From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 159B23537CC for ; Mon, 20 Apr 2026 19:00:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776711643; cv=none; b=uGCIZ+6OWc8/n5+SYB8ZlaVDNSuOazCJEh/MqoGz5W5BIibCqo/sfeaU8/5iEksV5n52rgAgn8RW7BIlTk6SImvomz0tBrcGVZHUBuqsnIkfVM/OlPqAtRvaW9Wbyy4zdS+/nMUvIgfleX5ADmuSaM/oedLmvPcIOpX6PVk8iTM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776711643; c=relaxed/simple; bh=uRwvGgzHbcEtZK6wo9qKRlNk2GDua1rojl3egr2ZjzM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=E3rU1tK4na8HTiwihlTrqL/DGVvg2AcZpe43n5JQ563kcrhdNOW2LtDbXdzCMqkR4tEeBCOBqIVVg8kwd2GpQ6IhlKnpCUr34L/UlsTHSH9ltZoHV6Kcz5lrK/5DmSSzpLxFWPFzu3fetnk5Sqfi2KEYfpijwqA5yzeP3F+gdR0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RpqJH48R; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="RpqJH48R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D83B2C19425; Mon, 20 Apr 2026 19:00:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776711642; bh=uRwvGgzHbcEtZK6wo9qKRlNk2GDua1rojl3egr2ZjzM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=RpqJH48RXTcs8FJSGZcYmrDP4K9N+qKoXv4m8p/2TWS+HFftLI2zUHPRkboBMdU5f oOTI8VTShKeZnIJZjA7ac1E137Vk8fnSFyO6rL1NHtW5B1vdbj+46jk+RErGgfQ+Mi lqkRtnHcFQM7OF5EeBTh6ujPIj+4VgAV9HaASwCKXSZeQs1l3om9o4mkfnXHXVI/aA OnKH07vr5Au18gKLXZjqXxUD9TCypvgp/3tFzXevu7YYnvLzRZz3prIYHh6NueDiqd tsF4U9xTAzAkusAt0gqBZQXL1CRUaDpBxVcvdA6DhYYi94dUB929jixXZ8BYKwRt4I L4SKEeopBx8WA== Message-ID: <07e26d39-6155-4661-b3df-c2419535ed43@kernel.org> Date: Mon, 20 Apr 2026 21:00:37 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm: shmem: always support large folios for internal shmem mount To: Baolin Wang , akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, ziy@nvidia.com, ljs@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <26f954be62348591e720c4e8b7a9099b74dc1d6d.1776331555.git.baolin.wang@linux.alibaba.com> <1b3c0401-6d10-4a28-97c8-8e3858d8dc3d@kernel.org> <015de194-99b9-4f9e-8c89-d35807c6fd08@linux.alibaba.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/17/26 14:45, Baolin Wang wrote: > > > On 4/17/26 5:52 PM, David Hildenbrand (Arm) wrote: >> On 4/17/26 11:27, Baolin Wang wrote: >>> >>> >>> >>> For tmpfs, yes. >> >> So, we could pass this check here, not setting >> mapping_set_large_folios(), but later someone toggles it and we missed >> to set mapping_set_large_folios()? > > Indeed. Good point. > >> >> Or would we always go through another __shmem_get_inode() after a >> remount? > > Not really. There could be files created before remount whose mappings > don't support large folios (with 'huge=never' option), while files > created after remount will have mappings that support large folios (if > remounted with 'huge=always' option). > > It looks like the previous commit 5a90c155defa was also problematic. The > huge mount option has introduced a lot of tricky issues:( > > Now I think Zi's previous suggestion should be able to clean up this > mess? That is, calling mapping_set_large_folios() unconditionally for > all shmem mounts, and revisiting Kefeng's first version to fix the > performance issue. Okay, so you'll send a patch to just set mapping_set_large_folios() unconditionally? > > [1] https://lore.kernel.org/all/20240914140613.2334139-1- > wangkefeng.wang@huawei.com/ Is that really required? Which call path would be the problematic bit with the above? I'd say, we'd check in the large folio allocation code whether ->huge is set to never instead? -- Cheers, David