When the pgd size is smaller than PAGE_SIZE, pgd_alloc() uses kzalloc()
to save space. However, this is not always naturally aligned as required
by the architecture. This patch creates a kmem_cache for pgd allocations
with the correct alignment.
The current kernel configurations with 4K pages + 39-bit VA and 64K
pages + 42-bit VA use a full page for the pgd and are not affected. The
patch is required for 48-bit VA with 64K pages where the pgd is 512
bytes.
Reported-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
#define PGD_SIZE (PTRS_PER_PGD * sizeof(pgd_t))
#define PGD_SIZE (PTRS_PER_PGD * sizeof(pgd_t))
+static struct kmem_cache *pgd_cache;
+
pgd_t *pgd_alloc(struct mm_struct *mm)
{
if (PGD_SIZE == PAGE_SIZE)
return (pgd_t *)get_zeroed_page(GFP_KERNEL);
else
pgd_t *pgd_alloc(struct mm_struct *mm)
{
if (PGD_SIZE == PAGE_SIZE)
return (pgd_t *)get_zeroed_page(GFP_KERNEL);
else
- return kzalloc(PGD_SIZE, GFP_KERNEL);
+ return kmem_cache_zalloc(pgd_cache, GFP_KERNEL);
}
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
}
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
if (PGD_SIZE == PAGE_SIZE)
free_page((unsigned long)pgd);
else
if (PGD_SIZE == PAGE_SIZE)
free_page((unsigned long)pgd);
else
+ kmem_cache_free(pgd_cache, pgd);
+}
+
+static int __init pgd_cache_init(void)
+{
+ /*
+ * Naturally aligned pgds required by the architecture.
+ */
+ if (PGD_SIZE != PAGE_SIZE)
+ pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
+ SLAB_PANIC, NULL);
+ return 0;
+core_initcall(pgd_cache_init);