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 9F9203002AB; Thu, 5 Mar 2026 19:07:52 +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=1772737672; cv=none; b=MJzKKSRB1b/QoWwQsiHpJulhwRy9tIbYy98xWOIF2kFpHwE/8uNUyLnkSmLy70y+YgZXUl2iEE6fNZx4uJPmhZAmnu4Im5WBLGKM6o9gCXEfX0mGLRTRcv5Cs+ah5C9ZIXY9YH640PXxdhAAHIOgd9iAcEy7t2s8OtyZ+XyKc8A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772737672; c=relaxed/simple; bh=5pMLMYsqUq30caMaqSsCRxg/LUKm2ZwH02Nogw/kZgk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=XRLrFtTAsJ96XaztqsTxRGahVaRYVryGqloISOz8aLpE7bnLcaOAz+i5YfKY2T7ejVIGdFlCQJAYHSSURD52zUZCzcjvY6qKJ9YShvZvHFYnjy4hivEiNtkIvqSQtJt1zVin94yYCykAjsqYNzPhhlJW172a9asiZgLYk1dm7Eg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Dj+S9NqJ; 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="Dj+S9NqJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2DEB6C116C6; Thu, 5 Mar 2026 19:07:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772737672; bh=5pMLMYsqUq30caMaqSsCRxg/LUKm2ZwH02Nogw/kZgk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Dj+S9NqJtdWz6RBKFzR5acMgUZFQJ3W9fnbktBvz0MaAXoouPnMmfQ67JZmI9sVaH XQQn6nGUQIhWbu93psky7lo+eqRxXjl34agykwtcFCvJvewXz2H9sBqggtK338M1DH xMqK0z98I7O58rU2ZExHxgDfn0muFBjv+va4ZBeTvQF1Iwu5bpIwVn7xVrLxpkhupp DOdrZ4sFZpJOpYA2rNekO31hBtA1G0t1/f5tBT933AusAvejWixb3X2YXLYp78nijl 5WoPlj74YRUASEEXS5XuY65yzkQQnpYLuAnUfI3m9ww+joTZUYCqAu4oOizyBIoyL/ rUJ6jp5aQodrA== Message-ID: Date: Thu, 5 Mar 2026 20:07:19 +0100 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 04/15] mm/gup: drop local variable in gup_fast_folio_allowed To: "Kalyazin, Nikita" , "kvm@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.linux.dev" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "bpf@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "kernel@xen0n.name" , "linux-riscv@lists.infradead.org" , "linux-s390@vger.kernel.org" , "loongarch@lists.linux.dev" Cc: "pbonzini@redhat.com" , "corbet@lwn.net" , "maz@kernel.org" , "oupton@kernel.org" , "joey.gouly@arm.com" , "suzuki.poulose@arm.com" , "yuzenghui@huawei.com" , "catalin.marinas@arm.com" , "will@kernel.org" , "seanjc@google.com" , "tglx@kernel.org" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "luto@kernel.org" , "peterz@infradead.org" , "willy@infradead.org" , "akpm@linux-foundation.org" , "lorenzo.stoakes@oracle.com" , "vbabka@suse.cz" , "rppt@kernel.org" , "surenb@google.com" , "mhocko@suse.com" , "ast@kernel.org" , "daniel@iogearbox.net" , "andrii@kernel.org" , "martin.lau@linux.dev" , "eddyz87@gmail.com" , "song@kernel.org" , "yonghong.song@linux.dev" , "john.fastabend@gmail.com" , "kpsingh@kernel.org" , "sdf@fomichev.me" , "haoluo@google.com" , "jolsa@kernel.org" , "jgg@ziepe.ca" , "jhubbard@nvidia.com" , "peterx@redhat.com" , "jannh@google.com" , "pfalcato@suse.de" , "shuah@kernel.org" , "riel@surriel.com" , "ryan.roberts@arm.com" , "jgross@suse.com" , "yu-cheng.yu@intel.com" , "kas@kernel.org" , "coxu@redhat.com" , "kevin.brodsky@arm.com" , "ackerleytng@google.com" , "maobibo@loongson.cn" , "prsampat@amd.com" , "mlevitsk@redhat.com" , "jmattson@google.com" , "jthoughton@google.com" , "agordeev@linux.ibm.com" , "alex@ghiti.fr" , "aou@eecs.berkeley.edu" , "borntraeger@linux.ibm.com" , "chenhuacai@kernel.org" , "dev.jain@arm.com" , "gor@linux.ibm.com" , "hca@linux.ibm.com" , "palmer@dabbelt.com" , "pjw@kernel.org" , "shijie@os.amperecomputing.com" , "svens@linux.ibm.com" , "thuth@redhat.com" , "wyihan@google.com" , "yang@os.amperecomputing.com" , "Jonathan.Cameron@huawei.com" , "Liam.Howlett@oracle.com" , "urezki@gmail.com" , "zhengqi.arch@bytedance.com" , "gerald.schaefer@linux.ibm.com" , "jiayuan.chen@shopee.com" , "lenb@kernel.org" , "osalvador@suse.de" , "pavel@kernel.org" , "rafael@kernel.org" , "vannapurve@google.com" , "jackmanb@google.com" , "aneesh.kumar@kernel.org" , "patrick.roy@linux.dev" , "Thomson, Jack" , "Itazuri, Takahiro" , "Manwaring, Derek" , "Cali, Marco" References: <20260126164445.11867-1-kalyazin@amazon.com> <20260126164445.11867-5-kalyazin@amazon.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 1/26/26 17:47, Kalyazin, Nikita wrote: > From: Nikita Kalyazin > > Move the check for pinning closer to where the result is used. > No functional changes. > > Signed-off-by: Nikita Kalyazin > --- > mm/gup.c | 19 ++++++++----------- > 1 file changed, 8 insertions(+), 11 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 9cad53acbc99..e72dacce3e34 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -2737,18 +2737,9 @@ EXPORT_SYMBOL(get_user_pages_unlocked); > */ > static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags) > { > - bool reject_file_backed = false; > struct address_space *mapping; > unsigned long mapping_flags; > > - /* > - * If we aren't pinning then no problematic write can occur. A long term > - * pin is the most egregious case so this is the one we disallow. > - */ > - if ((flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) == > - (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) > - reject_file_backed = true; > - > /* We hold a folio reference, so we can safely access folio fields. */ > if (WARN_ON_ONCE(folio_test_slab(folio))) > return false; > @@ -2793,8 +2784,14 @@ static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags) > */ > if (secretmem_mapping(mapping)) > return false; > - /* The only remaining allowed file system is shmem. */ > - return !reject_file_backed || shmem_mapping(mapping); > + > + /* > + * If we aren't pinning then no problematic write can occur. A long term > + * pin is the most egregious case so this is the one we disallow. > + * Also check the only remaining allowed file system - shmem. > + */ > + return (flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) != > + (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE) || shmem_mapping(mapping); Best to keep this split and a bit more readable. /* * If we aren't pinning then no problematic write can occur. A writable * long term pin is the most egregious case, so this is the one we * allow only for ... */ if ((flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) != (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE) return true; /* ... hugetlb (which we allowed above already) and shared memory. */ return shmem_mapping(mapping); > } > > static void __maybe_unused gup_fast_undo_dev_pagemap(int *nr, int nr_start, -- Cheers, David