diff mbox series

[bpf-next,3/3] selftsets/bpf: Retry map update for non-preallocated per-cpu map

Message ID 20231101032455.3808547-4-houtao@huaweicloud.com (mailing list archive)
State Accepted
Commit 57688b2a543be340d80c568b7f91c0660bb65c2f
Delegated to: BPF
Headers show
Series selftests/bpf: Fixes for map_percpu_stats test | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 9 this patch: 9
netdev/cc_maintainers warning 3 maintainers not CCed: shuah@kernel.org mykolal@fb.com linux-kselftest@vger.kernel.org
netdev/build_clang success Errors and warnings before: 9 this patch: 9
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 9 this patch: 9
netdev/checkpatch warning WARNING: line length of 96 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
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Commit Message

Hou Tao Nov. 1, 2023, 3:24 a.m. UTC 
From: Hou Tao <houtao1@huawei.com>

BPF CI failed due to map_percpu_stats_percpu_hash from time to time [1].
It seems that the failure reason is per-cpu bpf memory allocator may not
be able to allocate per-cpu pointer successfully and it can not refill
free llist timely, and bpf_map_update_elem() will return -ENOMEM.

So mitigate the problem by retrying the update operation for
non-preallocated per-cpu map.

[1]: https://github.com/kernel-patches/bpf/actions/runs/6713177520/job/18244865326?pr=5909

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 .../bpf/map_tests/map_percpu_stats.c          | 20 ++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c b/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c
index 8ad17d051ef8f..e152535e9e3ec 100644
--- a/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c
+++ b/tools/testing/selftests/bpf/map_tests/map_percpu_stats.c
@@ -141,6 +141,7 @@  struct upsert_opts {
 	__u32 map_type;
 	int map_fd;
 	__u32 n;
+	bool retry_for_nomem;
 };
 
 static int create_small_hash(void)
@@ -154,6 +155,11 @@  static int create_small_hash(void)
 	return map_fd;
 }
 
+static bool retry_for_nomem_fn(int err)
+{
+	return err == ENOMEM;
+}
+
 static void *patch_map_thread(void *arg)
 {
 	/* 8KB is enough for 1024 CPUs. And it is shared between N_THREADS. */
@@ -175,7 +181,12 @@  static void *patch_map_thread(void *arg)
 			val_ptr = &val;
 		}
 
-		ret = bpf_map_update_elem(opts->map_fd, &i, val_ptr, 0);
+		/* 2 seconds may be enough ? */
+		if (opts->retry_for_nomem)
+			ret = map_update_retriable(opts->map_fd, &i, val_ptr, 0,
+						   40, retry_for_nomem_fn);
+		else
+			ret = bpf_map_update_elem(opts->map_fd, &i, val_ptr, 0);
 		CHECK(ret < 0, "bpf_map_update_elem", "key=%d error: %s\n", i, strerror(errno));
 
 		if (opts->map_type == BPF_MAP_TYPE_HASH_OF_MAPS)
@@ -296,6 +307,13 @@  static void __test(int map_fd)
 	else
 		opts.n /= 2;
 
+	/* per-cpu bpf memory allocator may not be able to allocate per-cpu
+	 * pointer successfully and it can not refill free llist timely, and
+	 * bpf_map_update_elem() will return -ENOMEM. so just retry to mitigate
+	 * the problem temporarily.
+	 */
+	opts.retry_for_nomem = is_percpu(opts.map_type) && (info.map_flags & BPF_F_NO_PREALLOC);
+
 	/*
 	 * Upsert keys [0, n) under some competition: with random values from
 	 * N_THREADS threads. Check values, then delete all elements and check