5.10-stable review patch. If anyone has any objections, please let me know.
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From: Christoph Hellwig hch@lst.de
[ Upstream commit a006050575745ca2be25118b90f1c37f454ac542 ]
Allow for a RCU-sched critical section around find_module, following the lower level find_module_all helper, and switch the two callers outside of module.c to use such a RCU-sched critical section instead of module_mutex.
Reviewed-by: Petr Mladek pmladek@suse.com Acked-by: Miroslav Benes mbenes@suse.cz Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Jessica Yu jeyu@kernel.org Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/module.h | 2 +- kernel/livepatch/core.c | 5 +++-- kernel/module.c | 1 - kernel/trace/trace_kprobe.c | 4 ++-- 4 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/include/linux/module.h b/include/linux/module.h index 6264617bab4d4..86fae5d1c0e39 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -582,7 +582,7 @@ static inline bool within_module(unsigned long addr, const struct module *mod) return within_module_init(addr, mod) || within_module_core(addr, mod); }
-/* Search for module by name: must hold module_mutex. */ +/* Search for module by name: must be in a RCU-sched critical section. */ struct module *find_module(const char *name);
struct symsearch { diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index f5faf935c2d8f..e660ea4f90a28 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -19,6 +19,7 @@ #include <linux/moduleloader.h> #include <linux/completion.h> #include <linux/memory.h> +#include <linux/rcupdate.h> #include <asm/cacheflush.h> #include "core.h" #include "patch.h" @@ -57,7 +58,7 @@ static void klp_find_object_module(struct klp_object *obj) if (!klp_is_module(obj)) return;
- mutex_lock(&module_mutex); + rcu_read_lock_sched(); /* * We do not want to block removal of patched modules and therefore * we do not take a reference here. The patches are removed by @@ -74,7 +75,7 @@ static void klp_find_object_module(struct klp_object *obj) if (mod && mod->klp_alive) obj->mod = mod;
- mutex_unlock(&module_mutex); + rcu_read_unlock_sched(); }
static bool klp_initialized(void) diff --git a/kernel/module.c b/kernel/module.c index c0e51ffe26f0a..1f9f6133c30ef 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -641,7 +641,6 @@ static struct module *find_module_all(const char *name, size_t len,
struct module *find_module(const char *name) { - module_assert_mutex(); return find_module_all(name, strlen(name), false); }
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 7183572898998..5453af26ff764 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -124,9 +124,9 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) if (!p) return true; *p = '\0'; - mutex_lock(&module_mutex); + rcu_read_lock_sched(); ret = !!find_module(tk->symbol); - mutex_unlock(&module_mutex); + rcu_read_unlock_sched(); *p = ':';
return ret;