Messages in this thread | | | Date | Fri, 2 Sep 2022 17:39:43 +0800 | Subject | Re: [PATCH 2/2] mm: add pageblock_aligned() macro | From | Kefeng Wang <> |
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On 2022/9/2 17:04, David Hildenbrand wrote: > On 02.09.22 11:02, Kefeng Wang wrote: >> On 2022/9/2 16:42, David Hildenbrand wrote: >>> On 02.09.22 08:47, Kefeng Wang wrote: >>>> Add pageblock_aligned() and use it to simplify code. >>>> >>>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> >>>> --- >>> [...] >>> >>>> - unsigned long nr_pgmask = pageblock_nr_pages - 1; >>>> int nid = zone_to_nid(zone); >>>> unsigned long nr_pages = 0; >>>> int zid = zone_idx(zone); >>>> @@ -1977,7 +1974,7 @@ static unsigned long __init deferred_init_pages(struct zone *zone, >>>> if (!deferred_pfn_valid(pfn)) { >>>> page = NULL; >>>> continue; >>>> - } else if (!page || !(pfn & nr_pgmask)) { >>> I didn't sleep too well this night and am tired, please tell me why I'm >>> wrong :) >> Wish you have a good reset :) > Thanks, the headache isn't helping :D > >>> "pfn & (pageblock_nr_pages - 1)" is true if the pageblock is not aligned >>> >>> E.g., pfn = 1, pageblock_nr_pages = 512 >>> >>> pfn & (pageblock_nr_pages - 1) >>> -> 1 & (512 - 1) >>> -> 1 & 511 >>> -> true >>> >>> "!(pfn & (pageblock_nr_pages - 1))" is true if the pageblock is aligned >>> -> !(true) >>> -> false >>> >>> >>> However, "!pageblock_aligned(1)" = true >>> >>> >>>> + } else if (!page || !pageblock_aligned(pfn)) { >> pageblock_aligned(pfn) IS_ALIGNED((unsigned long)(pfn), pageblock_nr_pages) >> >> #define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0) (((pfn) & >> (pageblock_nr_pages - 1)) == 0) -> ((1 & 512 -1) == 0) -> ((1 & 511) == >> 0) -> ((511) == 0) -> false >> right ? > yes ... and inverting that would give you "true", which is not what we want? > oops... it's my fault, looks like I need to have a reset to save my brain... > Again, sorry if I'm wrong ... >
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