mm: move FOLL_* defs to mm_types.h (b5054174) · Commits · EulixOS / Software / Kernel

include/linux/mm.h

+0 −75

Original line number	Diff line number	Diff line
		@@ -3057,81 +3057,6 @@ static inline vm_fault_t vmf_error(int err)
		struct page follow_page(struct vm_area_struct vma, unsigned long address,
		unsigned int foll_flags);

		#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 */

		/*
		* 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
		* users like RDMA and V4L2 only establish mappings which coordinate usage with
		* the filesystem. Ideas for this coordination include revoking the longterm
		* pin, delaying writeback, bounce buffer page writeback, etc. As FS DAX was
		* added after the problem with filesystems was found FS DAX VMAs are
		* specifically failed. Filesystem pages are still subject to bugs and use of
		* FOLL_LONGTERM should be avoided on those pages.
		*
		* FIXME: Also NOTE that FOLL_LONGTERM is not supported in every GUP call.
		* Currently only get_user_pages() and get_user_pages_fast() support this flag
		* and calls to get_user_pages_[un]locked are specifically not allowed. This
		* is due to an incompatibility with the FS DAX check and
		* FAULT_FLAG_ALLOW_RETRY.
		*
		* In the CMA case: long term pins in a CMA region would unnecessarily fragment
		* that region. And so, CMA attempts to migrate the page before pinning, when
		* FOLL_LONGTERM is specified.
		*
		* FOLL_PIN indicates that a special kind of tracking (not just page->_refcount,
		* but an additional pin counting system) will be invoked. This is intended for
		* anything that gets a page reference and then touches page data (for example,
		* Direct IO). This lets the filesystem know that some non-file-system entity is
		* potentially changing the pages' data. In contrast to FOLL_GET (whose pages
		* are released via put_page()), FOLL_PIN pages must be released, ultimately, by
		* a call to unpin_user_page().
		*
		* FOLL_PIN is similar to FOLL_GET: both of these pin pages. They use different
		* and separate refcounting mechanisms, however, and that means that each has
		* its own acquire and release mechanisms:
		*
		* FOLL_GET: get_user_pages*() to acquire, and put_page() to release.
		*
		* FOLL_PIN: pin_user_pages*() to acquire, and unpin_user_pages to release.
		*
		* FOLL_PIN and FOLL_GET are mutually exclusive for a given function call.
		* (The underlying pages may experience both FOLL_GET-based and FOLL_PIN-based
		* calls applied to them, and that's perfectly OK. This is a constraint on the
		* callers, not on the pages.)
		*
		* FOLL_PIN should be set internally by the pin_user_pages*() APIs, never
		* directly by the caller. That's in order to help avoid mismatches when
		* releasing pages: get_user_pages*() pages must be released via put_page(),
		* while pin_user_pages*() pages must be released via unpin_user_page().
		*
		* Please see Documentation/core-api/pin_user_pages.rst for more information.
		*/

		static inline int vm_fault_to_errno(vm_fault_t vm_fault, int foll_flags)
		{
		if (vm_fault & VM_FAULT_OOM)

include/linux/mm_types.h

+75 −0

Original line number	Diff line number	Diff line
		@@ -1085,4 +1085,79 @@ enum fault_flag {

		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
		* users like RDMA and V4L2 only establish mappings which coordinate usage with
		* the filesystem. Ideas for this coordination include revoking the longterm
		* pin, delaying writeback, bounce buffer page writeback, etc. As FS DAX was
		* added after the problem with filesystems was found FS DAX VMAs are
		* specifically failed. Filesystem pages are still subject to bugs and use of
		* FOLL_LONGTERM should be avoided on those pages.
		*
		* FIXME: Also NOTE that FOLL_LONGTERM is not supported in every GUP call.
		* Currently only get_user_pages() and get_user_pages_fast() support this flag
		* and calls to get_user_pages_[un]locked are specifically not allowed. This
		* is due to an incompatibility with the FS DAX check and
		* FAULT_FLAG_ALLOW_RETRY.
		*
		* In the CMA case: long term pins in a CMA region would unnecessarily fragment
		* that region. And so, CMA attempts to migrate the page before pinning, when
		* FOLL_LONGTERM is specified.
		*
		* FOLL_PIN indicates that a special kind of tracking (not just page->_refcount,
		* but an additional pin counting system) will be invoked. This is intended for
		* anything that gets a page reference and then touches page data (for example,
		* Direct IO). This lets the filesystem know that some non-file-system entity is
		* potentially changing the pages' data. In contrast to FOLL_GET (whose pages
		* are released via put_page()), FOLL_PIN pages must be released, ultimately, by
		* a call to unpin_user_page().
		*
		* FOLL_PIN is similar to FOLL_GET: both of these pin pages. They use different
		* and separate refcounting mechanisms, however, and that means that each has
		* its own acquire and release mechanisms:
		*
		* FOLL_GET: get_user_pages*() to acquire, and put_page() to release.
		*
		* FOLL_PIN: pin_user_pages*() to acquire, and unpin_user_pages to release.
		*
		* FOLL_PIN and FOLL_GET are mutually exclusive for a given function call.
		* (The underlying pages may experience both FOLL_GET-based and FOLL_PIN-based
		* calls applied to them, and that's perfectly OK. This is a constraint on the
		* callers, not on the pages.)
		*
		* FOLL_PIN should be set internally by the pin_user_pages*() APIs, never
		* directly by the caller. That's in order to help avoid mismatches when
		* releasing pages: get_user_pages*() pages must be released via put_page(),
		* while pin_user_pages*() pages must be released via unpin_user_page().
		*
		* 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 */

		#endif /* _LINUX_MM_TYPES_H */