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Tue, 20 Apr 2021 23:42:35 -0400 Received: from mail-pf1-x42f.google.com (mail-pf1-x42f.google.com [IPv6:2607:f8b0:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 49F1EC06174A for ; Tue, 20 Apr 2021 20:42:02 -0700 (PDT) Received: by mail-pf1-x42f.google.com with SMTP id h15so9696346pfv.2 for ; Tue, 20 Apr 2021 20:42:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=dUmL888r4a+LpYSIBfs7CscY/g54lCVXYOagGpbPjVM=; b=Dc4Xe0xBbbGif9Gf3Rrn0GjZTgrU4YJB9/diduYpGSilOKnqXHUVIOuVuCYmz6C7Ly C0RiXXAJt+u5gtoqTx1oRhtMkru/P9kG8F6hfQLPSo/j99da+9NRQVokSgPt2wgSp/nL Qq9zRfpS2wQDKLkJDGc7lSUbJnQeb9EB7iv6Jj1+Gc6Vo3+gWw2rkNrn6gsiADQWDK7D tDmGYbpcgm71y32RH9mKhFwkr1L/K3Tlumc2K5RszcAm+wDKB3A+1LWpE99Zm6+fhlUH LVeFXy/tytc7OclmyaEAt9IppxoIQtfjlmcKJhrj6Ceu1GDwBNzriQTD/n3DWUBdnszo VhYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; 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charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Apr 20, 2021 at 6:35 PM Oscar Salvador wrote: > > On Thu, Apr 15, 2021 at 04:40:04PM +0800, Muchun Song wrote: > > bool mhp_supports_memmap_on_memory(unsigned long size) > > { > > + bool supported; > > unsigned long nr_vmemmap_pages = size / PAGE_SIZE; > > unsigned long vmemmap_size = nr_vmemmap_pages * sizeof(struct page); > > unsigned long remaining_size = size - vmemmap_size; > > @@ -1011,11 +1012,18 @@ bool mhp_supports_memmap_on_memory(unsigned long size) > > * altmap as an alternative source of memory, and we do not exactly > > * populate a single PMD. > > */ > > - return memmap_on_memory && > > - IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) && > > - size == memory_block_size_bytes() && > > - IS_ALIGNED(vmemmap_size, PMD_SIZE) && > > - IS_ALIGNED(remaining_size, pageblock_nr_pages << PAGE_SHIFT); > > + supported = memmap_on_memory && > > + IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) && > > + size == memory_block_size_bytes() && > > + IS_ALIGNED(vmemmap_size, PMD_SIZE) && > > + IS_ALIGNED(remaining_size, pageblock_nr_pages << PAGE_SHIFT); > > + > > + if (supported && is_hugetlb_free_vmemmap_enabled()) { > > + pr_info("Cannot enable memory_hotplug.memmap_on_memory, it is not compatible with hugetlb_free_vmemmap\n"); > > + supported = false; > > + } > > I would not print anything and rather have > > return memmap_on_memory && > !is_hugetlb_free_vmemmap_enabled && > IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) && > size == memory_block_size_bytes() && > IS_ALIGNED(vmemmap_size, PMD_SIZE) && > IS_ALIGNED(remaining_size, pageblock_nr_pages << PAGE_SHIFT); OK. Will do. > > Documentation/admin-guide/kernel-parameters.txt already provides an > explanation on memory_hotplug.memmap_on_memory parameter that states > that the feature cannot be enabled when using hugetlb-vmemmap > optimization. > > Users can always check whether the feature is enabled via > /sys/modules/memory_hotplug/parameters/memmap_on_memory. If memory_hotplug.memmap_on_memory is enabled $ cat /sys/module/memory_hotplug/parameters/memmap_on_memory $ Y If memory_hotplug.memmap_on_memory is disabled $ cat /sys/module/memory_hotplug/parameters/memmap_on_memory $ N > > Also, I did not check if it is, but if not, the fact about hugetlb-vmemmmap vs > hotplug-vmemmap should also be called out in the hugetlb-vmemmap kernel > parameter. Make sense. I will update the doc. Thanks. > > Thanks > > -- > Oscar Salvador > SUSE L3