[PATCH v2] fs/resctrl: Allocate rmid_ptrs[] using kvzalloc_objs()

[Ben Horgan]

On an MPAM system the number of entries in rmid_ptrs[] is the number of PARTIDs
multiplied by the number of PMGs. The maximum possible number of PARTIDs is
0x10000 and the maximum number of PMGs is 0x100. On a system pushing the limits
of the MPAM specification this can be large enough to consistently fail the
kzalloc_objs() allocation and hence fail to mount the resctrl filesystem.

Switch to allocating rmid_ptrs[] using kvzalloc_objs() so that large allocations
fall back to vmalloc().

Fixes: 264c285999fc ("arm_mpam: resctrl: Add monitor initialisation and domain boilerplate")
Signed-off-by: Ben Horgan <ben.horgan@xxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
---
I found this by testing the extremes of a software model and don't expect this
to effect real systems.
---
 fs/resctrl/monitor.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 73413cb128ea..2d7df60973d1 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -979,7 +979,7 @@ int setup_rmid_lru_list(void)
 		return 0;
 
 	idx_limit = resctrl_arch_system_num_rmid_idx();
-	rmid_ptrs = kzalloc_objs(struct rmid_entry, idx_limit);
+	rmid_ptrs = kvzalloc_objs(struct rmid_entry, idx_limit);
 	if (!rmid_ptrs)
 		return -ENOMEM;
 
@@ -1010,7 +1010,7 @@ void free_rmid_lru_list(void)
 		return;
 
 	mutex_lock(&rdtgroup_mutex);
-	kfree(rmid_ptrs);
+	kvfree(rmid_ptrs);
 	rmid_ptrs = NULL;
 	mutex_unlock(&rdtgroup_mutex);
 }
-- 
2.43.0