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 E41ADC43327 for ; Tue, 30 Jun 2026 13:54:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CEE916B00C7; Tue, 30 Jun 2026 09:54:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C78CB6B00C9; Tue, 30 Jun 2026 09:54:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AA3A86B00CA; Tue, 30 Jun 2026 09:54:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 6BAB16B00C7 for ; Tue, 30 Jun 2026 09:54:31 -0400 (EDT) Received: from smtpin10.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 7CB0FA04EF for ; Tue, 30 Jun 2026 13:54:30 +0000 (UTC) X-FDA: 84936723900.10.384D839 Received: from mail-lf1-f46.google.com (mail-lf1-f46.google.com [209.85.167.46]) by imf23.hostedemail.com (Postfix) with ESMTP id AF693140009 for ; Tue, 30 Jun 2026 13:54:28 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=S4KjF7DM; spf=pass (imf23.hostedemail.com: domain of urezki@gmail.com designates 209.85.167.46 as permitted sender) smtp.mailfrom=urezki@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1782827668; b=jxltla8lKX7p8gc4T1Lqg/QtwrwMJuDPcOctcV0gIi6BTslrboOQlkiXlhmJNX1SdAMURy 3uwdH+yX0Ban0VqPPFiHZxIrZR5onRuAdXS3nXyS2FhfyCFFqSK7x+4SXPKouwnsyrQcUH ucFQwSMdWbDcSJiWjxvoSIAwnr7MRZs= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1782827668; 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=8eNIJQnRMK2SdmmUofdTI44ZDndAOS8N0eRrZb61g0Q=; b=hQuAAI23N1dCVFITa3Qva7W4Z0rGwfcEnsDei3a9cf2iTwNtYmnFiC8R+45v0dUYKbO4WQ +kirTdaLi+wBj+KWiELO9RYhZWGGk5cmHD/n71A2juuX8LOslqdkhgyPVZKuDI6ldfyNX/ 7lb9ZXZL3MKNcYLQoM/oFlh2RFkuUOI= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=S4KjF7DM; spf=pass (imf23.hostedemail.com: domain of urezki@gmail.com designates 209.85.167.46 as permitted sender) smtp.mailfrom=urezki@gmail.com; dmarc=pass (policy=none) header.from=gmail.com Received: by mail-lf1-f46.google.com with SMTP id 2adb3069b0e04-5aeb8c19017so2540564e87.0 for ; Tue, 30 Jun 2026 06:54:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1782827667; x=1783432467; darn=kvack.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:date:from:from:to :cc:subject:date:message-id:reply-to; bh=8eNIJQnRMK2SdmmUofdTI44ZDndAOS8N0eRrZb61g0Q=; b=S4KjF7DMdCydtv9IX49TyoSIxCt8p8MxSTAIAmmkgRhSR4Bff2yWhMAuc9sZqJq5V8 r+Xi9aND1v1fzfE0oD4dRTqWmFoKVTKKgzwiVBMSJA6dXtBdEu9URU5YhzMGnOB3DLmc tUjVqnq/aa+JTsnxbKGmttlcseTsXH7GhAevDkJuGZ68UPLns4nTy2oIjfJjKEDAOciw JUy0L+lu6+n8hPxOuIv9BkvtkfHCMAAI1hClXIxlEntEtUvNNQ8ry+dedEZw7uQ/MKcG AqIpDm1rq+TnHUhSuJNSvcUmFEugDOqf8cPk13emF15l/zAhfI7Jg2hk05M7h7LbiYal 3NrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1782827667; x=1783432467; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:date:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=8eNIJQnRMK2SdmmUofdTI44ZDndAOS8N0eRrZb61g0Q=; b=E874kg2VPZcCJ1+8pgbVIyJME26Zax8/vUsX+F86wKoJax600VuQFjb/OE+Mct3OwB 1jJPeXuQh9zI9YSAF2/Ce/PuaoWskiTMA0u8Uh9RM9XIxyEvONk9Gdnq7yNz4QUcQAm0 VPEr7qwulWa2LVSpdE763tDFAzzugim46zb62IpQXIKOKeShNIy8qPiawaEMKMN5bZmk g/e4rJS35/i2Mk5GovqE0QwASf/jYe8Pn/nQwqsIL9jhOmuvFBbc0+U2AlsvITLK6oXU +0Ezvu++uxJ8j1zqLXGUKYnhnGdYeJNn0/p6vNVo2lCPOIEQFFTpo97wh9WZb7usCL44 BqRQ== X-Gm-Message-State: AOJu0YyQgd7ufhoKIuFueyRzAM6rD8IK0lpBSl4NGmz4TXrfqGAtjBxw pgXCk6xgSP/vKCqlKW0qVcDl21r53EexU6G8wvDhs+raKTuyVh1utukb X-Gm-Gg: AfdE7cn9y6zE5M1VTnqzUCI+kRTPDlF/7Jx9aZzvU6shWpD9mlZAC+0QphYGblLzWZv Kv5Nd33S+a+lfWbZYegrXtBpVJVawCDtNzxue24R/Bjp2BNQbFFCMtrNdBblRoY5a6FpJ3e1rtk h5GgqJ9VMCPjeZgkxvLMVizaKjevbMGaAhrErYPqdjvjb/mxC5OhA1tioeVeG4LzwzOF/vJ/SGQ 5bp+8uYjAFc4kpiniT9/3FDXwphMRG0ccWlQd0S/Fcs+8hBaAq0lx8+9wHYUCDhMRs7yNfU17Ms NyJIdPX1hNn2jV9GAqrDuifwHWGZ65O4cW7fwOzQK8f1aFuV6m1CY7ttenm5MNIo5rLLNn/FA9s swiR2ZNfB9GiTsEOs8llGwgtBK42LjqMIbezksETv/pmCbNrNhmZSuw== X-Received: by 2002:a05:6512:3410:b0:5ae:bf5c:bdc5 with SMTP id 2adb3069b0e04-5aebf5cbec4mr644835e87.52.1782827666670; Tue, 30 Jun 2026 06:54:26 -0700 (PDT) Received: from milan ([2001:9b1:d5a0:a500::24b]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5aebe344f03sm593321e87.30.2026.06.30.06.54.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jun 2026 06:54:26 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Tue, 30 Jun 2026 15:54:24 +0200 To: Wen Jiang Cc: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, urezki@gmail.com, baohua@kernel.org, Xueyuan.chen21@gmail.com, dev.jain@arm.com, rppt@kernel.org, david@kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, ajd@linux.ibm.com, linux-kernel@vger.kernel.org, jiangwen6@xiaomi.com, shanghaoqiang@xiaomi.com Subject: Re: [PATCH v4 5/6] mm/vmalloc: map contiguous pages in batches for vmap() if possible Message-ID: References: <20260618084726.1070022-1-jiangwen6@xiaomi.com> <20260618084726.1070022-6-jiangwen6@xiaomi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260618084726.1070022-6-jiangwen6@xiaomi.com> X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: AF693140009 X-Stat-Signature: 4odiy6j9ms5ktz54tpq5uzudb95f6cfn X-HE-Tag: 1782827668-573617 X-HE-Meta: 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 VsMWi/MU 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jun 18, 2026 at 04:47:25PM +0800, Wen Jiang wrote: > From: "Barry Song (Xiaomi)" > > In many cases, the pages passed to vmap() may include high-order > pages. For example, the systemheap often allocates pages in descending > order: order 8, then 4, then 0. Currently, vmap() iterates over every > page individually—even pages inside a high-order block are handled > one by one. > > This patch detects physically contiguous pages (regardless of whether > they are compound or non-compound) by scanning with > num_pages_contiguous(), and maps them as a single contiguous block > whenever possible. The mapping order is determined by taking the > minimum of the contiguous page count and the pfn alignment, allowing > graceful degradation when pfn alignment is less than the contiguous > range. > > Pages with the same page_shift are coalesced and mapped via > vmap_pages_range_noflush_walk() to avoid page table rewalk. > > As users typically allocate memory in descending orders (e.g. > 8 → 4 → 0), once an order-0 page is encountered, we stop scanning > for contiguous pages since subsequent pages are likely order-0 as well. > > Signed-off-by: Barry Song (Xiaomi) > Co-developed-by: Dev Jain > Signed-off-by: Dev Jain > Signed-off-by: Wen Jiang > Tested-by: Xueyuan Chen > --- > mm/vmalloc.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 85 insertions(+), 2 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 253e017130e09..fffb885cb2158 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3545,6 +3545,89 @@ void vunmap(const void *addr) > } > EXPORT_SYMBOL(vunmap); > > +static inline unsigned int vm_shift(pgprot_t prot, unsigned long size) > +{ > + if (arch_vmap_pmd_supported(prot) && size >= PMD_SIZE) > + return PMD_SHIFT; > + > + return arch_vmap_pte_supported_shift(size); > +} > + > +static inline int get_vmap_batch_order(struct page **pages, > + pgprot_t prot, unsigned int max_steps, unsigned int idx) > +{ > + unsigned int nr_contig; > + int order; > + > + if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMAP)) > + return 0; > + > + nr_contig = num_pages_contiguous(&pages[idx], max_steps); > + if (nr_contig < 2) > + return 0; > + > + order = ilog2(nr_contig); > + > + /* Limit order by pfn alignment */ > + order = min_t(int, order, __ffs(page_to_pfn(pages[idx]))); > + > + if (vm_shift(prot, PAGE_SIZE << order) == PAGE_SHIFT) > + return 0; > + > + return order; > +} > + > +static int vmap_batched(unsigned long addr, unsigned long end, > + pgprot_t prot, struct page **pages) > +{ > + unsigned int count = (end - addr) >> PAGE_SHIFT; > + unsigned int prev_shift = 0, idx = 0; > + unsigned long start = addr, map_addr = addr; > + int err; > + > + err = kmsan_vmap_pages_range_noflush(addr, end, prot, pages, > + PAGE_SHIFT, GFP_KERNEL); > + if (err) > + goto out; > + > + for (unsigned int i = 0; i < count; ) { > + unsigned int shift = PAGE_SHIFT + > + get_vmap_batch_order(pages, prot, count - i, i); > + > + if (!i) > + prev_shift = shift; > + > + if (shift != prev_shift) { > + err = vmap_pages_range_noflush_walk(map_addr, addr, > + prot, pages + idx, prev_shift); > + if (err) > + goto out; > + prev_shift = shift; > + map_addr = addr; > + idx = i; > + } > + > + /* > + * Once small pages are encountered, the remaining pages > + * are likely small as well. > + */ > + if (shift == PAGE_SHIFT) > + break; > + > + addr += 1UL << shift; > + i += 1U << (shift - PAGE_SHIFT); > + } > + > + /* Remaining */ > + if (map_addr < end) > + err = vmap_pages_range_noflush_walk(map_addr, end, > + prot, pages + idx, prev_shift); > + > +out: > + flush_cache_vmap(start, end); > + return err; > +} > + > /** > * vmap - map an array of pages into virtually contiguous space > * @pages: array of page pointers > @@ -3588,8 +3671,8 @@ void *vmap(struct page **pages, unsigned int count, > return NULL; > > addr = (unsigned long)area->addr; > - if (vmap_pages_range(addr, addr + size, pgprot_nx(prot), > - pages, PAGE_SHIFT) < 0) { > + if (vmap_batched(addr, addr + size, pgprot_nx(prot), > + pages) < 0) { > Better naming? vmap_pages_range_batched()? -- Uladzislau Rezki