[PATCH 6.12 394/567] powerpc/pseries/cmm: call balloon_devinfo_init() also without CONFIG_BALLOON_COMPACTION

Greg Kroah-Hartman
2026-01-06T17:35:59Z

From: David Hildenbrand <david@redhat.com>

commit fc6bcf9ac4de76f5e7bcd020b3c0a86faff3f2d5 upstream.

Patch series "powerpc/pseries/cmm: two smaller fixes".

Two smaller fixes identified while doing a bigger rework.

This patch (of 2):

We always have to initialize the balloon_dev_info, even when compaction is
not configured in: otherwise the containing list and the lock are left
uninitialized.

Likely not many such configs exist in practice, but let's CC stable to
be sure.

This was found by code inspection.

Link: https://lkml.kernel.org/r/20251021100606.148294-1-david@redhat.com
Link: https://lkml.kernel.org/r/20251021100606.148294-2-david@redhat.com
Fixes: fe030c9b85e6 ("powerpc/pseries/cmm: Implement balloon compaction")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/powerpc/platforms/pseries/cmm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -550,7 +550,6 @@ static int cmm_migratepage(struct balloo

static void cmm_balloon_compaction_init(void)
{
- balloon_devinfo_init(&b_dev_info);
b_dev_info.migratepage = cmm_migratepage;
}
#else /* CONFIG_BALLOON_COMPACTION */
@@ -572,6 +571,7 @@ static int cmm_init(void)
if (!firmware_has_feature(FW_FEATURE_CMO) && !simulate)
return -EOPNOTSUPP;

+ balloon_devinfo_init(&b_dev_info);
cmm_balloon_compaction_init();

rc = register_oom_notifier(&cmm_oom_nb);