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[86.156.84.164]) by smtp.gmail.com with ESMTPSA id u13-20020a05600c00cd00b003edf2dc7ca3sm11900712wmm.34.2023.04.17.06.25.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Apr 2023 06:25:55 -0700 (PDT) Date: Mon, 17 Apr 2023 14:25:54 +0100 From: Lorenzo Stoakes To: Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Matthew Wilcox , David Hildenbrand Subject: Re: [PATCH 4/7] mm/gup: introduce the FOLL_SAME_FILE GUP flag Message-ID: <7f9c3ec7-ea79-4f2f-bc23-acc4c11c9620@lucifer.local> References: <7ed66bd5243f7535030e0fa6a8a94b76dc5033f1.1681508038.git.lstoakes@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 3781120006 X-Stat-Signature: 73adyyw8h3kepi4jksi35rkz3h719mhn X-Rspam-User: X-HE-Tag: 1681737957-537904 X-HE-Meta: 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 2a6zKod4 tVt7Ar3JfE1QVmEVeAM5YIgO1VtXCVwSOF21fxCe4GY9pHfhVNzNtBSw1GgBXEyZPo/cbcNSqpH4kQkJ+iymXW8sPf+tcufMksr4YFBTLih7A+drGK1yB3L/3WPk8PuFeL0OosU7R7Ep2qsPzxvBgSIEZFgzquHmO0scPPbnqXn/VyTUiQguq/MxU5usoWB30B/HeiIY9bsLoSSdZctEW1jt72LOagfZQbVH0l0azqxVISUN+92aUCY2gkAOyvlr7GuG93qTgQP9kwfjjz1ci7DanTSp/oPnQTSBmCswlQBtqCl7vluZmoF+zI565lRF48x64CM93Llzxuwqk+vmtDZnDGHBOv+Kg8KsVY6sIQyYr78pY+bRkcosmZax2+LYvnQq7FYsidBZ8sZbViiBSPY5cst8oWdqZ25p2F+vCfNu8wisqoKckopoxDo+J8BN19/UM2CZFCTFTN8xyqwTZGJ3qm1aYOQBO1l9i X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Apr 17, 2023 at 10:14:02AM -0300, Jason Gunthorpe wrote: > On Sat, Apr 15, 2023 at 12:27:40AM +0100, Lorenzo Stoakes wrote: > > This flag causes GUP to assert that all VMAs within the input range possess > > the same vma->vm_file. If not, the operation fails. > > > > This is part of a patch series which eliminates the vmas parameter from the > > GUP API, implementing the one remaining assertion within the entire kernel > > that requires access to the VMAs associated with a GUP range. > > > > Signed-off-by: Lorenzo Stoakes > > --- > > include/linux/mm_types.h | 2 ++ > > mm/gup.c | 16 ++++++++++++---- > > 2 files changed, 14 insertions(+), 4 deletions(-) > > > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > > index 3fc9e680f174..84d1aec9dbab 100644 > > --- a/include/linux/mm_types.h > > +++ b/include/linux/mm_types.h > > @@ -1185,6 +1185,8 @@ enum { > > FOLL_PCI_P2PDMA = 1 << 10, > > /* allow interrupts from generic signals */ > > FOLL_INTERRUPTIBLE = 1 << 11, > > + /* assert that the range spans VMAs with the same vma->vm_file */ > > + FOLL_SAME_FILE = 1 << 12, > > I hope we don't add this flag, but it needs to be rejected in > internal_get_user_pages_fast() > intenal_get_user_pages_fast() checks against the complement of accepted masks, therefore it will reject this as-is unless I'm missing something. As for not adding the flag (an entirely understandable sentiment), it would be good to get an insight into the semantics of what you feel would be more suitable! > Jason