> -----Original Message----- > From: Mike Kravetz [mailto:mike.kravetz@xxxxxxxxxx] > Sent: Friday, July 10, 2020 6:58 AM > To: Song Bao Hua (Barry Song) <song.bao.hua@xxxxxxxxxxxxx>; Roman > Gushchin <guro@xxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>; linux-mm@xxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; Linuxarm <linuxarm@xxxxxxxxxx>; Jonathan > Cameron <jonathan.cameron@xxxxxxxxxx> > Subject: Re: [PATCH v3] mm/hugetlb: avoid hardcoding while checking if cma > is enable > > Looks like this produced a warning in linux-next. I suspect it is due to the > combination CONFIG_HUGETLB_PAGE && !CONFIG_CMA. > > Instead of adding the routine hugetlb_cma_enabled() to scan the hugetlb_cma > array, could we just use a boolean as follows? It can simply be set in > hugetlb_cma_reserve when we reserve CMA. Maybe just use hugetlb_cma_size? If hugetlb_cma_size is not 0, someone is trying to use cma, then bootmem for gigantic pages will be totally ignored according to discussion here: https://lkml.org/lkml/2020/7/8/1288 if somebody sets a wrong hugetlb_cma_size which causes that cma is not reserved. It is the fault of users? We just need to document hugetlb_cma will overwrite bootmem reservations? > -- > Mike Kravetz > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index fab4485b9e52..92cb882cf287 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -46,6 +46,7 @@ unsigned int default_hstate_idx; > struct hstate hstates[HUGE_MAX_HSTATE]; > > static struct cma *hugetlb_cma[MAX_NUMNODES]; > +static bool hugetlb_cma_enabled = false; > > /* > * Minimum page order among possible hugepage sizes, set to a proper value > @@ -2571,7 +2572,7 @@ static void __init hugetlb_hstate_alloc_pages(struct > hstate *h) > > for (i = 0; i < h->max_huge_pages; ++i) { > if (hstate_is_gigantic(h)) { > - if (IS_ENABLED(CONFIG_CMA) && hugetlb_cma[0]) { > + if (hugetlb_cma_enabled) { > pr_warn_once("HugeTLB: hugetlb_cma is enabled, skip > boot time allocation\n"); > break; > } > @@ -5708,6 +5709,7 @@ void __init hugetlb_cma_reserve(int order) > reserved += size; > pr_info("hugetlb_cma: reserved %lu MiB on node %d\n", > size / SZ_1M, nid); > + hugetlb_cma_enabled = true; > > if (reserved >= hugetlb_cma_size) > break; Thanks Barry
