From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8AAA134CFCC for ; Tue, 24 Feb 2026 22:49:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.184 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771973354; cv=none; b=oyPKMatCKV4y/fMGapl6wrG8PG1Hd7HwotTFO/zFinKn2YhNbbJwVDM1sitcJ1Tw6gcd9U01dC3hkoiBZXp02tkloYEiXVpQyd+SvcpL/oerhMUJu+NTQ7MKELz6Xr0OxfWnuNt5oPvJzx7i4jkT/yuYUg2szoSr9xARhH9uodo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771973354; c=relaxed/simple; bh=C3CcHTwIUdxmNWp2xQNbWACfFXPbfK/vbugzNWBytTY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eY2LJPeMjAz49M8OfePTeKtsSC3QyyS7ud5I6LRPgxxh2hfyWDaItWJVWQXx3NQblu0+xpLGsINXGt8jU3amgnu64We988McXsj+J53tkqaI2GuJuuHPKcAJUMl5OqwTJZj42xcvXEwq0PgODYKtM6NPEaihi1wejnZU35Dky8w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=X2VVjzd9; arc=none smtp.client-ip=91.218.175.184 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="X2VVjzd9" Message-ID: <1fcd6f57-8c09-4f66-a5fb-30615c40bf41@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1771973349; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=15vqhhJlB2nyjvlehQUoNAclVqI7YCRBU/x3BHmxoNk=; b=X2VVjzd94dmmtgu5yKNxrPEnY82z2uWwUFGZEd3BoeIJ5zNJUTZ9iMko6F2DMeQnFkK6WF CDGqQOcmQ3NwNA+V7A6ca3Bu+h6INpBTSKODGOvP+lTR7wix+N6/F4jlSYBEHaY2yHkFAr vwq26OsCwUZzqhmbebXdEPSLtjdvywc= Date: Tue, 24 Feb 2026 14:49:02 -0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v2] selftests/bpf: Fix flakiness of task_local_storage/sys_enter_exit To: Amery Hung Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Eduard Zingerman , Mykyta Yatsenko , bpf@vger.kernel.org, kernel-team@meta.com References: <20260224211202.214325-1-ihor.solodrai@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Ihor Solodrai In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 2/24/26 2:04 PM, Amery Hung wrote: > On Tue, Feb 24, 2026 at 1:12 PM Ihor Solodrai wrote: >> >> The test_sys_enter_exit test was setting target_pid before attaching >> the BPF programs, which causes syscalls made during the attach phase >> to be counted. This is flaky because, apparently, there is no >> guarantee that both on_enter and on_exit will trigger during the >> attachment. >> >> Move the target_pid assignment to after task_local_storage__attach() >> so that only explicit sys_gettid() calls are counted. >> >> Reported-by: BPF CI Bot (Claude Opus 4.6) >> Closes: https://github.com/kernel-patches/vmtest/issues/448 >> Signed-off-by: Ihor Solodrai >> >> --- >> >> v1->v2: reset skel->bss->target_pid to 0 before asserts (Amery) >> v1: https://lore.kernel.org/bpf/20260224015855.1481707-1-ihor.solodrai@linux.dev/ >> >> --- >> .../bpf/prog_tests/task_local_storage.c | 16 +++++++++++----- >> 1 file changed, 11 insertions(+), 5 deletions(-) >> >> diff --git a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c >> index 7bee33797c71..1b26c12f255a 100644 >> --- a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c >> +++ b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c >> @@ -25,24 +25,30 @@ >> static void test_sys_enter_exit(void) >> { >> struct task_local_storage *skel; >> + pid_t pid = sys_gettid(); >> int err; >> >> skel = task_local_storage__open_and_load(); >> if (!ASSERT_OK_PTR(skel, "skel_open_and_load")) >> return; >> >> - skel->bss->target_pid = sys_gettid(); >> - >> err = task_local_storage__attach(skel); >> if (!ASSERT_OK(err, "skel_attach")) >> goto out; >> >> + /* Set target_pid after attach so that syscalls made during >> + * attach are not counted. >> + */ >> + skel->bss->target_pid = pid; >> + >> sys_gettid(); >> sys_gettid(); >> >> - /* 3x syscalls: 1x attach and 2x gettid */ >> - ASSERT_EQ(skel->bss->enter_cnt, 3, "enter_cnt"); >> - ASSERT_EQ(skel->bss->exit_cnt, 3, "exit_cnt"); >> + skel->bss->target_pid = 0; >> + >> + /* 2x gettid syscalls */ >> + ASSERT_EQ(skel->bss->enter_cnt, 2, "enter_cnt"); >> + ASSERT_EQ(skel->bss->exit_cnt, 2, "exit_cnt"); > > Does tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c also > have the same flakiness issue and should also be updated in the same > way? I haven't seen similar failures on CI, but that may just mean we were lucky. Do you know of other tests that may have the same issue? I checked these, but only task_local_storage and cgrp_local_storage assert counts: $ grep -r 'skel->bss->target_pid = .*gettid' tools/testing/selftests/bpf/ tools/testing/selftests/bpf/prog_tests/cgroup_xattr.c: skel->bss->target_pid = sys_gettid(); tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c: skel->bss->target_pid = sys_gettid(); tools/testing/selftests/bpf/prog_tests/rcu_read_lock.c: skel->bss->target_pid = sys_gettid(); tools/testing/selftests/bpf/prog_tests/task_local_storage.c: skel->bss->target_pid = sys_gettid(); tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c: skel->bss->target_pid = sys_gettid(); tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c: skel->bss->target_pid = sys_gettid(); > >> ASSERT_EQ(skel->bss->mismatch_cnt, 0, "mismatch_cnt"); >> out: >> task_local_storage__destroy(skel); >> -- >> 2.53.0 >>