On Tue, 14 Jun 2011 19:47:19 -0500 H Hartley Sweeten <hartleys@xxxxxxxxxxxxxxxxxxx> wrote: > Hello all, > > Sparse is reporting a couple warnings in mm/memblock.c: > > warning: cast truncates bits from constant value (9f911029d74e35b becomes 9d74e35b) > > The warnings are due to the cast of RED_INACTIVE in memblock_analyze(): > > /* Check marker in the unused last array entry */ > WARN_ON(memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS].base > != (phys_addr_t)RED_INACTIVE); > WARN_ON(memblock_reserved_init_regions[INIT_MEMBLOCK_REGIONS].base > != (phys_addr_t)RED_INACTIVE); > > And in memblock_init(): > > /* Write a marker in the unused last array entry */ > memblock.memory.regions[INIT_MEMBLOCK_REGIONS].base = (phys_addr_t)RED_INACTIVE; > memblock.reserved.regions[INIT_MEMBLOCK_REGIONS].base = (phys_addr_t)RED_INACTIVE; > > Could this cause any problems? If not, is there anyway to quiet the sparse noise? > It's all just a debugging check and that check will continue to work OK despite this bug. But yes, it's ugly and should be fixed. I don't think that mm/memblock.c should have reused RED_INACTIVE. That's a slab thing and wedging it into a phys_addr_t was inappropriate. In fact I don't think RED_INACTIVE should exist. It's just inviting other subsystems to (ab)use it. It should be replaced by a slab-specific SLAB_RED_INACTIVE, as slub did with SLUB_RED_INACTIVE. I'd suggest something like the below, which I didn't test. Feel free to send it back at me, or ignore it ;) diff -puN include/linux/poison.h~a include/linux/poison.h --- a/include/linux/poison.h~a +++ a/include/linux/poison.h @@ -40,6 +40,12 @@ #define RED_INACTIVE 0x09F911029D74E35BULL /* when obj is inactive */ #define RED_ACTIVE 0xD84156C5635688C0ULL /* when obj is active */ +#ifdef CONFIG_PHYS_ADDR_T_64BIT +#define MEMBLOCK_INACTIVE 0x3a84fb0144c9e71bULL +#else +#define MEMBLOCK_INACTIVE 0x44c9e71bUL +#endif + #define SLUB_RED_INACTIVE 0xbb #define SLUB_RED_ACTIVE 0xcc diff -puN mm/memblock.c~a mm/memblock.c --- a/mm/memblock.c~a +++ a/mm/memblock.c @@ -758,9 +758,9 @@ void __init memblock_analyze(void) /* Check marker in the unused last array entry */ WARN_ON(memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS].base - != (phys_addr_t)RED_INACTIVE); + != MEMBLOCK_INACTIVE); WARN_ON(memblock_reserved_init_regions[INIT_MEMBLOCK_REGIONS].base - != (phys_addr_t)RED_INACTIVE); + != MEMBLOCK_INACTIVE); memblock.memory_size = 0; @@ -786,8 +786,8 @@ void __init memblock_init(void) memblock.reserved.max = INIT_MEMBLOCK_REGIONS; /* Write a marker in the unused last array entry */ - memblock.memory.regions[INIT_MEMBLOCK_REGIONS].base = (phys_addr_t)RED_INACTIVE; - memblock.reserved.regions[INIT_MEMBLOCK_REGIONS].base = (phys_addr_t)RED_INACTIVE; + memblock.memory.regions[INIT_MEMBLOCK_REGIONS].base = MEMBLOCK_INACTIVE; + memblock.reserved.regions[INIT_MEMBLOCK_REGIONS].base = MEMBLOCK_INACTIVE; /* Create a dummy zero size MEMBLOCK which will get coalesced away later. * This simplifies the memblock_add() code below... _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>