[PATCH 1/2] uprobes: Use a dedicated mutex to serialize prepare_uprobe()
From: Adriano Cordova <hidden>
Date: 2026-09-18 14:32:27
Also in:
lkml
Subsystem:
performance events subsystem, the rest, uprobes · Maintainers:
Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds, Masami Hiramatsu, Oleg Nesterov
prepare_uprobe() serializes its callers by taking consumer_rwsem for writing. That rwsem protects the consumer list, not the instruction copy. Give struct uprobe a dedicated prepare_mutex and use it instead. No functional change. Signed-off-by: Adriano Cordova <redacted> --- kernel/events/uprobes.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 7709ea882477..686585539ebf 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c@@ -64,6 +64,7 @@ struct uprobe { refcount_t ref; struct rw_semaphore register_rwsem; struct rw_semaphore consumer_rwsem; + struct mutex prepare_mutex; /* serializes prepare_uprobe() */ struct list_head pending_list; struct list_head consumers; struct inode *inode; /* Also hold a ref to inode */
@@ -1007,6 +1008,7 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset, INIT_LIST_HEAD(&uprobe->consumers); init_rwsem(&uprobe->register_rwsem); init_rwsem(&uprobe->consumer_rwsem); + mutex_init(&uprobe->prepare_mutex); RB_CLEAR_NODE(&uprobe->rb_node); refcount_set(&uprobe->ref, 1);
@@ -1104,8 +1106,8 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file, if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) return ret; - /* TODO: move this into _register, until then we abuse this sem. */ - down_write(&uprobe->consumer_rwsem); + /* Serialize concurrent prepare_uprobe() calls from uprobe_mmap(). */ + mutex_lock(&uprobe->prepare_mutex); if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) goto out;
@@ -1125,7 +1127,7 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file, set_bit(UPROBE_COPY_INSN, &uprobe->flags); out: - up_write(&uprobe->consumer_rwsem); + mutex_unlock(&uprobe->prepare_mutex); return ret; }
--
2.51.0