#include #include #include #include #include #include #include #include "debug.h" #include "tests.h" #include "machine.h" #include "thread_map.h" #include "symbol.h" #include "thread.h" #define THREADS 4 static int go_away; struct thread_data { pthread_t pt; pid_t tid; void *map; int ready[2]; }; static struct thread_data threads[THREADS]; static int thread_init(struct thread_data *td) { void *map; map = mmap(NULL, page_size, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_SHARED|MAP_ANONYMOUS, -1, 0); if (map == MAP_FAILED) { perror("mmap failed"); return -1; } td->map = map; td->tid = syscall(SYS_gettid); pr_debug("tid = %d, map = %p\n", td->tid, map); return 0; } static void *thread_fn(void *arg) { struct thread_data *td = arg; ssize_t ret; int go; if (thread_init(td)) return NULL; /* Signal thread_create thread is initialized. */ ret = write(td->ready[1], &go, sizeof(int)); if (ret != sizeof(int)) { pr_err("failed to notify\n"); return NULL; } while (!go_away) { /* Waiting for main thread to kill us. */ usleep(100); } munmap(td->map, page_size); return NULL; } static int thread_create(int i) { struct thread_data *td = &threads[i]; int err, go; if (pipe(td->ready)) return -1; err = pthread_create(&td->pt, NULL, thread_fn, td); if (!err) { /* Wait for thread initialization. */ ssize_t ret = read(td->ready[0], &go, sizeof(int)); err = ret != sizeof(int); } close(td->ready[0]); close(td->ready[1]); return err; } static int threads_create(void) { struct thread_data *td0 = &threads[0]; int i, err = 0; go_away = 0; /* 0 is main thread */ if (thread_init(td0)) return -1; for (i = 1; !err && i < THREADS; i++) err = thread_create(i); return err; } static int threads_destroy(void) { struct thread_data *td0 = &threads[0]; int i, err = 0; /* cleanup the main thread */ munmap(td0->map, page_size); go_away = 1; for (i = 1; !err && i < THREADS; i++) err = pthread_join(threads[i].pt, NULL); return err; } typedef int (*synth_cb)(struct machine *machine); static int synth_all(struct machine *machine) { return perf_event__synthesize_threads(NULL, perf_event__process, machine, 0, 500); } static int synth_process(struct machine *machine) { struct thread_map *map; int err; map = thread_map__new_by_pid(getpid()); err = perf_event__synthesize_thread_map(NULL, map, perf_event__process, machine, 0, 500); thread_map__put(map); return err; } static int mmap_events(synth_cb synth) { struct machine *machine; int err, i; /* * The threads_create will not return before all threads * are spawned and all created memory map. * * They will loop until threads_destroy is called, so we * can safely run synthesizing function. */ TEST_ASSERT_VAL("failed to create threads", !threads_create()); machine = machine__new_host(); dump_trace = verbose > 1 ? 1 : 0; err = synth(machine); dump_trace = 0; TEST_ASSERT_VAL("failed to destroy threads", !threads_destroy()); TEST_ASSERT_VAL("failed to synthesize maps", !err); /* * All data is synthesized, try to find map for each * thread object. */ for (i = 0; i < THREADS; i++) { struct thread_data *td = &threads[i]; struct addr_location al; struct thread *thread; thread = machine__findnew_thread(machine, getpid(), td->tid); pr_debug("looking for map %p\n", td->map); thread__find_addr_map(thread, PERF_RECORD_MISC_USER, MAP__FUNCTION, (unsigned long) (td->map + 1), &al); thread__put(thread); if (!al.map) { pr_debug("failed, couldn't find map\n"); err = -1; break; } pr_debug("map %p, addr %" PRIx64 "\n", al.map, al.map->start); } machine__delete_threads(machine); machine__delete(machine); return err; } /* * This test creates 'THREADS' number of threads (including * main thread) and each thread creates memory map. * * When threads are created, we synthesize them with both * (separate tests): * perf_event__synthesize_thread_map (process based) * perf_event__synthesize_threads (global) * * We test we can find all memory maps via: * thread__find_addr_map * * by using all thread objects. */ int test__mmap_thread_lookup(int subtest __maybe_unused) { /* perf_event__synthesize_threads synthesize */ TEST_ASSERT_VAL("failed with sythesizing all", !mmap_events(synth_all)); /* perf_event__synthesize_thread_map synthesize */ TEST_ASSERT_VAL("failed with sythesizing process", !mmap_events(synth_process)); return 0; } cted'>unified
authorLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
commit39cb2c9a316e77f6dfba96c543e55b6672d5a37e (patch)
tree98fe974ee4e20121253de7f61fc8d01bdb3821c1 /tools/perf/Documentation
parent2c5d9555d6d937966d79d4c6529a5f7b9206e405 (diff)
drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()
I've seen this trigger twice now, where the i915_gem_object_to_ggtt() call in intel_unpin_fb_obj() returns NULL, resulting in an oops immediately afterwards as the (inlined) call to i915_vma_unpin_fence() tries to dereference it. It seems to be some race condition where the object is going away at shutdown time, since both times happened when shutting down the X server. The call chains were different: - VT ioctl(KDSETMODE, KD_TEXT): intel_cleanup_plane_fb+0x5b/0xa0 [i915] drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper] intel_atomic_commit_tail+0x749/0xfe0 [i915] intel_atomic_commit+0x3cb/0x4f0 [i915] drm_atomic_commit+0x4b/0x50 [drm] restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper] drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper] drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper] intel_fbdev_set_par+0x18/0x70 [i915] fb_set_var+0x236/0x460 fbcon_blank+0x30f/0x350 do_unblank_screen+0xd2/0x1a0 vt_ioctl+0x507/0x12a0 tty_ioctl+0x355/0xc30 do_vfs_ioctl+0xa3/0x5e0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x13/0x94 - i915 unpin_work workqueue: intel_unpin_work_fn+0x58/0x140 [i915] process_one_work+0x1f1/0x480 worker_thread+0x48/0x4d0 kthread+0x101/0x140 and this patch purely papers over the issue by adding a NULL pointer check and a WARN_ON_ONCE() to avoid the oops that would then generally make the machine unresponsive. Other callers of i915_gem_object_to_ggtt() seem to also check for the returned pointer being NULL and warn about it, so this clearly has happened before in other places. [ Reported it originally to the i915 developers on Jan 8, applying the ugly workaround on my own now after triggering the problem for the second time with no feedback. This is likely to be the same bug reported as https://bugs.freedesktop.org/show_bug.cgi?id=98829 https://bugs.freedesktop.org/show_bug.cgi?id=99134 which has a patch for the underlying problem, but it hasn't gotten to me, so I'm applying the workaround. ] Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'tools/perf/Documentation')