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[2003:cb:c714:4800:2077:1bf6:40e7:2833]) by smtp.gmail.com with ESMTPSA id x13-20020a1c7c0d000000b003a5ca627333sm7456722wmc.8.2022.09.02.02.04.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 02 Sep 2022 02:04:28 -0700 (PDT) Message-ID: <2e7945e5-b0b0-bc44-c5eb-48d67532f78f@redhat.com> Date: Fri, 2 Sep 2022 11:04:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0 Subject: Re: [PATCH 2/2] mm: add pageblock_aligned() macro To: Kefeng Wang , Andrew Morton , linux-mm@kvack.org Cc: Mike Rapoport , Oscar Salvador , linux-kernel@vger.kernel.org, Vlastimil Babka References: <20220902064751.17890-1-wangkefeng.wang@huawei.com> <20220902064751.17890-2-wangkefeng.wang@huawei.com> <79d05f57-8b3a-2450-43bf-f45de53a8c8e@huawei.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <79d05f57-8b3a-2450-43bf-f45de53a8c8e@huawei.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662109472; a=rsa-sha256; cv=none; b=laYNuzauwtonNnWTgxGRV7ChHeS86JTUi83WiixcHAJdmLDwj0YQONpELBgB6O9zhXV3ls /z1yJd7LVPcJddA3Q8D7mask8dZjB46TqKAuhKo30D+1uVOJ/OZuFIGV3F7sDOBZEFJf0v yy7OT9BhAYonWvE83lCTHfVDi3fe4GA= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Ym7QC7ur; spf=pass (imf20.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662109472; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=paxwFROiQn9wOtjKP9jQhB8HGgVytBOJmG9Pfk5FrI8=; b=NDA0UcQvDQXHQNjmayZWzvDOzrjbd0uRfC3JftVZp2NSMJyjokTzx3v77pq+ey9E4PkWv7 2rPsec2uj/LrWBwG0H8ydGuzVJZ4U6vIQR9o3TC8AAph7TIpKO1m53dSSbPkPtkGdsKM0V SnFmMZ/RdhFh8vWezOxgUdJPDgocwos= Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Ym7QC7ur; spf=pass (imf20.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 24F8E1C005E X-Stat-Signature: jepninfqjj8tmgkojdtkxb87imf69jqf X-HE-Tag: 1662109472-133758 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 >>> --- >> [...] >> >>> - 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? Again, sorry if I'm wrong ... -- Thanks, David / dhildenb