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 <jgg@xxxxxxxxxx> > --- > 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.
