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bh=IGg1NVAvP8AA+2Lue1CJFOOVV20eNuHRk39gyPIwoxE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=f2QuOynAiaDFgF/D1tvnG4K5XZ+EbE5KVZcWDd4xtWNAaNAsYt1G4e/jEN6HelUwV /6zAOzLtNgjbfFMoR0jkHvrYlHn406GZ/O2wUak7XXDbjj2A6FFbhBrp2GrCyiRWTY BUhPW29A+w5jMwO9Q4HBcd588dfSYmuh4VTTff3DCDN2jKnjiOFJ9UixMoT40Yf9BJ cDDurf5bDdMbpk0TC41SJJdeY8epRtIKB4dP+FkSMVyQ5wHpdl1VGlfpa5QamW/m46 E4qY9Acwl3/5X5rlqpm2U+76jsuSyJC2fQMLvevOroRFO1zK3Nsjcfy0Kb3X6bEA39 YutQxqCfgnmjw== Date: Thu, 19 Jan 2023 13:18:08 +0200 From: Mike Rapoport To: Jason Gunthorpe Cc: Alistair Popple , John Hubbard , linux-mm@kvack.org Subject: Re: [PATCH 5/8] mm/gup: add FOLL_UNLOCK Message-ID: References: <0-v1-dd94f8f0d5ad+716-gup_tidy_jgg@nvidia.com> <5-v1-dd94f8f0d5ad+716-gup_tidy_jgg@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5-v1-dd94f8f0d5ad+716-gup_tidy_jgg@nvidia.com> X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: b3y4obphpt14wizxzqy5ebeifqxtpme1 X-Rspamd-Queue-Id: 4FFA040008 X-HE-Tag: 1674127100-313042 X-HE-Meta: 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 p6H++nUr fqoaQ+gFy+Q8lgfsNcMAA+0P+/O2Uz4LPX8aWOymqU9tzsykywp8hAVDSq2zMpSEFwQBPIlKtr36pJpw= 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 Tue, Jan 17, 2023 at 11:58:36AM -0400, 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 */ Please add a comment that this is an internal flag. > /* > * FOLL_PIN and FOLL_LONGTERM may be used in various combinations with each -- Sincerely yours, Mike.