From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (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 E0F1D3D330E; Tue, 21 Apr 2026 13:45:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776779131; cv=none; b=J1SRg4SLGPfSOEkNbhddt9pf/VO+OFiiK94ckR1loyhYbe+mN1HvbVDJ53hEDAr6/TTFPcrSp60bgghES4JeChh08qU0r7pgjXDdHguCaEm5mfvXCIZkts9JqMkhcmLELeW3pTseAIebfAwln/PgOhLqtOoA33ljtxzoQNSPxuQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776779131; c=relaxed/simple; bh=9Wm7Dl8/F3pYBq3qZXT8kJfTkQ2Zpb38Hb44JyLLdyM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=SteDw3oyB1jNylJg8FPlirnvq92ZWYZYCg8Z5hIkHJdKhgXeu33ZXy2B2ANuYHXO0H1wQ+n23rTEvnCz1h6zBiAlLn9kNzgWWR+X7V2fSuo9+mCq9VrcxX/bOtBVHYTEOlaiO1TJtK4PSe2f995GlnIRFKZ+ob3/NyWs9R5aB7Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org; spf=none smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=N29+8gwv; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="N29+8gwv" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:Cc:To:In-Reply-To:References: Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description; bh=zmmnr8TWW6YxLTw+YepayNd7RYX3r8i4j8goyBNWTgE=; b=N29+8gwvrkSpXl7c4jicvS8gXy 6ta1kv+OwClGLqjvT1ArLhmoGzZp3cSIV6aFXG0+ZGyEe6MRFI+YTmQeA0fTMzFB0GthI/tMj+Tey laWL/wF9g2Oa1lU0ViwqetoDK0HVErkPLUdXGESdi2x0X5z4zbmaVYHEifvEQGQmuvxRK0GVR3hfX sNsWTGPb8dm96X3Hry2ICsCOb102XsjD1wDbwppdLebr6F7ZP2mMaa110BEtOUqFC6WIUXYKbqIie 784EINV6W7umYr/Zy/MSEwDgi7926LvZCqstXQNGDS6vYxQ1JdxB6drsZfArZQdKtXeWxMtCdRv3w UlHQBrEg==; Received: from authenticated user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1wFBPr-000tUk-14; Tue, 21 Apr 2026 13:45:27 +0000 From: Breno Leitao Date: Tue, 21 Apr 2026 06:45:05 -0700 Subject: [PATCH 2/2] selftests/mm: add kmemleak verbose dedup test Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260421-kmemleak_dedup-v1-2-65e31c6cdf0c@debian.org> References: <20260421-kmemleak_dedup-v1-0-65e31c6cdf0c@debian.org> In-Reply-To: <20260421-kmemleak_dedup-v1-0-65e31c6cdf0c@debian.org> To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Catalin Marinas Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, kernel-team@meta.com, Breno Leitao X-Mailer: b4 0.16-dev-453a6 X-Developer-Signature: v=1; a=openpgp-sha256; l=4082; i=leitao@debian.org; h=from:subject:message-id; bh=9Wm7Dl8/F3pYBq3qZXT8kJfTkQ2Zpb38Hb44JyLLdyM=; b=owEBbQKS/ZANAwAIATWjk5/8eHdtAcsmYgBp539pSZsITzdPAca14zLveMIHnMZh4OdAp07TV mIYE4BT87CJAjMEAAEIAB0WIQSshTmm6PRnAspKQ5s1o5Of/Hh3bQUCaed/aQAKCRA1o5Of/Hh3 bQE+D/4puL//7G+Ueti7kPpEa74j38TB6C8TVaq0xhyFPzwKqvkgXIIyQZIvPWFYfWI0qM0g4/u ZQtEt/RgTOs+dfiHFMvKiCAFRKoTxap1JADx117OPqH9gJXB8hDh4N1C1Tkchwbfw6mEUiyjGDQ YGpUFU7iIH1bSSQm/rxKHt2b/DHLu/CDZTbnoYABgiEi379B5vv4UZrbtealqDojBf1ynzml6Vf 8kfeVnSUM4AMk/V3aCYrEZ0WBqTkhOueoxBGAeZdlfVcXy3Mf4bxIxtFikbelLTK95D049gYdnH 9ixA1dwUbcKO909t5Ht4vM4L5HsmM+kM2RP+l7/TdcBytlp/07c3IvMNVG50Ohl4WH3GdlFcQ8Z vb5BisLQHh31KY2d9X/6QPX7BSO0LF/UXR1xjHWd4dd4eU/gzytNtSd89XSyWm6SFbSM8uUnTs4 2mzQHug8xNU0mC9bORJA93FYYFYwhMAe4tErwEN6x8jF6GN00GaaHZpd5x4vLH2hOsE8Xy30RwR qDLuBivyVI8wRcZrZoH8JF6RB3MduoQZVMrcSzQ6nUNVMrM4R2vSEeEj35iqH8BDCHImCdiVRrE r0XOXE014XcmS9fYC8U8c4WNsT7tEiN0rurBKg2KUlV5IlcMyNK28z6IgwdW7VRBlu/WXi/VcJA 5qs3aK+Xx9hJ4jg== X-Developer-Key: i=leitao@debian.org; a=openpgp; fpr=AC8539A6E8F46702CA4A439B35A3939FFC78776D X-Debian-User: leitao Exercise the per-scan dedup of kmemleak's verbose leak output added in the previous commit. The test depends on the kmemleak-test sample module (CONFIG_SAMPLE_KMEMLEAK=m); load it and unload it to orphan ten list entries from a single kzalloc() call site that all share one stackdepot trace_handle, trigger two scans, and assert that the number of "unreferenced object" lines printed in dmesg is strictly less than the number of leaks reported. Skip cleanly when kmemleak is absent, disabled at runtime, or CONFIG_SAMPLE_KMEMLEAK is not built in. Signed-off-by: Breno Leitao --- tools/testing/selftests/mm/test_kmemleak_dedup.sh | 86 +++++++++++++++++++++++ 1 file changed, 86 insertions(+) diff --git a/tools/testing/selftests/mm/test_kmemleak_dedup.sh b/tools/testing/selftests/mm/test_kmemleak_dedup.sh new file mode 100755 index 0000000000000..1a1b6efd6470a --- /dev/null +++ b/tools/testing/selftests/mm/test_kmemleak_dedup.sh @@ -0,0 +1,86 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Verify that kmemleak's verbose scan output deduplicates leaks that share +# the same allocation backtrace. The kmemleak-test module leaks 10 list +# entries from a single kzalloc() call site, so they share one stackdepot +# trace_handle. With dedup, only one "unreferenced object" line should be +# printed for that backtrace per scan, while the per-scan leak counter +# still accounts for every object. +# +# The expected output is something like: +# PASS: kmemleak verbose output deduplicated (11 printed for 61 leaks) +# +# Author: Breno Leitao + +ksft_skip=4 +KMEMLEAK=/sys/kernel/debug/kmemleak +VERBOSE_PARAM=/sys/module/kmemleak/parameters/verbose +MODULE=kmemleak-test + +skip() { + echo "SKIP: $*" + exit $ksft_skip +} + +fail() { + echo "FAIL: $*" + exit 1 +} + +[ "$(id -u)" -eq 0 ] || skip "must run as root" +[ -r "$KMEMLEAK" ] || skip "no kmemleak debugfs (CONFIG_DEBUG_KMEMLEAK)" +[ -w "$VERBOSE_PARAM" ] || skip "kmemleak verbose param missing" +modinfo "$MODULE" >/dev/null 2>&1 || + skip "$MODULE not built (CONFIG_SAMPLE_KMEMLEAK)" + +# kmemleak can be present but disabled at runtime (boot arg kmemleak=off, +# or it self-disabled after an internal error). In that state writes other +# than "clear" return EPERM, so probe once and skip if so. +if ! echo scan > "$KMEMLEAK" 2>/dev/null; then + skip "kmemleak is disabled (check dmesg or kmemleak= boot arg)" +fi + +prev_verbose=$(cat "$VERBOSE_PARAM") +cleanup() { + echo "$prev_verbose" > "$VERBOSE_PARAM" 2>/dev/null + rmmod "$MODULE" 2>/dev/null +} +trap cleanup EXIT + +echo 1 > "$VERBOSE_PARAM" + +# Drain the existing leak set so the next scan only reports our objects. +echo clear > "$KMEMLEAK" + +modprobe "$MODULE" || fail "failed to load $MODULE" +# Removing the module orphans the list elements without freeing them. +rmmod "$MODULE" || fail "failed to unload $MODULE" + +# Two scans: kmemleak requires the object to survive a full scan cycle +# before it is reported as unreferenced. +dmesg -C >/dev/null +echo scan > "$KMEMLEAK"; sleep 6 +echo scan > "$KMEMLEAK"; sleep 6 + +log=$(dmesg) + +new_leaks=$(echo "$log" | + sed -n 's/.*kmemleak: \([0-9]\+\) new suspected.*/\1/p' | tail -1) +[ -n "$new_leaks" ] || fail "no 'new suspected memory leaks' line found" + +# Count "unreferenced object" lines emitted in verbose output. +printed=$(echo "$log" | grep -c 'kmemleak: unreferenced object') + +echo "new_leaks=$new_leaks printed=$printed" + +# The kzalloc(sizeof(*elem)) loop alone contributes 10 leaks sharing one +# backtrace, so without dedup printed >= 10. With dedup the printed count +# must be strictly less than the reported leak total. +[ "$new_leaks" -ge 10 ] || fail "expected >=10 new leaks, got $new_leaks" +[ "$printed" -lt "$new_leaks" ] || \ + fail "no dedup: printed=$printed new_leaks=$new_leaks" + +echo "PASS: kmemleak verbose output deduplicated" \ + "($printed printed for $new_leaks leaks)" +exit 0 -- 2.52.0