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 1FFF529B781 for ; Thu, 3 Sep 2026 22:31:31 +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=1788474693; cv=none; b=QZ7PJoOxE/KikRBvrJ77OSEVZ24boI1vA1EntpmXzcaLjdXsjXttlGicZBuVFVxO6PIapmDB4jow74Irit25mayy1ya4hDujDfi0+hhTOrMZzxhvv9I36KQNZEke+uQY2QrCRd/EZD8U/LfrP71l2jvlTyiz3ll0aKxbgNUi5jk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788474693; c=relaxed/simple; bh=M9sZvZiwGlvGC460n8Jj2mL19cwUTLmL3RtZj7Yvjj0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=niNum7+/IIl+S3xRSG479a+aoE2lgyQyrc6+iBTu1VeSqm2NwRysT5bQuAn+nXoLnXZPdTFEm0h2oEL3wJ4K0KGg9qR8VpWaBEbt+8qHKPoyyk+sdL0cVczW8T6TaDyr/omQHExpLm5ru61cww/BngVr9F6rwYOXUdD3W6JFejA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BT7b7Za3; 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="BT7b7Za3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A0E01F000E9; Thu, 3 Sep 2026 22:31:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788474691; bh=wZRafv82sQFne/iyvg+3lsCtUL77Ie7WzaM1bF6aLww=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BT7b7Za3LJZe5Xzd83/xZOJmBFesiHiE2Ogq6lQ/ELBHPJa1Bhp51cUgUr5nhW+U4 7OY+RxOctKi5wWamkFuQ+KKbSP//JeoiOPtsaOxMTp+lgMCSkBSB6eLGb2INgO0fIX 4OHANOi5qrxIm/UGPzp/ZaMZLETZ62AiN+pOy8WTHo5eGw1FBdPTtf/6FrEspJDfK6 gg4qSXU2ObqamzizEtRktjrvQ5wtwv+WDYhlf9fjeWP4KMT8F/uR+pGMGH2WZduB78 q8xynFg85Lupi2RsGB0Aoc6qrB6kwQuKKmS4Ghk9ekZDaYhQkrbsd9NIqeHujQ1hAY ZSl7aVFl6jxSQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Jim Cromie , Catalin Marinas , Andrew Morton , Sasha Levin Subject: [PATCH 6.6.y 1/4] kmemleak: drop (age ) from leak record Date: Thu, 3 Sep 2026 18:31:26 -0400 Message-ID: <20260903223129.1741728-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090345-kabob-hardcopy-cdf7@gregkh> References: <2026090345-kabob-hardcopy-cdf7@gregkh> 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: 3541a2b06ecd ("mm/kmemleak: report RCU-tasks quiescent states during the scan") 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 e2e41de55c02b..b6e57e344bd6e 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -355,14 +355,12 @@ 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