Re: [PATCH] mm/vmstat: fix outdated vmstat_text

[Jann Horn <jannh@google.com>]

On Sat, Sep 29, 2018 at 5:07 AM kbuild test robot <lkp@intel.com> wrote:
>
> Hi Jann,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on linus/master]
> [also build test ERROR on v4.19-rc5 next-20180928]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
>
> url:    https://github.com/0day-ci/linux/commits/Jann-Horn/mm-vmstat-fix-outdated-vmstat_text/20180929-102147
> config: i386-randconfig-x005-201838 (attached as .config)
> compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=i386
>
> All error/warnings (new ones prefixed by >>):
>
>    In file included from include/linux/export.h:45:0,
>                     from include/linux/linkage.h:7,
>                     from include/linux/fs.h:5,
>                     from mm/vmstat.c:12:
>    mm/vmstat.c: In function 'vmstat_start':
> >> include/linux/compiler.h:358:38: error: call to '__compiletime_assert_1664' declared with attribute error: BUILD_BUG_ON failed: stat_items_size != ARRAY_SIZE(vmstat_text) * sizeof(unsigned long)

Nice. Looks like the 0day test bot indeed found another mismatch:

#ifdef CONFIG_DEBUG_TLBFLUSH
#ifdef CONFIG_SMP
       "nr_tlb_remote_flush",
       "nr_tlb_remote_flush_received",
#endif /* CONFIG_SMP */
       "nr_tlb_local_flush_all",
       "nr_tlb_local_flush_one",
#endif /* CONFIG_DEBUG_TLBFLUSH */

vs

#ifdef CONFIG_DEBUG_TLBFLUSH
               NR_TLB_REMOTE_FLUSH,    /* cpu tried to flush others' tlbs */
               NR_TLB_REMOTE_FLUSH_RECEIVED,/* cpu received ipi for flush */
               NR_TLB_LOCAL_FLUSH_ALL,
               NR_TLB_LOCAL_FLUSH_ONE,
#endif /* CONFIG_DEBUG_TLBFLUSH */

So if you build with CONFIG_VM_EVENT_COUNTERS=y &&
CONFIG_DEBUG_TLBFLUSH=y && CONFIG_SMP=n, vmstat output is bogus.

I like having my decisions to add asserts immediately validated by the
0day test bot. ^^

I'll send a v2 with that fixed up.