[PATCH] perf: Add RCU read lock protection to perf_iterate_ctx()
From: Breno Leitao
Date: Fri Jan 17 2025 - 09:41:33 EST
The perf_iterate_ctx() function performs RCU list traversal but
currently lacks RCU read lock protection. This causes lockdep warnings
when running perf probe with unshare(1) under CONFIG_PROVE_RCU_LIST=y:
WARNING: suspicious RCU usage
kernel/events/core.c:8168 RCU-list traversed in non-reader section!!
Call Trace:
lockdep_rcu_suspicious
? perf_event_addr_filters_apply
perf_iterate_ctx
perf_event_exec
begin_new_exec
? load_elf_phdrs
load_elf_binary
? lock_acquire
? find_held_lock
? bprm_execve
bprm_execve
do_execveat_common.isra.0
__x64_sys_execve
do_syscall_64
entry_SYSCALL_64_after_hwframe
This protection was previously present but was removed in commit
bd2756811766 ("perf: Rewrite core context handling"). Add back the
necessary rcu_read_lock()/rcu_read_unlock() pair around
perf_iterate_ctx() call in perf_event_exec().
CC: stable@xxxxxxxxxxxxxxx
Fixes: bd2756811766 ("perf: Rewrite core context handling")
Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
---
kernel/events/core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 065f9188b44a0d8ee66cc76314ae247dbe45cb57..e2adb06f8d81307b2762375474bee1c9e8a74598 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8277,7 +8277,9 @@ void perf_event_exec(void)
perf_event_enable_on_exec(ctx);
perf_event_remove_on_exec(ctx);
+ rcu_read_lock();
perf_iterate_ctx(ctx, perf_event_addr_filters_exec, NULL, true);
+ rcu_read_unlock();
perf_unpin_context(ctx);
put_ctx(ctx);
---
base-commit: dbb0aea70ce4b85915a52d7adf9af57bd80f330a
change-id: 20250117-fix_perf_rcu-2ff93190950a
Best regards,
--
Breno Leitao <leitao@xxxxxxxxxx>