
../lib/iomap.c:264:6: warning: no previous prototype for ‘iowrite64_lo_hi’ [-Wmissing-prototypes]
  264 | void iowrite64_lo_hi(u64 val, void __iomem *addr)
      |      ^~~~~~~~~~~~~~~
../lib/iomap.c:272:6: warning: no previous prototype for ‘iowrite64_hi_lo’ [-Wmissing-prototypes]
  272 | void iowrite64_hi_lo(u64 val, void __iomem *addr)
      |      ^~~~~~~~~~~~~~~
../lib/iomap.c:280:6: warning: no previous prototype for ‘iowrite64be_lo_hi’ [-Wmissing-prototypes]
  280 | void iowrite64be_lo_hi(u64 val, void __iomem *addr)
      |      ^~~~~~~~~~~~~~~~~
../lib/iomap.c:288:6: warning: no previous prototype for ‘iowrite64be_hi_lo’ [-Wmissing-prototypes]
  288 | void iowrite64be_hi_lo(u64 val, void __iomem *addr)
      |      ^~~~~~~~~~~~~~~~~
make[5]: *** [../scripts/Makefile.build:485: drivers/gpu/drm] Error 2
make[4]: *** [../scripts/Makefile.build:485: drivers/gpu] Error 2
make[3]: *** [../scripts/Makefile.build:485: drivers] Error 2
make[2]: *** [/kernel/Makefile:1919: .] Error 2
make[1]: *** [/kernel/Makefile:240: __sub-make] Error 2
make: *** [Makefile:240: __sub-make] Error 2

[17:11:29] Configuring KUnit Kernel ...
Generating .config ...
Populating config with:
$ make ARCH=um O=.kunit olddefconfig
[17:11:33] Building KUnit Kernel ...
Populating config with:
$ make ARCH=um O=.kunit olddefconfig
Building with:
$ make ARCH=um O=.kunit --jobs=48
+ cleanup
++ stat -c %u:%g /kernel
+ chown -R 1003:1003 /kernel