From nobody Wed Sep 10 05:50:41 2025 Received: from mail-yw1-f169.google.com (mail-yw1-f169.google.com [209.85.128.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7EC2C1DFF7 for ; Mon, 8 Sep 2025 22:16:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.169 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757369820; cv=none; b=S3ggx3yLOeVtdnrdTA78fhI8uzDtBIo/LoMZPA+YZBloiGHUW/cdsYZZePk/Rhw0L9fn7f9ctnrQ75gYg7HwHU1W1A0nIDEo/bhFRChzUQQs6SAor1hb4nkfwPVgPjH0atw9t4PPmSZx2pZ1LuJacEz3z3hxQRQKFjjIkXmNlD0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757369820; c=relaxed/simple; bh=H42CHv/0ozdq1Ls2/9Wm26l9P0ywjQmPNMk/fPUfx3A=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=e5dSz34x7c/uVFuWMLADR+1SDs7a7ezqp+QHTWQU64YSCTJRzTQareAyZDeHBaRb+ybHDpay3AS9Wy3rRegYkhUY78GdGP/LB0MCyBwaKSA31Hc//ieiU306sEp/qcbhPTPQ/dsGEw2GjrPzjzUn3bhwELWDvM1QvwBKIP1sI+4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=IRHDSvBR; arc=none smtp.client-ip=209.85.128.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="IRHDSvBR" Received: by mail-yw1-f169.google.com with SMTP id 00721157ae682-724b9ba6e65so39316357b3.2 for ; Mon, 08 Sep 2025 15:16:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1757369817; x=1757974617; darn=vger.kernel.org; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=zVYLSetMwrX/VynVtA83hBzGTxxW5OBc+rZUcVQE0NA=; b=IRHDSvBRZ3z0hjkZyZTJtNj2OshQ8Z4uM0wIzui3vNc624IOBNYUHFNQSUmjhJFmW8 Yds8MevmmwVpuyNm+8y64No2X76dNKfIu/z6ytPs6Krx/ctSro7N1wNBs84vLT0MmmIt SHoO/VlfMLJ+evs8fao1KgT/znW8UNpYp3KifgioJIVgiA5M6xTHWOTHSWiKH/wfB9xz OP7m4K+R/pIDzjvG75lhzjMSoiB0ydQZDKIOo2F/14E3l2+uSS1ZayHbSb+byI0nPQUG hmneh9tymyc9m6bkLsEWEmjteNw9SKWrwgIQgo2mYu+x92DRqI/gZe2qpa/VpW3yXp0o Lodg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757369817; x=1757974617; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=zVYLSetMwrX/VynVtA83hBzGTxxW5OBc+rZUcVQE0NA=; b=WxKFK7E/YidjSuLL21J0N050CSXV7x2atewGFvs0/xRSI1d/4/SncY2KT9l7DGoCLZ ybLqGs956zXNp0yfnfiMvWOUC98enidV6bPdkR4JLLBF5jsKX4jPiRgmTSmvDyA7ca7M v/uY/PQZcRRKVxa6cmOR0ieBjoEjGgrSIwCRzRdR6jTvlS1bVY7vav4CCfzFRxPMVJ+o Fgct7/Bm0clnwAbHrhqMt20/3xm6w/3mzxkRis9Hu4Lm3ONWD3NjSxZS+iVtKL/Grs4t gW7ocx10PxOKevvIQgdmVcn2+BqUMN6XUNC55aEv8jKCeWrlDMN20ZKxS62G8Xr/cKU2 NdPg== X-Forwarded-Encrypted: i=1; AJvYcCXM+dXXIwHA0IFZhHStRwu2unP95Ccf/cWhD7szu/llRXW8MZGM7IBurVSwG10rRW78yaVzFwKXxb5+bRs=@vger.kernel.org X-Gm-Message-State: AOJu0Ywj5Zb2iameanP+hjns7xoa5WQ+pHHzSfvYzBDjaDGHplmMSWB7 b6LL8jIvLgqOd5a9YGZ47qw66ORZT5LxlbyUqbWaDRHDe23068+cEsUVhs080c/l5w== X-Gm-Gg: ASbGnct2U/v0rQ2gJj4LqVASjfbyRcS0e4fw5ppbTvUNswuWObZ3d41UF1spcy/J1tM dTC4B0TCmKDfcy8aI2rUhGDoZxVBcIiMICr341pF33eIjGoRyMR7qp2X1+iJWnoqBDwAWIpYAhj FZZ9fjK2mmKKxzc+0gssP3j7DGdeSnqvu2J76UWf6HB/GK6rFkEcs6StbAK6SmhxiS/raj5oGKS 4ca6BfkLiFRGYWuJF1Lm1ABGO29DUC+oRfhToj2t8jMIloCBYQOIYC6QUS5gs6BnUNvoGxnma/T wsY9DaYggLsbEqgXusl5vSE5xFSv6p8D+747naMBS5wghcyQEvzZHSnbk/MhHfatS8rKurywfh/ 1GpTdn1CFqtBAh4KYx/Jjr0qlU+ICJ3KL+TAzViTQQu6Zfkk9ZGtOQXYfG9ogLWJubjYS71+Rpn stNO50Nzovo8ez2gxEEoeFeKbH7RCT X-Google-Smtp-Source: AGHT+IEFGtIXAPyyGQ3/HR/zcX4Kvh/xfXBtsgo7O+saKjkOvxNMfjk5bY+RsPrpYJS0IY8LbDuMMQ== X-Received: by 2002:a05:690c:4d88:b0:724:2cad:8df6 with SMTP id 00721157ae682-727f2ebd695mr84968267b3.16.1757369817188; Mon, 08 Sep 2025 15:16:57 -0700 (PDT) Received: from darker.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-608110cabd6sm5167388d50.8.2025.09.08.15.16.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Sep 2025 15:16:56 -0700 (PDT) Date: Mon, 8 Sep 2025 15:16:53 -0700 (PDT) From: Hugh Dickins To: Andrew Morton cc: Alexander Krabler , "Aneesh Kumar K.V" , Axel Rasmussen , Chris Li , Christoph Hellwig , David Hildenbrand , Frederick Mayle , Jason Gunthorpe , Johannes Weiner , John Hubbard , Keir Fraser , Konstantin Khlebnikov , Li Zhe , Matthew Wilcox , Peter Xu , Rik van Riel , Shivank Garg , Vlastimil Babka , Wei Xu , Will Deacon , yangge , Yuanchu Xie , Yu Zhao , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 2/6] mm/gup: local lru_add_drain() to avoid lru_add_drain_all() In-Reply-To: <41395944-b0e3-c3ac-d648-8ddd70451d28@google.com> Message-ID: <66f2751f-283e-816d-9530-765db7edc465@google.com> References: <41395944-b0e3-c3ac-d648-8ddd70451d28@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In many cases, if collect_longterm_unpinnable_folios() does need to drain the LRU cache to release a reference, the cache in question is on this same CPU, and much more efficiently drained by a preliminary local lru_add_drain(), than the later cross-CPU lru_add_drain_all(). Marked for stable, to counter the increase in lru_add_drain_all()s from "mm/gup: check ref_count instead of lru before migration". Note for clean backports: can take 6.16 commit a03db236aebf ("gup: optimize longterm pin_user_pages() for large folio") first. Signed-off-by: Hugh Dickins Cc: Acked-by: David Hildenbrand --- mm/gup.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index 82aec6443c0a..b47066a54f52 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2287,8 +2287,8 @@ static unsigned long collect_longterm_unpinnable_foli= os( struct pages_or_folios *pofs) { unsigned long collected =3D 0; - bool drain_allow =3D true; struct folio *folio; + int drained =3D 0; long i =3D 0; =20 for (folio =3D pofs_get_folio(pofs, i); folio; @@ -2307,10 +2307,17 @@ static unsigned long collect_longterm_unpinnable_fo= lios( continue; } =20 - if (drain_allow && folio_ref_count(folio) !=3D - folio_expected_ref_count(folio) + 1) { + if (drained =3D=3D 0 && + folio_ref_count(folio) !=3D + folio_expected_ref_count(folio) + 1) { + lru_add_drain(); + drained =3D 1; + } + if (drained =3D=3D 1 && + folio_ref_count(folio) !=3D + folio_expected_ref_count(folio) + 1) { lru_add_drain_all(); - drain_allow =3D false; + drained =3D 2; } =20 if (!folio_isolate_lru(folio)) --=20 2.51.0