Commit 2c224108 authored by Jason Gunthorpe's avatar Jason Gunthorpe Committed by Andrew Morton
Browse files

mm/gup: move private gup FOLL_ flags to internal.h 

Move the flags that should not/are not used outside gup.c and related into
mm/internal.h to discourage driver abuse.

To make this more maintainable going forward compact the two FOLL ranges
with new bit numbers from 0 to 11 and 16 to 21, using shifts so it is
explicit.

Switch to an enum so the whole thing is easier to read.

Link: https://lkml.kernel.org/r/13-v2-987e91b59705+36b-gup_tidy_jgg@nvidia.com


Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 63b60512

include/linux/mm_types.h

+35 −22
Original line number Diff line number Diff line
@@ -1040,9 +1040,6 @@ typedef unsigned int __bitwise zap_flags_t; 
 * FOLL_PIN and FOLL_LONGTERM may be used in various combinations with each

 * other. Here is what they mean, and how to use them:

 *

 * FOLL_LONGTERM indicates that the page will be held for an indefinite time

 * period _often_ under userspace control.  This is in contrast to

 * iov_iter_get_pages(), whose usages are transient.

 *

 * FIXME: For pages which are part of a filesystem, mappings are subject to the

 * lifetime enforced by the filesystem and we need guarantees that longterm
@@ -1086,24 +1083,40 @@ typedef unsigned int __bitwise zap_flags_t; 
 * Please see Documentation/core-api/pin_user_pages.rst for more information.

 */



#define FOLL_WRITE	0x01	/* check pte is writable */

#define FOLL_TOUCH	0x02	/* mark page accessed */

#define FOLL_GET	0x04	/* do get_page on page */

#define FOLL_DUMP	0x08	/* give error on hole if it would be zero */

#define FOLL_FORCE	0x10	/* get_user_pages read/write w/o permission */

#define FOLL_NOWAIT	0x20	/* if a disk transfer is needed, start the IO

				 * and return without waiting upon it */

#define FOLL_NOFAULT	0x80	/* do not fault in pages */

#define FOLL_HWPOISON	0x100	/* check page is hwpoisoned */

#define FOLL_TRIED	0x800	/* a retry, previous pass started an IO */

#define FOLL_REMOTE	0x2000	/* we are working on non-current tsk/mm */

#define FOLL_ANON	0x8000	/* don't do file mappings */

#define FOLL_LONGTERM	0x10000	/* mapping lifetime is indefinite: see below */

#define FOLL_SPLIT_PMD	0x20000	/* split huge pmd before returning */

#define FOLL_PIN	0x40000	/* pages must be released via unpin_user_page */

#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_UNLOCKABLE	0x400000 /* allow unlocking the mmap lock (internal only) */

enum {

	/* check pte is writable */

	FOLL_WRITE = 1 << 0,

	/* do get_page on page */

	FOLL_GET = 1 << 1,

	/* give error on hole if it would be zero */

	FOLL_DUMP = 1 << 2,

	/* get_user_pages read/write w/o permission */

	FOLL_FORCE = 1 << 3,

	/*

	 * if a disk transfer is needed, start the IO and return without waiting

	 * upon it

	 */

	FOLL_NOWAIT = 1 << 4,

	/* do not fault in pages */

	FOLL_NOFAULT = 1 << 5,

	/* check page is hwpoisoned */

	FOLL_HWPOISON = 1 << 6,

	/* don't do file mappings */

	FOLL_ANON = 1 << 7,

	/*

	 * FOLL_LONGTERM indicates that the page will be held for an indefinite

	 * time period _often_ under userspace control.  This is in contrast to

	 * iov_iter_get_pages(), whose usages are transient.

	 */

	FOLL_LONGTERM = 1 << 8,

	/* split huge pmd before returning */

	FOLL_SPLIT_PMD = 1 << 9,

	/* allow returning PCI P2PDMA pages */

	FOLL_PCI_P2PDMA = 1 << 10,

	/* allow interrupts from generic signals */

	FOLL_INTERRUPTIBLE = 1 << 11,



	/* See also internal only FOLL flags in mm/internal.h */

};



#endif /* _LINUX_MM_TYPES_H */

mm/internal.h

+15 −0
Original line number Diff line number Diff line
@@ -858,6 +858,21 @@ int migrate_device_coherent_page(struct page *page); 
struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags);

int __must_check try_grab_page(struct page *page, unsigned int flags);



enum {

	/* mark page accessed */

	FOLL_TOUCH = 1 << 16,

	/* a retry, previous pass started an IO */

	FOLL_TRIED = 1 << 17,

	/* we are working on non-current tsk/mm */

	FOLL_REMOTE = 1 << 18,

	/* pages must be released via unpin_user_page */

	FOLL_PIN = 1 << 19,

	/* gup_fast: prevent fall-back to slow gup */

	FOLL_FAST_ONLY = 1 << 20,

	/* allow unlocking the mmap lock */

	FOLL_UNLOCKABLE = 1 << 21,

};



/*

 * Indicates for which pages that are write-protected in the page table,

 * whether GUP has to trigger unsharing via FAULT_FLAG_UNSHARE such that the