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 ACA07C5DF66 for ; Mon, 17 Aug 2026 12:22:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B1FDE6B00BB; Mon, 17 Aug 2026 08:22:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AD05C6B00F5; Mon, 17 Aug 2026 08:22:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9E5C76B0106; Mon, 17 Aug 2026 08:22:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 7F74F6B00BB for ; Mon, 17 Aug 2026 08:22:06 -0400 (EDT) Received: from smtpin29.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 18D67C06D0 for ; Mon, 17 Aug 2026 12:22:06 +0000 (UTC) X-FDA: 85110673452.29.A268B5B Received: from mta0.migadu.com (out-87.mta0.migadu.com [91.218.175.87]) by imf01.hostedemail.com (Postfix) with ESMTP id F40564000C for ; Mon, 17 Aug 2026 12:22:03 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=XkldS3CH; spf=pass (imf01.hostedemail.com: domain of brendan.jackman@linux.dev designates 91.218.175.87 as permitted sender) smtp.mailfrom=brendan.jackman@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=1786969324; 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=Ksysbh4dcTuDtSNajt7R605hngUF6zYW8EyMCk1D+1g=; b=EAktfeq7cRP9kci2pWU7EwoDYkZKQ0q9HhEtLA5KpVDh7jZUbtYgM5IFyP52NvJ5uQzeLh T9gSAPst/9IBJlK7hy3P/4l6lnFeFj2ymKI8kiCUhWgXNvsJoyeGRH85PXRvQtkaPGquCT 4Dfj4M1p7h8HwV1cPVMi/sthtn7Lyhs= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=XkldS3CH; spf=pass (imf01.hostedemail.com: domain of brendan.jackman@linux.dev designates 91.218.175.87 as permitted sender) smtp.mailfrom=brendan.jackman@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1786969324; b=esfs9vie6QCgqwofcqxJr+ig4UWC92kQaD8Ulnk+b/QQbXYW0FFqr8tlUsUrAHdoPmENnk QKwlU7UCdEX3rFkHu4JzBY9hHPOKV/HNlW2uiZjozfgqIUwW1jDkJu5x7+aWJZAxj1KL1e sM3OHFsXvjWapbsKCO+NayQvFYal1Rg= X-Envelope-To: linux-mm@kvack.org DKIM-Signature: a=rsa-sha256; bh=XUz20HjX88HKc3zhTmA9XIj0WBNTBdnuMyd7s0rygf4=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786969322; v=1; x=1787574122; b=XkldS3CHg9hCBivEOhkQQzkmUhdPITkRmMuNYQi3cCkftCjtJWWLDRiDP/+pw18b1esq4lNP slbcZxty0whFStgDGAoQnHGUK2wfA2IpllM//lyHcu35MfQ6dkOPY6w42V/iiNp8rSh+jXtT66Q Gkbjx9DvRnQfiagSi2bv5dsQ= X-Envelope-To: linux-mm@kvack.org Received: from localhost (185.201.63.253) by smtp.migadu.com with ESMTPS id ac101bf52cfc1249; Mon, 17 Aug 2026 12:22:02 +0000 X-Migadu-Flow: FLOW_OUT Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 17 Aug 2026 14:21:41 +0200 Message-Id: Cc: =?utf-8?q?Adrian_Barna=C5=9B?= , "Albert Ou" , "Alexander Gordeev" , "Alexandre Ghiti" , "Andy Lutomirski" , "Borislav Petkov" , "Brendan Jackman" , "Catalin Marinas" , "Christian Borntraeger" , "Dave Hansen" , "David Hildenbrand" , "Gerald Schaefer" , "Heiko Carstens" , "Huacai Chen" , "Ingo Molnar" , "Len Brown" , "Palmer Dabbelt" , "Paul Walmsley" , "Pavel Machek" , "Peter Zijlstra" , "H. Peter Anvin" , "Rafael J. Wysocki" , "Ryan Roberts" , "Sven Schnelle" , "Thomas Gleixner" , "Uladzislau Rezki" , "Vasily Gorbik" , "WANG Xuerui" , "Will Deacon" , , , , , , , , Subject: Re: [PATCH 4/6] mm/vmalloc: make set_area_direct_map HUGE_VMAP friendly From: "Brendan Jackman" To: "Mike Rapoport (Microsoft)" , "Andrew Morton" X-Mailer: aerc 0.21.0 References: <20260816-execmem-set-vm-perms-v0-2-v1-0-90944a3ad43f@kernel.org> <20260816-execmem-set-vm-perms-v0-2-v1-4-90944a3ad43f@kernel.org> In-Reply-To: <20260816-execmem-set-vm-perms-v0-2-v1-4-90944a3ad43f@kernel.org> X-Stat-Signature: i3ojiufcb9tb11ozzgn3afd5g7cbsxtr X-Rspamd-Queue-Id: F40564000C X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1786969323-212444 X-HE-Meta: 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 OBlqFVTN WbdnG7/Z+tsTs/nZuzdGBdvcOOR/BPwnKjcbuSvyYzZr3Z8nbjZwBkgDhDKDQKSFFo4Vz3xeE17b6+Lvh1J7z1Gg6FYxmYJJT5sDa4t2tgtj9DnFjV+QI43CC9ttxPL7PKZZpRPms05l/mLk3rMdZcV8Up1yTATqkVR//tXZBcx6rsVEmgIszPMjHe7dckW+KqkD8djwbgLZO2MtGXgP6pmy+cSOV21YUcmnsJE09ixeQEa8GZEW3DUCOz7Kh3hEq+MMFywBmx12TV5U9jfrCgwbZMhJD6Mxz4T+0oGeW+uHA6l9bvSTYakkjBhjqDakSr5NxXstBfRHV6HnMUsQzichdycxQTmyZzGUMU4QC6TlxubxRiUCTEPiBrgtmt5zV/FCO Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun Aug 16, 2026 at 12:59 PM CEST, Mike Rapoport (Microsoft) wrote: > set_area_direct_map() always updates direct map alias permissions in > single page increments. > > For HUGE_VMAP areas it's suboptimal. Not only the loop in > set_area_direct_map() needlessly has more iterations (e.g times 512 on > x86), but it also causes fragmentation of the direct map that could be > avoided for the HUGE_VMAP areas populated with large pages. > > All pages in an area are always of the same order: either same-order > large pages when VM_ALLOW_HUGE_VMAP is set and all huge pages were > successfully allocated, or order-0 page when VM_ALLOW_HUGE_VMAP is > cleared or when huge pages allocation fails and fallback path is taken. > > Instead of updating the direct map permissions for every order-0 page in > an area, use the area's page_order as the loop increment and update the > large pages in one call to set_direct_map_{invalid,default}_noflush(). > > Signed-off-by: Mike Rapoport (Microsoft) > --- > mm/vmalloc.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index fc7993db4152..11170d1ee5be 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3361,12 +3361,15 @@ static inline void set_area_direct_map(const stru= ct vm_struct *area, > int (*set_direct_map)(struct page *page, > unsigned int nr)) > { > - unsigned long i; > + unsigned int nr =3D (1U << vm_area_page_order(area)); > + > + for (unsigned long i =3D 0; i < area->nr_pages; i +=3D nr) { > + if (page_address(area->pages[i])) { > + int err =3D set_direct_map(area->pages[i], nr); > =20 > - /* HUGE_VMALLOC passes small pages to set_direct_map */ > - for (i =3D 0; i < area->nr_pages; i++) > - if (page_address(area->pages[i])) > - set_direct_map(area->pages[i], 1); > + WARN_ON_ONCE(err); Nit: Maybe worth a comment on why this is expected to always succeed? I.e. I think we are assuming the only failure mode is allocation but=20 because we know vm_area_page_order() there shouldn't be any allocation?