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Wong" , mcgrof@kernel.org, gost.dev@samsung.com, kernel@pankajraghav.com, hch@lst.de, Pankaj Raghav Subject: [PATCH v2 4/5] mm: add largest_zero_folio() routine Date: Mon, 7 Jul 2025 16:23:18 +0200 Message-ID: <20250707142319.319642-5-kernel@pankajraghav.com> In-Reply-To: <20250707142319.319642-1-kernel@pankajraghav.com> References: <20250707142319.319642-1-kernel@pankajraghav.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 54AFC4000B X-Stat-Signature: 7pm7cqzhhkhajprhemrwzsdtdm4epgzz X-Rspam-User: X-HE-Tag: 1751898238-892258 X-HE-Meta: U2FsdGVkX1+JpgAaP+fBaZMgx9XuyP/gomvzlIXGqk0syT9arz1Knp3xSu3CqukZ9OiN9YwZNHsFMOVGdIo/CCQGeaqoue8nRwqGENxYcNJ8QDiFonm8Dljrwy6jpImTQXAb1AvXKY/GkV/fprAh8eOu+8nTfnw5xYjP3teSP7j9BPYF0Tric6+6PdoTvkuPeRXhQnf7mzNqAelxLpGs5qCxF+v3mvD5ty10UTI54TlR4+3mcyfK/XBH8m+JAid0w7S/I5Qpd4GAsUE5eWoYgQAbnzqzkbMn9eavQJgYRIo9nTqnPKsh7KApxNYkQzSxrK84lwFPDT1qeEbnoY8nCItR3DdMRc+oAc54lv0BaOetKX/sCJgtSmN39irZR3CcBW6tMI2TPtJjAmWIbirnhc3QPZHZIHHlNDqXQYDqaRE3jAwRaMXkOYr1gbD6Adtv5PPPnWz4EpiGWIQ2+FYwpOrrFhhNJICfYlFHhCwK8lKPB0AO0gkJn6X6qQ+e+kWOWKPUdcalmJeOamd6+y3aikbWh5AEE1qrls1coiTXQecfeBGa+dycKGvLDeVb5mNObEdFBEFdCRO4bmXT5h9G7XW3EnbzJidc63ZRWRmOJwK7OeN42Bg5bkuYucA8U1TPA8ocKrniCJY5GnlvEOOjBVyCag4+lJYb/4tio2BHwJX2Ci2YQV6ex0Vuo8NNZZwjxOjpCjd+SDIF/nH6MBJyB0hJLq6qwc4k1snA7uB0ikJRHig6dGv2YAvkk3AXpwmsqwE2oTtN2Fx17VaUbNUVKfnPpD8ScvQTPGQW/Bn+VHVvIGbf4gE+4bc4dne8BLD1D73wJgXEOtIdcXiHx41UZ3vG0Ndx8mwMvO+bAy1GKrIH3Mh2yAgRQznC5WzSQF43CQPRiNPtJlrL44X9FWY9Lzl1e52dPp4cbqc9cYtZZ0o9u5rUFDwTWHnFgVv+3P8PcBxGGo/yzsSWS3Ha8+O FwfgSHFZ XTDiwt+KcfCGvvvKgn7ANv2qIqakgbMTEN1B3NMo8KW0hDR7KMzk2qD6cGmCchoInhh6I9w/5bIYiAv7oLbwdGLY0gKN8o1KtiRQBsEshiQWqr3G8rAl3n8s0DLUjyZsnh6z8gglFEkg23+Wlit81TfLsgh83dQ7BRvz2gGc0RzK7kW3+IvgckWUjq1SQdl8+yWKD/M6SGj6MtQBRUp4wKfxC6S0qlMbWCUhfq2zcM9AdDaMC17W63/sGXzJvTS7KjKeTs3bqaHsUrDOyBrjpmifyUnrr54Rp0GKFovv3+oh1gY4LbrmLPG+pI6VOj5+BnwvM3uLCwq89C5ddLCBlw/ALkFQkR9eKhPC9j6IfO1mfl47D7O/+eMs7A2MRz9SaQdJ+ 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: List-Subscribe: List-Unsubscribe: From: Pankaj Raghav Add largest_zero_folio() routine so that huge_zero_folio can be used without the need to pass any mm struct. This will return ZERO_PAGE folio if CONFIG_STATIC_PMD_ZERO_PAGE is disabled or if we failed to allocate a PMD page from memblock. This routine can also be called even if THP is disabled. Signed-off-by: Pankaj Raghav --- include/linux/mm.h | 28 ++++++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 428fe6d36b3c..d5543cf7b8e9 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4018,17 +4018,41 @@ static inline bool vma_is_special_huge(const struct vm_area_struct *vma) #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ +extern struct folio *huge_zero_folio; +extern unsigned long huge_zero_pfn; + #ifdef CONFIG_STATIC_PMD_ZERO_PAGE extern void __init static_pmd_zero_init(void); + +/* + * largest_zero_folio - Get the largest zero size folio available + * + * This function will return a PMD sized zero folio if CONFIG_STATIC_PMD_ZERO_PAGE + * is enabled. Otherwise, a ZERO_PAGE folio is returned. + * + * Deduce the size of the folio with folio_size instead of assuming the + * folio size. + */ +static inline struct folio *largest_zero_folio(void) +{ + if(!huge_zero_folio) + return page_folio(ZERO_PAGE(0)); + + return READ_ONCE(huge_zero_folio); +} + #else static inline void __init static_pmd_zero_init(void) { return; } + +static inline struct folio *largest_zero_folio(void) +{ + return page_folio(ZERO_PAGE(0)); +} #endif -extern struct folio *huge_zero_folio; -extern unsigned long huge_zero_pfn; #ifdef CONFIG_TRANSPARENT_HUGEPAGE static inline bool is_huge_zero_folio(const struct folio *folio) -- 2.49.0