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Fri, 11 Jul 2025 09:26:09 -0700 (PDT) Received: from [192.168.86.142] ([90.253.47.31]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b5e8e2710bsm4851898f8f.99.2025.07.11.09.26.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Jul 2025 09:26:09 -0700 (PDT) Message-ID: <51de7373-1b8d-426d-b720-ad9134c170bd@neon.tech> Date: Fri, 11 Jul 2025 17:26:08 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: [PATCH v5 4/4] x86/mm: Use GFP_KERNEL for alloc_low_pages() after boot From: Em Sharnoff To: linux-kernel@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org Cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , "Edgecombe, Rick P" , Oleg Vasilev , Arthur Petukhovsky , Stefan Radig , Misha Sakhnov References: <4fe0984f-74dc-45fe-b2b6-bdd81ec15bac@neon.tech> Content-Language: en-US In-Reply-To: <4fe0984f-74dc-45fe-b2b6-bdd81ec15bac@neon.tech> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 2989F18000A X-Stat-Signature: j8e1zxb4wf6kswqs1cxyucyd88pdxtjy X-Rspam-User: X-HE-Tag: 1752251170-428921 X-HE-Meta: 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 fmINgbvi 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 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: Currently it's GFP_ATOMIC. GFP_KERNEL seems more correct. >From Ingo M. [1] > There's no real reason why it should be GFP_ATOMIC AFAICS, other than > some historic inertia that nobody bothered to fix. and previously Mike R. [2] > The few callers that effectively use page allocator for the direct map > updates are gart_iommu_init() and memory hotplug. Neither of them > happen in an atomic context so there is no reason to use GFP_ATOMIC > for these allocations. > > Replace GFP_ATOMIC with GFP_KERNEL to avoid using atomic reserves for > allocations that do not require that. [1]: https://lore.kernel.org/all/aEE6_S2a-1tk1dtI@gmail.com/ [2]: https://lore.kernel.org/all/20211111110241.25968-5-rppt@kernel.org/ Signed-off-by: Em Sharnoff --- Changelog: - v2: Add this patch - v3: No changes - v4: No changes --- arch/x86/mm/init.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 474a7294016c..b37ac1d546af 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -132,7 +132,7 @@ __ref void *alloc_low_pages(unsigned int num) unsigned int order; order = get_order((unsigned long)num << PAGE_SHIFT); - return (void *)__get_free_pages(GFP_ATOMIC | __GFP_ZERO, order); + return (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, order); } if ((pgt_buf_end + num) > pgt_buf_top || !can_use_brk_pgt) { -- 2.39.5