Bug#1080096: fail to build with kernel 6.10.6+bpo-amd64 - implicit declaration of function ‘follow_pfn’

[Stefano Zacchiroli]

tags 1080096 patch
thanks

On Tue, Sep 03, 2024 at 06:35:06PM +0200, fr.hame...@gmail.com wrote:
> To solve it have applied the patches given by nvidia the 21 of July
> here :
> https://forums.developer.nvidia.com/t/gpl-only-symbols-follow-pte-and-rcu-read-unlock-prevent-470-256-02-to-build-with-kernel-6-10/300052/4

I can confirm it worked for me too, thanks a lot for the pointer!

For convenience, I'm attaching the patch I used to this message (its 2
messages down from the above, but it's not directly downloadable).

It does not apply cleanly to nvidia-kernel-dkms 535.183.01-1~deb12u1 ,
but it's trivial to fix manually.

Cheers

diff -ruNb a/kernel/conftest.sh b/kernel/conftest.sh
--- a/conftest.sh        2024-07-19 04:36:26.183701185 -0500
+++ b/conftest.sh        2024-07-19 04:36:26.230366381 -0500
@@ -4464,20 +4464,22 @@
             compile_check_conftest "$CODE" "NV_DRM_GEM_OBJECT_VMAP_HAS_MAP_ARG" "" "types"
         ;;

-        unsafe_follow_pfn)
+        follow_pfn)
             #
-            # Determine if unsafe_follow_pfn() is present.
+            # Determine if follow_pfn() is present.
             #
-            # unsafe_follow_pfn() was added by commit 69bacee7f9ad
-            # ("mm: Add unsafe_follow_pfn") in v5.13-rc1.
+            # follow_pfn() was added by commit 3b6748e2dd69
+            # ("mm: introduce follow_pfn()") in v2.6.31-rc1, and removed
+            # by commit 233eb0bf3b94 ("mm: remove follow_pfn")
+            # from linux-next 233eb0bf3b94.
             #
             CODE="
             #include <linux/mm.h>
-            void conftest_unsafe_follow_pfn(void) {
-                unsafe_follow_pfn();
+            void conftest_follow_pfn(void) {
+                follow_pfn();
             }"

-            compile_check_conftest "$CODE" "NV_UNSAFE_FOLLOW_PFN_PRESENT" "" "functions"
+            compile_check_conftest "$CODE" "NV_FOLLOW_PFN_PRESENT" "" "functions"
         ;;

         drm_plane_atomic_check_has_atomic_state_arg)
diff -ruNb a/kernel/nvidia/nvidia.Kbuild b/kernel/nvidia/nvidia.Kbuild
--- a/nvidia/nvidia.Kbuild       2022-10-12 04:29:57.000000000 -0500
+++ b/nvidia/nvidia.Kbuild       2024-07-19 05:17:39.148448922 -0500
@@ -164,7 +164,7 @@ NV_CONFTEST_FUNCTION_COMPILE_TESTS += cc
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += iterate_fd
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += seq_read_iter
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += sg_page_iter_page
-NV_CONFTEST_FUNCTION_COMPILE_TESTS += unsafe_follow_pfn
+NV_CONFTEST_FUNCTION_COMPILE_TESTS += follow_pfn
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += drm_gem_object_get
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += drm_gem_object_put_unlocked
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += set_close_on_exec
diff -ruNb a/kernel/nvidia/os-mlock.c b/kernel/nvidia/os-mlock.c
--- a/nvidia/os-mlock.c  2022-10-12 04:30:26.000000000 -0500
+++ b/nvidia/os-mlock.c  2024-07-19 04:36:26.230366381 -0500
@@ -18,10 +18,10 @@
                                 unsigned long address,
                                 unsigned long *pfn)
 {
-#if defined(NV_UNSAFE_FOLLOW_PFN_PRESENT)
-    return unsafe_follow_pfn(vma, address, pfn);
-#else
+#if defined(NV_FOLLOW_PFN_PRESENT)
     return follow_pfn(vma, address, pfn);
+#else
+    return -1;
 #endif
 }