From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 2E2D6369D54 for ; Thu, 3 Sep 2026 18:47:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788461262; cv=none; b=T4oWcnL/655Nya8Z//YfxxmMv5nXio6wmi1sGiSg+dCSBsuheigftlNqHb1Aa6PHBhcP1+/hJiq+gHQSbZsQidKe0CtC9I9CHlfukca5VvJbVHY+uEtl7Smh6D/28/2C7DysVxawNZIAsWxgfDh2DhEmI3ZIDJ0TsSFUz5zT1vM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788461262; c=relaxed/simple; bh=7vXmtkF5ncKr52ewsDO3zw4mGoKqRuLnbylghFY/56k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CUQedm8SZAvo6TFay8q/MqZ+9/jsWXmYJNdJnAjgtT8aulV44z5NoG36DiIDd64EuSo/VdUE1LYyeiqSka622jPXoZ83ksaYnVViBb3w6zn8FP7w/+JwEs/pKxuQAXQ1qZ+rgIGC19gDl60AVntNDctjDL/1UHpmFQ7emHylpDM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JNyxNUtG; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JNyxNUtG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A3CE1F00A3E; Thu, 3 Sep 2026 18:47:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788461261; bh=V9so9yQw6hhSrHxlot6udv/5pH6Wk+3BZRqgQ6mzWCQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JNyxNUtG3c+egraOw/eSwV7dOjgcfOMRcBZLgq/7gVAOVmEgrVEc/HEe4J77Lu24U ey9aoGyHHSYBbOzPK1rHxNvLXisRyRpbmeunu8BDcU3Q/zcLgd2XJds4BzaDUvtH8C lav97Dc9FyNml2d1CWXlHPqh2DC0cVX1WagZozng/j4WjVXeDa2XjQ/UDTfkBs6FjA e54YxYATea7yT6RjNP5GmCaqUPdyHDaRDVNq/nSGDnUGuDyiOy4QHtIBzAPIL1CdHw 5BMFAX9gIROR2OQ0J1HZOysC6lVT7v5fEH4VRwzLJAxFPJVA0gJBnH1qXW+48NBZLF KXO5bEAv4n8dA== From: Sasha Levin To: stable@vger.kernel.org Cc: Jim Cromie , Catalin Marinas , Andrew Morton , Sasha Levin Subject: [PATCH 5.15.y 6/7] kmemleak: drop (age ) from leak record Date: Thu, 3 Sep 2026 14:47:32 -0400 Message-ID: <20260903184733.1484444-6-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260903184733.1484444-1-sashal@kernel.org> References: <2026090333-boney-opium-0272@gregkh> <20260903184733.1484444-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jim Cromie [ Upstream commit 88f9ee2b3040991ff40628fa9e3516ebe36dd6fa ] Patch series "tweak kmemleak report format". These 2 patches make minor changes to the report: 1st strips "age " from output. This makes the output idempotent; unchanging until a new leak is reported. 2nd adds the backtrace.checksum to the "backtrace:" line. This lets a user see repeats without actually reading the whole backtrace. So now the backtrace line looks like this: backtrace (crc 603070071): I surveyed for un-wanted effects upon users: Syzkaller parses kmemleak in executor/common_linux.h: static void check_leaks(char** frames, int nframes) It just counts occurrences of "unreferenced object", specifically it does not look for "age", nor would it choke on "crc" being added. github has 3 repos with "kmemleak" mentioned, all are moribund. gitlab has 0 hits on "kmemleak". This patch (of 2): Displaying age is pretty, but counter-productive; it changes with current-time, so it surrenders idempotency of the output, which breaks simple hash-based cataloging of the records by the user. The trouble: sequential reads, wo new leaks, get new results: :#> sum /sys/kernel/debug/kmemleak 53439 74 /sys/kernel/debug/kmemleak :#> sum /sys/kernel/debug/kmemleak 59066 74 /sys/kernel/debug/kmemleak and age is why (nothing else changes): :#> grep -v age /sys/kernel/debug/kmemleak | sum 58894 67 :#> grep -v age /sys/kernel/debug/kmemleak | sum 58894 67 Since jiffies is already printed in the "comm" line, age adds nothing. Notably, syzkaller reads kmemleak only for "unreferenced object", and won't care about this reform of age-ism. A few moribund github repos mention it, but don't compile. Link: https://lkml.kernel.org/r/20231116224318.124209-1-jim.cromie@gmail.com Link: https://lkml.kernel.org/r/20231116224318.124209-2-jim.cromie@gmail.com Signed-off-by: Jim Cromie Reviewed-by: Catalin Marinas Signed-off-by: Andrew Morton Stable-dep-of: 5d10d4e19e6d ("mm/kmemleak: avoid soft lockup when scanning task stacks") Signed-off-by: Sasha Levin --- mm/kmemleak.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 6c26262aac844..023d1300dbb40 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -345,14 +345,12 @@ static void print_unreferenced(struct seq_file *seq, int i; unsigned long *entries; unsigned int nr_entries; - unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies); nr_entries = stack_depot_fetch(object->trace_handle, &entries); warn_or_seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n", object->pointer, object->size); - warn_or_seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n", - object->comm, object->pid, object->jiffies, - msecs_age / 1000, msecs_age % 1000); + warn_or_seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu\n", + object->comm, object->pid, object->jiffies); hex_dump_object(seq, object); warn_or_seq_printf(seq, " backtrace:\n"); -- 2.53.0