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[2003:cb:c704:1100:65a0:c03a:142a:f914]) by smtp.gmail.com with ESMTPSA id l18-20020a1c7912000000b003db00747fdesm10398272wme.15.2023.01.23.03.37.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 Jan 2023 03:37:18 -0800 (PST) Message-ID: Date: Mon, 23 Jan 2023 12:37:17 +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: <5-v1-dd94f8f0d5ad+716-gup_tidy_jgg@nvidia.com> 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: 6CA25140010 X-Stat-Signature: sum5dqr15kjo5qwe96gmhp9ag91mrbe3 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1674473842-847833 X-HE-Meta: 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 QvlZaHG4 59Adg6R1djuVfvn8yJzQsLgpe1MN7jNtJw8AbisOuWRfzHDLhcUhI28brbH4wEPfVp6LZtPv3B37Hyd3P0KxadEWmuW+Tv1/8bzEKCqPgidS7PIyn4DaTPlaKhcQjL0YW5VTA2PSt6ldeCxg2NuZIte+vmUkwsh0Rh8Sw7SAv+yx+K9NQaf5Cf9eV4WtXA5/oMP6TAUEFAHnGc29aLU2OwKQotKIn/UM2kHqiqbOf/zFRXAzAx8sPplArzUplkcZdVxMi+a3eQlL2NSE2lOFBzno7v+QL12OoH2LsI1VwMt3c0tkh5bRAKXTtfpJ/NKaPtukRFG7jh5z2+qh3RtZ66B86e60kE93KnzAcKEF27PUc4zz/zIxLhPXGagpmYVJ3kLJ19rqE7YvG7hhU1Gw1ZD/NFyBbOuK5qAxh0iGR6jheBGHgCWVKFO9L7VrAWF7zd/wpx/uXcJurnqgaPrsBN1SEyw== 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 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. Not that I particularly like adding new internal FOLL flags where avoidable :P -- Thanks, David / dhildenb