[PATCH] arm64/mm: don't initialize pgd_cache twice

[Mike Rapoport]

When PGD_SIZE != PAGE_SIZE, arm64 uses kmem_cache for allocation of PGD
memory. That cache was initialized twice: first through
pgtable_cache_init() alias and then as an override for weak
pgd_cache_init().

After enabling accounting for the PGD memory, this created a confusion for
memcg and slub sysfs code which resulted in the following errors:

[   90.608597] kobject_add_internal failed for pgd_cache(13:init.scope) (error: -2 parent: cgroup)
[   90.678007] kobject_add_internal failed for pgd_cache(13:init.scope) (error: -2 parent: cgroup)
[   90.713260] kobject_add_internal failed for pgd_cache(21:systemd-tmpfiles-setup.service) (error: -2 parent: cgroup)

Removing the alias from pgtable_cache_init() and keeping the only pgd_cache
initialization in pgd_cache_init() resolves the problem and allows
accounting of PGD memory.

Reported-by: Qian Cai <cai@xxxxxx>
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
---
 arch/arm64/include/asm/pgtable.h | 3 +--
 arch/arm64/mm/pgd.c              | 5 +----
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 3191b9f..c7a802d 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -851,8 +851,7 @@ extern int kern_addr_valid(unsigned long addr);
 
 #include <asm-generic/pgtable.h>
 
-void pgd_cache_init(void);
-#define pgtable_cache_init	pgd_cache_init
+static inline void pgtable_cache_init(void) { }
 
 /*
  * On AArch64, the cache coherency is handled via the set_pte_at() function.
diff --git a/arch/arm64/mm/pgd.c b/arch/arm64/mm/pgd.c
index 53c48f5..3f0a744 100644
--- a/arch/arm64/mm/pgd.c
+++ b/arch/arm64/mm/pgd.c
@@ -32,13 +32,10 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
 {
 	gfp_t gfp = GFP_PGTABLE_USER;
 
-	if (unlikely(mm == &init_mm))
-		gfp = GFP_PGTABLE_KERNEL;
-
 	if (PGD_SIZE == PAGE_SIZE)
 		return (pgd_t *)__get_free_page(gfp);
 	else
-		return kmem_cache_alloc(pgd_cache, GFP_PGTABLE_KERNEL);
+		return kmem_cache_alloc(pgd_cache, gfp);
 }
 
 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
-- 
2.7.4


> [1] https://cailca.github.io/files/dmesg.txt
> 
> -- 
> Sincerely yours,
> Mike.
> 

-- 
Sincerely yours,
Mike.