On 11/9/20 8:25 AM, Andrew Morton wrote: > On Mon, 9 Nov 2020 08:20:05 +0530 Anshuman Khandual <anshuman.khandual@xxxxxxx> wrote: > >> >> >> On 11/7/20 10:37 AM, Andrew Morton wrote: >>> On Fri, 06 Nov 2020 08:19:36 +0800 kernel test robot <lkp@xxxxxxxxx> wrote: >>> >>>> tree/branch: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master >>>> branch HEAD: 0a6f624a86e766a27d23cbb73c23be62231d10ff Add linux-next specific files for 20201105 >>>> >>>> Error/Warning reports: >>>> >>>> https://lore.kernel.org/linux-mm/202010281624.9m2gZw45-lkp@xxxxxxxxx >>>> https://lore.kernel.org/linux-mm/202010290238.M1tDrV8p-lkp@xxxxxxxxx >>>> https://lore.kernel.org/linux-mm/202010291054.WEZO3olr-lkp@xxxxxxxxx >>>> https://lore.kernel.org/linux-mm/202011020749.5XQ3Hfzc-lkp@xxxxxxxxx >>>> >>>> ... >>>> >>>> mm/kasan/init.c:318:9: warning: variable 'pud' set but not used [-Wunused-but-set-variable] >>>> >>> >>> This is because mm/kasan/init.c does >>> >>> static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d) >>> { >>> pud_t *pud; >>> int i; >>> >>> for (i = 0; i < PTRS_PER_PUD; i++) { >>> pud = pud_start + i; >>> if (!pud_none(*pud)) >>> return; >>> } >>> >>> pud_free(&init_mm, (pud_t *)page_to_virt(p4d_page(*p4d))); >>> p4d_clear(p4d); >>> } >>> >>> but arch/arm/include/asm/pgtable-2level.h does >>> >>> #define pud_none(pud) (0) >>> >>> The solution here is for the arm implementation to reference `pud'. >>> Typically this is done via the use of an empty static inline C function >>> rather than a macro. But really all of these >>> >>> #define pud_none(pud) (0) >>> #define pud_bad(pud) (0) >>> #define pud_present(pud) (1) >>> #define pud_clear(pudp) do { } while (0) >>> #define set_pud(pud,pudp) do { } while (0) >>> >>> should be thus converted. >>> >>> Could someone in arm world please attend to this? >> >> + Ard Biesheuvel <ardb@xxxxxxxxxx> >> + Linus Walleij <linus.walleij@xxxxxxxxxx> >> >> There were some earlier discussions to solve this in a different way. >> >> https://lore.kernel.org/linux-mm/CACRpkdbAXCMTW--BmVs8SQ_u5baaeUob+U57E=4=CrMxWtMO2g@xxxxxxxxxxxxxx/ >> >> with a subsequent follow up patch. >> >> https://lore.kernel.org/linux-arm-kernel/20201106085157.11211-1-linus.walleij@xxxxxxxxxx/ > > Yes, but why? macros-pretending-to-be-functions just keep on causing > problems and they're so unnecessary. Why not just write functions in > the first place?? Did anyone try implementing that? Just build tested this. Observed that set_pud()'s arguments here seems to have been reversed. If this looks okay, will send out. diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h index 3502c2f..9d4f5ee 100644 --- a/arch/arm/include/asm/pgtable-2level.h +++ b/arch/arm/include/asm/pgtable-2level.h @@ -177,11 +177,28 @@ * the pud: the pud entry is never bad, always exists, and can't be set or * cleared. */ -#define pud_none(pud) (0) -#define pud_bad(pud) (0) -#define pud_present(pud) (1) -#define pud_clear(pudp) do { } while (0) -#define set_pud(pud,pudp) do { } while (0) +static inline int pud_none(pud_t pud) +{ + return 0; +} + +static inline int pud_bad(pud_t pud) +{ + return 0; +} + +static inline int pud_present(pud_t pud) +{ + return 1; +} + +static inline void pud_clear(pud_t *pudp) +{ +} + +static inline void set_pud(pud_t *pudp, pud_t pud) +{ +}
