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 <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 */
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
