From: Daniel Gomez <[email protected]>
The -EEXIST error code is reserved by the module loading infrastructure
to indicate that a module is already loaded. When a module's init
function returns -EEXIST, userspace tools like kmod interpret this as
"module already loaded" and treat the operation as successful, returning
0 to the user even though the module initialization actually failed.
This follows the precedent set by commit 54416fd76770 ("netfilter:
conntrack: helper: Replace -EEXIST by -EBUSY") which fixed the same
issue in nf_conntrack_helper_register().
Affected modules:
* dm_cache dm_clone dm_integrity dm_mirror dm_multipath dm_pcache
* dm_vdo dm-ps-round-robin dm_historical_service_time dm_io_affinity
* dm_queue_length dm_service_time dm_snapshot
Signed-off-by: Daniel Gomez <[email protected]>
---
The error code -EEXIST is reserved by the kernel module loader to
indicate that a module with the same name is already loaded. When a
module's init function returns -EEXIST, kmod interprets this as "module
already loaded" and reports success instead of failure [1].
The kernel module loader will include a safety net that provides -EEXIST
to -EBUSY with a warning [2], and a documentation patch has been sent to
prevent future occurrences [3].
These affected code paths were identified using a static analysis tool
[4] that traces -EEXIST returns to module_init(). The tool was developed
with AI assistance and all findings were manually validated.
Link: https://lore.kernel.org/all/[email protected]/ [1]
Link:
https://lore.kernel.org/all/[email protected]/
[2]
Link:
https://lore.kernel.org/all/20251218-dev-module-init-eexists-modules-docs-v1-0-361569aa7...@samsung.com/
[3]
Link: https://gitlab.com/-/snippets/4913469 [4]
---
drivers/md/dm-exception-store.c | 2 +-
drivers/md/dm-log.c | 2 +-
drivers/md/dm-path-selector.c | 2 +-
drivers/md/dm-target.c | 2 +-
4 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index c3799757bf4a..88f119a0a2ae 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -116,7 +116,7 @@ int dm_exception_store_type_register(struct
dm_exception_store_type *type)
if (!__find_exception_store_type(type->name))
list_add(&type->list, &_exception_store_types);
else
- r = -EEXIST;
+ r = -EBUSY;
spin_unlock(&_lock);
return r;
diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 9d85d045f9d9..bced5a783ee3 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -121,7 +121,7 @@ int dm_dirty_log_type_register(struct dm_dirty_log_type
*type)
if (!__find_dirty_log_type(type->name))
list_add(&type->list, &_log_types);
else
- r = -EEXIST;
+ r = -EBUSY;
spin_unlock(&_lock);
return r;
diff --git a/drivers/md/dm-path-selector.c b/drivers/md/dm-path-selector.c
index d0b883fabfeb..2b0ac200f1c0 100644
--- a/drivers/md/dm-path-selector.c
+++ b/drivers/md/dm-path-selector.c
@@ -107,7 +107,7 @@ int dm_register_path_selector(struct path_selector_type
*pst)
if (__find_path_selector_type(pst->name)) {
kfree(psi);
- r = -EEXIST;
+ r = -EBUSY;
} else
list_add(&psi->list, &_path_selectors);
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index 8fede41adec0..1fd41289de36 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -88,7 +88,7 @@ int dm_register_target(struct target_type *tt)
if (__find_target_type(tt->name)) {
DMERR("%s: '%s' target already registered",
__func__, tt->name);
- rv = -EEXIST;
+ rv = -EBUSY;
} else {
list_add(&tt->list, &_targets);
}
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251218-dev-module-init-eexists-dm-devel-2d656f9f2365
Best regards,
--
Daniel Gomez <[email protected]>
