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AJvYcCV/uh2qHtCC+w832oftBsPF724tYoR38dxrTPIyWuW1/Be1WULCmsENtZRGziG4uFC9n8I2qZ/Ujg==@kvack.org X-Gm-Message-State: AOJu0YxNMF1EYt0Zhoo7EQDZ4bKBxx5UGtfkRXmZ6kbhNOoKrMjyEhaF zwo2EZTSEBuD/4XmTcT/D5Wh4m0lSOxz0sMRTnJcBrf9BHTasImXSGlex8U8eUbgANHdP4c2YS+ cQNmUiuXsC9nAXw== X-Google-Smtp-Source: AGHT+IH4X90kdSgY4gS6T2ygfWyabi8rSDiiqcDLF1Md3MDGtyvaNqc10OgaH/bpc5lD84VGSrNHO3O0B1jxUw== X-Received: from pgac24.prod.google.com ([2002:a05:6a02:2958:b0:bd9:a349:94c7]) (user=jackmanb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:e082:b0:252:2bfe:b65a with SMTP id adf61e73a8af0-36617e36e06mr9940237637.7.1765259056752; Mon, 08 Dec 2025 21:44:16 -0800 (PST) Date: Tue, 09 Dec 2025 05:44:14 +0000 Mime-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAC23N2kC/4WNQQrDIBRErxL+uhYVQ5Kueo8Sitpf80Fj0CAtI XevTQ/Q3byBebNBxkSY4dJskLBQpjhXkKcG7KRnh4welUFy2QrJe2YUK0F7Hy0L5Kb1/stdq3Q 3CFQoONTxkvBJr0N8GytPlNeY3sdPEd/2r7IIJtig9GBMj9bw/upidB7PNgYY933/AOsBhcq9A AAA X-Change-Id: 20251208-b4-vmalloc-might_alloc-754a791e4e10 X-Mailer: b4 0.14.2 Message-ID: <20251209-b4-vmalloc-might_alloc-v2-1-2462ba26ead1@google.com> Subject: [PATCH v2] mm/vmalloc: clarify why vmap_range_noflush() might sleep From: Brendan Jackman To: Andrew Morton , Uladzislau Rezki Cc: Anshuman Khandual , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Brendan Jackman Content-Type: text/plain; charset="utf-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 0E2A5140005 X-Stat-Signature: e4ij4x4mtzxx4mjprp9g348i1sxzanp3 X-Rspam-User: X-HE-Tag: 1765259057-689133 X-HE-Meta: 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 ozDHmggV 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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: The only reason vmap_range_noflush() can sleep is because of pagetable allocations. The actual allocation mechanism is arch-specific so might_alloc() doesn't work here (what GFP flags would be used?). Hence, just add a comment. Signed-off-by: Brendan Jackman --- Changes in v2: - Switched from might_alloc() to keeping might_sleep() + comment - Link to v1: https://lore.kernel.org/r/20251208-b4-vmalloc-might_alloc-v1-1-94a9bb8ecb08@google.com --- mm/vmalloc.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index a53c7462671bdd896f95712af71398ffbe22fb80..c23d378dd4446e2784505ec3d5bb9568fb0d3c9a 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -305,6 +305,7 @@ static int vmap_range_noflush(unsigned long addr, unsigned long end, int err; pgtbl_mod_mask mask = 0; + /* Might allocate pagetables. */ might_sleep(); BUG_ON(addr >= end); --- base-commit: ecc46e02e0abe025a6e840cba2d647f23fd1d721 change-id: 20251208-b4-vmalloc-might_alloc-754a791e4e10 Best regards, -- Brendan Jackman