On Fri, 2 Jul 2021 at 09:45, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> tree: git://anongit.freedesktop.org/drm-intel drm-intel-gt-next
> head: 5cd57f676bb946a00275408f0dd0d75dbc466d25
> commit: cf586021642d8017cde111b7dd1ba86224e9da51 [8/14] drm/i915/gt: Pipelined page migration
> config: x86_64-randconfig-m001-20210630 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> New smatch warnings:
> drivers/gpu/drm/i915/gt/selftest_migrate.c:102 copy() error: uninitialized symbol 'rq'.
> drivers/gpu/drm/i915/gt/selftest_migrate.c:113 copy() error: uninitialized symbol 'vaddr'.
>
> Old smatch warnings:
> drivers/gpu/drm/i915/gem/i915_gem_object.h:182 __i915_gem_object_lock() error: we previously assumed 'ww' could be null (see line 171)
>
> vim +/rq +102 drivers/gpu/drm/i915/gt/selftest_migrate.c
>
> cf586021642d80 Chris Wilson 2021-06-17 32 static int copy(struct intel_migrate *migrate,
> cf586021642d80 Chris Wilson 2021-06-17 33 int (*fn)(struct intel_migrate *migrate,
> cf586021642d80 Chris Wilson 2021-06-17 34 struct i915_gem_ww_ctx *ww,
> cf586021642d80 Chris Wilson 2021-06-17 35 struct drm_i915_gem_object *src,
> cf586021642d80 Chris Wilson 2021-06-17 36 struct drm_i915_gem_object *dst,
> cf586021642d80 Chris Wilson 2021-06-17 37 struct i915_request **out),
> cf586021642d80 Chris Wilson 2021-06-17 38 u32 sz, struct rnd_state *prng)
> cf586021642d80 Chris Wilson 2021-06-17 39 {
> cf586021642d80 Chris Wilson 2021-06-17 40 struct drm_i915_private *i915 = migrate->context->engine->i915;
> cf586021642d80 Chris Wilson 2021-06-17 41 struct drm_i915_gem_object *src, *dst;
> cf586021642d80 Chris Wilson 2021-06-17 42 struct i915_request *rq;
> cf586021642d80 Chris Wilson 2021-06-17 43 struct i915_gem_ww_ctx ww;
> cf586021642d80 Chris Wilson 2021-06-17 44 u32 *vaddr;
> cf586021642d80 Chris Wilson 2021-06-17 45 int err = 0;
>
> One way to silence these warnings would be to initialize err = -EINVAL.
> Then Smatch would know that we goto err_out for an empty list.
>
> cf586021642d80 Chris Wilson 2021-06-17 46 int i;
> cf586021642d80 Chris Wilson 2021-06-17 47
> cf586021642d80 Chris Wilson 2021-06-17 48 src = create_lmem_or_internal(i915, sz);
> cf586021642d80 Chris Wilson 2021-06-17 49 if (IS_ERR(src))
> cf586021642d80 Chris Wilson 2021-06-17 50 return 0;
> cf586021642d80 Chris Wilson 2021-06-17 51
> cf586021642d80 Chris Wilson 2021-06-17 52 dst = i915_gem_object_create_internal(i915, sz);
> cf586021642d80 Chris Wilson 2021-06-17 53 if (IS_ERR(dst))
> cf586021642d80 Chris Wilson 2021-06-17 54 goto err_free_src;
> cf586021642d80 Chris Wilson 2021-06-17 55
> cf586021642d80 Chris Wilson 2021-06-17 56 for_i915_gem_ww(&ww, err, true) {
> cf586021642d80 Chris Wilson 2021-06-17 57 err = i915_gem_object_lock(src, &ww);
> cf586021642d80 Chris Wilson 2021-06-17 58 if (err)
> cf586021642d80 Chris Wilson 2021-06-17 59 continue;
> cf586021642d80 Chris Wilson 2021-06-17 60
> cf586021642d80 Chris Wilson 2021-06-17 61 err = i915_gem_object_lock(dst, &ww);
> cf586021642d80 Chris Wilson 2021-06-17 62 if (err)
> cf586021642d80 Chris Wilson 2021-06-17 63 continue;
> cf586021642d80 Chris Wilson 2021-06-17 64
> cf586021642d80 Chris Wilson 2021-06-17 65 vaddr = i915_gem_object_pin_map(src, I915_MAP_WC);
> cf586021642d80 Chris Wilson 2021-06-17 66 if (IS_ERR(vaddr)) {
> cf586021642d80 Chris Wilson 2021-06-17 67 err = PTR_ERR(vaddr);
> cf586021642d80 Chris Wilson 2021-06-17 68 continue;
> cf586021642d80 Chris Wilson 2021-06-17 69 }
> cf586021642d80 Chris Wilson 2021-06-17 70
> cf586021642d80 Chris Wilson 2021-06-17 71 for (i = 0; i < sz / sizeof(u32); i++)
> cf586021642d80 Chris Wilson 2021-06-17 72 vaddr[i] = i;
> cf586021642d80 Chris Wilson 2021-06-17 73 i915_gem_object_flush_map(src);
> cf586021642d80 Chris Wilson 2021-06-17 74
> cf586021642d80 Chris Wilson 2021-06-17 75 vaddr = i915_gem_object_pin_map(dst, I915_MAP_WC);
> cf586021642d80 Chris Wilson 2021-06-17 76 if (IS_ERR(vaddr)) {
> cf586021642d80 Chris Wilson 2021-06-17 77 err = PTR_ERR(vaddr);
> cf586021642d80 Chris Wilson 2021-06-17 78 goto unpin_src;
> cf586021642d80 Chris Wilson 2021-06-17 79 }
> cf586021642d80 Chris Wilson 2021-06-17 80
> cf586021642d80 Chris Wilson 2021-06-17 81 for (i = 0; i < sz / sizeof(u32); i++)
> cf586021642d80 Chris Wilson 2021-06-17 82 vaddr[i] = ~i;
> cf586021642d80 Chris Wilson 2021-06-17 83 i915_gem_object_flush_map(dst);
> cf586021642d80 Chris Wilson 2021-06-17 84
> cf586021642d80 Chris Wilson 2021-06-17 85 err = fn(migrate, &ww, src, dst, &rq);
> cf586021642d80 Chris Wilson 2021-06-17 86 if (!err)
> cf586021642d80 Chris Wilson 2021-06-17 87 continue;
>
> Does fn() initialize "rq" on the success path? Anyway Smatch would
> complain anyway because it thinks the list could be empty or that we
> might hit and early continue for everything.
The fn() will always first initialize the rq to NULL. If it returns
success then rq will always be a valid rq. If it returns an err then
the rq might be NULL, or a valid rq depending on how far the copy/fn
got.
And for_i915_gem_ww() will always run at least once, since ww->loop =
true, so this looks like a false positive?
>
> cf586021642d80 Chris Wilson 2021-06-17 88
> cf586021642d80 Chris Wilson 2021-06-17 89 if (err != -EDEADLK && err != -EINTR && err != -ERESTARTSYS)
> cf586021642d80 Chris Wilson 2021-06-17 90 pr_err("%ps failed, size: %u\n", fn, sz);
> cf586021642d80 Chris Wilson 2021-06-17 91 if (rq) {
> cf586021642d80 Chris Wilson 2021-06-17 92 i915_request_wait(rq, 0, HZ);
> cf586021642d80 Chris Wilson 2021-06-17 93 i915_request_put(rq);
> cf586021642d80 Chris Wilson 2021-06-17 94 }
> cf586021642d80 Chris Wilson 2021-06-17 95 i915_gem_object_unpin_map(dst);
> cf586021642d80 Chris Wilson 2021-06-17 96 unpin_src:
> cf586021642d80 Chris Wilson 2021-06-17 97 i915_gem_object_unpin_map(src);
> cf586021642d80 Chris Wilson 2021-06-17 98 }
> cf586021642d80 Chris Wilson 2021-06-17 99 if (err)
> cf586021642d80 Chris Wilson 2021-06-17 100 goto err_out;
> cf586021642d80 Chris Wilson 2021-06-17 101
> cf586021642d80 Chris Wilson 2021-06-17 @102 if (rq) {
> cf586021642d80 Chris Wilson 2021-06-17 103 if (i915_request_wait(rq, 0, HZ) < 0) {
> cf586021642d80 Chris Wilson 2021-06-17 104 pr_err("%ps timed out, size: %u\n", fn, sz);
> cf586021642d80 Chris Wilson 2021-06-17 105 err = -ETIME;
> cf586021642d80 Chris Wilson 2021-06-17 106 }
> cf586021642d80 Chris Wilson 2021-06-17 107 i915_request_put(rq);
> cf586021642d80 Chris Wilson 2021-06-17 108 }
> cf586021642d80 Chris Wilson 2021-06-17 109
> cf586021642d80 Chris Wilson 2021-06-17 110 for (i = 0; !err && i < sz / PAGE_SIZE; i++) {
> cf586021642d80 Chris Wilson 2021-06-17 111 int x = i * 1024 + i915_prandom_u32_max_state(1024, prng);
> cf586021642d80 Chris Wilson 2021-06-17 112
> cf586021642d80 Chris Wilson 2021-06-17 @113 if (vaddr[x] != x) {
> cf586021642d80 Chris Wilson 2021-06-17 114 pr_err("%ps failed, size: %u, offset: %zu\n",
> cf586021642d80 Chris Wilson 2021-06-17 115 fn, sz, x * sizeof(u32));
> cf586021642d80 Chris Wilson 2021-06-17 116 igt_hexdump(vaddr + i * 1024, 4096);
> cf586021642d80 Chris Wilson 2021-06-17 117 err = -EINVAL;
> cf586021642d80 Chris Wilson 2021-06-17 118 }
> cf586021642d80 Chris Wilson 2021-06-17 119 }
> cf586021642d80 Chris Wilson 2021-06-17 120
> cf586021642d80 Chris Wilson 2021-06-17 121 i915_gem_object_unpin_map(dst);
> cf586021642d80 Chris Wilson 2021-06-17 122 i915_gem_object_unpin_map(src);
> cf586021642d80 Chris Wilson 2021-06-17 123
> cf586021642d80 Chris Wilson 2021-06-17 124 err_out:
> cf586021642d80 Chris Wilson 2021-06-17 125 i915_gem_object_put(dst);
> cf586021642d80 Chris Wilson 2021-06-17 126 err_free_src:
> cf586021642d80 Chris Wilson 2021-06-17 127 i915_gem_object_put(src);
> cf586021642d80 Chris Wilson 2021-06-17 128
> cf586021642d80 Chris Wilson 2021-06-17 129 return err;
> cf586021642d80 Chris Wilson 2021-06-17 130 }
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
>
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