diff options
| -rw-r--r-- | drivers/block/zram/zram_drv.c | 2 | ||||
| -rw-r--r-- | drivers/block/zram/zram_drv.h | 15 |
2 files changed, 9 insertions, 8 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 607f4634c27d..eb021db21ddf 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -2131,6 +2131,8 @@ static int __init zram_init(void) { int ret; + BUILD_BUG_ON(__NR_ZRAM_PAGEFLAGS > BITS_PER_LONG); + ret = cpuhp_setup_state_multi(CPUHP_ZCOMP_PREPARE, "block/zram:prepare", zcomp_cpu_up_prepare, zcomp_cpu_dead); if (ret < 0) diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 80c3b43b4828..a2bda53020fd 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -30,16 +30,15 @@ /* - * The lower ZRAM_FLAG_SHIFT bits of table.flags is for - * object size (excluding header), the higher bits is for - * zram_pageflags. + * ZRAM is mainly used for memory efficiency so we want to keep memory + * footprint small and thus squeeze size and zram pageflags into a flags + * member. The lower ZRAM_FLAG_SHIFT bits is for object size (excluding + * header), which cannot be larger than PAGE_SIZE (requiring PAGE_SHIFT + * bits), the higher bits are for zram_pageflags. * - * zram is mainly used for memory efficiency so we want to keep memory - * footprint small so we can squeeze size and flags into a field. - * The lower ZRAM_FLAG_SHIFT bits is for object size (excluding header), - * the higher bits is for zram_pageflags. + * We use BUILD_BUG_ON() to make sure that zram pageflags don't overflow. */ -#define ZRAM_FLAG_SHIFT 24 +#define ZRAM_FLAG_SHIFT (PAGE_SHIFT + 1) /* Flags for zram pages (table[page_no].flags) */ enum zram_pageflags { |