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d=samsung.com; s=mail20170921; t=1774622522; bh=7bk0dNR0zbUSNuzz8HU1AITn/eIsQuxRxjKTkb9qTHA=; h=Date:Subject:To:Cc:From:In-Reply-To:References:From; b=f9GADw8exPA2pVqpc0qboQT+Sy/jnB8ErnC5Qxv0djC6GCim3q4etY2PpzH24UY8O 7Qep4pkrHEwLMs1ACeuzsMQ+fh0iZ+IbqDSH3iKHqqqJLg/2MCUB/uj6DQCJzOZpm3 rD07b3C5yrAHKWmF8/mfyXaa3FgFSCYIyPSQnJ8E= Received: from eusmtip2.samsung.com (unknown [203.254.199.222]) by eucas1p2.samsung.com (KnoxPortal) with ESMTPA id 20260327144201eucas1p2fba2f0b4d62780ba545ca81d1e42397f~gucgC2W412070520705eucas1p2u; Fri, 27 Mar 2026 14:42:01 +0000 (GMT) Received: from [106.210.134.192] (unknown [106.210.134.192]) by eusmtip2.samsung.com (KnoxPortal) with ESMTPA id 20260327144159eusmtip22ec2e6c7eb865005539396807c731900~guceHbtB72669926699eusmtip2n; Fri, 27 Mar 2026 14:41:59 +0000 (GMT) Message-ID: <455f1419-77ed-419d-b53e-e787dbd638a8@samsung.com> Date: Fri, 27 Mar 2026 15:41:59 +0100 MIME-Version: 1.0 User-Agent: Betterbird (Windows) Subject: Re: [PATCH] mm/slab: align kmalloc to cacheline when DMA API debugging is active To: Mikhail Gavrilov , "Vlastimil Babka (SUSE)" Cc: Catalin Marinas , 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, andy.shevchenko@gmail.com, hch@lst.de, Jeff.kirsher@gmail.com, Robin Murphy Content-Language: en-US From: Marek Szyprowski In-Reply-To: Content-Transfer-Encoding: 8bit X-CMS-MailID: 20260327144201eucas1p2fba2f0b4d62780ba545ca81d1e42397f X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20260327122625eucas1p10eabcb31aada4e11b5c2ebcff4cb3c39 X-EPHeader: CA X-CMS-RootMailID: 20260327122625eucas1p10eabcb31aada4e11b5c2ebcff4cb3c39 References: <20260327055846.248829-1-mikhail.v.gavrilov@gmail.com> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 79CBF40010 X-Stat-Signature: u786rmf3dg5petgni4mccxtax63kfoqw X-Rspam-User: X-HE-Tag: 1774622524-14554 X-HE-Meta: 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 Pu0QwBnf tPNoo4KUJFWA4aESO9zukLMgPA5MgUl5KvE3ZQvH2lW8iAsowoUrkYFzOSc3NgpjdMqYRX1UdG0TawQ5kzFrR5RaFzbDLVz0nWe5F2yQIsvtC7kllTMop4alZQBnKAdKftbwaAgPdL623dMf25I2K4pprIvIy4SV7dxLw6ORh5qgV+oXQpelLHA7eloQkF6t1E6JFfvPoWsDhrz8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 27.03.2026 15:37, Mikhail Gavrilov wrote: > On Fri, Mar 27, 2026 at 7:30 PM Vlastimil Babka (SUSE) > wrote: >> So what about Harry's proposal [1]? Mikhail seems to be on board? [2] >> >> It seems it would achieve the goal that enabling DMA_API_DEBUG doesn't >> change the kernel behavior? But I don't know this area too well so >> maybe there's a catch. >> >> [1] https://lore.kernel.org/all/acYlxRBhSMcwBnja@hyeyoo/ >> [2] https://lore.kernel.org/all/CABXGCsO_C8%2B%2B4%2BoPfZ%2BbQyrBnEGy5JFpXHkGNpfy%2B8%3D5BvVNfg@mail.gmail.com/ > Hi Vlastimil, > > Yes, I've already sent v2 based on Harry's suggestion: > https://lore.kernel.org/all/20260327124156.24820-1-mikhail.v.gavrilov@gmail.com/ > > It adds a dma_get_cache_alignment() >= L1_CACHE_BYTES check in > add_dma_entry() instead of changing ARCH_KMALLOC_MINALIGN, so > enabling DMA_API_DEBUG no longer affects allocator behavior. This looks like a good fix, but let me think a bit more about all possible cases. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland