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[2003:cb:c707:9d00:9303:90ce:6dcb:2bc9]) by smtp.gmail.com with ESMTPSA id l15-20020a05600c4f0f00b003d9df9e59c4sm14347278wmq.37.2023.01.24.05.08.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 24 Jan 2023 05:08:38 -0800 (PST) Message-ID: <534e281e-4164-20a1-ba7f-0516f2321c5e@redhat.com> Date: Tue, 24 Jan 2023 14:08:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH 5/8] mm/gup: add FOLL_UNLOCK To: Jason Gunthorpe Cc: Alistair Popple , John Hubbard , linux-mm@kvack.org References: <5-v1-dd94f8f0d5ad+716-gup_tidy_jgg@nvidia.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 960DE140013 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: uzfy4seja47ktcasde8wgubpqioenojo X-HE-Tag: 1674565722-693469 X-HE-Meta: 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 r0Ogg6dJ w0Y99mq8o4LtyIUuOLpsHdKGetil6I4B2lashR7EsXgr7+yJjEfdlcqAGDund8JHyiI6SkxO/L/aX7IDjlmR5/jEZEg6O6EKBJJppDsr7qbqITKyprXJygQo98f4epPv9IvZ8thuqDa/6RQAb3WXbzMBO9TRLE8GjdlvXWY5u5gAifCpJBLoa1jMDSF/qzG5qGb/rn1gAqHJKPJuwhzEH96wWHokr/YvTZFzJ59mY2dZL3nPz9d2kOZ5AoaJ3+oV01UJuQTa5qNkWdK05WL9hV448O3zPzN7tLP/zErH8Xg8nUOPhipVRM18JyCLyVRQkcdzU6chIPkZuxyUFwt/SomUuFrE/XLc3s3Y3lb2SfpM25PyL/C4iM1gDRQ== 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 23.01.23 18:58, Jason Gunthorpe wrote: > On Mon, Jan 23, 2023 at 12:37:17PM +0100, David Hildenbrand wrote: >> On 17.01.23 16:58, Jason Gunthorpe wrote: >>> Setting FOLL_UNLOCK allows GUP to lock/unlock the mmap lock on its own. It >>> is a more explicit replacement for locked != NULL. This clears the way for >>> passing in locked = 1, without intending that the lock can be unlocked. >>> >>> Set the flag in all cases where it is used, eg locked is present in the >>> external interface or locked is used internally with locked = 0. >>> >>> Signed-off-by: Jason Gunthorpe >>> --- >>> include/linux/mm.h | 1 + >>> mm/gup.c | 31 +++++++++++++++++++------------ >>> 2 files changed, 20 insertions(+), 12 deletions(-) >>> >>> diff --git a/include/linux/mm.h b/include/linux/mm.h >>> index f3f196e4d66d6f..7496a5c8acede1 100644 >>> --- a/include/linux/mm.h >>> +++ b/include/linux/mm.h >>> @@ -3089,6 +3089,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, >>> #define FOLL_FAST_ONLY 0x80000 /* gup_fast: prevent fall-back to slow gup */ >>> #define FOLL_PCI_P2PDMA 0x100000 /* allow returning PCI P2PDMA pages */ >>> #define FOLL_INTERRUPTIBLE 0x200000 /* allow interrupts from generic signals */ >>> +#define FOLL_UNLOCK 0x400000 /* allow unlocking the mmap lock */ >> >> So it's more like "FOLL_UNLOCKABLE" ? FOLL_UNLOCK sounds like an instruction >> instead. > > Sure, I renamed it > >> Not that I particularly like adding new internal FOLL flags where avoidable >> :P > > How about, I made a patch to move all the internal FOLL_ flags into > mm/internal.h ? That would be a significant improvement. Maybe we could compress each set and move the internal ones to the highest bits. -- Thanks, David / dhildenb