From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=115.124.30.130 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793872388; b=BWbyJGuuPIzmKgqenx57SRSLleFL89bM3uW25UORI8b8kIUpGDEfq55DECcB3gxn+jj2 lfrOIZaEtlhG7l0pcuhTDvf2ELuIym8yCb8i/eX25GOhAVWGFzhwxpoVpCrMIZLvtRoI0 fdcfwbAu3DBoeGNuYdDxKteQSy0tl6T7E3yLi4kyNK80DuipTVxW7suH/Z9Cfbg4MNLhe Xendxn40jZaoeSyGxBajFyyb8Mn6zs09n+2nH8i6WF+7WEFVqJbJIOHcaPDV4s01dzS4Q cGABX4wzeIlfyHPHUrH0pJrp1BDVoyChk5vxiwuSLjBInJ9bLoVcEniLwLeZ5T0UBZQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793872388; h=DMARC-Filter:DKIM-Signature:X-Alimail-AntiSpam:Received:From:To:Cc: Subject:Date:Message-ID:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=Idn+SmsO2M3f0YI+n9T3ryw9MvtjbedDGjimEeioACw=; b=E1DXTwNq0GdV+4IwLe0yR6aWL5/lxkfg0Ag5cVREudwYVjH7CcahNHHkfVCs3f48lVF4 +N8OirTV3kflvYmF2tkAoSPmjfHbSWUMwnnOeLXe2/J80DfQM1wOLgvCqG9y3uczvKL2A uREgpLGukLag55iu5Pw+lxrCNglyU8COL7u+tMWujzzj8OcB6ZVMdyHApIq6xFYt+17Of xI+FosGm/lpIWRmRlkEd+U49GKiWECkx/a/6ssXCM87EBpiLsZUU01vrSYolixTfrvWiD 3MRcwmQVNgJ7WAMN9ATQImqrHFwHYhcYoAeSQ+zZnuhEkyBmG4siLrOAcTxZqTf2XAA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b="cwt/ENdp"; arc=none smtp.remote-ip=115.124.30.130 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7E160606A32D for ; Thu, 5 Nov 2026 09:53:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 7E160606A32D Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.a=rsa-sha256 header.s=default header.b=cwt/ENdp DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1793872385; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=Idn+SmsO2M3f0YI+n9T3ryw9MvtjbedDGjimEeioACw=; b=cwt/ENdpsNSpqxL/yIjsjtB/jVOB5EEk9RidqDu2Va6s+SyPjDnnVASOuIaW/NhlENCx8FRZ/XURN4Xi1x8E8IC6RuiYyE2S3AMBXMJzrKMCfh/TOYAhM90JJ9+RsqertZnemTRZXM8aIWJ4AT/GDOqUwZ14Ls7oMsKN1V9G0j0= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam011083073210;MF=tongweilin@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0XE8JNsH_1793872384; Received: from x31l07246.sqa.na131.tbsite.net(mailfrom:tongweilin@linux.alibaba.com fp:SMTPD_---0XE8JNsH_1793872384 cluster:ay36) by smtp.aliyun-inc.com; Thu, 05 Nov 2026 17:53:04 +0800 From: Weilin Tong To: catalin.marinas@arm.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] mm: kmemleak: reschedule while reading reports Date: Thu, 5 Nov 2026 17:52:50 +0800 Message-ID: <70139bdb8c7a61913d5081671fcc2af37348fffd.1793871596.git.tongweilin@linux.alibaba.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: References: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Reading a kmemleak report walks all tracked objects under RCU, even when the report is empty. On large debug kernels this can stall RCU. Use kmemleak_cond_resched() in both seq traversal loops. Request a break when need_resched() is set and periodically every 256 positions, since preemption can clear need_resched() without ending the RCU read-side critical section. The helper pins a linked cursor and defers its removal across RCU breaks. Already removed cursors remain under RCU to protect their forward links. This allows RCU grace periods to progress during long report reads. Fixes: f5886c7f96f2 ("kmemleak: Protect the seq start/next/stop sequence by rcu_read_lock()") Assisted-by: LLM Signed-off-by: Weilin Tong --- mm/kmemleak.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/mm/kmemleak.c b/mm/kmemleak.c index d959d11f6..0fe7d336c 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -2216,6 +2216,9 @@ static void stop_scan_thread(void) } } +/* Also break RCU periodically when preemption clears need_resched(). */ +#define KMEMLEAK_SEQ_RESCHED_INTERVAL 256 + /* * Iterate over the object_list and return the first valid object at or after * the required position with its use_count incremented. The function triggers @@ -2233,6 +2236,9 @@ static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos) rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { + if (need_resched() || !(n % KMEMLEAK_SEQ_RESCHED_INTERVAL)) + kmemleak_cond_resched(object); + if (n-- > 0) continue; if (get_object(object)) @@ -2256,6 +2262,9 @@ static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos) ++(*pos); list_for_each_entry_continue_rcu(obj, &object_list, object_list) { + if (need_resched() || !(*pos % KMEMLEAK_SEQ_RESCHED_INTERVAL)) + kmemleak_cond_resched(obj); + if (get_object(obj)) { next_obj = obj; break;