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selftests/bpf: Fix flaky test btf_map_in_map/lookup_update
[ Upstream commit 14bb1e8c8d
]
Recently, I frequently hit the following test failure:
[root@arch-fb-vm1 bpf]# ./test_progs -n 33/1
test_lookup_update:PASS:skel_open 0 nsec
[...]
test_lookup_update:PASS:sync_rcu 0 nsec
test_lookup_update:FAIL:map1_leak inner_map1 leaked!
#33/1 btf_map_in_map/lookup_update:FAIL
#33 btf_map_in_map:FAIL
In the test, after map is closed and then after two rcu grace periods,
it is assumed that map_id is not available to user space.
But the above assumption cannot be guaranteed. After zero or one
or two rcu grace periods in different siturations, the actual
freeing-map-work is put into a workqueue. Later on, when the work
is dequeued, the map will be actually freed.
See bpf_map_put() in kernel/bpf/syscall.c.
By using workqueue, there is no ganrantee that map will be actually
freed after a couple of rcu grace periods. This patch removed
such map leak detection and then the test can pass consistently.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240322061353.632136-1-yonghong.song@linux.dev
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
9233170689
commit
4a6adfe5a7
1 changed files with 1 additions and 25 deletions
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@ -25,7 +25,7 @@ static void test_lookup_update(void)
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int map1_fd, map2_fd, map3_fd, map4_fd, map5_fd, map1_id, map2_id;
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int map1_fd, map2_fd, map3_fd, map4_fd, map5_fd, map1_id, map2_id;
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int outer_arr_fd, outer_hash_fd, outer_arr_dyn_fd;
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int outer_arr_fd, outer_hash_fd, outer_arr_dyn_fd;
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struct test_btf_map_in_map *skel;
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struct test_btf_map_in_map *skel;
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int err, key = 0, val, i, fd;
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int err, key = 0, val, i;
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skel = test_btf_map_in_map__open_and_load();
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skel = test_btf_map_in_map__open_and_load();
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if (CHECK(!skel, "skel_open", "failed to open&load skeleton\n"))
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if (CHECK(!skel, "skel_open", "failed to open&load skeleton\n"))
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@ -102,30 +102,6 @@ static void test_lookup_update(void)
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CHECK(map1_id == 0, "map1_id", "failed to get ID 1\n");
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CHECK(map1_id == 0, "map1_id", "failed to get ID 1\n");
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CHECK(map2_id == 0, "map2_id", "failed to get ID 2\n");
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CHECK(map2_id == 0, "map2_id", "failed to get ID 2\n");
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test_btf_map_in_map__destroy(skel);
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skel = NULL;
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/* we need to either wait for or force synchronize_rcu(), before
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* checking for "still exists" condition, otherwise map could still be
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* resolvable by ID, causing false positives.
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*
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* Older kernels (5.8 and earlier) freed map only after two
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* synchronize_rcu()s, so trigger two, to be entirely sure.
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*/
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CHECK(kern_sync_rcu(), "sync_rcu", "failed\n");
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CHECK(kern_sync_rcu(), "sync_rcu", "failed\n");
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fd = bpf_map_get_fd_by_id(map1_id);
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if (CHECK(fd >= 0, "map1_leak", "inner_map1 leaked!\n")) {
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close(fd);
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goto cleanup;
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}
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fd = bpf_map_get_fd_by_id(map2_id);
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if (CHECK(fd >= 0, "map2_leak", "inner_map2 leaked!\n")) {
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close(fd);
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goto cleanup;
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}
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cleanup:
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cleanup:
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test_btf_map_in_map__destroy(skel);
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test_btf_map_in_map__destroy(skel);
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}
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}
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