> Am 28.01.2021 um 22:54 schrieb David Rientjes <rientjes@xxxxxxxxxx>: > > On Thu, 28 Jan 2021, David Hildenbrand wrote: > >> diff --git a/mm/vmstat.c b/mm/vmstat.c >> index 7758486097f9..957680db41fa 100644 >> --- a/mm/vmstat.c >> +++ b/mm/vmstat.c >> @@ -1650,6 +1650,11 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat, >> zone->spanned_pages, >> zone->present_pages, >> zone_managed_pages(zone)); >> +#ifdef CONFIG_CMA >> + seq_printf(m, >> + "\n cma %lu", >> + zone->cma_pages); >> +#endif >> >> seq_printf(m, >> "\n protection: (%ld", > > Hmm, not sure about this. If cma is only printed for CONFIG_CMA, we can't > distinguish between (1) a kernel without your patch without including some > version checking and (2) a kernel without CONFIG_CMA enabled. IOW, > "cma 0" carries value: we know immediately that we do not have any CMA > pages on this zone, period. > > /proc/zoneinfo is also not known for its conciseness so I think printing > "cma 0" even for !CONFIG_CMA is helpful :) > > I think this #ifdef should be removed and it should call into a > zone_cma_pages(struct zone *zone) which returns 0UL if disabled. > Yeah, that’s also what I proposed in a sub-thread here. The last option would be going the full mile and not printing nr_free_cma. Code might get a bit uglier though, but we could also remove that stats counter ;) I don‘t particularly care, while printing „0“ might be easier, removing nr_free_cma might be cleaner. But then, maybe there are tools that expect that value to be around on any kernel? Thoughts? Thanks
