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 4A6CD2C11F9; Thu, 28 May 2026 20:17:55 +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=1779999476; cv=none; b=i6BTs4xqvG6ScAR2sq0cx8LmzN1a1SArRPyDf6ba6jFWh5/3zGzmEWyzqbvaktUTf1pjPczQc2EN1Tb0raBkjnhgCm1kaarMWFmObzgOAi3Of8m6PySTw7VIUyE3CrfmJdsPTgngJ0v0TT1eP3xwRhNSodDsDMIQKXocx21QaYs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779999476; c=relaxed/simple; bh=+dijsxdvTUJYXqQXXOfQf2UXrj8t2ffa/5xsXu6H0p0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dYyvE3h3G2uq0dTm0kA7+TLW5RTEQ+rJzfkW9D9GnqV+SXzL88i7/265JguBn7BNq95vLSHJp7dFWBBCA2VAcmNUskHlInTmfzS0s14Ik1Ff97ci1QfRhZlB9hzxNqoNXKePv5YdJ84UEqj8eG5PuduXjaDL6wdWJlYctAhnIT8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=qm0thQnX; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="qm0thQnX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7549D1F00A3A; Thu, 28 May 2026 20:17:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779999475; bh=lvtaA0q0psWlSmC8eNriOejvCiBA2ETeqyG5yTDV5fc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=qm0thQnX5mepHAtYLRdbiY4PPknCoXy4qrV0hzdWeCueDN9KyCBGLjaslDhyvxCXl K9kxbrnwC1OOj+7Xa1V2JdIssmaocGnsQMzM8Xy25wM2TM0ZJhj1Gr/utSliGrZ5sC ceNi+qmrpObBfB3rEk1WOJhnkwIKdc0VFSduMviA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Masami Hiramatsu (Google)" , Sasha Levin Subject: [PATCH 6.18 073/377] tracing/fprobe: Avoid kcalloc() in rcu_read_lock section Date: Thu, 28 May 2026 21:45:11 +0200 Message-ID: <20260528194640.479942037@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260528194638.371537336@linuxfoundation.org> References: <20260528194638.371537336@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Masami Hiramatsu (Google)" [ Upstream commit aa72812b49104bb5a38272fc9541feb62ca6fd32 ] fprobe_remove_node_in_module() is called under RCU read locked, but this invokes kcalloc() if there are more than 8 fprobes installed on the module. Sashiko warns it because kcalloc() can sleep [1]. [1] https://sashiko.dev/#/patchset/177552432201.853249.5125045538812833325.stgit%40mhiramat.tok.corp.google.com To fix this issue, expand the batch size to 128 and do not expand the fprobe_addr_list, but just cancel walking on fprobe_ip_table, update fgraph/ftrace_ops and retry the loop again. Link: https://lore.kernel.org/all/177669367206.132053.1493637946869032744.stgit@mhiramat.tok.corp.google.com/ Fixes: 0de4c70d04a4 ("tracing: fprobe: use rhltable for fprobe_ip_table") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) Stable-dep-of: 0ac0058a74ac ("tracing/fprobe: Check the same type fprobe on table as the unregistered one") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- kernel/trace/fprobe.c | 92 ++++++++++++++++++++++++-------------------------- 1 file changed, 45 insertions(+), 47 deletions(-) --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -344,11 +344,10 @@ static bool fprobe_is_ftrace(struct fpro } #ifdef CONFIG_MODULES -static void fprobe_set_ips(unsigned long *ips, unsigned int cnt, int remove, - int reset) +static void fprobe_remove_ips(unsigned long *ips, unsigned int cnt) { - ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, remove, reset); - ftrace_set_filter_ips(&fprobe_ftrace_ops, ips, cnt, remove, reset); + ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, 1, 0); + ftrace_set_filter_ips(&fprobe_ftrace_ops, ips, cnt, 1, 0); } #endif #else @@ -367,10 +366,9 @@ static bool fprobe_is_ftrace(struct fpro } #ifdef CONFIG_MODULES -static void fprobe_set_ips(unsigned long *ips, unsigned int cnt, int remove, - int reset) +static void fprobe_remove_ips(unsigned long *ips, unsigned int cnt) { - ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, remove, reset); + ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, 1, 0); } #endif #endif /* !CONFIG_DYNAMIC_FTRACE_WITH_ARGS && !CONFIG_DYNAMIC_FTRACE_WITH_REGS */ @@ -543,7 +541,7 @@ static void fprobe_graph_remove_ips(unsi #ifdef CONFIG_MODULES -#define FPROBE_IPS_BATCH_INIT 8 +#define FPROBE_IPS_BATCH_INIT 128 /* instruction pointer address list */ struct fprobe_addr_list { int index; @@ -551,45 +549,24 @@ struct fprobe_addr_list { unsigned long *addrs; }; -static int fprobe_addr_list_add(struct fprobe_addr_list *alist, unsigned long addr) +static int fprobe_remove_node_in_module(struct module *mod, struct fprobe_hlist_node *node, + struct fprobe_addr_list *alist) { - unsigned long *addrs; - - /* Previously we failed to expand the list. */ - if (alist->index == alist->size) - return -ENOSPC; - - alist->addrs[alist->index++] = addr; - if (alist->index < alist->size) + if (!within_module(node->addr, mod)) return 0; - /* Expand the address list */ - addrs = kcalloc(alist->size * 2, sizeof(*addrs), GFP_KERNEL); - if (!addrs) - return -ENOMEM; - - memcpy(addrs, alist->addrs, alist->size * sizeof(*addrs)); - alist->size *= 2; - kfree(alist->addrs); - alist->addrs = addrs; + if (delete_fprobe_node(node)) + return 0; + /* If no address list is available, we can't track this address. */ + if (!alist->addrs) + return 0; + alist->addrs[alist->index++] = node->addr; + if (alist->index == alist->size) + return -ENOSPC; return 0; } -static void fprobe_remove_node_in_module(struct module *mod, struct fprobe_hlist_node *node, - struct fprobe_addr_list *alist) -{ - if (!within_module(node->addr, mod)) - return; - if (delete_fprobe_node(node)) - return; - /* - * If failed to update alist, just continue to update hlist. - * Therefore, at list user handler will not hit anymore. - */ - fprobe_addr_list_add(alist, node->addr); -} - /* Handle module unloading to manage fprobe_ip_table. */ static int fprobe_module_callback(struct notifier_block *nb, unsigned long val, void *data) @@ -598,29 +575,50 @@ static int fprobe_module_callback(struct struct fprobe_hlist_node *node; struct rhashtable_iter iter; struct module *mod = data; + bool retry; if (val != MODULE_STATE_GOING) return NOTIFY_DONE; alist.addrs = kcalloc(alist.size, sizeof(*alist.addrs), GFP_KERNEL); - /* If failed to alloc memory, we can not remove ips from hash. */ - if (!alist.addrs) - return NOTIFY_DONE; + /* + * If failed to alloc memory, ftrace_ops will not be able to remove ips from + * hash, but we can still remove nodes from fprobe_ip_table, so we can avoid + * the potential wrong callback. So just print a warning here and try to + * continue without address list. + */ + WARN_ONCE(!alist.addrs, + "Failed to allocate memory for fprobe_addr_list, ftrace_ops will not be updated"); mutex_lock(&fprobe_mutex); +again: + retry = false; + alist.index = 0; rhltable_walk_enter(&fprobe_ip_table, &iter); do { rhashtable_walk_start(&iter); while ((node = rhashtable_walk_next(&iter)) && !IS_ERR(node)) - fprobe_remove_node_in_module(mod, node, &alist); + if (fprobe_remove_node_in_module(mod, node, &alist) < 0) { + retry = true; + break; + } rhashtable_walk_stop(&iter); - } while (node == ERR_PTR(-EAGAIN)); + } while (node == ERR_PTR(-EAGAIN) && !retry); rhashtable_walk_exit(&iter); + /* Remove any ips from hash table(s) */ + if (alist.index > 0) { + fprobe_remove_ips(alist.addrs, alist.index); + /* + * If we break rhashtable walk loop except for -EAGAIN, we need + * to restart looping from start for safety. Anyway, this is + * not a hotpath. + */ + if (retry) + goto again; + } - if (alist.index > 0) - fprobe_set_ips(alist.addrs, alist.index, 1, 0); mutex_unlock(&fprobe_mutex); kfree(alist.addrs);