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Shutemov" , John Hubbard , David Rientjes , Vlastimil Babka , Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v6 4/9] mm: thp: Introduce anon_orders and anon_always_mask sysfs files Message-Id: <20230929155530.a51e68e03e47a06b6b84c689@linux-foundation.org> In-Reply-To: <20230929114421.3761121-5-ryan.roberts@arm.com> References: <20230929114421.3761121-1-ryan.roberts@arm.com> <20230929114421.3761121-5-ryan.roberts@arm.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 23E2B40003 X-Stat-Signature: xd467efih9h8aph58hgp5ireoi3iqhnp X-Rspam-User: X-HE-Tag: 1696028134-655939 X-HE-Meta: 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 GokA/BDG k7SuiovLo2MNtLmRp+5NMWOupY31OL5qCNzv3oT1KRd5lHRMPbM/cNVuDdCFAWSAlFGeQfxz1qh/yOeOm9C8vdstCCnYTSTDzLtFgp4LJy+Yy/ll3RCkdIw7K11J6Y6E1F7VZgxqN33/UMvDUzNs7Gg4L96KB3tDh6SyWyhh0VdaGtqv97L+R/oyjYt5TWXwh+FlxKnIU0oE0x0wFjiVQbZPEmoGLSxDIoISUdy//Zlk8Ll/l5EbOsuWe0x6li4BLhNCfc9JFcNOFRiv5fgvbWI39fFQDDBtptD2al4eAymXCUQhV82KdaYmW5I6sSVVp5bs0U36aHoNWbzwrgP3z2UOwx3KuV+VkNA2XM+f0Ai7PaoaEiMJhKDkOe7hG79t0SwN64O/km6IFdWdTd3KCwkyrTNAErpzYFSWa 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 Fri, 29 Sep 2023 12:44:15 +0100 Ryan Roberts wrote: > In preparation for adding support for anonymous large folios that are > smaller than the PMD-size, introduce 2 new sysfs files that will be used > to control the new behaviours via the transparent_hugepage interface. > For now, the kernel still only supports PMD-order anonymous THP, so when > reading back anon_orders, it will reflect that. Therefore there are no > behavioural changes intended here. powerpc strikes again. ARCH=powerpc allmodconfig: In file included from ./include/linux/bits.h:6, from ./include/linux/ratelimit_types.h:5, from ./include/linux/printk.h:9, from ./include/asm-generic/bug.h:22, from ./arch/powerpc/include/asm/bug.h:116, from ./include/linux/bug.h:5, from ./include/linux/mmdebug.h:5, from ./include/linux/mm.h:6, from mm/huge_memory.c:8: ./include/vdso/bits.h:7:33: error: initializer element is not constant 7 | #define BIT(nr) (UL(1) << (nr)) | ^ mm/huge_memory.c:77:47: note: in expansion of macro 'BIT' 77 | unsigned int huge_anon_orders __read_mostly = BIT(PMD_ORDER); | ^~~ We keep tripping over this. I wish there was a way to fix it. Style whine: an all-caps identifier is supposed to be a constant, dammit. #define PTE_INDEX_SIZE __pte_index_size Nope. I did this: --- a/mm/huge_memory.c~mm-thp-introduce-anon_orders-and-anon_always_mask-sysfs-files-fix +++ a/mm/huge_memory.c @@ -74,7 +74,7 @@ static unsigned long deferred_split_scan static atomic_t huge_zero_refcount; struct page *huge_zero_page __read_mostly; unsigned long huge_zero_pfn __read_mostly = ~0UL; -unsigned int huge_anon_orders __read_mostly = BIT(PMD_ORDER); +unsigned int huge_anon_orders __read_mostly; static unsigned int huge_anon_always_mask __read_mostly; /** @@ -528,6 +528,9 @@ static int __init hugepage_init_sysfs(st { int err; + /* powerpc's PMD_ORDER isn't a compile-time constant */ + huge_anon_orders = BIT(PMD_ORDER); + *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); if (unlikely(!*hugepage_kobj)) { pr_err("failed to create transparent hugepage kobject\n"); _ I assume this is set up early enough. I don't know why powerpc's PTE_INDEX_SIZE is variable. Hopefully it has been set up by this time and it won't get altered.