Re: [PATCH] uprobes: get RCU trace lock before list iteration
From: Andrii Nakryiko <hidden>
Date: 2024-11-07 18:15:02
Also in:
linux-perf-users, lkml
On Thu, Nov 7, 2024 at 9:16 AM Breno Leitao [off-list ref] wrote:
Acquire RCU trace lock in filter_chain() to protect
list_for_each_entry_rcu() iteration, protecting the list iteration in a
RCU read section.
Prior to this fix, list_for_each_entry_srcu() was called without holding
the required lock, triggering warnings when RCU_PROVING is enabled:
kernel/events/uprobes.c:937 RCU-list traversed without holding the required lock!!
Signed-off-by: Breno Leitao <leitao@debian.org>
Fixes: cc01bd044e6a ("uprobes: travers uprobe's consumer list locklessly under SRCU protection")
---
kernel/events/uprobes.c | 2 ++
1 file changed, 2 insertions(+)LGTM, thanks Reviewed-by: Andrii Nakryiko <andrii@kernel.org>
quoted hunk ↗ jump to hunk
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index fa04b14a7d72353adc440742016b813da6c812d2..afdaa45a43ac3948f7983175eda808c989e8738a 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c@@ -1103,11 +1103,13 @@ static bool filter_chain(struct uprobe *uprobe, struct mm_struct *mm) bool ret = false; down_read(&uprobe->consumer_rwsem); + rcu_read_lock_trace(); list_for_each_entry_rcu(uc, &uprobe->consumers, cons_node, rcu_read_lock_trace_held()) { ret = consumer_filter(uc, mm); if (ret) break; } + rcu_read_unlock_trace(); up_read(&uprobe->consumer_rwsem); return ret;--- base-commit: 5b913f5d7d7fe0f567dea8605f21da6eaa1735fb change-id: 20241107-rcu_probe-bef660d84990 Best regards, -- Breno Leitao [off-list ref]