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 09DBCCD5BD5 for ; Thu, 28 May 2026 16:57:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5B2B36B008C; Thu, 28 May 2026 12:57:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 564816B0092; Thu, 28 May 2026 12:57:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 479EC6B0093; Thu, 28 May 2026 12:57:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 3870E6B008C for ; Thu, 28 May 2026 12:57:03 -0400 (EDT) Received: from smtpin03.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id CFCA81620B3 for ; Thu, 28 May 2026 16:57:02 +0000 (UTC) X-FDA: 84817433484.03.1B5C583 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) by imf14.hostedemail.com (Postfix) with ESMTP id 226D8100010 for ; Thu, 28 May 2026 16:57:00 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="BZZc/ms8"; spf=pass (imf14.hostedemail.com: domain of usama.arif@linux.dev designates 91.218.175.170 as permitted sender) smtp.mailfrom=usama.arif@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1779987421; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=nPlFnYwCWz7+rdxCNeqNN0vuzrC3LBz56c9GLgbIR0Y=; b=pp2xnrpurv4/XugiKQ31H7ubVP4VQkoz4Lo0io8g95w0Z7xRtXQju2DLtyTgFuf8Rxa7bO 9Y4nWJZCIoAulp0Ns93XY2ayen5FGwWma6Mfk62Xltqcz587O+pVaEOcIUJxfp0z6r6oyH AEzjo3hFt+9HqmDRnICzig6USJuUUtg= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1779987421; a=rsa-sha256; cv=none; b=Rk//mF9pYejvGS80+GwYeXenSSmarCpieug1tiQ7Tg+2ug9JM5sokyCg+Gf9k60aBDw2K6 y7B/DSQi8IMjv1Wo9lnL+u/h5cYC3XEdv9GDkUsCLeQ5hdjwCiDd07psjsj9zDlwsZsshg m5w+WXoX/WytYRP7B5bRHCspNOR7mkM= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="BZZc/ms8"; spf=pass (imf14.hostedemail.com: domain of usama.arif@linux.dev designates 91.218.175.170 as permitted sender) smtp.mailfrom=usama.arif@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1779987419; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nPlFnYwCWz7+rdxCNeqNN0vuzrC3LBz56c9GLgbIR0Y=; b=BZZc/ms8dlyybEyEd97Qc3TtKn6BE7b3CTiqFTmXtlHzcU6PuSRN1DFtW97UC0epSY2v62 F/XbJ1L0eo71OfYpoHTrPzv+yekeKLqrRmKFVwJyvhS9Fw1HV/CiygSLi8uiixVbvT++py UNXt8ater3KcJQTVMfd4V8UF9Q+Yv6c= From: Usama Arif To: Andrew Morton , david@kernel.org, willy@infradead.org, ryan.roberts@arm.com, linux-mm@kvack.org Cc: r@hev.cc, jack@suse.cz, Andrew Donnellan , apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, brauner@kernel.org, catalin.marinas@arm.com, dev.jain@arm.com, kees@kernel.org, kevin.brodsky@arm.com, lance.yang@linux.dev, Liam R.Howlett , linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ljs@kernel.org, mhocko@suse.com, npache@redhat.com, pasha.tatashin@soleen.com, rmclure@linux.ibm.com, rppt@kernel.org, surenb@google.com, vbabka@kernel.org, Al Viro , wilts.infradead.org@kvack.org, "linux-fsdevel@vger.kernel.l"@kernel.org, ziy@nvidia.com, hannes@cmpxchg.org, kas@kernel.org, shakeel.butt@linux.dev, kernel-team@meta.com, Usama Arif Subject: [PATCH v6 2/2] mm: use mapping_max_folio_order() for force_thp_readahead order Date: Thu, 28 May 2026 09:55:20 -0700 Message-ID: <20260528165635.2068012-3-usama.arif@linux.dev> In-Reply-To: <20260528165635.2068012-1-usama.arif@linux.dev> References: <20260528165635.2068012-1-usama.arif@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam11 X-Stat-Signature: rdpfo98xco148nnmcc8u6p41aupwndak X-Rspamd-Queue-Id: 226D8100010 X-Rspam-User: X-HE-Tag: 1779987420-426962 X-HE-Meta: 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 BAAOB/7y 7FH03V81d1bZ/6VKFJg+8N559P8/tHf3QfHJRWIIqhTU2LN94rhZvU8FwKAY/H4C4gBVu6eGYg045Ed2nuxW2ujb1QwGhFyBWsF9Iaz6QnJvnBSta7NEat8x7HiARhHKHSKsGx/lWzjyLevhY1i7r+R+/o8xH2mvqAbdSu7xFvEUXqmBa4XLvMVz5xHndS1IHxs1E123GLvlKJ/pOOzb5a37GshEQyrcN3UqsuEfqXARdNItaxCXQzBgMmWFjhzpYc2+QokyKdgwSSY5fvZA6QMkdSITrP2BMMoFsZsEGFf73sOuWYixrXOZC1kzUniW/aEcY Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The force_thp_readahead path in do_sync_mmap_readahead() is gated on HPAGE_PMD_ORDER <= MAX_PAGECACHE_ORDER and always requests HPAGE_PMD_ORDER / HPAGE_PMD_NR. On configurations where HPAGE_PMD_ORDER exceeds MAX_PAGECACHE_ORDER, notably arm64 with a 64K base page size, VM_HUGEPAGE mappings cannot use this path and fall back to the non-forced mmap readahead path even when the mapping supports useful large folios. Keep the existing PMD-sized behavior when HPAGE_PMD_ORDER fits in the page cache. When it does not, enable forced readahead for mappings that support large folios and request an order capped by both mapping_max_folio_order(mapping) and 2MB. 2MB is chosen as the cap because it matches the PMD size on x86_64 and on arm64 with 4K or 16K base pages, so the size/memory-pressure tradeoff for folios of that size is already well understood. On arm64 with a 64K base page size, 2MB is also the contiguous-PTE (contpte) block size, so the resulting folios coalesce into a single TLB entry and reduce TLB pressure on the readahead path. The final allocation order may still be clamped by page_cache_ra_order() to the mapping and request geometry, but this gives VM_HUGEPAGE mappings on such configurations a large-folio readahead request instead of dropping back to base-page readahead. Signed-off-by: Usama Arif --- mm/filemap.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index a16b33e0fc71..bfb891d9da1f 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3312,14 +3312,23 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) struct file *fpin = NULL; vm_flags_t vm_flags = vmf->vma->vm_flags; bool force_thp_readahead = false; + unsigned int thp_order = 0; unsigned short mmap_miss; ractl._max_index = vmf->vma->vm_pgoff + vma_pages(vmf->vma) - 1; /* Use the readahead code, even if readahead is disabled */ - if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && - (vm_flags & VM_HUGEPAGE) && HPAGE_PMD_ORDER <= MAX_PAGECACHE_ORDER) - force_thp_readahead = true; + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && (vm_flags & VM_HUGEPAGE)) { + if (HPAGE_PMD_ORDER <= MAX_PAGECACHE_ORDER) { + force_thp_readahead = true; + thp_order = HPAGE_PMD_ORDER; + } else if (mapping_large_folio_support(mapping)) { + force_thp_readahead = true; + thp_order = min_t(unsigned int, + mapping_max_folio_order(mapping), + get_order(SZ_2M)); + } + } if (!force_thp_readahead) { /* @@ -3354,17 +3363,19 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) } if (force_thp_readahead) { + unsigned long folio_nr_pages = 1UL << thp_order; + fpin = maybe_unlock_mmap_for_io(vmf, fpin); - ractl._index &= ~((unsigned long)HPAGE_PMD_NR - 1); - ra->size = HPAGE_PMD_NR; + ractl._index &= ~(folio_nr_pages - 1); + ra->size = folio_nr_pages; /* - * Fetch two PMD folios, so we get the chance to actually + * Fetch two folios so we get the chance to actually * readahead, unless we've been told not to. */ if (!(vm_flags & VM_RAND_READ)) ra->size *= 2; - ra->async_size = HPAGE_PMD_NR; - ra->order = HPAGE_PMD_ORDER; + ra->async_size = folio_nr_pages; + ra->order = thp_order; page_cache_ra_order(&ractl, ra); return fpin; } -- 2.52.0