[bug report] mmu_notifiers: rename invalidate_range notifier

[Dan Carpenter <dan.carpenter@linaro.org>]

Hello Alistair Popple,

The patch 828fe4085cae: "mmu_notifiers: rename invalidate_range
notifier" from Jul 19, 2023 (linux-next), leads to the following
Smatch static checker warning:

mm/mmu_notifier.c:1020 mmu_interval_notifier_insert_locked()
error: NULL dereference inside function __mmu_notifier_register()

mm/mmu_notifier.c:671 __mmu_notifier_register()
warn: variable dereferenced before check 'subscription' (see line 624)

mm/mmu_notifier.c
    1010         unsigned long start, unsigned long length,
    1011         const struct mmu_interval_notifier_ops *ops)
    1012 {
    1013         struct mmu_notifier_subscriptions *subscriptions =
    1014                 mm->notifier_subscriptions;
    1015         int ret;
    1016 
    1017         mmap_assert_write_locked(mm);
    1018 
    1019         if (!subscriptions || !subscriptions->has_itree) {
--> 1020                 ret = __mmu_notifier_register(NULL, mm);

subscription is NULL here

    1021                 if (ret)
    1022                         return ret;
    1023                 subscriptions = mm->notifier_subscriptions;
    1024         }
    1025         return __mmu_interval_notifier_insert(interval_sub, mm, subscriptions,
    1026                                               start, length, ops);
    1027 }

regards,
dan carpenter