From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7904510ED66D for ; Fri, 27 Mar 2026 12:35:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9E8CD6B0095; Fri, 27 Mar 2026 08:35:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 999406B0096; Fri, 27 Mar 2026 08:35:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 887E16B0098; Fri, 27 Mar 2026 08:35:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 727A16B0095 for ; Fri, 27 Mar 2026 08:35:40 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id DF97A1B96BD for ; Fri, 27 Mar 2026 12:35:39 +0000 (UTC) X-FDA: 84591789198.11.C845AA5 Received: from mail-ej1-f47.google.com (mail-ej1-f47.google.com [209.85.218.47]) by imf26.hostedemail.com (Postfix) with ESMTP id A5F02140003 for ; Fri, 27 Mar 2026 12:35:37 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=A+DiUO5q; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf26.hostedemail.com: domain of andy.shevchenko@gmail.com designates 209.85.218.47 as permitted sender) smtp.mailfrom=andy.shevchenko@gmail.com; arc=pass ("google.com:s=arc-20240605:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774614937; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=5cOyBNoqrTish9nBBS87UAnS6CU3/R9H+gkn7UHvmow=; b=V3OmE3Qu0bmh9HZ46mDHifnfr6xjuaCSadoYlXLv/ZlgUmpcz647M7pDLkUy6EdROgRuqt JVC+HzvGkGJgw7SRqSqkILpk7V29SvRNk3uyqiSnfSBWRNj54mnusQj3Hvrqwy1XqZKpLe lvcM59vgwhwzHGuBOBRS7+dD0C38fdA= ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1774614937; a=rsa-sha256; cv=pass; b=O9ccm/StJKb1ev33ydKo10jZOLUz5Im/rPCAkQ9WiXxhOwq97OiFW/MQGbojETa+d52mth qNDSSOMj9S/bNAH2MQ2OHJOFUHfEb/I/VnV8XkDyj8cmow1gtIK65ugRxz6Cy7F/C5M1pB /Z68VHajlcNbi3NJ21TNpFTZid7CraQ= ARC-Authentication-Results: i=2; imf26.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=A+DiUO5q; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf26.hostedemail.com: domain of andy.shevchenko@gmail.com designates 209.85.218.47 as permitted sender) smtp.mailfrom=andy.shevchenko@gmail.com; arc=pass ("google.com:s=arc-20240605:i=1") Received: by mail-ej1-f47.google.com with SMTP id a640c23a62f3a-b98133bdc4bso241467666b.0 for ; Fri, 27 Mar 2026 05:35:37 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1774614936; cv=none; d=google.com; s=arc-20240605; b=gyMmkS/n+bfoTbsdzoxrEuVnKJJM41g/42yBNbR8BPSB24LGn2CNxciT3sdr9ZdI4V qEwAhKhETMkuFR0f6C0WqMLdjhE5Y2vnYAee/lj9NHW7TZB8yoaVFi9alVVwlTk/0422 Adc4AvN/iaAHYrNoA0+f8G5UWQnWcYyCeIcIL6Dtdfz4m35ovAbK6o7vbN5NEErqpHMy bfJrgF+6vL0KOYrnNbSE2t8wwTqLtMGl2LrzHap5S6ceiZS/ckdP4hvo8ejlXW908JqE dMt8SZEqff7BbZnhU0QaIUB18w8V8PdfK//Km/gHbsAFMBWnpYNyc0XmpDoH/MyoS9TP 6HTA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20240605; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:dkim-signature; bh=5cOyBNoqrTish9nBBS87UAnS6CU3/R9H+gkn7UHvmow=; fh=dpbwxV39jNr+QVSFAlvKP0Jwe6iRJ9KA3J4Cmxd+Kxw=; b=UMishCyYFjRITfXY6T0gLwXbCCXhofEKJfGqdWP49GZqLFdzFNskev7U8n8R1XatJP Q4O4Kmkd650q2DDSLa4rBBhiTVvVa7VTuycAa2LlE983f7cAaEcHoQ5B/8vB+oF3jWqA Ku+KjHv1Y11Z3fSrCfFIk3IScoOIVSwE+20XI4/iIL2AdDA54n5W8Eh4hdu0YnMs+UJh 4yczvpx/a8KX7lL5+7qTqUzuVWwziHDw+cBeI1xyWoJU/od2mgYJbAp5lCnC7uvcX4wO KlEEVRjZdc8aLXs2Rtaime0Ny9ht5l8hFE8c6EUi1dxXfvhbbMih93rid6KMBpEV8DXn Wc6Q==; darn=kvack.org ARC-Authentication-Results: i=1; mx.google.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1774614936; x=1775219736; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=5cOyBNoqrTish9nBBS87UAnS6CU3/R9H+gkn7UHvmow=; b=A+DiUO5qBDBRwfkrTAKfiEX1nWWQ6a9pbHlhJKD7hlaJLI7e0ADGnO/lwj5cshj9h2 GdJUQYcT38J7DFFAEeVHuYuX908RnO9N3Sl+68ptLbY5FwNYFWp3Mt35eEAhAdmiwAgN CP6lC8AnKMphXrlplfqO+cYTzsdIF1Edt4tJtFWwOY2bfyMSs3Fd+oR/PwalI/Qxxbi3 qND6WCJwujhbCcXNg49T7adIUvrV2UPCdizpmsO+cI2dPkNV2N74Hf4BjoZay0lpO/hW vO32/t5jg/7cUnlP/Im+Rx60tGA/2rxtmujX5yUYKhJYmWRQ1O1vYRNddeBzqzoLTpPc B2pw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774614936; x=1775219736; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=5cOyBNoqrTish9nBBS87UAnS6CU3/R9H+gkn7UHvmow=; b=nsXrLKajEHzPv+opgFtKfWt8VM/rDih+b0XaeW/VtVSmuaj2eS3aFr6GBGr0Lx1x9h FEU8YnXuS/PJ05H/nWVxXO3e0azFvKC59W7QRYGUnDGH2iQq4LM/J8dkY+TM0pgT4Lvs SPGCxsR44E7U6qY8GVtQ0zQ2fjPU4tjiuNKPLFcBLUPw6B8tbzOI/wR8eZ26ILxoJW0d Bli7SrQOoDzbxG/Rpq/ImJYXuoFryHRKgHCUtCDfZSGWrjzkBVkGLw6+Tdq0WCZJe5rE eIQfZ0ydgDbN3kpSJn3xukisoKT6AXPWEnPN3yLXr0rZAr0AdlV8IOByAaRtnhgoJfOA BKzA== X-Forwarded-Encrypted: i=1; AJvYcCXj8fRj5fJGQYlq70YS42sQlv8n61mrFRM0WXRHsWM8cR1qj2bdKz1pH6iFegusP/tpdbl3k4phCw==@kvack.org X-Gm-Message-State: AOJu0YzieuindLQ1TVSXNbBIuam/rGumG8NCPmxCqLU1Lk8pqRVjZBtH AmJsyjpqouwtaj0DHVu3dLahgJDTrVAMGrUVCTHabAMTTWiKKfStwFicZxlm46S7slf68vbi/lh L/IzLwKagchy5uocXD3zexfPPJBU8zjM= X-Gm-Gg: ATEYQzzBV1U56Y2yzEgQFnaz82KRMXLu0vMjyoGIG5tev2uttBQmY3mgFMrDuzLi64P bHGKDHaCQKA0FIRfLtqpQeeKPscGlbhk1lNLhIl1J0NWgZ0I/pViIrEtZQCvWmGzmFtPS0/fgKg f7RQ2qTp9J1zITqwWHXXoaL82qQwzQFsQ9+kUunuN2iHX10zHhf92Ptdkv/8G2sBZdeTULl6ZXt WEiXXmAXD/e9Rn6x7bPoXTKBA/1X/xVNjKZbQ1klsU3g+w4RukCf+hlq0ns7RzGb/zTG4gI7fyi 7j7AgjqnDaq2ub7Q+PNL4JIQYVu1JH+zETmClQcyye8WSoRtUGeHkYJCCj/j6BuBUBIXWAXhV61 uS9l5dV0= X-Received: by 2002:a17:907:3f07:b0:b8f:b32e:e196 with SMTP id a640c23a62f3a-b9b507b20ebmr158948066b.30.1774614935669; Fri, 27 Mar 2026 05:35:35 -0700 (PDT) MIME-Version: 1.0 References: <20260327055846.248829-1-mikhail.v.gavrilov@gmail.com> In-Reply-To: From: Andy Shevchenko Date: Fri, 27 Mar 2026 14:34:58 +0200 X-Gm-Features: AQROBzAf3n6UCCCVOWz8_h19fmxDUeJxeUYrZ9qKYYIvgXaEOz3JyzyW2dWdB10 Message-ID: Subject: Re: [PATCH] mm/slab: align kmalloc to cacheline when DMA API debugging is active To: Catalin Marinas Cc: Mikhail Gavrilov , vbabka@kernel.org, harry.yoo@oracle.com, akpm@linux-foundation.org, hao.li@linux.dev, cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, stern@rowland.harvard.edu, linux@roeck-us.net, hch@lst.de, Jeff.kirsher@gmail.com, Marek Szyprowski , Robin Murphy Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: A5F02140003 X-Stat-Signature: swp861ckucuxeknmxuawaip1op9urp35 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1774614937-938552 X-HE-Meta: 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 YOBevdVI hoXcrNxQjQqV/WCTCtMIJbGwUAWH+3HqaOI9qMOIstMBDqny79dAUXf4PBrgzwNKCY5AxZH/wsA++u862LPN6RErntdrMJLM4EWHmHDpmN1/RtIV2LLY72Cn/JZcoQdO+53rjb0w8rmq5kbseIGC2eCFoEP9HbM6dsmpbJ2UYs5ZvqR1bPwCmp96/e1iOkbL8GMmE0oCbiGJDWJR6jTJaUJsNQtFZRHKvO6yNNTHR43agUGI4vxxMHI3798UDqOzKA4qDYYyltyd5rR9Y/ojjNbEiGANsGTcxwwbzXXPfBbtQS/vazCJdTwkuKukLMYPnJjx1tAG47V80dwKoMFNiNRwobcg5ubLwUDZ7pYI26tdpP5gEokRPQh9bKLfn7iU/DUqBPHIjlTHwPYUWNFeToeLbspPhoVdRcAKFkPcYK+J2JjDlHRQUYgPSWhrp4BRa9a1orDXchGpKaTEVVSK9nMl/zAqJZscS6wlGp7B+HdeGSRWtofPiwlPRFA6kztAkw9pb3aHMaOHmNtpVuxE9Zrf6W8yA4Qtzx4cUwFrfTsKdJ/fKkCCyshx7MQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Mar 27, 2026 at 2:26=E2=80=AFPM Catalin Marinas wrote: > On Fri, Mar 27, 2026 at 10:58:46AM +0500, Mikhail Gavrilov wrote: > TL;DR: I think this is fine: > > Reviewed-by: Catalin Marinas > > I'm not sure that's the best way to hide the warning but there > are no great solutions either. On one hand, we want the DMA debug to > capture potential problems on architectures it's not running on. OTOH, > we also want to avoid false positives on coherent architectures/devices. > I don't think reconciling the two requirements is easy. > > When DMA_API_DEBUG is enabled, the above will change the x86 behaviour > that could have implications beyond DMA (e.g. may not catch some buffer > overflow because it's within L1_CACHE_BYTES). Similarly for non-coherent > architectures that select DMA_BOUNCE_UNALIGNED_KMALLOC (arm64 and riscv > currently). arm64 defines ARCH_DMA_MINALIGN to 128 but > ARCH_KMALLOC_MINALIGN to 8 (why 128 is larger than L1_CACHE_BYTES is > another matter but let's ignore it for now). Maybe for the cases where we do not warn we should introduce a dev_dbg_/pr_debug_once()? At least users may be informed about potential is= sues. --=20 With Best Regards, Andy Shevchenko