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Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH 2/2] mm: add pageblock_aligned() macro Content-Language: en-US To: David Hildenbrand , Andrew Morton , CC: Mike Rapoport , Oscar Salvador , , Vlastimil Babka References: <20220902064751.17890-1-wangkefeng.wang@huawei.com> <20220902064751.17890-2-wangkefeng.wang@huawei.com> <79d05f57-8b3a-2450-43bf-f45de53a8c8e@huawei.com> <2e7945e5-b0b0-bc44-c5eb-48d67532f78f@redhat.com> From: Kefeng Wang In-Reply-To: <2e7945e5-b0b0-bc44-c5eb-48d67532f78f@redhat.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662111589; a=rsa-sha256; cv=none; b=6FCRAkNGT4UPHSLrrJ/MuQaGLe2u4aLprXt7W88NLpprrXmhIZb6a1gClW0sRu54WRUBWh 0U/GgIX3QY2q7B/LCR6Sqh2+cRoKtWLuycFtkBDqKLqs5qni7JXWRFvxU91SFp3VKGXDDf 47czEjVaMigAd+7JjtbRJnF3S7uzU8s= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf28.hostedemail.com: domain of wangkefeng.wang@huawei.com designates 45.249.212.189 as permitted sender) smtp.mailfrom=wangkefeng.wang@huawei.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662111589; 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; bh=cQAHTHFznye5zIkHztElQ2jjlfhLQFxpu/JGnPsrg3I=; b=2c7lGphqeUMK8sHFcguZjLSsZwohnapkgVucfNTTeUDCqdC3/vLdX5NADwouZPWWMlMaxo zP7wT0Ljl/dYmGCb9u3LNkghuQhZig4hEjmFANDGZ5zz/qNlxxL37G6uWn8agURSN+iFZm q+9yfaET06NXk1BM04/qqqJG7xdWGfo= X-Rspamd-Server: rspam09 Authentication-Results: imf28.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf28.hostedemail.com: domain of wangkefeng.wang@huawei.com designates 45.249.212.189 as permitted sender) smtp.mailfrom=wangkefeng.wang@huawei.com X-Rspam-User: X-Stat-Signature: r7u8ursadk9wueaebkjosjqxio5dbh4b X-Rspamd-Queue-Id: C531CC006E X-HE-Tag: 1662111587-179562 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 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 >>>> --- >>> [...] >>> >>>> - 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 ... >